Environmental Quality (CEQ) (40 CFR part 1500), require Federal
agencies to consider the consequences of major Federal actions and
prepare a detailed statement on actions that significantly affect the
quality of the human environment. The CEQ regulations require Federal
agencies to conduct an environmental review considering: (1) The need
for the proposed action; (2) alternatives to the proposed action; (3)
probable environmental impacts of the proposed action and alternatives;
and (4) the agencies and persons consulted during the consideration
process.
1. Need for the Action
    This final rule responds to 20 petitions for rulemaking submitted
by the regulated community. The issues discussed in this final rule
will update and expand the use of currently authorized industry
consensus standards; revise the construction, marking, and testing
requirements of DOT 4-series cylinders; clarify the filling
requirements for cylinders; discuss the handling of cylinders used in
fire suppression systems; and revise the requalification requirements
for cylinders.
    This final rule discusses the following amendments to the HMR:
     Replace the currently incorporated Seventh Edition of the
CGA's publication C-6 Standards for Visual Inspection of Steel
Compressed Gas Cylinders with the revised Eleventh Edition and update
the appropriate references throughout the HMR.
     Revise the manufacturing requirements for certain DOT 4-
series cylinders.
     Revise the requirements for the requalification of DOT-
specification cylinders by pressure testing found in 49 CFR part 180,
subpart C.
     Allow the use of the labels described in the Eighth
Edition of CGA's publication C-7 Guide to the Preparation of
Precautionary Labeling and Marking of Compressed Gas Containers (Tenth
edition currently incorporated by reference in the HMR) Appendix A on
cylinders contained in overpacks.
     Require manufacturers to mark certain newly manufactured
cylinders suitable for the transport of liquefied compressed gas with
the mass weight or tare weight, and water capacity.
     Allow non-specification cylinders used in a fixed fire
suppression system to be transported under the same exceptions as those
provided for fire extinguishers, under certain conditions and
limitations.
     Clarify filling limits for a liquefied compressed gas in a
manifold or a multiple element gas container (MEGC).
     Clarify the requirements for filling non-specification
cylinders for export or use on board a vessel.
2. Alternatives Considered
    Alternative (1) No Action: Under this alternative, the current
regulatory standards would remain in effect. PHMSA would not adopt any
of the petitions or incorporate any of the special permits under
consideration. As a result, PHMSA would not update, clarify, and
provide relief from certain existing regulatory requirements to promote
safer transportation practices, eliminate unnecessary regulatory
requirements, and facilitate international commerce. We rejected the no
action alternative.
    Alternative (2) Preferred Alternative: With this alternative, PHMSA
responds to 20 petitions for rulemaking, clarifies other requirements
in the HMR, and addresses areas of concern that are currently left out
of the HMR.
3. Environmental Impacts
    Hazardous materials are substances that may pose a threat to public
safety or the environment during transportation because of their
physical, chemical, or nuclear properties. Under the HMR, hazardous
materials are transported by aircraft, vessel, rail, and highway. The
hazardous materials regulatory system is a risk management system that
is prevention-oriented and focused on identifying a safety hazard and
reducing the probability and quantity of a hazardous material release.
The potential for environmental damage or contamination exists when
packages of hazardous materials are involved in accidents or en route
incidents resulting from cargo shifts, valve failures, package
failures, loading, unloading, collisions, handling problems, or
deliberate sabotage. The release of hazardous materials can cause the
loss of ecological resources (e.g., wildlife habitats) and the
contamination of air, aquatic environments, and soil. Contamination of
soil can lead to the contamination of ground water. Compliance with the
HMR substantially reduces the possibility of accidental release of
hazardous materials.
    Anticipated Impact under Alternative (1) No Action: Potential for
increased releases of hazardous materials due to unclear regulatory
language and use of outdated industry standards.
    Anticipated Impact under Alternative (2) Preferred Alternative:
Decreased releases of hazardous materials due to increased clarity of
regulatory requirements and updated industry standards. Specifically,
increased clarity for MEGC filling requirements will decrease the
chances of pressure receptacle overfill which can result in
catastrophic releases of hazardous materials. It is anticipated that
the petitions discussed in this final rule would have minimal, if any,
environmental consequences.
4. Agencies Consulted
Occupational Safety and Health Administration
National Institute of Standards and Technology
U.S. Environmental Protection Agency
5. Conclusion
    PHMSA has conducted a technical review of the amendments discussed
in this final rule and determined that no significant environmental
impact will result from this final rule. The amendments would provide
protection against the release of hazardous materials based on sound
scientific methods and would not result in unusual stresses on the
cylinders used to contain these hazardous materials or adversely impact
human health or the environment. PHMSA received no comments
specifically addressing the environmental impacts of changes made in
this final rule.

