[Federal Register Volume 88, Number 103 (Tuesday, May 30, 2023)]
[Proposed Rules]
[Pages 34568-34622]
[FR Doc No: 2023-07109]

Vol. 88

Tuesday,

No. 103

May 30, 2023

Part II

Department of Transportation

-----------------------------------------------------------------------

Pipeline and Hazardous Materials Safety Administration

-----------------------------------------------------------------------

49 CFR Parts 171, 172, et al.

Hazardous Materials: Harmonization With International Standards;
Proposed Rule

Federal Register / Vol. 88 , No. 103 / Tuesday, May 30, 2023 /
Proposed Rules

-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Pipeline and Hazardous Materials Safety Administration

49 CFR Parts 171, 172, 173, 175, 176, 178, and 180

[Docket No. PHMSA-2021-0092 (HM-215Q)]
RIN 2137-AF57

Hazardous Materials: Harmonization With International Standards

AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA),
Department of Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: PHMSA proposes to amend the Hazardous Materials Regulations to
maintain alignment with international regulations and standards by
adopting various amendments, including changes to proper shipping
names, hazard classes, packing groups, special provisions, packaging
authorizations, air transport quantity limitations, and vessel stowage
requirements.

DATES: Comments must be received by July 31, 2023. To the extent
possible, PHMSA will consider late-filed comments while a final rule is
developed.

ADDRESSES: You may submit comments by any of the following methods:
     Federal Rulemaking Portal: http://www.regulations.gov.
Follow the online instructions for submitting comments.
     Fax: 1-202-493-2251.
     Mail: Docket Management System; U.S. Department of
Transportation, Docket Operations, M-30, Ground Floor, Room W12-140,
1200 New Jersey Avenue SE, Washington, DC 20590-0001.
     Hand Delivery: U.S. Department of Transportation, Docket
Operations, M-30, Ground Floor, Room W12-140, 1200 New Jersey Avenue
SE, Washington, DC 20590-0001 between 9 a.m. and 5 p.m., Monday through
Friday, except federal holidays.
    Instructions: Include the agency name and docket number PHMSA-2021-
0092 (HM-215Q) or RIN 2137-AF57 for this rulemaking at the beginning of
your comment. Note that all comments received will be posted without
change to http://www.regulations.gov including any personal information
provided. If sent by mail, comments must be submitted in duplicate.
Persons wishing to receive confirmation of receipt of their comments
must include a self-addressed stamped postcard.
    Docket: For access to the dockets to read background documents
(including the Preliminary Regulatory Impact Analysis (PRIA)) or
comments received, go to http://www.regulations.gov or DOT's Docket
Operations Office (see ADDRESSES).
    Confidential Business Information: Confidential Business
Information (CBI) is commercial or financial information that is both
customarily and actually treated as private by its owner. Under the
Freedom of Information Act (FOIA; 5 U.S.C. 552), CBI is exempt from
public disclosure. If your comments responsive to this NPRM contain
commercial or financial information that is customarily treated as
private, that you actually treat as private, and that is relevant or
responsive to this NPRM, it is important that you clearly designate the
submitted comments as CBI. Please mark each page of your submission
containing CBI as ``PROPIN.'' Submissions containing CBI should be sent
to Candace Casey, U.S. Department of Transportation, 1200 New Jersey
Avenue SE, Washington, DC 20590-0001. Any commentary that PHMSA
receives which is not specifically designated as CBI will be placed in
the public docket for this rulemaking.

FOR FURTHER INFORMATION CONTACT: Candace Casey, Standards and
Rulemaking, or Aaron Wiener, International Program, at<PHONE_NUMBER>,
Pipeline and Hazardous Materials Safety Administration, U.S. Department
of Transportation, 1200 New Jersey Avenue SE, East Building, 2nd Floor,
Washington, DC 20590-0001.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary
II. Background
III. Incorporation by Reference Discussion Under 1 CFR Part 51
IV. Amendments Not Being Proposed for Adoption
V. Section-by-Section Review of NPRM Proposals
VI. Regulatory Analyses and Notices
    A. Statutory/Legal Authority for This Rulemaking
    B. Executive Order 12866 and DOT Regulatory Policies and
Procedures
    C. Executive Order 13132
    D. Executive Order 13175
    E. Regulatory Flexibility Act, Executive Order 13272, and DOT
Policies and Procedures
    F. Paperwork Reduction Act
    G. Unfunded Mandates Reform Act of 1995
    H. Environment Assessment
    I. Executive Order 12898
    J. Privacy Act
    K. Executive Order 13609 and International Trade Analysis
    L. National Technology Transfer and Advancement Act
    M. Executive Order 13211

I. Executive Summary

    The Pipeline and Hazardous Materials Safety Administration (PHMSA)
proposes to amend certain sections of the Hazardous Materials
Regulations (HMR; 49 CFR parts 171 to 180) to maintain alignment with
international regulations and standards by adopting various changes,
including changes to proper shipping names (PSN), hazard classes,
packing groups (PG), special provisions (SP), packaging authorizations,
air transport quantity limitations, and vessel stowage requirements.
The proposed amendments are discussed in detail in ``Section V.
Section-by-Section Review of NPRM Proposals.''
    Adoption of the regulatory amendments proposed in this NPRM will
maintain the high safety standard currently achieved under the HMR.
PHMSA also notes that because harmonization of the HMR with
international regulations and consensus standards could reduce delays
and interruptions of hazardous materials during transportation, the
proposed amendments may also lower greenhouse gas (GHG) emissions and
safety risks to minority, low-income, underserved, and other
disadvantaged populations and communities in the vicinity of interim
storage sites and transportation arteries and hubs.
    The following list summarizes noteworthy proposals set forth in
this NPRM:
     Incorporation by Reference: PHMSA proposes to incorporate
by reference updated versions of the following international hazardous
materials regulations and standards: the 2023-2024 edition of the
International Civil Aviation Organization Technical Instructions for
the Safe Transport of Dangerous Goods by Air (ICAO Technical
Instructions); Amendment 41-22 to the International Maritime Dangerous
Goods Code (IMDG Code); and the 22nd revised edition of the United
Nations Recommendations on the Transport of Dangerous Goods--Model
Regulations (UN Model Regulations);
     Hazardous Materials Table: PHMSA proposes amendments to
the Hazardous Materials Table (HMT; 49 CFR 172.101) to add, revise, or
remove certain PSNs, hazard classes, PGs, SPs, packaging
authorizations, bulk packaging requirements, and passenger and cargo
aircraft maximum quantity limits.

     Polymerizing Substances: In 2017--as part of the HM-215N
final rule \1\--PHMSA added four new Division 4.1 (flammable solid)
entries for polymerizing substances to the HMT and added defining
criteria, authorized packagings, and safety requirements including, but
not limited to, stabilization methods and operational controls into the
HMR. These changes remained in effect until January 2, 2019, while
PHMSA used the interim period to review and research the implications
of the polymerizing substance amendments. In 2020--as part of the HM-
215O \2\ final rule--PHMSA extended the date the provisions remained in
effect from January 2, 2019, to January 2, 2023, to allow for the
additional research to be completed on the topic. In this NPRM, PHMSA
proposes to remove the phaseout date (January 2, 2023) from the
transport provisions for polymerizing substances to allow for continued
use of the provisions.
---------------------------------------------------------------------------

    \1\ 82 FR 15796 (Mar. 30, 2017).
    \2\ 85 FR 27810 (May 11, 2020).
---------------------------------------------------------------------------

     Cobalt dihydroxide powder containing not less than 10
percent respirable particles: PHMSA proposes to add a new entry to HMT,
``UN3550 Cobalt dihydroxide powder, containing not less than 10%
respirable particles'' and corresponding packaging provisions. Cobalt
is a key strategic mineral used in various advanced medical and
technical applications around the world, including various types of
batteries. Historically, this hazardous material has been classified
and transported as a Class 9 material under ``UN3077, Environmentally
hazardous substance, solid, n.o.s.'' however testing required under
Registration, Evaluation, Authorisations and Restriction of Chemicals
(REACH) regulations \3\ for comprehensive GHS testing, determined that
this material poses an inhalation toxicity hazard. Following this
determination, the 22nd revised edition of the UN Model Regulations
developed a new entry on the Dangerous Goods List (DGL) and packaging
authorizations specifically for this hazardous material to facilitate
continued global transport of this material. In this NPRM, PHMSA
proposes to do likewise by adding a new entry for cobalt dihydroxide
containing not less than 10 percent respirable particles and assigning
it UN3550 on the HMT, in addition to adding packaging provisions,
including the authorization to transport this material in flexible
IBCs. PHMSA expects that these provisions will facilitate the continued
transport of this material, to keep global supply chains open. See
172.101 of the Section-by-Section Review for additional discussion of
these amendments.
---------------------------------------------------------------------------

    \3\ Regulation (EC) No 1907/2006 of the European Parliament and
of the Council of 18 December 2006.
---------------------------------------------------------------------------

     Lithium Battery Exceptions: PHMSA proposes to remove the
exceptions provided for small lithium cells and batteries for
transportation by aircraft. This is consistent with the elimination of
similar provisions in the ICAO Technical Instructions. See 173.185 of
the Section-by-Section Review for additional discussion of these
amendments.
    All the proposed amendments are expected to maintain the HMR's high
safety standard for the public and the environment. Additionally, PHMSA
anticipates that there are safety benefits to be derived from improved
compliance related to consistency amongst domestic and international
regulations. PHMSA solicits comment on the amendments proposed in this
NPRM pertaining to the need, benefits, and costs of the proposed HMR
revisions; impact on safety and the environment; impact on
environmental justice and equity; and any other relevant information.
In addition, PHMSA solicits comment regarding approaches to reducing
the costs of this rule while maintaining or increasing safety benefits.
As further explained in the PRIA, PHMSA expects that the aggregate
benefits of the amendments proposed in this NPRM justify their
aggregate costs. Nonetheless, PHMSA solicits comment on specific
changes (e.g., greater flexibility with regard to a particular
proposal) that might improve the rule.

II. Background

    The Federal Hazardous Materials Transportation Law (49 U.S.C. 5101,
et seq.) directs PHMSA to participate in relevant international
standard-setting bodies and encourages alignment of the HMR with
international transport standards, as consistent with promotion of
safety and the public interest. See 49 U.S.C. 5120. This statutory
mandate reflects the importance of international standard-setting
activity, in light of the globalization of commercial transportation of
hazardous materials. Harmonization of the HMR with those efforts can
reduce the costs and other burdens of complying with multiple or
inconsistent safety requirements between nations. Consistency between
the HMR and current international standards can also enhance safety by
(1) ensuring that the HMR are informed by the latest best practices and
lessons learned; (2) improving understanding of, and compliance with,
pertinent requirements; (3) facilitating the flow of hazardous
materials from their points of origin to their points of destination,
thereby avoiding risks to the public and the environment from release
of hazardous materials due to delays or interruptions in the
transportation of those materials; and (4) enabling consistent
emergency response procedures in the event of a hazardous materials
incident.
    PHMSA participates in the development of international regulations
and standards for the transportation of hazardous materials. It also
adopts within the HMR international consensus standards and regulations
consistent with PHMSA's safety mission. PHMSA reviews and evaluates
each international standard it considers for incorporation within the
HMR on its own merits, including the effects on transportation safety,
the environmental impacts, and any economic impact. PHMSA's goal is to
harmonize with international standards without diminishing the level of
safety currently provided by the HMR or imposing undue burdens on the
regulated community.
    In final rule HM-181,\4\ PHMSA's predecessor, the Research and
Special Programs Administration (RSPA), comprehensively revised the HMR
for greater consistency with the UN Model Regulations. The UN Model
Regulations constitute a set of recommendations issued by the United
Nations Sub-Committee of Experts (UNSCOE) on the Transport of Dangerous
Goods and on the Globally Harmonized System of Classification and
Labelling of Chemicals (GHS). The UN Model Regulations are amended and
updated biennially by the UNSCOE and serve as the basis for national,
regional, and international modal regulations, including the ICAO
Technical Instructions and IMDG Code.
---------------------------------------------------------------------------

    \4\ 55 FR 52401 (Dec. 21, 1990).
---------------------------------------------------------------------------

    PHMSA has evaluated recent updates to the international standards,
including review of numerous updated standards for the design,
manufacture, testing, and use of packagings, and proposes to revise the
HMR to adopt changes consistent with revisions to the 2023-2024 edition
of the ICAO Technical Instructions, Amendment 41-22 to the IMDG Code,
and the 22nd revised edition of the UN Model Regulations, all of which
will be published by or in effect on January 1, 2023,\5\ while also
ensuring the changes are consistent with

PHMSA's safety mission. Consequently, PHMSA proposes to incorporate by
reference these revised international regulations, several new or
updated International Organization for Standards (ISO) standards, and a
new Organization for Economic Co-operation and Development (OECD)
standard. The regulations and standards incorporated by reference are
authorized for use for domestic transportation, under specific
conditions, in part 171, subpart C of the HMR.
---------------------------------------------------------------------------

    \5\ Amendment 41-22 of the IMDG Code will become mandatory on
January 1, 2024. Voluntary compliance begins on January 1, 2023.
---------------------------------------------------------------------------