K. Privacy Act

    In accordance with 5 U.S.C. 553(c), DOT solicits comments from the
public to better inform its rulemaking process. DOT posts these
comments, without edit, including any personal information the
commenter provides, to www.regulations.gov, as described in the system
of records notice (DOT/ALL-14 FDMS), which can be reviewed at
www.dot.gov/privacy.

L. International Trade Analysis and Executive Order 13609

    The Trade Agreements Act of 1979 (Pub. L. 96-39), as amended by the
Uruguay Round Agreements Act (Pub. L. 103-465), prohibits Federal
agencies from establishing any standards or engaging in related
activities that create unnecessary obstacles to the foreign commerce of
the United States. Pursuant to these Acts, the establishment of
standards is not considered an unnecessary obstacle to the foreign
commerce of the United States, so long as the standards have a
legitimate domestic objective, such as the protection of safety, and do
not operate in a manner that excludes imports that meet this objective.
The statute also requires consideration of international standards, and
where appropriate, that they be the basis for U.S. standards. PHMSA
notes the purpose is to ensure the safety of the American public and
has assessed the effects of this final rule to ensure that it does not
exclude imports that meet this objective. The final rule may have
positive impacts on international trade because it increases the level
of harmonization between U.S. regulations and international standards,
which is also consistent with the policy in Executive Order 13609,
``Promoting International Regulatory Cooperation,'' 77 FR 26413. As a
result, this final rule is not considered as creating an unnecessary
obstacle to foreign commerce.

M. National Technology Transfer and Advancement Act

    The National Technology Transfer and Advancement Act of 1995 (15
U.S.C. 272 note) directs Federal agencies to use voluntary consensus
standards in their regulatory activities unless doing so would be
inconsistent with applicable law or otherwise impractical. Voluntary
consensus standards are technical standards (e.g., specification of
materials, test methods, or performance requirements) that are
developed or adopted by voluntary consensus standards bodies. This
final rule adopts five voluntary consensus standards developed by the
Compressed Gas Association, which are discussed in detail in the
``Section-by-Section Review'' for Sec.  171.7.

List of Subjects

49 CFR Part 107

    Administrative practice and procedure, Hazardous materials
transportation, Penalties, Reporting and recordkeeping requirements.

49 CFR Part 171

    Exports, Hazardous materials transportation, Hazardous waste,
Imports, Incorporation by reference, Reporting and recordkeeping
requirements.

49 CFR Part 173

    Hazardous materials transportation, Incorporation by reference,
Packaging and containers, Radioactive materials, Reporting and
recordkeeping requirements, Uranium.

49 CFR Part 178

    Hazardous materials transportation, Incorporation by reference,
Motor vehicle safety, Packaging and containers, Reporting and
recordkeeping requirements.

49 CFR Part 180

    Hazardous materials transportation; Motor carriers, Incorporation
by reference, Motor vehicle safety, Packaging and containers, Railroad
safety, Reporting and recordkeeping requirements.

    In consideration of the foregoing, PHMSA amends 49 CFR chapter I as
follows:

PART 107--HAZARDOUS MATERIALS PROGRAM PROCEDURES

0
1. The authority citation for part 107 continues to read as follows:

    Authority:  49 U.S.C. 5101-5128, 44701; Pub. L. 101-410, Section
4; Pub. L. 104-121, Sections 212-213; Pub. L. 104-134, Section
31001; Pub. L. 114-74, Section 4 (28 U.S.C. 2461 note); 49 CFR 1.81
and 1.97; 33 U.S.C. 1321.

0
2. In Sec.  107.803, revise paragraph (c)(3) to read as follows:

Sec.  107.803   Approval of an independent inspection agency (IIA).

* * * * *
    (c) * * *
    (3) Detailed description of the applicant's qualifications and
ability to perform the inspections and to verify the inspections
required by parts 178 and 180 of this chapter; or those required under
the terms of a special permit issued under this part.
* * * * *

0
3. In Sec.  107.805, revise paragraphs (c)(3) and (4) and add paragraph
(c)(5) to read as follows:

Sec.  107.805   Approval of cylinder and pressure receptacle
requalifiers.

* * * * *
    (c) * * *
    (3) A certification that the facility will operate in compliance
with the applicable requirements of subchapter C of this chapter;
    (4) The signature of the person making the certification and the
date on which it was signed; and
    (5) For a mobile unit operation (as defined in Sec.  180.203 of
subchapter C of this chapter), the type of equipment to be used, the
specific vehicles to be used, the geographic area the applicant is
requesting to operate within, and any differences between the mobile
operation and the facility operation as described under paragraph
(c)(2) of this section.
* * * * *

PART 171--GENERAL INFORMATION, REGULATIONS, AND DEFINITIONS

0
4. The authority citation for part 171 continues to read as follows:

    Authority: 49 U.S.C. 5101-5128, 44701; Pub. L. 101-410, Section
4; Pub. L. 104-134, Section 31001; Pub. L. 114-74, Section 4 (28
U.S.C. 2461 note); 49 CFR 1.81 and 1.97.

0
5. In Sec.  171.7:
0
a. Revise paragraph (a)(2)(ii);
0
b. Remove paragraph (n)(16) and redesignate paragraphs (n)(1) through
(15) as paragraphs (n)(2) through (16);
0
c. Add new paragraph (n)(1) and revise newly redesignated paragraphs
(n)(2), (4), and (13) and paragraph (n)(18).
    The revisions and addition read as follows:

Sec.  171.7   Reference material.

    (a) * * *
    (2) * * *
    (ii) The National Archives and Records Administration (NARA). For
information on the availability of this material at NARA, email
<EMAIL_ADDRESS>or go to www.archives.gov/federal-register/cfr/ibr-locations.html.
* * * * *
    (n) * * *
    (1) CGA C-1--2016, Methods for Pressure Testing Compressed Gas
Cylinders, Eleventh edition, copyright 2016, into Sec. Sec.  178.36,
178.37, 178.38, 178.39, 178.42, 178.44, 178.45, 178.46, 178.47; 178.50;
178.51; 178.53; 178.55; 178.56; 178.57; 178.58; 178.59; 178.60; 178.61;
178.65; 178.68; 180.205, 180.209.
    (2) CGA C-3--2005 (Reaffirmed 2011), Standards for Welding on Thin-
Walled Steel Cylinders, Seventh edition, copyright 2005, into
Sec. Sec.  178.47; 178.50; 178.51; 178.53; 178.55; 178.56; 178.57;
178.58; 178.59; 178.60; 178.61; 178.65; 178.68; 180.211.
* * * * *
    (4) CGA C-6--2013, Standards for Visual Inspection of Steel
Compressed

Gas Cylinders, Eleventh edition, copyright 2013, into Sec. Sec.
172.102, 173.3, 173.198, 180.205, 180.209, 180.211, 180.411, 180.519.
* * * * *
    (13) CGA C-14--2005 (Reaffirmed 2010), Procedures for Fire Testing
of DOT Cylinder Pressure Relief Device Systems, Fourth edition,
copyright 2005, into Sec. Sec.  173.301; 173.323.
* * * * *
    (18) CGA S-1.1--2011, Pressure Relief Device Standards--Part 1--
Cylinders for Compressed Gases, Fourteenth edition, copyright 2011,
into Sec. Sec.  173.301; 173.304a; 178.75.
* * * * *

0
6. In Sec.  171.23, revise paragraph (a)(5)(i) to read as follows:

Sec.  171.23   Requirements for specific materials and packagings
transported under the ICAO Technical Instructions, IMDG Code, Transport
Canada TDG Regulations, or the IAEA Regulations.

* * * * *
    (a) * * *
    (5) * * *
    (i) The cylinder has been requalified and marked in accordance with
subpart C of part 180 of this subchapter, or has been requalified as
authorized by the Associate Administrator;
* * * * *

PART 173--SHIPPERS--GENERAL REQUIREMENTS FOR SHIPMENTS AND
PACKAGINGS

0
7. The authority citation for part 173 continues to read as follows:

    Authority:  49 U.S.C. 5101-5128, 44701; 49 CFR 1.81, 1.96 and
1.97.