    PHMSA issued an enforcement discretion on November 28, 2022,\6\
stating that while PHMSA is considering the 2023-2024 Edition of the
ICAO Technical Instructions and Amendment 41-22 of the IMDG Code for
potential adoption into the HMR, PHMSA and other federal agencies that
enforce the HMR (the Federal Railroad Administration (FRA), the Federal
Aviation Administration (FAA), the Federal Motor Carrier Safety
Administration (FMCSA), and the United States Coast Guard (USCG)) will
not take enforcement action against any offeror or carrier who uses
these standards as an alternative to complying with current HMR
requirements when all or part of the transportation is by air with
respect to the ICAO Technical Instructions, or by vessel with respect
to the IMDG Code. In addition, PHMSA and its partners will not take
enforcement action against any offeror or carrier who offers or accepts
for domestic or international transportation by any mode packages
marked or labeled in accordance with these standards. This notice
remains in effect until withdrawn or otherwise modified.
---------------------------------------------------------------------------

    \6\ https://www.phmsa.dot.gov/regulatory-compliance/phmsa-guidance/phmsa-notice-enforcement-policy-regarding-international.
---------------------------------------------------------------------------

III. Incorporation by Reference Discussion Under 1 CFR Part 51

    According to the Office of Management and Budget (OMB), Circular A-
119, ``Federal Participation in the Development and Use of Voluntary
Consensus Standards and in Conformity Assessment Activities,''
government agencies must use voluntary consensus standards wherever
practical in the development of regulations.
    PHMSA currently incorporates by reference into the HMR all or parts
of numerous standards and specifications developed and published by
standard development organizations (SDO). In general, SDOs update and
revise their published standards every two to five years to reflect
modern technology and best technical practices. The National Technology
Transfer and Advancement Act of 1995 (NTTAA; Pub. L. 104-113) directs
federal agencies to use standards developed by voluntary consensus
standards bodies in lieu of government-written standards whenever
possible. Voluntary consensus standards bodies develop, establish, or
coordinate technical standards using agreed-upon procedures. OMB issued
Circular A-119 to implement section 12(d) of the NTTAA relative to the
utilization of consensus technical standards by federal agencies. This
circular provides guidance for agencies participating in voluntary
consensus standards bodies and describes procedures for satisfying the
reporting requirements in the NTTAA. Accordingly, PHMSA is responsible
for determining which standards currently referenced in the HMR should
be updated, revised, or removed, and which standards should be added to
the HMR. Revisions to materials incorporated by reference in the HMR
are handled via the rulemaking process, which allows for the public and
regulated entities to provide input. During the rulemaking process,
PHMSA must also obtain approval from the Office of the Federal Register
to incorporate by reference any new materials. The Office of the
Federal Register issued a rulemaking \7\ that revised 1 CFR 51.5 to
require that an agency detail in the preamble of an NPRM the ways the
materials it proposes to incorporate by reference are reasonably
available to interested parties, or how the agency worked to make those
materials reasonably available to interested parties. Proposed changes
to the material incorporated by reference in the HMR are discussed in
detail in the Sec.  171.7 discussion in ``Section V. Section-by-Section
Review of NPRM Proposals.''
---------------------------------------------------------------------------

    \7\ 79 FR 66278 (Nov. 7, 2014).
---------------------------------------------------------------------------

    The UN Model Regulations, the United Nations Manual of Tests and
Criteria (UN Manual of Tests and Criteria),\8\ and the OECD standard
(i.e., Test No. 439) are free and easily accessible to the public on
the internet, with access provided through the parent organization
websites. The ICAO Technical Instructions, IMDG Code, and all ISO
standard references are available for interested parties to purchase in
either print or electronic versions through the parent organization
websites. The price charged for those references not freely available
helps to cover the cost of developing, maintaining, hosting, and
accessing these standards and regulations.
---------------------------------------------------------------------------

    \8\ U.N. Econ. Comm'n for Europe, Transportation Division,
Manual of Tests and Criteria, 7th Rev. Ed., Amend. 1, U.N. Sales No.
21. VIII. 2 (2021).
---------------------------------------------------------------------------

IV. Amendments Not Being Proposed for Adoption

    PHMSA determined that certain elements of updated international
regulations and standards should not be adopted into the HMR because
the structure of the HMR is such that it makes adoption unnecessary, or
PHMSA has deemed it is a safer approach to authorize certain transport
requirements through issuance of a special permit rather than allow for
general applicability by adopting those requirements into the HMR. Use
of a special permit allows for greater oversight and development of
transport history and data prior to determining whether to adopt the
terms of the special permit in the HMR for broad application.
    The following is a list of international regulations and standards
updates that PHMSA is not proposing for adoption in this NPRM, and the
rationale for those decisions:
     Fiber-reinforced plastic UN portable tanks: The 22nd
revised edition of the UN Model Regulations and Amendment 41-22 of the
IMDG Code include provisions for the design, construction, approval,
use, and testing of fiber-reinforced plastic (FRP) UN portable tanks.
These are UN portable tanks with shells made of FRP materials instead
of traditional steel. PHMSA is not proposing to make corresponding
amendments to the HMR to authorize general multi-modal transport of FRP
UN portable tanks. PHMSA believes further research is necessary in
areas covering material fatigue, suitability of the pool fire test and
impact testing as packaging qualification methods, and in the
identification of the most appropriate non-destructive test methodology
to qualify FRP UN portable tanks. The results of this research will be
used to better gauge the appropriateness of full adoption of the
provisions, amendments to the requirements for approval or use, or a
continued exclusion from the HMR. However, PHMSA is proposing an
amendment to Sec.  171.25--Additional requirements for the use of the
IMDG Code--that would allow limited import and export of FRP UN
portable tanks within a single port area. See ``Section V. Section-by-
Section Review of NPRM Proposals'' for a discussion of Sec.  171.25
changes.
     Pressure receptacles: The 22nd revised edition of the UN
Model Regulations, the 2023-2024 edition of the ICAO Technical
Instructions, and Amendment 41-22 to the IMDG Code

amended various definitions and other language concerning the terms
``pressure receptacles'' and associated requirements for assessing
conformance of UN cylinders built to ISO standards. PHMSA is not
proposing to make changes to the HMR consistent with these amendments.
Terminology used in international standards and HMR differ such that an
evaluation is necessary to determinate the full impacts beyond merely
using consistent terminology. PHMSA may consider making relevant
changes regarding UN cylinders as needed in future rulemakings.
     Aerosol containers: The 22nd revised edition of the UN
Model Regulations, the 2023-2024 edition of the ICAO Technical
Instructions, and Amendment 41-22 to the IMDG Code adopted maximum
internal pressure limits for aerosol containers. Prior to these
changes, these international regulations and standards had no specific
pressure limits for aerosol containers. PHMSA welcomes this additional
safety measure for the transport of aerosol containers, as it makes
aerosol containers constructed and filled in accordance with
international standards more consistent with existing domestic
requirements for aerosol containers, which are subject to internal
pressure limits as part of the performance standards for their
construction and use. Noting existing differences in the HMR, include
the definition for aerosol and the performance standards for their
construction and use and thus because of the complexity involved in
trying to harmonize the maximum pressure limits, PHMSA is not proposing
to adopt these internationally implemented maximum internal pressure
limits. Such harmonization would necessitate a review and evaluation
beyond the scope of this rulemaking.

V. Section-by-Section Review of NPRM Proposals

    The following is a section-by-section review of proposed amendments
to harmonize the HMR with international regulations and standards.

A. Part 171

Section 171.7
    Section 171.7 provides a listing of all voluntary consensus
standards incorporated by reference into the HMR, as directed by the
NTTAA. PHMSA evaluated updated international consensus standards
pertaining to PSNs, hazard classes, PGs, special provisions, packaging
authorizations, air transport quantity limitations, and vessel stowage
requirements. PHMSA contributed to the development of those standards--
each of which build on the well-established and documented safety
histories of earlier editions--as it participated in the discussions
and working group activities associated with their proposal, revision,
and approval. Those activities, in turn, have informed PHMSA's
evaluation of the effect the updated consensus standards would have on
safety, when incorporated by reference and with provisions adopted into
the HMR. Further, PHMSA notes that some of the consensus standards
proposed for incorporation by reference within the HMR in this
rulemaking have already been adopted into the regulatory schemes of
other countries. Additionally, as noted above, PHMSA has issued past
enforcement discretions authorizing their use of the consensus
standards as an interim strategy for complying with current HMR
requirements. PHMSA is not aware of adverse safety impacts from that
operational experience. For these reasons, PHMSA expects their
incorporation by reference will maintain the high safety standard
currently achieved under the HMR. Therefore, PHMSA proposes to add or
revise the following incorporation by reference materials.\9\
---------------------------------------------------------------------------

    \9\ All other standards that are set out as part of the
regulatory text of Sec.  171.7(w) were previously approved for
incorporation by reference and no changes are proposed.
---------------------------------------------------------------------------

     In paragraph (t)(1), incorporate by reference the 2023-
2024 edition of the ICAO Technical Instructions, to replace the 2021-
2022 edition, which is currently referenced in Sec. Sec.  171.8; 171.22
through 171.24; 172.101; 172.202; 172.401; 172.407; 172.512; 172.519;
172.602; 173.56; 173.320; 175.10, 175.33; and 178.3. The ICAO Technical
Instructions specify detailed instructions for the international safe
transport of dangerous goods by air. The requirements in the 2023-2024
edition have been amended to align better with the 22nd revised edition
of the UN Model Regulations and the International Atomic Energy Agency
(IAEA) Regulations for the Safe Transport of Radioactive Material.
Notable changes in the 2023-2024 edition of the ICAO Technical
Instructions include new packing and stowage provisions, new and
revised entries on its Dangerous Goods List, and editorial corrections.
The 2023-2024 edition of the ICAO Technical Instructions is available
for purchase on the ICAO website at https://store.icao.int/en/shop-by-areas/safety/dangerous-goods.
     In paragraph (v)(2), incorporate by reference the 2022
edition of the IMDG Code, Incorporating Amendment 41-22 (English
Edition), to replace Incorporating Amendment 40-20, 2020 Edition, which
is currently referenced in Sec. Sec.  171.22; 171.23; 171.25; 172.101;
172.202; 172.203; 172.401; 172.407; 172.502; 172.519; 172.602; 173.21;
173.56; 176.2; 176.5; 176.11; 176.27; 176.30; 176.83; 176.84; 176.140;
176.720; 176.906; 178.3; and 178.274. The IMDG Code is a unified
international code that outlines standards and requirements for the
transport of dangerous goods by sea (i.e., by vessel). Notable changes
in Amendment 41-22 of the IMDG Code include new packing and stowage
provisions, new and revised entries on its Dangerous Goods List, and
editorial corrections. Distributors of the IMDG Code can be found on
the International Maritime Organization (IMO) website at: https://www.imo.org/en/publications/Pages/Distributors-default.aspx.
     In paragraph (w), incorporate by reference or remove the
following ISO documents to include new and updated standards for the
specification, design, construction, testing, and use of gas cylinders:

--ISO 9809, Parts 1 through 3. ISO 9809 is comprised of four parts (ISO
9809-1 through 9809-4) and specifies minimum requirements for the
material, design, construction, and workmanship; manufacturing
processes; and examination and testing at time of manufacture for
various types of refillable seamless steel gas cylinders and tubes.
PHMSA proposes to incorporate by reference the most recent versions of
Parts 1 through 3.

     Incorporate by reference the third edition of ISO 9809-
1:2019(E), ``Gas cylinders--Design, construction and testing of
refillable seamless steel gas cylinders and tubes--Part 1: Quenched and
tempered steel cylinders and tubes with tensile strength less than 1100
Mpa'' in paragraph (w)(32). Additionally, PHMSA proposes a sunset date
of December 31, 2026, for continued use and phase out of the second
edition of ISO 9809-1:2010, which is currently referenced in Sec.
178.37, Sec.  178.71, and Sec.  178.75. Part 1 of ISO 9809 is
applicable to cylinders and tubes for compressed, liquefied, and
dissolved gases and for quenched and tempered steel cylinders and tubes
with a maximum actual tensile strength of less than 1100 MPa, which is
equivalent to U.S. customary unit of about 160,000 psi. As part of its
periodic review of all standards, ISO reviewed ISO 9809-