0
8. In Sec.  173.3, revise paragraph (d)(1) to read as follows:

Sec.  173.3   Packaging and exceptions.

* * * * *
    (d) * * *
    (1) Except for Class 1, Division 6.2, Class 7, or acetylene
material, a cylinder containing a hazardous material may be overpacked
in a salvage cylinder.
* * * * *

0
9. In Sec.  173.301:
0
a. In paragraphs (c) and (f), remove ``<IP_ADDRESS>'' and add in its place
``9.1.1'' in each place it appears; and
0
b. Revise paragraph (f)(4).
    The revision reads as follows:

Sec.  173.301   General requirements for shipment of compressed gases
and other hazardous materials in cylinders, UN pressure receptacles and
spherical pressure vessels.

* * * * *
    (f) * * *
    (4)(i) A pressure relief device is required on a DOT 39 cylinder
regardless of cylinder size or filled pressure.
    (ii) A DOT 39 cylinder used for liquefied Division 2.1 materials
must be equipped with a metal pressure relief device.
    (iii) Fusible pressure relief devices are not authorized on a DOT
39 cylinder containing a liquefied gas.
    (iv) A pressure relief device for oxidizing gases transported by
air in a DOT 39 cylinder must meet the requirements of Sec.
173.302(f)(2)(iii) of this subpart for permanent gases and Sec.
173.304(f)(2)(iii) for liquefied compressed gases.
* * * * *

0
10. In Sec.  173.302, revise paragraphs (f)(2)(i) and (ii) and add
paragraph (f)(2)(iii) to read as follows:

Sec.  173.302   Filling of cylinders with nonliquefied (permanent)
compressed gases or adsorbed gases.

* * * * *
    (f) * * *
    (2) * * *
    (i) The rated burst pressure of a rupture disc for DOT 3A, 3AA,
3AL, and 3E cylinders, and UN pressure receptacles ISO 9809-1, ISO
9809-2, ISO 9809-3 and ISO 7866 cylinders must be 100% of the cylinder
minimum test pressure with a tolerance of plus zero to minus 10%;
    (ii) The rated burst pressure of a rupture disc for a DOT 3HT
cylinder must be 90% of the cylinder minimum test pressure with a
tolerance of plus zero to minus 10%; and
    (iii) The rated burst pressure of a rupture disc for a DOT 39
cylinder must be not more than 80 percent of cylinder burst pressure
but not less than 105 percent of cylinder test pressure. Cylinders
filled and offered for transportation in accordance with the
requirements of the section before January 27, 2021 may continue to be
used for the life of the packaging.
* * * * *

0
11. In Sec.  173.302a, revise paragraphs (a)(3) and (c)(4)(i) and (ii)
and add paragraph (c)(4)(iii) to read as follows:

Sec.  173.302a   Additional requirements for shipment of nonliquefied
(permanent) compressed gases in specification cylinders.

    (a) * * *
    (3) DOT 39 cylinders. When the cylinder is filled with a Division
2.1 flammable gas, the internal volume of the cylinder may not exceed
1.23 L (75 in\3\). For chemical under pressure (see Sec.  172.102 of
this subchapter (special provision 362)), the internal volume may not
exceed the size limits of the specification as provided in Sec.
178.65(a)(1) of this subchapter.
* * * * *
    (c) * * *
    (4) * * *
    (i) Cylinders less than 1.7 m (65 inches) in length must be
equipped with fusible metal backed frangible disc devices;
    (ii) Cylinders 1.7 m (65 inches) or greater in length and 24.5 cm
(9.63 inches) in diameter or larger must be equipped with fusible metal
backed frangible disc devices or frangible disc devices, except as
provided in paragraph (c)(4)(iii) of this section. Cylinders with a
diameter of 0.56 m (22 inches) or larger must be equipped with
frangible disc devices except as provided in paragraph (c)(4)(iii) of
this section.
    (iii) Cylinders greater than 3.66 m (144 inches) in length that are
horizontally mounted on a motor vehicle, in an ISO framework, or other
framework of equivalent structural integrity are not required to be
equipped with pressure relief devices. If such devices are installed,
they must be selected in accordance with Sec.  173.301(f).
* * * * *

0
12. In Sec.  173.304, revise paragraphs (f)(2)(i) and (ii) and add
paragraph (f)(2)(iii) to read as follows:

Sec.  173.304   Filling of cylinders with liquefied compressed gases.

* * * * *
    (f) * * *
    (2) * * *
    (i) The rated burst pressure of a rupture disc for DOT 3A, 3AA,
3AL, and 3E cylinders, and UN pressure receptacles ISO 9809-1, ISO
9809-2, ISO 9809-3, and ISO 7866 cylinders must be 100% of the cylinder
minimum test pressure with a tolerance of plus zero to minus 10%;
    (ii) The rated burst pressure of a rupture disc for a DOT 3HT
cylinder must be 90% of the cylinder minimum test pressure with a
tolerance of plus zero to minus 10%; and
    (iii) The rated burst pressure of a rupture disc for a DOT 39
cylinder must be not more than 80 percent of cylinder burst pressure
but not less than 105 percent of cylinder test pressure. Cylinders
filled and offered for transportation in accordance with the
requirements of the section before January 27, 2021 may continue to be
used for the life of the packaging.

0
13. In Sec.  173.304a:
0
a. Revise paragraph (a)(2); and
0
b. Add paragraph (a)(3); and
0
c. Revise paragraph (d)(3)(i).

    The revisions and addition read as follows:

Sec.  173.304a   Additional requirements for shipment of liquefied
compressed gases in specification cylinders.

    (a) * * *
    (2) For the gases named, the requirements in table 1 to paragraph
(a)(2) apply (for cryogenic liquids, see Sec.  173.316):