1:2010(E) and published an updated version, ISO 9809-1:2019(E), which
was published in 2019 and adopted in the 22nd revised edition of the UN
Model Regulations. The updated standard has technical revisions
including limiting the bend test only for prototype tests. Updating
references to this document would align the HMR with changes adopted in
the 22nd revised edition of the UN Model Regulations pertaining to the
design and construction of UN cylinders. PHMSA has reviewed this
edition as part of its regular participation in the review of
amendments proposed for the UN Model Regulations and concludes
incorporation of the revised third edition will maintain or improve the
safety standards associated with its use.
     Incorporate by reference the third edition of ISO 9809-
2:2019(E), ``Gas cylinders--Design, construction and testing of
refillable seamless steel gas cylinders and tubes--Part 2: Quenched and
tempered steel cylinders and tubes with tensile strength greater than
or equal to 1100 MPa'' in paragraph (w)(35). ISO 9809-2:2019 is the
third edition of ISO 9809-2. Additionally, PHMSA proposes a sunset date
of December 31, 2026, for continued use and phaseout of the second
edition of ISO 9809-2:2010, which is currently referenced in Sec.
178.71, and Sec.  178.75. ISO 9809-2:2019 specifies minimum
requirements for the material, design, construction and workmanship,
manufacturing processes, examination and testing at time of manufacture
for refillable seamless steel gas cylinders and tubes with water
capacities up to and including 450 L. Part 2 of ISO 9809 is applicable
to cylinders and tubes for compressed, liquefied, and dissolved gases
and for quenched and tempered steel cylinders and tubes with an actual
tensile strength greater than or equal to 1100 MPa. As part of its
periodic review of all standards, ISO reviewed ISO 9809-2:2010 and
published an updated version, ISO 9809-2:2019, in 2019; this updated
version was adopted in the 22nd revised edition of the UN Model
Regulations. The updated standard has technical revisions including
expanded cylinder size (i.e., allowed water capacity is extended from
below 0.5 L to up to and including 450 L); the introduction of specific
batch sizes for tubes; limiting the bend test only for prototype tests;
the addition of test requirements for check analysis (tolerances
modified); and the addition of new test requirements for threads.
Updating references to this document would align the HMR with changes
adopted in the 22nd revised edition of the UN Model Regulations
pertaining to the design and construction of UN cylinders. PHMSA has
reviewed this edition as part of its regular participation in the
review of amendments proposed for the UN Model Regulations and
concludes incorporation of the revised third edition will maintain or
improve the safety standards associated with its use.
     Incorporate by reference the third edition of ISO 9809-
3:2019(E), ``Gas cylinders--Design, construction and testing of
refillable seamless steel gas cylinders and tubes--Part 3: Normalized
steel cylinders and tubes'' in paragraph (w)(38). Additionally, PHMSA
proposes a sunset date of December 31, 2026, for continued use phaseout
of the second edition of ISO 9809-3:2010, which is currently referenced
in Sec.  178.71 and Sec.  178.75. ISO 9809-3 is applicable to cylinders
and tubes for compressed, liquefied, and dissolved gases and for
normalized or normalized and tempered, steel cylinders and tubes. As
part of its periodic review of all standards, ISO reviewed ISO 9809-
3:2010 and published an updated version, ISO 9809-3:2019. The updated
standard has technical revisions including: a wider scope of cylinders
(i.e., allowed water capacity is extended from below 0.5 L up to and
including 450 L); the introduction of specific batch sizes for tubes;
limiting the bend test only for prototype tests; the addition of test
requirements for check analysis (tolerances modified); and the addition
of new test requirements for threads. Updating references to the 2019
edition would align the HMR with changes adopted in the 22nd revised
edition of the UN Model Regulations, which added this version
pertaining to the design and construction of UN cylinders. PHMSA has
reviewed this edition as part of its regular participation in the
review of amendments proposed for the UN Model Regulations and
concludes incorporation of the revised third edition will maintain or
improve the safety standards associated with its use.

--Incorporate by reference supplemental amendment ISO 10462:2013/Amd
1:2019(E), ``Gas cylinders--Acetylene cylinders--Periodic inspection
and maintenance--Amendment 1'' in paragraph (w)(48). This proposed
change would add a reference to ISO 10462:2013/Amd 1:2019(E) in Sec.
180.207(d)(3), where ISO 10462:2013 is currently required, and add a
sunset date of December 31, 2024, for continued use and phaseout of ISO
10462:2013 without the supplemental amendment. ISO 10462:2013 specifies
requirements for the periodic inspection of acetylene cylinders as
required for the transport of dangerous goods and for maintenance in
connection with periodic inspection. It applies to acetylene cylinders
with and without solvent and with a maximum nominal water capacity of
150 L. As part of a periodic review of its standards, ISO reviewed ISO
10462:2013, and in June 2019 published a short supplemental amendment,
ISO 10462:2013/Amd 1:2019. The supplemental document includes updates
such as simplified marking requirements for rejected cylinders.
Updating references to this document would align the HMR with documents
referenced in the 22nd revised edition of the UN Model Regulations
pertaining to the requalification procedures for acetylene UN
cylinders. PHMSA has reviewed this edition as part of its regular
participation in the review of amendments proposed for the UN Model
Regulations and concludes the incorporation of the supplemental
document maintains the HMR safety standards for use of acetylene
cylinders.
--Incorporate by reference the third edition of ISO 11117:2019(E),
``Gas cylinders--Valve protection caps and guards--Design, construction
and tests'' in paragraph (w)(56). This amendment would authorize the
use of the third edition until further notice and add an end date of
December 31st, 2026, to the authorization for use of the second
edition, ISO 11117:2008 and the associated corrigendum, which are
currently referenced in Sec.  173.301b. ISO 11117 specifies the
requirements for valve protection caps and valve guards used on
cylinders for liquefied, dissolved, or compressed gases. The changes in
this revised standard pertain to the improvement of the
interoperability of both the valve protection caps and the valve
guards, with the cylinders and the cylinder valves. To that end, the
drop test, the marking, and test report requirements have been revised
and clarified. Updating references to this document would align the HMR
with changes adopted in the 22nd revised edition of the UN Model
Regulations pertaining to valve protection on UN pressure receptacles.
PHMSA has reviewed this edition as part of its regular participation in
the review of amendments proposed for the UN Model Regulations and does
not

expect any degradation of safety standards in association with its use.
--Incorporate by reference ISO 11118:2015/Amd 1:2019(E), ``Gas
cylinders--Non-refillable metallic gas cylinders--Specification and
test methods--Amendment 1'' in paragraph (w)(59). ISO 11118:2015/Amd
1:2019(E) is a short supplemental amendment that is intended to be used
in conjunction with ISO 11118:2015, which is currently referenced in
Sec.  178.71. This amendment would authorize the use of this
supplemental amendment in conjunction with ISO 11118:2015 until further
notice and add an end date of December 31, 2026, until which ISO
11118:2015 may continue to be used without this supplemental amendment.
ISO 11118:2015, which specifies minimum requirements for the material,
design, inspections, construction and workmanship, manufacturing
processes, and tests at manufacture of non-refillable metallic gas
cylinders of welded, brazed, or seamless construction for compressed
and liquefied gases including the requirements for their non-refillable
sealing devices and their methods of testing. ISO 11118:2015/Amd 1:2019
corrects the identity of referenced clauses and corrects numerous
typographical errors. The amendment also includes updates to the
marking requirements in the normative Annex A, which includes
clarifications, corrections, and new testing requirements. Updating
references to this document would align the HMR with documents
referenced in the 22nd revised edition of the UN Model Regulations
pertaining to non-refillable UN cylinders. PHMSA has reviewed this
amended document as part of its regular participation in the review of
amendments proposed for the UN Model Regulations and determined that
the added corrections and clarifications provide important additional
utility for users of ISO 11118:2015(E) and does not expect any
degradation of safety standards in association with its use.
--Incorporate by reference ISO 11513:2019, ``Gas cylinders--Refillable
welded steel cylinders containing materials for sub-atmospheric gas
packaging (excluding acetylene)--Design, construction, testing, use and
periodic inspection'' in paragraph (w)(71). ISO 11513:2019 is the
second edition of ISO 11513. This amendment would authorize the use of
the second edition and add an end date to the authorization for use of
the first edition, ISO 11513:2011 (including Annex A), which is
currently referenced in Sec.  173.302c, Sec.  178.71, and Sec.
180.207. ISO 11513 specifies minimum requirements for the material,
design, construction, workmanship, examination and testing at
manufacture of refillable welded steel cylinders for the sub-
atmospheric pressure storage of liquefied and compressed gases. The
second edition has been updated to amend packing instructions and
remove a prohibition on the use of ultrasonic testing during periodic
inspection. Updating references to this document would align the HMR
with documents referenced in the 22nd revised edition of the UN Model
Regulations pertaining to the shipment of adsorbed gases in UN pressure
receptacles. PHMSA has reviewed this edition as part of its regular
participation in the review of amendments proposed for the UN Model
Regulations and does not expect any degradation of safety standards in
association with its use.
--Incorporate by reference ISO 16111:2018, ``Transportable gas storage
devices--Hydrogen absorbed in reversible metal hydride'' in paragraph
(w)(80). ISO 16111:2018 is the second edition of ISO 16111. This
amendment would authorize the use of the second edition until further
notice and add an end date of December 31, 2026, on the authorization
to use the first edition, ISO 16111:2008, which is referenced in
Sec. Sec.  173.301b, 173.311, and 178.71. ISO 16111 defines the
requirements applicable to the material, design, construction, and
testing of transportable hydrogen gas storage systems which utilize
shells not exceeding 150 L internal volume and having a maximum
developed pressure not exceeding 25 MPa. This updated standard includes
additional information pertaining to service temperature conditions
which have been described in detail; new references related to shell
design; modified drop test conditions; modified acceptance criteria for
leak testing; modified hydrogen cycling conditions; new warning
labelling; and updated information on safety data sheets. Updating
references to this document would align the HMR with documents
referenced in the 22nd revised edition of the UN Model Regulations
pertaining to metal hydride storage systems. PHMSA has reviewed this
edition as part of its regular participation in the review of
amendments proposed for the UN Model Regulations and does not expect
any degradation of safety standards in association with its use.
--Incorporate by reference ISO 17871:2020(E), ``Gas cylinders--Quick-
release cylinder valves--Specification and type testing'' in paragraph
(w)(83). ISO 17871:2020 is the second edition of ISO 17871. This
amendment would authorize the use of the second edition and add an end
date of December 31st, 2026, to the authorization for use of the first
edition, ISO 17871:2015(E), which is currently referenced in 173.301b.
This document, in conjunction with ISO 10297 and ISO 14246, specifies
design, type testing, marking, and manufacturing tests, and
examinations requirements for quick-release cylinder valves intended to
be fitted to refillable transportable gas cylinders, pressure drums and
tubes which convey certain gases such as compressed or liquefied gases
or extinguishing agents charged with compressed gases to be used for
fire-extinguishing, explosion protection, and rescue applications. As
part of its regular review of its standards, ISO updated and published
the second edition of ISO 17871 as ISO 17871:2020. The 2020 edition of
this standard broadens the scope to include quick release valves for
pressure drums and tubes and specifically excludes the use of quick
release valves with flammable gases. Other notable changes include the
addition of the valve burst test pressure, the deletion of the flame
impingement test, and the deletion of internal leak tightness test at -
40 [deg]C for quick release cylinder valves used only for fixed fire-
fighting systems installed in buildings. Updating references to this
document would align the HMR with changes adopted in the 22nd revised
edition of the UN Model Regulations pertaining to the shipment of gases
in UN pressure receptacles. PHMSA has reviewed this edition as part of
its regular participation in the review of amendments proposed for the
UN Model Regulations and does not expect any degradation of safety
standards in association with its use.
--Incorporate by reference ISO 21172-1:2015/Amd 1:2018, ``Gas
cylinders--Welded steel pressure drums up to 3000 litres capacity for
the transport of gases--Design and construction--Part 1: Capacities up
to 1000 litres--Amendment 1'' in paragraph (w)(89). ISO 21172-1:2015/
Amd1:2018 is a short supplemental amendment that is intended to be used
in conjunction with ISO 21172-1:2015, which is currently referenced in
Sec.  178.71. This

amendment would authorize the use of this supplemental document in
conjunction with the first edition, ISO 21172-1:2015. It would also add
an end date of December 31, 2026, until which ISO 21172-1:2015 may
continue to be used without this supplemental amendment. ISO 21172-
1:2015 specifies the minimum requirements for the material, design,
fabrication, construction, workmanship, inspection, and testing at
manufacture of refillable welded steel gas pressure drums of volumes
150 L to 1000 L and up to 300 bar (30 MPa) test pressure for compressed
and liquefied gases. This supplemental amendment includes updated
references and removes the restriction on corrosive substances.
Updating references to this document would align the HMR with documents
referenced in the 22nd revised edition of the UN Model Regulations
pertaining to the design and construction of UN pressure drums. PHMSA
has reviewed this edition as part of its regular participation in the
review of amendments proposed for the UN Model Regulations and does not
expect any degradation of safety standards in association with its use.
--Incorporate by reference ISO 23088:2020, ``Gas cylinders--Periodic
inspection and testing of welded steel pressure drums--Capacities up to
1000 l'' in paragraph (w)(91). This amendment would incorporate by
reference the first edition of ISO 23088, which specifies the
requirements for periodic inspection and testing of welded steel
transportable pressure drums of water capacity from 150 L up to 1,000 L
and up to 300 bar (30 MPa) test pressure intended for compressed and
liquefied gases in Sec.  180.207. This new standard was adopted in the
22nd revised edition of the UN Model Regulations because it fulfills
the need for specific periodic inspection instructions for pressure
drums constructed in accordance with ISO 21172-1. Incorporating by
reference this document would align the HMR with standards adopted in
the 22nd revised edition of the UN Model Regulations pertaining to the
design, construction, and inspection of UN pressure drums. PHMSA has
reviewed this document as part of its regular participation in the
review of amendments proposed for the UN Model Regulations and expects
that its addition will facilitate the continued use of UN pressure
drums with no degradation of safety.

     In paragraph (aa)(3), incorporate by reference the OECD
Guidelines for the Testing of Chemicals ``Test No. 439: In Vitro Skin
Irritation: Reconstructed Human Epidermis Test Method'' (2015). This
Test Guideline (TG) provides an in vitro procedure that may be used for
the hazard identification of irritant chemicals. PHMSA proposes to
reference this test in Sec.  173.137, and to authorize the use of this
test method in addition to those already referenced in that section.
This test method is used to specifically exclude a material from
classification as corrosive and to maintain alignment with the 22nd
revised edition of the UN Model Regulations. This test method provides
an in vitro procedure that may be used for the hazard identification of
irritant chemicals (substances and mixtures). OECD test methods can be
found in the OECD iLibrary available at https://www.oecd-ilibrary.org/.
     In paragraph (dd), incorporate by reference United Nations
standards including:

--``The Recommendations on the Transport of Dangerous Goods--Model
Regulations,'' 22nd revised edition (2021), Volumes I and II, in
paragraph (dd)(1), which are referenced in Sec. Sec.  171.8; 171.12;
172.202; 172.401; 172.407; 172.502; 172.519; 173.22; 173.24; 173.24b;
173.40; 173.56; 173.192; 173.302b; 173.304b; 178.75; and 178.274. The
Model Regulations provide framework provisions promoting uniform
development of national and international regulations governing the
transportation of hazardous materials by various modes of transport. At
its tenth session on December 11, 2020, the UNSCOE on the Transport of
Dangerous Goods adopted amendments to the UN Model Regulations on the
Transport of Dangerous Goods concerning, inter alia, electric storage
systems (including modification of the lithium battery mark and
provisions for transport of assembled batteries not equipped with
overcharge protection), requirements for the design, construction,
inspection and testing of portable tanks with shells made of fiber
reinforced plastics (FRP) materials, modified listings of dangerous
goods; and additional harmonization with the IAEA Regulations for the
Safe Transport of Radioactive Material. PHMSA participates in the
development of the UN Model Regulations and has determined that the
amendments adopted in the 22nd revised edition support the safe
transport of hazardous materials and as such are appropriate for
incorporation in the HMR. The 22nd revised edition of the UN Model
Regulations is available online at: https://unece.org/transport/dangerous-goods/un-model-regulations-rev-22.
--``The Manual of Tests and Criteria, Amendment 1 to the Seventh
revised edition'' (Rev.7/Amend.1) (2021), in paragraph (dd)(2)(ii),
which is referenced in Sec. Sec.  171.24, 172.102; 173.21; 173.56;
173.57; 173.58; 173.60; 173.115; 173.124; 173.125; 173.127; 173.128;
173.137; 173.185; 173.220; 173.221; 173.224; 173.225; 173.232; part
173, appendix H; 175.10; 176.905; and 178.274. The Manual of Tests and
Criteria contains instruction for the classification of hazardous
materials for purposes of transportation according to the UN Model
Regulations. At its tenth session the Committee of Experts on the
Transport of Dangerous Goods and on the Globally Harmonized System of
Classification and Labelling of Chemicals adopted a set of amendments
to the seventh revised edition of the Manual, which were circulated and
collected in amendment 1 to the seventh revised edition. The new
amendments adopted in December 2020 pertain to the transport of
explosives, including alignment with revised Chapter 2.1 of the GHS,
classification of self-reactive substances and polymerizing substances,
and the assessment of the thermal stability of samples and temperature
control assessment for transport of self-reactive substances and
organic peroxides. PHMSA has reviewed and approved the amendments
adopted in this document and further expects that their incorporation
in the HMR will provide an additional level of safety. PHMSA proposes
to incorporate by reference this document as a supplement, to be used
in conjunction with the seventh revised edition (2019). The amendments
to the manual can be accessed at https://unece.org/transport/dangerous-goods/rev7-files.
--``Globally Harmonized System of Classification and Labelling of
Chemicals (GHS),'' ninth revised edition (2021) in paragraph (dd)(3),
which is referenced in Sec.  172.401. The GHS standard provides a basic
scheme to identify the hazards of substances and mixtures and to
communicate these hazards. At its tenth session on December 11, 2020,
the Committee of Experts on the Transport of Dangerous Goods and on the
Globally Harmonized System of

Classification and Labelling of Chemicals adopted a set of amendments
to the eighth revised edition of the GHS which include, inter alia:
revisions to Chapter 2.1 (explosives) to better address their explosion
hazard when they are not in their transport configuration; revisions to
decision logics; revisions to classification and labelling summary
tables in Annex 1; revisions and additional rationalization of
precautionary statements; and updates of references to OECD test
guidelines for the testing of chemicals in Annexes 9 and 10. PHMSA has
reviewed and approved the amendments incorporated in this document and
further expects that its incorporation in the HMR will provide an
additional level of safety. The ninth revised edition of the GHS can be
accessed at https://unece.org/transport/standards/transport/dangerous-goods/ghs-rev9-2021.
Section 171.12
    Section 171.12 prescribes requirements for shipments of hazardous
materials in North America, including use of the Transport Canada (TC)
Transportation of Dangerous Goods (TDG) Regulations. In rule HM-
215N,\10\ PHMSA amended the HMR to expand recognition of cylinders and
pressure receptacles, and certificates of equivalency--Transport
Canada's equivalent of a special permit--approved in accordance with
the TDG Regulations. The goal of these amendments was to promote
flexibility and permit the use of modern technology for the
requalification and use of pressure receptacles, to expand the universe
of pressure receptacles authorized for use in hazardous material
transport, to reduce the need for special permits, and to facilitate
cross-border transportation of these pressure receptacles. In
accordance with Sec.  171.12(a)(4), when the provisions of the HMR
require the use of either a DOT specification or a UN pressure
receptacle for transport of a hazardous material, a packaging
authorized by Transport Canada's TDG Regulations may be used only if it
corresponds to the DOT specification or UN standard. HM-215N revised
paragraph (a)(4)(iii) to include a table listing Canadian Railway
Commission (CRC), Board of Transport Commissioners for Canada (BTC),
Canadian Transport Commission (CTC) or Transport Canada (TC)
specification cylinders, in accordance with the TDG Regulations, and in
full conformance with the TDG Regulations, that correspond with a DOT
specification cylinder.
---------------------------------------------------------------------------

    \10\ 82 FR 15796 (Mar. 30, 2017).
---------------------------------------------------------------------------

    However, there are currently no TC specification cylinders
corresponding to DOT specification cylinders listed in the table for
DOT-8 and DOT-8AL cylinders used to transport acetylene. During the
development of HM-215N, PHMSA conducted a comparative analysis of DOT
and TC cylinder specifications and only those TC cylinder
specifications that corresponded directly to DOT cylinder
specifications were included. The result was that PHMSA did not include
TC-8WM and TC-8WAM specifications for the transport of acetylene in the
table of corresponding cylinders at Sec.  171.12(a)(4)(iii). This
omission was primarily due to concerns over differing solvent
authorizations, calculations, and methods of construction for the
design associated with the TC-8WM and TC-8WAM specifications. PHMSA
conducted a second comparative analysis of DOT and TC cylinder
specifications for transport of acetylene and concluded that the
initial concerns were unwarranted. Therefore, PHMSA proposes to add TC-
8WM and TC-8WAM specifications to the table of corresponding DOT
specifications in Sec.  171.12(a)(4)(iii) as comparable cylinders to
DOT-8 and DOT-8AL, respectively.
    PHMSA's supplemental review indicates the differences between the
TC and DOT specifications for transport of acetylene are minor and the
standard for safety of transportation of acetylene in cylinders under
the HMR is maintained. This proposal would allow for TC acetylene
cylinders manufactured in Canada to be filled, used, and requalified
(including rebuild, repair, reheat-treatment) in the United States,
facilitating cross border movement of acetylene and eliminates the need
for a special permit to allow transport of acetylene in these TC-8WM
and TC-8AWM cylinders while maintaining an equivalent level of safety.
Additionally, this proposal would provide reciprocity to Transport
Canada's authorized use of DOT-8 and DOT-8AL cylinders for acetylene
transport.
Section 171.23
    Section 171.23 outlines the requirements for specific materials and
packagings transported under the ICAO Technical Instructions, IMDG
Code, Transport Canada TDG Regulations, or the IAEA Regulations. It
also includes authorized use, under specific conditions, of pi-marked
pressure receptacles that comply with the Agreement Concerning the
International Carriage of Dangerous Goods by Road (ADR), and the EU
Directive 2010/35/EU,\11\ and marked with a pi ([pi]) symbol to denote
such compliance for transport of hazardous materials. PHMSA proposes to
amend the language in the provisions for pi-marked pressure receptacles
in paragraph (a)(3) to clarify the scope of pressure receptacles
authorized by this section. Pressure receptacles is a collective term
that may be used to refer to many types of pressurized containers of
various sizes, such as cylinders, tubes, pressure drums, closed
cryogenic receptacles, metal hydride storage systems, bundles of
cylinders or salvage pressure receptacles. When PHMSA adopted the
provisions for pi-marked pressure receptacles,\12\ we did not intend to
broadly apply the scope to all pressure receptacle types. Instead,
PHMSA's intent was to apply the authorized use of pi-marked pressure
receptacles domestically to only cylinders, as indicated in current
paragraph (a)(3)(iii), which specifically references cylinders. Some of
the pressure receptacles authorized in accordance with the ADR standard
do not have an equivalent packaging authorized in the HMR, and some
have large capacities, both of which give pause to PHMSA with respect
to the hazardous materials authorized in these packagings. Therefore,
PHMSA proposes to replace the words ``pressure receptacles'' in
paragraph (a)(3) with ``cylinders with a water capacity not exceeding
150 L,'' as defined in Sec.  171.8, to specify the scope of pi-marked
pressure receptacles authorized under Sec.  171.23. PHMSA expects that
this amendment will improve safety by providing additional clarity with
regard to the scope of authorized use of pi-marked pressure receptacles
for transport of hazardous material in the United States. PHMSA is
aware of growing interest in the authorization for use of other pi-
marked pressure receptacles and PHMSA plans to address that issue in a
future rulemaking.
---------------------------------------------------------------------------

    \11\ U.N. Econ. Comm'n for Europe, Transportation Division,
Agreement Concerning the Int'l Carriage of Dangerous Goods by Road,
110th Sess., ECE/TRANS/300, U.N. Sales No. E. 21. VIII. 1 (2020).
    \12\ 85 FR 75680 (Nov. 25, 2020).
---------------------------------------------------------------------------

Section 171.25
    Section 171.25 outlines additional requirements for the use of the
IMDG Code in addition to those found in Sec.  171.22 and Sec.  171.23.
As discussed above in Section IV. Amendments Not Being Considered for
Adoption, specifically Issue #1, PHMSA is not proposing to adopt
provisions for UN FRP portable tanks in the HMR.

However, to facilitate limited import and export of these tanks in
international commerce, and to gain additional experience with their
transport, PHMSA proposes to add a new paragraph Sec.  171.25(c)(5)
that would prohibit the general transportation of UN FRP portable tanks
designed and constructed in accordance with Chapter 6.10 of the IMDG
Code within the United States, yet allow for the tanks to be
transported within a single port area in the United States in
accordance with the provisions of Sec.  171.25(d) covering the use of
the IMDG Code in port areas. This action will maintain the safe
transportation of hazardous material under the HMR while facilitating
international commerce by permitting the import or export of hazardous
materials in UN FRP portable tanks and limiting their use and movement
within the confines of a single port area.