                                           Table 1 to Paragraph (a)(2)
----------------------------------------------------------------------------------------------------------------
                                                                                Packaging marked as shown in
                                                                                this column or of the same
                                                                                type with higher service
                                            Maximum permitted filling  density     pressure must be used, except
              Kind of gas                         (percent) (see Note 1)             as provided in Sec.  Sec.
                                                                                173.301(l), 173.301a(e),  and
                                                                                180.205(a) (see notes
                                                                                following table)
----------------------------------------------------------------------------------------------------------------
Anhydrous ammonia.....................  54.......................................  DOT-3A480; DOT-3AA480; DOT-
                                                                                3A480X; DOT-4AA480; DOT-3;
                                                                                DOT-3E1800; DOT-3AL480.
Bromotrifluoromethane (R-13B1 or H-     124......................................  DOT-3A400; DOT-3AA400; DOT-
 1301).                                                                             3B400; DOT-4AA480; DOT-
                                                                                4B400; DOT-4BA400; DOT-
                                                                                4BW400; DOT-3E1800; DOT-39;
                                                                                DOT-3AL400.
Carbon dioxide (see Notes 4, 7, and 8)  68.......................................  DOT-3A1800; DOT-3AX1800; DOT-
                                                                                3AA1800; DOT-3AAX1800; DOT-
                                                                                3; DOT-3E1800; DOT-3T1800;
                                                                                DOT-3HT2000; DOT-39; DOT-
                                                                                3AL1800.
Carbon dioxide (see Notes 4, 7, and 8)  70.3.....................................  DOT-3A2000, DOT-3AA2000, DOT-
                                                                                3AX2000, DOT-3AAX2000, DOT-
                                                                                3T2000.
Carbon dioxide (see Notes 4, 7, and 8)  73.2.....................................  DOT-3A2265, DOT-3AA2265, DOT-
                                                                                3AX2265, DOT-3AAX2265, DOT-
                                                                                3T2265.
Carbon dioxide (see Notes 4, 7, and 8)  74.5.....................................  DOT-3A2400, DOT-3AA2400, DOT-
                                                                                3AX2400, DOT-3AAX2400, DOT-
                                                                                3T2400.
Carbon dioxide, refrigerated liquid     .........................................  DOT-4L.
 (see paragraph (e) of this section).
Chlorine (see Note 2).................  125......................................  DOT-3A480; DOT-3AA480; DOT-3;
                                                                                DOT-3BN480; DOT-3E1800.
Chlorodifluroethane or 1-Chloro-1, 1-   100......................................  DOT-3A150; DOT-3AA150; DOT-
 difluoroethane (R-142b).                                                           3B150; DOT-4B150; DOT-
                                                                                4BA225; DOT-4BW225; DOT-
                                                                                3E1800; DOT-39; DOT-3AL150.
Chlorodifluoromethane (R-22) (see Note  105......................................  DOT-3A240; DOT-3AA240; DOT-
 8).                                                                                3B240; DOT-4B240; DOT-
                                                                                4BA240; DOT-4BW240; DOT-
                                                                                4B240ET; DOT-4E240; DOT-39;
                                                                                DOT-3E1800; DOT-3AL240.
Chloropentafluorethane (R-115)........  110......................................  DOT-3A225; DOT-3AA225; DOT-
                                                                                3B225; DOT-4BA225; DOT-
                                                                                4B225; DOT-4BW225; DOT-
                                                                                3E1800; DOT-39; DOT-3AL225.
Chlorotrifluoromethane (R-13) (see      100......................................  DOT-3A1800; DOT-3AA1800; DOT-
 Note 8).                                                                           3; DOT-3E1800; DOT-39; DOT-
                                                                                3AL1800.
Cyclopropane (see Notes 8 and 9)......  55.......................................  DOT-3A225; DOT-3A480X; DOT-
                                                                                3AA225; DOT-3B225; DOT-
                                                                                4AA480; DOT4B225; DOT-
                                                                                4BA225; DOT-4BW225; DOT-
                                                                                4B240ET; DOT-3; DOT-3E1800;
                                                                                DOT-39; DOT-3AL225.
Dichlorodifluoromethane (R-12) (see     119......................................  DOT-3A225; DOT-3AA225; DOT-
 Note 8).                                                                           3B225; DOT-4B225; DOT-
                                                                                4BA225; DOT-4BW225; DOT-
                                                                                4B240ET; DOT-4E225; DOT-39;
                                                                                DOT-3E1800; DOT-3AL225.
Dichlorodifluoromethane and             Not liquid full at 131 [deg]F............  DOT-3A240; DOT-3AA240; DOT-
 difluoroethane mixture (constant                                                   3B240; DOT-3E1800; DOT-
 boiling mixture) (R-500) (see Note 8).                                             4B240; DOT-4BA240; DOT-
                                                                                4BW240; DOT-4E240; DOT-39.
1,1-Difluoroethane (R-152a) (see Note   79.......................................  DOT-3A150; DOT-3AA150; DOT-
 8).                                                                                3B150; DOT-4B150; DOT-
                                                                                4BA225; DOT-4BW225; DOT-
                                                                                3E1800; DOT-3AL150.
1,1-Difluoroethylene (R-1132A)........  73.......................................  DOT-3A2200; DOT-3AA2200; DOT-
                                                                                3AX2200; DOT-3AAX2200; DOT-
                                                                                3T2200; DOT-39.
Dimethylamine, anhydrous..............  59.......................................  DOT-3A150; DOT-3AA150; DOT-
                                                                                3B150; DOT-4B150; DOT-
                                                                                4BA225; DOT-4BW225; ICC-
                                                                                3E1800.
Ethane (see Notes 8 and 9)............  35.8.....................................  DOT-3A1800; DOT-3AX1800; DOT-
                                                                                3AA1800; DOT-3AAX1800; DOT-
                                                                                3; DOT-3E1800; DOT-3T1800;
                                                                                DOT-39; DOT-3AL1800.
Ethane (see Notes 8 and 9)............  36.8.....................................  DOT-3A2000; DOT-3AX2000; DOT-
                                                                                3AA2000; DOT-3AAX2000; DOT-
                                                                                3T2000; DOT-39; DOT-3AL2000.
Ethylene (see Notes 8 and 9)..........  31.0.....................................  DOT-3A1800; DOT-3AX1800; DOT-
                                                                                3AA1800; DOT-3AAX1800; DOT-
                                                                                3; DOT-3E1800; DOT-3T1800;
                                                                                DOT-39; DOT-3AL1800.
Ethylene (see Notes 8 and 9)..........  32.5.....................................  DOT-3A2000; DOT-3AX2000; DOT-
                                                                                3AA2000; DOT-3AAX2000; DOT-
                                                                                3T2000; DOT-39; DOT-3AL2000.
Ethylene (see Notes 8 and 9)..........  35.5.....................................  DOT-3A2400; DOT-3AX2400; DOT-
                                                                                3AA2400; DOT-3AAX2400; DOT-
                                                                                3T2400; DOT-39; DOT-3AL2400.
Hydrogen chloride, anhydrous..........  65.......................................  DOT-3A1800; DOT-3AA1800; DOT-
                                                                                3AX1800; DOT-3AAX1800; DOT-
                                                                                3; DOT-3T1800; DOT-3E1800.
Hydrogen sulfide (Note 10)............  62.5.....................................  DOT-3A; DOT-3AA; DOT-3B; DOT-
                                                                                4B; DOT-4BA; DOT-4BW; DOT-
                                                                                3E1800; DOT-3AL.