B. Part 172

Section 172.101 Hazardous Materials Table (HMT)
    The HMT summarizes terms and conditions governing transportation of
listed hazardous materials under the HMR. For each entry, the HMT
identifies information such as the PSN, UN identification number, and
hazard class. The HMT specifies additional information or reference
requirements in the HMR such as hazard communication, packaging,
quantity limits aboard aircraft, and stowage of hazardous materials
aboard vessels. PHMSA proposes several changes to the HMT as discussed
below. For purposes of the Government Publishing Office's typesetting
procedures, proposed changes to the HMT appear under three sections of
the HMT: ``remove,'' ``add,'' and ``revise.'' Certain entries in the
HMT, such as those with revisions to the PSNs, appear as a ``remove''
and ``add.'' Proposed amendments to the HMT include the following:
New HMT Entry
    PHMSA proposes to add new entry, ``UN3550, Cobalt dihydroxide
powder, containing not less than 10% respirable particles, Division
6.1, PG I'' to the HMT. Cobalt is a key strategic mineral used in
various advanced medical and technical applications around the world,
and it is essential to keep the global supply chains for this material
open. This material has a 40-year history of safe global transport as
``UN3077, Environmentally hazardous substance, solid, n.o.s., Class 9''
in different forms, including as crude material directly from mines,
high moisture content paste, and very fine refined powders in flexible
IBCs rated for PG III. However, recent testing required for compliance
with the REACH Regulation in the European Union, and subsequent
evaluation against the hazard classification criteria of the EU
Classification, Labelling, and Packaging (CLP) Regulation resulted in a
classification of Acute toxicity by inhalation Category 1, which is
equivalent to the Division 6.1 hazard classification. As a result of
this testing, it was determined that when this material is in fine
powder form, it must no longer be transported as Class 9 miscellaneous
hazard material. In powder form, cobalt dihydroxide powder must now be
classified as a Division 6.1 toxic-by-inhalation solid material, for
which a unique UN identification number and associated classification,
hazard communication, and packing instructions does not currently exist
in the HMT. This change in classification led to the development of the
new UN identification number UN3550 and associated transportation
requirements by the UNSCOE. To that end, the UNSCOE developed
appropriate packaging provisions, including a special packaging
condition, which permits the continued use of certain flexible IBCs.
PHMSA notes that other forms of cobalt dihydroxide powder may continue
to be classified and described as ``UN3077, Environmentally hazardous,
solid, n.o.s., 9, PG III.'' Specifically, the UNSCOE addressed shipper
concerns that flexible IBCs are not otherwise permitted for transport
of Division 6.1 toxic solids, yet there is a 40-year record of safe
transport of the refined material as UN3077 material in flexible IBCs,
with no recorded accidents, incidents, or health issues. PHMSA proposes
to also add a corresponding special provision (IP22) to indicate that
the use of certain flexible IBCs is permitted for UN3550, which is
discussed further in Sec.  172.102 of this Section-by-Section Review).
The other packaging provisions for this cobalt dihydroxide powder are
consistent with those for other Division 6.1 solid materials assigned
PG I, such as ``UN3467, Organometallic compound, solid, toxic, n.o.s.''
An entry for UN3550 was also added in the 2023-2024 ICAO Technical
Instructions and aligns with the proposed packaging requirements in
this NPRM. PHMSA agrees with the UN provision to allow for the
continued transport of this hazardous material in flexible IBCs, or in
accordance with other special provisions and packaging requirements
outlined in Part 173. The addition of this new HMT entry will maintain
the HMR's safety standard for transportation of Division 6.1 solid
materials.
HMT Corrections
    PHMSA proposes to make corrections to multiple HMT entries that
were inadvertently modified in previous rulemakings. Specifically, for
the PGII and PGIII entries for ``UN3129, Water-reactive liquid,
corrosive, n.o.s'' and ``UN3148, Water-reactive liquid, n.o.s'', the
references to exceptions in Sec.  173.151 in Column 8A were removed and
replaced with the word ``None''. While there are no exceptions these
materials when assigned to PGI, PHMSA did not intend to remove the
exceptions for PGII and III materials. Additionally, for the PGIII
entry for ``UN3148, Water-reactive liquid, n.o.s'', the ``G'' in Column
1, which indicates that a technical name must be provided in
association with the proper shipping name, was also inadvertently
deleted. PHMSA expects that making these editorial corrections will
prevent frustrations in shipping due to the inadvertent removal of the
reference to authorized shipping exceptions and confusion regarding the
required shipping description. PHMSA also proposes a correction to the
entry ``UN0512, Detonators, electronic programmable for blasting''. In
HM-215P, PHMSA added three new entries for electronic detonators to
distinguish them from electric detonators, which have different
functioning characteristics but similar regulatory provisions for their
transport. PHMSA incorrectly assigned an obsolete special provision,
Special Provision 103, which was removed from the HMR by final rule HM-
219C.\13\ UN0512 is comparable to the entry UN0255 and therefore should
reflect the same special provision, Special Provision 148. Therefore,
PHMSA proposes to remove the reference to Special Provision 103 in
Column 7 for UN0512 and replace it with Special Provision 148
consistent with the entry of UN0255. PHMSA expects that this correction
will remove confusion surrounding additional provisions for these
detonators. Lastly, PHMSA proposes a correction to the proper shipping
name for UN3380, which should read ``Desensitized explosive, solid,
n.o.s.''. In the previous HM-215 rulemaking, the word ``explosive'' was
inadvertently made plural. This spelling is in conflict with a similar
material on the HMT, ``UN3379. Desensitized explosive, liquid, n.o.s.''
and international regulations. Therefore, PHMSA expects that this
correction will remove

confusion surrounding the proper shipping name for these materials.
---------------------------------------------------------------------------

    \13\ 85 FR 75680 (November 25, 2020).
---------------------------------------------------------------------------

    Lastly, PHMSA proposes to make a correction to the HMT entry for
``UN1791, Hypochlorite Solutions''. In HM-215O, PHMSA added stowage
codes 53 and 58--which require stowage ``separated from alkaline
compounds'' and ``separated from cyanides,'' respectively--to Column
10B of the HMT for several hazardous materials for consistency with
changes included in Amendment 39-18 of the IMDG Code. These stowage
codes were intended to be applied to several HMT entries to ensure
proper segregation between acids and both amines and cyanides but
should not have included UN1791. Therefore, PHMSA proposes to remove
stowage codes 53 and 58 from Column 10B for this entry. PHMSA expects
that this correction will remove the burden faced by shippers who have
had to segregate hypochlorite solutions for compliance with the HMR,
which is inconsistent with the requirements of the IMDG Code.
Column (2) Hazardous Materials Descriptions and Proper Shipping Names
    Section 172.101(c) describes column (2) of the HMT and the
requirements for hazardous materials descriptions and PSNs. PHMSA
proposes to consolidate two entries in the HMT that are currently
listed under ``UN1169, Extracts, aromatic, liquid'' (PGII and PGIII)
and ``UN1197, Extracts, flavoring, liquid'' (PGII and PGIII).
Specifically, PHMSA proposes to remove the table entry for ``UN1169,
Extracts, aromatic, liquid'' and modify the PSN associated with the
table entry for UN1197 to reflect materials that have been historically
transported separately under UN1169 and UN1197. The 22nd revised
edition of the UN Model Regulations made these same changes, deleting
UN1169 from the Dangerous Goods List and changing the PSN for UN1197 to
``Extracts, liquid, for flavor or aroma'' to remove confusion
associated with selection of the appropriate PSNs across the various
languages of nations engaged in international shipments of the
material. It became apparent that, whether for a flavor extract or
aroma extract, the PSNs were often used interchangeably as there is no
difference between the two with regard to classification, hazard
communication, and packaging for transport. PHMSA agrees that the
existence of two interchangeable UN numbers does not provide any
additional value and, therefore, proposes to remove the table entry for
UN1169 and modify the PSN for UN1197 to read ``Extracts, liquid, for
flavor or aroma''. Additionally, PHMSA proposes to amend the text of
paragraph (c)(12)(ii), which outlines requirements for generic or
n.o.s. descriptions. The text of this paragraph provides an example
using ``Extracts, flavoring, liquid.'' Therefore, PHMSA proposes to
amend the wording of that example by replacing ``Extracts, flavoring,
liquid'' with ``Extracts, liquid, for flavor or aroma'' to correspond
to the amended PSN for UN1197. This proposed action maintains the
current level of safety for transportation of liquid extracts.
Column (3) Hazard Class or Division
    Section 172.101(d) describes column (3) of the HMT, which
designates the hazard class or division corresponding to the PSN of
that entry. Consistent with changes adopted in the 22nd revised edition
of the UN Model Regulations, PHMSA proposes to change the primary
hazard classification for the entry ``UN1891, Ethyl Bromide,'' from a
toxic liquid of Division 6.1 to a Class 3 flammable liquid. This change
in classification is consistent with the change adopted in the 2023-
2024 ICAO Technical Instructions as well as the UN Model Regulations
and is based on new test data indicating that the flash point and
boiling point of ethyl bromide has a core flammability hazard according
to the Class 3 classification criteria of the ICAO Technical
Instructions. More specifically, different data sources showed that its
flash point of -20 [deg]C (-4 [deg]F) and its boiling point of 38
[deg]C (100.4 [deg]F) meet the criteria for assignment as a Class 3 at
the PG II level--the criteria of which is having a flash point <23
[deg]C and boiling point >35 [deg]C. Additionally, rather than
classifying ethyl bromide solely as a Class 3 flammable liquid, it was
determined that the Division 6.1 hazard still applies and should remain
assigned as a subsidiary hazard. This is consistent with the HMR
precedence of the hazard table in Sec.  173.2a that instructs for a
material that meets criteria for classification as both Class 3 and
Division 6.1 (except for when a material meets the PG I poison-by-
inhalation criteria), the flammability hazard takes precedence and is
the primary hazard. These changes in hazard class and associated
packaging requirements were adopted to ensure that the hazards of ethyl
bromide are accurately communicated and appropriately packaged. PHMSA
reviewed these findings and agrees that it is appropriate to classify
ethyl bromide as a flammable liquid, with a subsidiary Division 6.1
hazard. Because of this change in hazard class, additional conforming
changes to the HMT entry for ethyl bromide are required in column (6),
as discussed below. Additionally, PHMSA expects that clearly
identifying the flammability hazard posed by this material will improve
safety by ensuring that the material is handled appropriately before
and during transport.
Column (6) Label Codes
    Section 172.101(g) describes column (6) of the HMT, which contains
label codes representing the hazard warning labels required for a
package filled with a material conforming to the associated hazard
class and proper shipping name, unless the package is otherwise
excepted from labeling. The first code is indicative of the primary
hazard of the material. Additional label codes are indicative of
subsidiary hazards. As discussed above, PHMSA proposes to modify the
primary hazard class for ``UN1891, Ethyl bromide'' to Class 3.
Consistent with this change, PHMSA proposes to assign Class 3 as the
primary hazard label and Division 6.1 as a subsidiary hazard label.
Consequently, PHMSA proposes to amend column (6) of the HMT for this
entry to reflect the warning labels required for the transport of this
hazardous material. PHMSA expects that this proposed change will
improve safety by clearly communicating the transportation hazards of
this material.
Column (7) Special Provisions
    Section 172.101(h) describes column (7) of the HMT, which assigns
special provisions for each HMT entry. Section 172.102 provides for the
meaning and requirements of the special provisions assigned to entries
in the HMT. The proposed revisions to column (7) of certain entries in
the HMT are discussed below.
Special Provision 396
    PHMSA proposes to add a new special provision, Special Provision
396, and assigning it to ``UN3538, Articles containing non-flammable,
non-toxic gas, n.o.s.'' For additional information, see Sec.  172.102
of the Section-by-Section Review.
Special Provision 398
    PHMSA proposes to assign a newly added special provision, Special
Provision 398, which pertains to the potential classification of
butylene and butylene mixtures as UN1012. This special provision
clarifies that butylene mixtures and certain butylene isomers may be
assigned to UN1012, while specifically excluding isobutylene from this
UN classification. For additional

information, see Sec.  172.102 of the Section-by-Section Review.
Special Provisions A4 and A5
    PHMSA proposes to assign Special Provision A4 to the entry
``UN2922, Corrosive liquid, toxic, n.o.s.'' and Special Provision A5 to
the entry ``UN2923, Corrosive solid, toxic, n.o.s.''. Special
Provisions A4 and A5 address liquids and solids in PG I that also pose
an inhalation toxicity hazard by limiting or prohibiting their
transportation on aircraft. In principle, all liquids or solids that
have an inhalation toxicity hazard, and assigned PG I, should be
subject to one of the two special provisions, as appropriate. However,
UN2922 and UN2923 are assigned Class 8 as the primary hazard and
Division 6.1 as a subsidiary hazard because of classification
guidelines which require hazardous materials that meet the criteria of
Class 8 and that have an inhalation toxicity of dusts and mists (LC50)
in the range of PG I, but toxicity through oral ingestion or dermal
contact only in the range of PG III or less, must be assigned to Class
8 as the primary hazard rather than Division 6.1. In reviewing these
provisions, the ICAO Dangerous Goods Panel (DGP) determined that
additional restrictions should be implemented for these hazardous
materials as the corrosive classification assigned to UN2922 and UN2923
does not negate the inhalation toxicity hazard. Because of the
inhalation hazard posed by these materials, the 2023-2024 ICAO
Technical Instructions included an amendment to impose quantity limits
for transportation of these materials by air. PHMSA agrees with this
determination and therefore proposes to assign Special Provision A4 to
UN2922, which prohibits it from transport on passenger and cargo
aircraft. PHMSA also proposes to assign Special Provision A5 to UN2923,
which prohibits this material on passenger aircraft and limits the
amount that may be transported on cargo aircraft. PHMSA expects that
correcting this conflict will improve safety by prohibiting corrosive
materials that also pose inhalation hazards on passenger aircraft and
limiting their transport on cargo aircraft.
Special Provisions A224 and A225
    PHMSA proposes to add two new air special provisions, A224 and
A225, and assign them to HMT entries ``UN3548, Articles containing
miscellaneous dangerous goods, n.o.s.'' and ``UN3538, Articles
containing non-flammable, non-toxic gas, n.o.s.,'' respectively. These
special provisions would allow for transport on both passenger aircraft
and cargo aircraft under certain conditions. For additional
information, see 172.102 of the Section-by-Section Review. Also, see
Sec.  172.102 of the Section-By-Section Review below for a detailed
discussion of the special provision amendments addressed in this NPRM.
Column (8) Packaging
    Section 172.101(i) explains the purpose of column (8) in the HMT.
Columns (8A), (8B), and (8C) specify the applicable sections for
exceptions, non-bulk packaging requirements, and bulk packaging
requirements, respectively. Columns (8A), (8B), and (8C) are completed
in a manner which indicates that ``Sec.  173.'' precedes the designated
numerical entry. Column (8A) contains exceptions from some of the
requirements of this subchapter. The referenced exceptions are in
addition to those specified in subpart A of part 173 and elsewhere in
subchapter C. The word ``None'' in this column means no packaging
exceptions are authorized, except as may be provided by special
provisions in column (7). For example, the entry ``151'' in column
(8A), associated with the proper shipping name ``Nitrocellulose with
water,'' indicates that, for this material, packaging exceptions are
provided in Sec.  173.151 of this subchapter.
    PHMSA proposes to remove references to Sec.  173.151, which provide
exceptions for Class 4 hazardous materials, in column (8A), and add the
word ``None'' for three solid desensitized explosive entries: ``UN2555,
Nitrocellulose with water with not less than 25 percent water by
mass''; ``UN2556, Nitrocellulose with alcohol with not less than 25
percent alcohol by mass, and with not more than 12.6 percent nitrogen,
by dry mass''; and ``UN2557, Nitrocellulose, with not more than 12.6
percent nitrogen, by dry mass mixture with or without plasticizer, with
or without pigment.'' These changes would remove the applicability of
the limited quantity exceptions for these hazardous materials to
correct an inconsistency regarding solid desensitized explosives.
Consistent with the UN Model Regulations, PHMSA has not authorized
limited quantity packaging exceptions for 30 other solid desensitized
explosives.\14\ Solid desensitized explosives are explosive substances
which are wetted with water or alcohols or are diluted with other
substances to form a homogeneous solid mixture to suppress their
explosive properties. Like PG I materials, solid desensitized
explosives in PG II are specifically prohibited from transport under
the limited quantity provisions in the UN Model Regulations. However,
this inconsistency was identified with respect to air transport by the
ICAO DGP (Dangerous Goods Panel), resulting in a similar amendment in
the 2023-2024 ICAO Technical Instructions. In this NPRM, PHMSA also
proposes related editorial amendments in Sec.  173.27, general
requirements for transportation by aircraft (see additional discussion
in Sec.  173.27 of Section-by-Section Review). PHMSA expects that
correcting this oversight to require that these nitrocellulose mixtures
be transported in accordance with all requirements of the HMR, rather
than permitting the use of the limited quantity exceptions in Sec.
173.151, will not only add an additional level of safety, but that it
will also facilitate the transport of these materials by streamlining
packaging and hazard communication requirements to be consistent with
requirements for similar materials and with international regulations.
---------------------------------------------------------------------------

    \14\ UN1310, UN1320, UN1321, UN1322, UN1336, UN1337, UN1344,
UN1347, UN1348, UN1349, UN1354, UN1355, UN1356, UN1357, UN1517,
UN1571, UN2555, UN2556, UN2557, UN2852, UN2907, UN3317, UN3319,
UN3344, UN3364, UN3365, UN3366, UN3367, UN3368, UN3369, UN3370,
UN3376, UN3380, and UN3474.UN1517, UN1571, UN2555, UN2556, UN2557,
UN2852, UN2907, UN3317, UN3319, UN3344, UN3364, UN3365, UN3366,
UN3367, UN3368, UN3369, UN3370, UN3376, UN3380, and UN3474.
---------------------------------------------------------------------------

Column (9) Quantity Limitations
    Section 172.101(j) explains the purpose of column (9) in the HMT.
Column (9) specifies quantity limitations for packages transported by
air and rail. Column (9) is divided into two columns: column (9A)
provides quantity limits for passenger aircraft/rail, and column (9B)
provides quantity limits for cargo aircraft.
    Consistent with changes adopted in the 2023-2024 edition of the
ICAO Technical Instructions, PHMSA proposes to amend the quantity
limitations for UN 1891, Ethyl bromide, when transported by passenger
aircraft. Previously, the maximum net quantity per package for
passenger aircraft was 5 L on the Dangerous Goods List of the ICAO
Technical Instructions; this same quantity limit is currently in place
for passenger aircraft, as indicated in column (9A) of the HMT. As a
result of the reclassification of UN1891 as a Class 3 flammable liquid,
the permitted quantity was reduced in the ICAO Technical Instructions
to 1L per packaging. This change is in line with the quantity limits
for many other Class 3 materials. PHMSA proposes to make a
corresponding change for passenger

aircraft limits in column (9A). With regard to cargo aircraft, no
changes to the 60 L maximum net quantity were made in the ICAO
Technical Instructions, as that limit is the same for Class 3 and
Division 6.1 materials. PHMSA expects that this change will provide an
additional level of safety commensurate to the newly recognized
flammability hazard posed by this material.
    PHMSA also proposes to modify the packaging limits aboard cargo
aircraft for three battery entries: ``UN2794, Batteries, wet, filled
with acid, electric storage''; ``UN2795, Batteries, wet, filled with
alkali, electric storage''; and ``UN3292, Batteries, containing
sodium.'' Specifically, these changes would limit the quantity per
packaging to 400 kg, as there is currently no limit for these items.
Typically, these articles must be packed in UN specification
packagings, and 400 kg is the maximum quantity permitted in such
packagings. These proposed changes are consistent with changes made in
the 2023-2024 ICAO Technical Instructions, which were made as a
correction to an inconsistency between the ICAO Technical Instructions
and the UN Model Regulations. Therefore, in column (9B) of the HMT, the
words ``no limit'' will be replaced by 400 kg. PHMSA expects that this
change will streamline packaging requirements by providing packaging
limits for similar items in similar packagings, consistent with
analogous international regulations. This streamlining will also
increase safety by increasing clarity on the packaging limits for these
similar items.
Section 172.102 Special Provisions
    Section 172.102 lists special provisions applicable to the
transportation of specific hazardous materials. Special provisions
contain various provisions including packaging requirements,
prohibitions, and exceptions applicable to particular quantities or
forms of hazardous materials. PHMSA proposes the following revisions to
the special provisions in this section:
Special Provision 78
    Special Provision 78 currently states that ``UN1002, Air,
compressed'' may not be used to describe compressed air which contains
more than 23.5% oxygen. It also stipulates that compressed air
containing more than 23.5% oxygen must be shipped using the description
``UN3156, Compressed gas, oxidizing, n.o.s.'' which has a Class 5
subsidiary hazard classification. PHMSA proposes to amend Special
Provision 78, in order to provide additional clarity with regard to the
permitted use of the proper shipping description UN1002. In an effort
to address specific mixtures of nitrogen and oxygen that are
commercially called ``synthetic air,'' the 22nd revised edition of the
UN Model Regulations includes a new special provision that was intended
to clarify that ``synthetic air'' may be transported under UN1002,
provided that it does not contain more than 23.5% oxygen. ``Synthetic
air'' is typically a mixture containing up to 23.5% oxygen with the
balance being nitrogen. This mixture is used in a variety of
applications, including medical and non-medical, and may be used when
ambient air is not sufficient due to the presence of contaminants. This
new special provision specifies that mixtures of nitrogen and oxygen
containing not less than 19.5% and not more than 23.5% oxygen by volume
may be transported under UN1002 when no other oxidizing gases are
present. It also states that a Division 5.1 subsidiary hazard label is
not required for any concentrations within this limit. While this
language is not drastically different than the current language in the
HMR, PHMSA expects that rewording Special Provision 78 to include the
19.5% lower bound for oxygen and the note regarding the use of the
Division 5.1 subsidiary hazard label will improve safety by providing
clearer and more useful instructions for shippers of compressed
synthetic or ambient air.
Special Provision 156
    PHMSA proposes to amend Special Provision 156 to require that, when
transported by air, a shipping paper, such as an air waybill
accompanying the shipment must indicate that the package containing
asbestos is not restricted for shipment. Currently, this special
provision excepts asbestos from the requirements of 49 CFR Subchapter C
when it is immersed or fixed in a natural or artificial binder--such as
cement, plastics, asphalt, resins, or mineral ore--in such a way that
no escape of hazardous quantities of respirable asbestos fibers can
occur. It was noted that confusion over whether a shipment was or was
not excepted from the regulations had led to delays and frustrated
shipments. The 2023-2024 ICAO Technical Instructions amended a similar
special provision to assist in providing evidence of compliance with
its requirements. PHMSA's proposed amendment to Special Provision 156
would require that, when transported by air, packages or shipping
documentation be marked to indicate that the package containing
asbestos is not restricted for shipment. PHMSA expects that this
requirement will facilitate the safe shipment of asbestos by preventing
them from being mistaken as fully regulated hazardous materials.
Special Provision 387
    Special Provision 387 provides shippers of polymerizing substances
with information regarding stabilization requirements for their
shipments. As discussed below, in an earlier rulemaking, PHMSA placed
sunset dates on the HMR provisions concerning transport provisions for
polymerizing substances to allow time for the completion of research on
various topics concerning their transport and to gather and review
empirical evidence concerning the appropriate transport provisions for
polymerizing substances. In line with other amendments proposed in this
NPRM for the transport of polymerizing substances, PHMSA is proposing
to amend Special Provision 387 to remove the sunset date of January 2,
2023. The result of this proposed amendment is that the existing
stabilization requirements noted in this special provision remain and
the sunset date is removed. See 173.21 of the Section-by-Section Review
for the full discussion of changes pertaining to polymerizing
substances.
Special Provision 396
    PHMSA proposes to add a new special provision, Special Provision
396, and assign it to ``UN3538, Articles containing non-flammable, non-
toxic gas, n.o.s,'' to authorize the transport of large and robust
articles (e.g., transformers) that include cylinders containing UN1066
``Nitrogen''; UN1956 ``Compressed gas N.O.S.''; or UN1002 ``Air,
compressed'' with the valves open to allow low quantities of gas to be
constantly supplied through a pressure regulator from a gas cylinder
connected to the transformer. Similar provisions were added in the 22nd
revised edition of the UN Model Regulations and Amendment 41-22 of the
IMDG Code to address shipments of transformers, which are typically
pressurized with nitrogen or with air but are not gas tight. Prior to
2020, transformers were transported as ``UN 3363, Dangerous Goods in
Machinery/Apparatus''; however, the packing provisions for UN3363
imposed quantity limits requiring multiple approvals from competent
authorities as specified in Special Provision 136 in the HMR (SP 301 in
the UN Model Regulations). Following more recent amendments to

the UN Model Regulations, these transformers were eligible for
transport under UN 3538, the provisions which allow these transformers
to be transported unpackaged, do not explicitly require the transformer
to be gas-tight, but instead require the valves to be closed during
transport. To obviate the need for an approval each time such
transformers are transported, a new special provision was added to the
22nd revised edition of UN Model Regulations because these transformers
only emit small quantities of nitrogen or synthetic air, which are
neither flammable, toxic, corrosive, nor oxidizing. PHMSA proposes
several safety controls in shipments of this type that are largely
consistent with the provisions adopted in the UN Model Regulations and
the IMDG Code. These proposed controls include requiring that cylinders
be connected to the article through pressure regulators and have fixed
piping to keep the pressure below 35 kPa (0.35) bar; the cylinders must
be secured to prevent shifting; the cylinders and other components must
be protected from damage and impacts during transport; the shipping
paper must include a reference to shipping under this special
provision; and if placed inside a cargo transport unit (CTU), the CTU
must be well ventilated. PHMSA notes that these international
regulations require marking the CTU with the asphyxiation warning mark
for CTUs. The HMR has not adopted this mark and is not proposing to do
so at this time. PHMSA is not proposing this mark because it views the
additional controls, specifically, the indication on the shipping
paper, as well as other operational controls noted in the proposed
special provision, as providing sufficient warning to those in the
transport chain of the dangers present and mitigation of potential
hazards. PHMSA expects that the addition of this special provision will
facilitate the transport of this specialized machinery without imposing
excessive manufacturing requirements to ensure gas tightness to prevent
the release of relatively innocuous gases during transport.
Special Provision 398
    PHMSA proposes to add Special Provision 398, pertaining to the
classification of hazardous materials under UN1012, Butylene. This new
special provision would clarify that butylene mixtures and certain
butylene isomers may be assigned to UN1012, while specifically
excluding UN1055, Isobutylene from this UN classification. Butylene,
also known as butene, includes four different isomers, corresponding to
one general chemical formula, C4H8. One of these isomers is
isobutylene, which, while similar to the other three isomers, has been
assigned a separate UN number, UN1055, which has its own set of
packaging provisions. To avoid ``UN1055, Isobutylene'' being classified
and transported under UN1012, this amendment would facilitate
consistent and proper classification of this group of hazardous
materials. This clarification for UN1012, Butylene, was added in the
22nd revised edition of the UN Model Regulations for consistency with
European regulations, which made similar changes to avoid ``UN1055,
Isobutylene'' being classified and transported under UN1012. PHMSA
proposes to add this clarifying special provision with the expectation
that it will facilitate consistent and proper classification of this
group of hazardous materials.
Special Provision 421
    Special Provision 421 is assigned to the four polymerizing
substance entries in the HMT. Currently this special provision notes
that these entries will no longer be effective on January 2, 2023,
unless extended or terminated prior to this date. As discussed in the
``Executive Summary'' section of this rulemaking, PHMSA had placed
sunset dates on the HMR provisions concerning transport provisions for
polymerizing substances to allow time for the completion of research on
various topics concerning their transport and to gather and review
empirical evidence concerning the appropriate transport provisions for
polymerizing substances. As we have completed this review, we are
proposing to delete Special Provision 421 and to maintain the existing
polymerizing substance HMT entries.
Special Provision 441
    PHMSA proposes to add a new Special Provision 441, assigning it to
``UN1045, Fluorine, compressed.'' This new special provision would
specifically address gas mixtures containing fluorine and inert gases
in UN pressure receptacles in accordance with changes adopted in the
22nd revised edition of the UN Model Regulations. Specifically, this
change would provide latitude with regard to the maximum allowable
working pressure when fluorine is a part of a mixture, which contains
less reactive gases, such as nitrogen, when the mixture is transported
in UN pressure receptacles. As a strongly oxidizing gas, pure fluorine
requires specific safety measures because it reacts spontaneously with
many organic materials and metals. Additionally, because of its
reactive properties, the UN Model Regulations limit the maximum
allowable working pressure for pure fluorine in cylinders to 30 bar and
a minimum test pressure of 200 bar is also required. However, prior to
changes adopted in the 22nd revised edition of the UN Model
Regulations, there was no guidance on the maximum allowable working
pressure and minimum test pressure for mixtures of gases which contain
fluorine. Commercially, these mixtures are often placed on the market
and used in concentrations, which may include as little as one percent
fluorine combined with noble gases, or ten to twenty percent fluorine
mixed with nitrogen. Due to the lack of specific provisions addressing
fluorine gas mixtures, such mixtures containing relatively
inconsequential amounts of fluorine were subject to the same
requirements (restrictive maximum allowable working pressures) as pure
fluorine. Given that fluorine, in a mixture with inert gases or
nitrogen, is less reactive towards materials than pure fluorine, the
UNSCOE determined that gas mixtures containing less than 35% fluorine
by volume should no longer be treated like pure fluorine and may use a
higher maximum allowable working pressure. The new packing provision
added in the 22nd revised edition of the UN Model Regulations allows
for pressure receptacles containing mixtures of fluorine and inert
gases (including nitrogen) to have higher working pressures by allowing
for consideration of the partial pressures exerted by the other
constituents in the mixture, rather than limiting the pressure in the
receptacle based on fluorine alone. Specifically, the provision permits
mixtures of fluorine and nitrogen with a fluorine concentration below
35% by volume to be filled in pressure receptacles up to a maximum
allowable working pressure for which the partial pressure of fluorine
does not exceed 31 bar absolute. Additionally, for mixtures of true
inert gases and fluorine, where the concentration of fluorine is below
35% by volume, pressure receptacles may be filled up to a maximum
allowable working pressure for which the partial pressure of fluorine
does not exceed 31 bar absolute, provided that when calculating the
partial pressure, the coefficient of nitrogen equivalency is determined
and accounted for in accordance with ISO 10156:2017. Finally, the newly
added provision for these two types of gas mixtures limits the working
pressure to 200 bar or less