Insecticide, gases liquefied (see       Not liquid full at 131 [deg]F............  DOT-3A300; DOT-3AA300; DOT-
 Notes 8 and 12).                                                                   3B300; DOT-4B300; DOT-
                                                                                4BA300; DOT-4BW300; DOT-
                                                                                3E1800.
Liquefied nonflammable gases, other     Not liquid full at 131 [deg]F............  Specification packaging
 than classified flammable, corrosive,                                              authorized in paragraph
 toxic & mixtures or solution thereof                                               (a)(1) of this section and
 filled w/nitrogen, carbon dioxide, or                                              DOT-3HT; DOT-4D; DOT-4DA;
 air (see Notes 7 and 8)..                                                          DOT-4DS.
Methyl acetylene-propadiene, mixtures,  Not liquid at 131 [deg]F.................  DOT-4B240 without brazed
 stabilized; (see Note 5)..                                                         seams; DOT-4BA240 without
                                                                                brazed seams; DOT-3A240; DOT-
                                                                                3AA240; DOT-3B240; DOT-
                                                                                3E1800; DOT-4BW240; DOT-
                                                                                4E240; DOT-4B240ET; DOT-
                                                                                3AL240.
Methyl chloride.......................  84.......................................  DOT-3A225; DOT-3AA225; DOT-
                                                                                3B225; DOT-4B225; DOT-
                                                                                4BA225; DOT-4BW225; DOT-3;
                                                                                DOT-3E1800; DOT-4B240ET.
                                                                                Cylinders complying with DOT-
                                                                                3A150; DOT-3B150; and DOT-
                                                                                4B150 manufactured prior to
                                                                                Dec. 7, 1936 are also
                                                                                authorized.
Methyl mercaptan......................  80.......................................  DOT-3A240; DOT-3AA240; DOT-
                                                                                3B240; OT-4B240; DOT-
                                                                                4B240ET; DOT-3E1800; DOT-
                                                                                4BA240; DOT-4BW240.
Nitrosyl chloride.....................  110......................................  DOT-3BN400 only.
Nitrous oxide (see Notes 7, 8, and 11)  68.......................................  DOT-3A1800; DOT-3AX1800; DOT-
                                                                                3AA1800; DOT-3AAX1800; DOT-
                                                                                3; DOT-3E1800; DOT-3T1800;
                                                                                DOT-3HT2000; DOT-39; DOT-
                                                                                3AL1800.
Nitrous oxide (see Notes 7, 8, and 11)  70.3.....................................  DOT-3A2000, DOT-3AA2000, DOT-
                                                                                3AX2000, DOT-3AAX2000, DOT-
                                                                                3T2000.
Nitrous oxide (see Notes 7, 8, and 11)  73.2.....................................  DOT-3A2265, DOT-3AA2265, DOT-
                                                                                3AX2265, DOT-3AAX2265, DOT-
                                                                                3T2265.
Nitrous oxide (see Notes 7, 8, and 11)  74.5.....................................  DOT-3A2400, DOT-3AA2400, DOT-
                                                                                3AX2400, DOT-3AAX2400, DOT-
                                                                                3T2400.
Nitrous oxide, refrigerated liquid      .........................................  DOT-4L.
 (see paragraph (e) of this section.).
Refrigerant gas, n.o.s. or Dispersant   Not liquid full at 130 [deg]F............  DOT-3A240; DOT-3AA240; DOT-
 gas, n.o.s. (see Notes 8 and 13).                                                  3B240; DOT-3E1800; DOT-
                                                                                4B240; DOT-4BA240; DOT-
                                                                                4BW240; DOT-4E240; DOT-39;
                                                                                DOT-3AL240.