and requires that the minimum test pressure of pressure receptacles for
these mixtures equals 1.5 times the working pressure or 200 bar, with
the greater value to be applied. While PHMSA is not adding similar
provisions for this type of mixture in DOT specification cylinders in
this rulemaking, PHMSA has evaluated the rationale and the methods for
determining the pressure limits in UN pressure receptacles and finds
that they provide an equivalent level of safety. For this reason, PHMSA
proposes to adopt the packing instruction as drafted in the UN Model
Regulations as a new special provision for UN1045.
Special Provision A54
    Special Provision A54 specifies that, irrespective of the quantity
limits in column (9B) of the Sec.  172.101 table, a lithium battery,
including a lithium battery packed with, or contained in, equipment
that otherwise meets the applicable requirements of Sec.  173.185, may
have a mass exceeding 35 kg, if approved by the Associate Administrator
prior to shipment. PHMSA proposes to amend this special provision to
require that, when this special provision is used, the special
provision number must be indicated on the shipping paper. PHMSA expects
that this amendment will enhance safety by improving the communication
of potential hazards, as without such indication, the need for shipment
acceptance staff to check and ensure a copy of the approval
accompanying the shipment can potentially be missed.
Special Provisions A224 and A225
    The 2023-2024 ICAO Technical Instructions added two new special
provisions permitting the transport of articles containing hazardous
materials aboard passenger and cargo aircraft. Currently these articles
are forbidden from transport on passenger and cargo aircraft, as
specified in column (9) of the HMT. However, the ICAO DGP developed
these packaging provisions, which include provisions that ensure
appropriate gas containment during transport. The aim of these special
provisions was to facilitate the transport of large articles containing
environmentally hazardous substances (such as aircraft landing gear
struts filled with hydraulic fluid) and large articles containing a
non-flammable, non-toxic gas (such as new types of magnetic resonance
imaging (MRI) scanners which often contain compressed helium as well as
lithium cells or batteries). These amendments were adopted in the 2022-
2023 ICAO Technical Instructions and PHMSA proposes to mirror these
provisions by adding two new air-specific special provisions, A224 and
A225, and assigning them to HMT entries ``UN3548, Articles containing
miscellaneous dangerous goods, n.o.s.'' and ``UN 3538, Articles
containing non-flammable, non-toxic gas, n.o.s.'' respectively.
    These special provisions would allow for the transport of large
articles containing a non-flammable, non-toxic gas or environmentally
hazardous substances on both passenger aircraft and cargo aircraft only
under certain conditions. Specifically, under Special Provision A224,
``UN3548, Articles containing miscellaneous dangerous goods, n.o.s.''
would be permitted on passenger and cargo aircraft, provided that the
only dangerous goods in the article are environmentally hazardous
substances with or without lithium cells or batteries that comply with
Sec.  173.185(c). Similarly, under Special Provision A225, ``UN3538,
Articles containing non-flammable, non-toxic gas, n.o.s.'' would be
permitted aboard passenger and cargo aircraft, provided that the
article contains only a Division 2.2 gas that does not have a
subsidiary hazard but excluding refrigerated liquefied gases and other
gases forbidden for transport on passenger aircraft with or without
lithium cells or batteries that comply with Sec.  173.185(c). In
addition to containing only the permitted hazardous materials, the
special provision would also require that shippers comply with
additional packaging requirements, specified in Sec.  173.232, and that
the special provision be indicated on shipping documentation.
    The ICAO DGP agreed that these provisions were appropriate given
that environmentally hazardous substances pose a very low hazard in air
and that non-flammable, non-toxic gases without subsidiary hazard are
already allowed on both passenger and cargo aircraft as well as certain
other articles containing similar gases. PHMSA agrees and expects that,
in addition to aligning the HMR with recent changes added to the 2023-
2024 ICAO Technical Instructions, the addition of these provisions will
facilitate the transport of these materials by air while maintaining
the current level of safety for air transport of certain hazardous
materials.
IP Codes
    IP Codes are special provisions that are assigned to specific
commodities, applicable when that commodity is transported in IBCs.
Table 2 in Sec.  172.102 specifies the requirements corresponding to
the IP Code indicated in column (7) of the HMT. In this NPRM, PHMSA
proposes to amend the text of IP15 and to add a new IP Code, IP22.
IP15
    PHMSA proposes to amend the text of IP15 to clarify language
pertaining to the authorized period of use of composite IBCs.
Currently, IP15 states that for IBCs containing UN2031 with more than
55% nitric acid, rigid plastic IBCs and composite IBCs that have a
rigid plastic inner receptacle are authorized for two years from the
date of IBC manufacture. A change to a corresponding special provision
was adopted in the 22nd revised edition of the UN Model Regulations to
make clear that the authorized two-year period of use specifically
refers to the duration of use of the inner receptacle of composite IBCs
and not to the outer framework. The intent of this requirement is to
limit the inner receptacle for composite IBCs to the two-year period of
use when used for this specific corrosive material, rather than
requiring that the outer framework be inspected as often. The entire
composite IBC remains subject to the five-year inspection interval,
prescribed in Sec.  180.352. This change in the UN Model Regulations
was in response to mistranslations of the UN Model Regulations, which
led to inconsistent maintenance of composite IBCs. While PHMSA is not
aware of any issues surrounding the language in IP15, PHMSA expects
that making this editorial change will ensure that international users
are not confused by the text of the HMR, and this clarification will
enhance safe transport of hazardous materials in such IBCs.
IP22
    As discussed earlier, PHMSA proposes to add a new IP code, IP22,
for the new entry ``UN 3550, Cobalt dihydroxide powder, containing not
less than 10% respirable particles.'' This special provision would
authorize the transport of Cobalt dihydroxide powder, a Division 6.1
solid, in flexible IBCs that are equipped with siftproof liners that
would prevent any egress of dust during transport. This hazardous
material was recently classified as a solid with a toxic-by-inhalation
hazard. Prior to this Division 6.1 classification, cobalt dihydroxide
had been transported as ``UN3077, Environmentally hazardous substance,
solid, n.o.s., Class 9'' in unlined flexible IBCs. However, this
reclassification posed a problem for shippers because flexible IBCs are
not authorized for Division 6.1 toxic solids. In response to the recent
EU GHS changes, many shippers stopped using

unlined flexible IBCs and began using lined 13H3 or 13H4 flexible IBCs
to prevent the release of dust.\15\ Additionally, the industry also
developed a new design type flexible IBC with an improved liner to
prevent egress of dust. This new design type 13H3 flexible IBC has been
tested and approved to PG I by international competent authorities.
Consequently, to address the packaging problem shippers faced as a
result of new classification criteria, the UNSCOE created a special
provision that would allow this material to be transported in lined
siftproof packagings. This decision was based on the forty-year record
of safe transport in this material in PG III packagings, as well as the
additional level of sift-proofness provided by the new design track
record of the new siftproof packagings. PHMSA agrees with the UNSCOE's
determination that siftproof flexible IBCs are appropriate packagings
for this material and expects that this special provision will avoid
unnecessary disruptions in the transport of this essential raw material
while still ensuring safe transport of this material. The lack of a UN
entry for this specific combination of physical and hazardous
attributes--solid and toxic-by-inhalation--led to the development of
this new UN entry by the UNSCOE. More specifically, UN3550 was created
for cobalt dihydroxide to resolve the packaging and transport problem
faced by shippers because of the new Division 6.1 classification.
Consequently, based on the record of safe transport by multi-modal
means in flexible IBCs, with no recorded accidents, incidents, or
health issues as UN3077, the UNSCOE's resolution of this packaging
conflict was to develop a new UN number, assigning appropriate packing
provisions and creating a special packaging condition which permits the
use of flexible IBCs.
---------------------------------------------------------------------------

    \15\ https://unece.org/DAM/trans/doc/2019/dgac10c3/UN-SCETDG-56-INF19e.pdf.
---------------------------------------------------------------------------

C. Part 173

Section 173.4b
    Section 173.4b specifies the hazard criteria and packaging
requirements to qualify for the de minimis exception--i.e., exceptions
from certain HMR requirements for very minor amounts of hazardous
material. For non-infectious biological specimens that contain minor
amounts of preservatives that are a hazardous material, PHMSA proposes
to add a reference to formaldehyde solution in paragraphs (b)(1)(i) and
(b)(1)(ii) to clarify that the conditions for packing of the specimens
applies to formaldehyde solution too. Currently, paragraph (b) excepts
non-infectious biological specimens, such as those of mammals, birds,
amphibians, reptiles, fish, insects, and other invertebrates,
containing small quantities of chemical preservatives like ethanol or
formaldehyde solution from the HMR, provided certain conditions are
met. For example, paragraph (b)(1) provides instruction for when
alcohol or an alcohol solution is used, such as when a specimen is
placed in a plastic bag, that any free liquid in the bag must not
exceed 30 mL. The ICAO Technical Instructions include a similar
instruction, yet during a review of the ICAO Technical Instructions,
the ICAO DGP noted that the exception does not address when
formaldehyde solutions are used as preservatives for specimens; thus,
there was no specified limit on the amount of free liquid formaldehyde
solution that may be in a packaging. Consequently, the 2023-2024 ICAO
Technical Instructions include an amendment to the de minimis
provisions to specify limits for formaldehyde solutions. PHMSA agrees
with this clarifying amendment and expects that adopting a similar
change will enhance safety by removing uncertainty about whether the
quantity limits also apply formaldehyde solutions.
Section 173.21
    Section 173.21 describes situations in which offering for transport
or transportation of certain materials or packages is forbidden.
Examples of such forbidden shipments include materials designated as
``Forbidden'' in Column (3) of the HMT; electrical devices that are
likely to generate sparks and/or a dangerous amount of heat; and
materials that are likely to decompose or polymerize and generate
dangerous quantities of heat or gas during decomposition or
polymerization. This last group of materials is addressed in paragraph
(f) of this section, which outlines the conditions under which
materials which are likely to decompose or polymerize unless stabilized
or inhibited in some manner (e.g., with temperature controls or
chemical stabilization) are authorized for transport.
    PHMSA proposes to lower the temperature threshold at which
transport of certain materials in portable tanks require temperature
control. Specifically, this amendment would lower this threshold
temperature for a material which is likely to decompose with a self-
accelerated decomposition temperature (SADT) or polymerize with a self-
accelerated polymerization temperature (SAPT) from 50 [deg]C (122
[deg]F) to 45 [deg]C (113 [deg]F) when transported in portable tanks.
This means that if adopted, portable tanks containing materials likely
to decompose or polymerize at temperatures greater than 45 [deg]C will
not be required to be stabilized or inhibited by temperature control
and otherwise be forbidden from transport. In an earlier rulemaking,
HM-215N, PHMSA gave notice that at that time, it would not adopt
reductions in temperature thresholds for shipments in portable tanks
and maintained a 50 [deg]C (122 [deg]F) threshold for requiring
temperature control to allow for additional time to conduct research on
the impacts of such a change and to allow additional time to fully
consider the issue. However, PHMSA-sponsored research, which was
completed in February 2021 by APT Research, Inc. (APT),\16\ has
informed our proposals in this NPRM. That research aimed to gather more
information concerning temperature control of polymerizing substances
in portable tanks and testing requirements for these substances
intended to be transported in portable tanks or intermediate bulk
containers (IBCs), as these two areas of safety controls in the HMR
differed from those adopted in the international consensus standards
and regulations. The report following research conducted by APT noted
that ``relaxing the temperature control requirements as proposed by HM-
215N is assessed to be an appropriate approach since it will harmonize
U.S. regulations with international requirements and no additional
hazards were identified for any common polymers during transport.
Polymers in industry with SAPTs approaching 45 [deg]C or 50 [deg]C were
found to be uncommon.'' PHMSA agrees with this assessment and is
proposing to lower this temperature threshold at which temperature
control is required for portable tanks containing a material which is
likely to decompose with a SADT or polymerize with a SAPT from 50
[deg]C (122 [deg]F) or less to 45 [deg]C (113 [deg]F) or less. Although
the APT research focused on polymerizing materials, PHMSA believes
decomposing materials to behave similarly and has opted to apply the
changed to both material types. PHMSA believes this proposed amendment
will help facilitate international transportation of these goods and
while maintaining the high standard of safety in the HMR for
transportation of decomposing and polymerizing materials. To that end,
PHMSA also proposes to amend the table in paragraph (f)(1) to
accommodate

the specific temperature controls applicable to decomposing and
polymerizing substances transported in portable tanks. This proposed
amendment would align the HMR with temperature thresholds for
substances with SADTs and SAPTs transported in portable tanks with
those found in the UN Model Regulations and the IMDG Code. Further,
based on this change specific to use of portable tanks, PHMSA would
revise the table in paragraph (f)(1) to include packaging type as a
factor in determining the criteria for control temperatures and
emergency temperatures. Lastly, PHMSA proposes to amend paragraph (f)
to provide a reference to the lower threshold of 45 [deg]C (113 [deg]F)
for portable tanks and include a reference to proposed language
concerning organic peroxides that require temperature control.
Paragraph (f)(2) would be revised to (f)(2)(i)-(iii) to indicate
general temperature control requirements for organic peroxides by type.
These requirements are consistent with the UN Model Regulations and
ensure that appropriate temperature control provisions are applied to
organic peroxides not specifically listed in the Organic Peroxide Table
in Sec.  173.225.
---------------------------------------------------------------------------

    \16\ Report can be accessed in Docket No. PHMSA-2021-0092 on
www.regulations.gov.
---------------------------------------------------------------------------

    Additionally, to fully adopt these proposed changes, PHMSA proposes
to remove the phaseout language currently found in (f)(1)(i), which
states that the provisions concerning polymerizing substances in
paragraph (f) will be effective until January 2, 2023. Finally, based
on results of the research, PHMSA proposes to maintain the current
defining criteria for polymerizing substances, in Sec.  173.124, that a
polymerizing substance must successfully pass the UN Test Series E at
the ``None'' or ``Low'' level, or achieve equivalent criteria using an
alternative test method with the approval of the Associate
Administrator, prior to selection of an appropriate portable tank or
IBC. While this rulemaking action is being completed through the final
rule stage, PHMSA directs stakeholders to review the enforcement
discretion notice available on the PHMSA website \17\ and in this
rulemaking docket for the continued movement of these materials in
accordance with regulations in effect prior to January 2, 2023.
---------------------------------------------------------------------------

    \17\ https://www.phmsa.dot.gov/regulatory-compliance/phmsa-guidance/phmsa-notice-enforcement-policy-regarding-international.
---------------------------------------------------------------------------

Section 173.27
    Section 173.27 outlines general requirements for transportation by
aircraft, including requirements and limitations for hazardous
materials transported in limited quantities. Currently, the provisions
for combination packagings in paragraph (f)(2) specify that materials
or articles not authorized as a limited quantity for transportation by
aircraft include all PG I materials; self-reactive flammable solids in
Division 4.1; spontaneously combustible materials in Division 4.2; and
liquids that are dangerous when wet in Division 4.3. The ICAO Technical
Instructions included similar language for Division 4.1 materials by
allowing non-self-reactive Division 4.1 materials assigned to PG II or
PG III to be transported as limited quantities. However, the ICAO DGP
identified a conflict with limited quantity provisions in the ICAO
Technical Instructions and the limited quantity provisions in the UN
Model Regulations pertaining to four Division 4.1 materials, assigned
PG II: ``UN 2555, Nitrocellulose with water with not less than 25
percent water by mass''; ``UN 2556, Nitrocellulose with alcohol with
not less than 25 percent alcohol by mass, and with not more than 12.6
percent nitrogen, by dry mass''; ``UN 2557, Nitrocellulose, with not
more than 12.6 percent nitrogen, by dry mass mixture with or without
plasticizer, with or without pigment''; and ``UN 2907, Isosorbide
dinitrate mixture with not less than 60 percent lactose, mannose,
starch or calcium hydrogen phosphate.'' Despite not being defined as
self-reactive, the UN Model Regulations have never included these
specific Division 4.1 flammable solid materials for transport as
limited quantities. The ICAO Technical Instructions were amended for
consistency with the UN Model Regulations to clearly indicate that the
transport of these four PG II materials in Division 4.1 are not
authorized for transportation by aircraft as limited quantities. PHMSA
proposes to add language in Sec.  173.27(f)(2)(i)(D) to explicitly
include the UN identification numbers for these materials, indicating
that these materials may not be transported as limited quantities by
aircraft. PHMSA expects that this change will add an additional level
of safety by correcting this packaging provision, which has been
inconsistent with those in place for materials that pose similar
hazards.
Section 173.124
    Section 173.124 outlines defining criteria for Divisions 4.1
(Flammable solid), 4.2 (Spontaneously combustible), and 4.3 (Dangerous
when wet material). In an earlier rulemaking, PHMSA placed phaseout
dates on the HMR provisions concerning transport provisions for
polymerizing substances to allow time for the completion of research on
various topics concerning their transport and to gather and review
empirical evidence concerning the appropriate transport provisions for
polymerizing substances. In line with other amendments proposed in this
NPRM for the transport of polymerizing substances, PHMSA is proposing
to remove paragraph (a)(4)(iv), which is the phaseout date of January
2, 2023. The result of this proposed amendment will be to remove the
phaseout date and keep the existing requirements--as outlined in
paragraph (a)(4)--effective beyond the January 2, 2023, date.
Section 173.137
    Section 173.137 prescribes the requirements for assigning a packing
group to Class 8 (corrosive) materials. PHMSA proposes to authorize the
use of an additional test method, Test No. 439, In Vitro Skin
Irritation: Reconstructed Human Epidermis Test Method'' as well as
editorial changes to this section to provide clarity regarding the use
of the authorized OECD Guidelines for the Testing of Chemicals.
    Currently, the HMR requires offerors to classify Class 8 materials
and assign a packing group based on tests performed in accordance with
various OECD Guidelines for the Testing of Chemicals (TG), including a
skin corrosion test (in vivo) and various in vitro testing guidelines
that do not involve animal testing. Data obtained from the currently
authorized test guidelines is the only data acceptable for
classification and assignment of a packing group. Specifically for PG
I, II, or III determinations, the HMR authorize the use of OECD
Guidelines for the Testing of Chemicals, Test No. 435, ``In Vitro
Membrane Barrier Test Method for Skin Corrosion'' and Test No. 404,
``Acute Dermal Irritation/Corrosion'' (an in vivo test method). The HMR
also authorize the use of OECD Test No. 430 ``In Vitro Skin Corrosion:
Transcutaneous Electrical Resistance Test (TER)'' and Test No. 431,
``In Vitro Skin Corrosion: Reconstructed Human Epidermis (RHE) Test
Method'', however the scope of what these tests can determine is
limited. For that reason, Test No. 430 is authorized for use only to
determine whether a material is corrosive or not; materials that are
determined to be corrosive using this test require additional testing
using Test Nos. 435 or 404 or assignment to the most conservative
packing group, PG I. Similarly, Test No. 431 may also be used to
determine whether or not a material is corrosive,

however while this can identify when a corrosive must be assigned PG I,
it cannot differentiate between PG II and III materials. Consistent
with the UN Model Regulations, when this method does not clearly
distinguish between PG II or PG III, the HMR allow the material to be
transported as PGII without further in vivo testing. Consistent with
changes made to the 22nd revised edition of the UN Model Regulations,
PHMSA proposes to authorize an additional TG, OECD Test No. 439, ``In
Vitro Skin Irritation: Reconstructed Human Epidermis Test Method'', as
an authorized test, which may be used to exclude a material from
classification as a corrosive material. Test No. 439 was adopted in the
UN Model Regulations because it provides another means of testing,
without the use of live animals, that can easily identify materials as
non-corrosive. However, while Test No. 439 may be used for the hazard
identification of irritant chemicals, it is limited in that it simply
allows materials to be identified as either corrosive or non-corrosive
to skin. Because this test method only identifies the material as
corrosive or not, the UN Model Regulations added an additional
provision requiring that materials, which are tested using Test No. 439
and indicate corrosivity, must be assigned to the most conservative PG
(i.e., PG I), unless additional tests are performed to provide more
specific data that can be used to assign a less conservative PG. The
addition of Test No. 439 as an authorized test method will provide
greater flexibility for shippers to classify, package, and transport
corrosive material, while maintaining the HMR safety standard for
transport of corrosive materials.
    With regard to the editorial changes in this section, PHMSA
proposes to amend the text of this section to provide clarity regarding
the authorized OECD Testing of Chemicals. Additionally, PHMSA proposes
to amend the last paragraph of the introductory text, which currently
states that assignment to packing groups I through III must be made
based on data obtained from tests conducted in accordance with OECD
Guideline Number 404 or Number 435, to remove the reference to Test No.
435. Since its update in 2015, the criteria for packing group
assignments in Test No. 435 are no longer the same as the criteria for
Test Guideline 404. PHMSA expects that these amendments will enhance
safety by providing clarity regarding the proper testing and assignment
of packing groups and promote efficiency by streamlining the assignment
of packing groups.
Section 173.167
    Section 173.167 contains the packaging instructions and exceptions
for ID8000 consumer commodities. The ID8000 entry was added to the HMR
in final rule HM-215K,\18\ with the intent of aligning the HMR with the
ICAO Technical Instructions for the air transportation of limited
quantities of consumer commodity material. Based on inquiries from
shippers and carriers, PHMSA understands that confusion exists
regarding the requirements for hazard communication and ability to
withstand pressure differential for packages of ID8000, consumer
commodity material when moved by modes other than air. In 2012 and
2017, PHMSA issued letters of interpretation regarding the
applicability and hazard communication requirements for ID8000
shipments.\19\ Both of these letters of interpretation recognized that
ID8000 shipments are inherently ``limited quantity'' and provided the
opinion that for transportation by highway, rail, and vessel, ID8000
packages could be marked with the standard marking found in Sec.
172.315(a)(1) (i.e., without the ``Y''). In 2022, PHMSA received a
petition for rulemaking, designated P-1762,\20\ from the Council on the
Safe Transportation of Hazardous Articles (COSTHA) relating to ID8000.
---------------------------------------------------------------------------

    \18\ 76 FR 3307 (Jan. 19, 2011).
    \19\ Ref. No. 11-0090 (May 3. 2012); Ref. No. 16-0075 (Jan. 9,
2016).
    \20\ https://www.regulations.gov/document/PHMSA-2022-0007-0001.
---------------------------------------------------------------------------

    In consideration of P-1762 and consistent with these letters of
interpretation regarding the requirements for ID8000 shipments, PHMSA
proposes to revise the requirements in Sec.  173.167 for ID8000,
consumer commodity material. The intent of this proposed revision is to
clearly address requirements for all modes of transportation, while
continuing to recognize that the history and intent of the ID8000,
consumer commodity, entry is closely tied to the ICAO Technical
Instructions and air transportation.
    First, PHMSA proposes editorial revisions to the title of the
section and introductory language in paragraph (a). PHMSA proposes to
rename the section ``ID8000 consumer commodities'' to distinguish this
section from the historical ``ORM-D, consumer commodity'' HMT entry and
an exception that ceased to be effective on December 31, 2020. PHMSA
purposely phased out the ``ORM-D, consumer commodity'' classification
and description to remove the dual system of shipping certain limited
quantities domestically and internationally, as it was a source of
confusion.
    PHMSA acknowledges that there may be circumstances where persons
need to transport ID8000 packages between locations--e.g., to a
warehouse for consolidation, etc.--without needing or using air
transportation. Therefore, PHMSA recognizes the need to not only
accommodate that portion of transport but also provide assurances that
any ID8000 package is appropriately prepared for air transportation,
regardless of whether air transportation is actually used. PHMSA also
proposes to clarify that ID8000 material is inherently a limited
quantity, by adding the phrase ``limited quantity'' to the Sec.
173.167(a) introductory text. Finally, PHMSA proposes to remove the
phrase ``when offered for transportation by aircraft'' from the
introductory language in paragraph (a) and to restructure the existing
first sentence of the section into two separate statements. This
revision is intended to clarify that the materials and quantities
listed in this section may be transported by all modes and to clarify
that only the materials listed in paragraph (a) are eligible to be
transported as ``ID8000, consumer commodity.''
    More significantly, PHMSA proposes to revise the structure of the
section by moving the two requirements in the currently effective
language of paragraph (b)--applicable only to air transportation--to
new subparagraphs (6) and (7) of paragraph (a). This would have the
effect of making all packages of ID8000 material subject to the limited
quantity marking requirements of Sec.  172.315(b) to include the ``Y''
limited quantity marking, and other markings required by part 172
subpart D, including the ID number marking and PSN. This revision would
also have the effect of requiring compliance with the Sec.  173.27(c)
pressure differential requirement for transportation by all modes. The
intent of this proposed revision is two-fold:
    1. Provide clarity to shippers on the hazard communication and
pressure differential requirements for all shipments of ID8000,
consumer commodity packages.
    2. Ensure that ID8000, consumer commodity packages--wherever they
are in the transportation stream--meet the requirements for air
transportation.
    As proposed, ID8000 packages would continue to be provided
exceptions from shipping papers and labels when transported by highway
and rail. PHMSA proposes to provide a labeling exception for ID8000
packages transported by vessel, which aligns with the labeling
exception provided to