Sulfur dioxide (see note 8)...........  125......................................  DOT-3A225; DOT-3AA225; DOT-
                                                                                3B225; DOT-4B225; DOT-
                                                                                4BA225; DOT-4BW225; DOT-
                                                                                4B240ET; DOT-3; DOT-39; DOT-
                                                                                3E1800; DOT-3AL225.
Sulfur hexafluoride...................  120......................................  DOT-3A1000; DOT-3AA1000; DOT-
                                                                                AAX2400; DOT-3; DOT-3AL1000;
                                                                                DOT-3E1800; DOT-3T1800.
Sulfuryl fluoride.....................  106......................................  DOT-3A480; DOT-3AA480; DOT-
                                                                                3E1800; DOT-4B480; DOT-
                                                                                4BA480; DOT-4BW480.
Tetrafluoroethylene, stabilized.......  90.......................................  DOT-3A1200; DOT-3AA1200; DOT-
                                                                                3E1800.
Trifluorochloroethylene, stabilized...  115......................................  DOT-3A300; DOT-3AA300; DOT-
                                                                                3B300; DOT-4B300; DOT-
                                                                                4BA300; DOT-4BW300; DOT-
                                                                                3E1800.
Trimethylamine, anhydrous.............  57.......................................  DOT-3A150; DOT-3AA150; DOT-
                                                                                3B150; DOT-4B150; DOT-
                                                                                4BA225; DOT-4BW225; DOT-
                                                                                3E1800.
Vinyl chloride (see Note 5)...........  84.......................................  DOT-4B150 without brazed
                                                                                seams; DOT-4BA225 without
                                                                                brazed seams; DOT-4BW225;
                                                                                DOT-3A150; DOT-3AA150; DOT-
                                                                                3E1800; DOT-3AL150.
Vinyl fluoride, stabilized............  62.......................................  DOT-3A1800; DOT-3AA1800; DOT-
                                                                                3E1800; DOT-3AL1800.
Vinyl methyl ether, stabilized (see     68.......................................  DOT-4B150, without brazed
 Note 5).                                                                           seams; DOT-4BA225 without
                                                                                brazed seams; DOT-4BW225;
                                                                                DOT-3A150; DOT-3AA150; DOT-
                                                                                3B1800; DOT-3E1800.
----------------------------------------------------------------------------------------------------------------
Note 1 to paragraph (a)(2): ``Filling density'' means the percent ratio of the weight of gas in a packaging to
  the weight of water that the container will hold at 16 [deg]C (60 [deg]F). (1 lb of water = 27.737 in\3\ at 60
  [deg]F.).
Note 2 to paragraph (a)(2): Cylinders purchased after Oct. 1, 1944, for the transportation of chlorine must
  contain no aperture other than that provided in the neck of the cylinder for attachment of a valve equipped
  with an approved pressure relief device. Cylinders purchased after Nov. 1, 1935, and filled with chlorine may
  not contain over 68.04 kg (150 lb) of gas.
Note 4 to paragraph (a)(2): Special carbon dioxide mining devices containing a heating element and filled with
  not over 2.72 kg (6 lb) of carbon dioxide may be filled to a density of not over 85 percent, provided the
  cylinder is made of steel with a calculated bursting pressure in excess of 39000 psig, fitted with a frangible
  disc that will operate at not over 57 percent of that pressure, and is able to withstand a drop of 10 feet
  when striking crosswise on a steel rail while under a pressure of at least 3000 psig. Such devices must be
  shipped in strong boxes or must be wrapped in heavy burlap and bound by 12-gauge wire with the wire completely
  covered by friction tape. Wrapping must be applied so as not to interfere with the functioning of the
  frangible disc pressure relief device. Shipments must be described as ``liquefied carbon dioxide gas (mining
  device)'' and marked, labeled, and certified as prescribed for liquefied carbon dioxide.
Note 5 to paragraph (a)(2): All parts of valve and pressure relief devices in contact with contents of cylinders
  must be of a metal or other material, suitably treated if necessary, that will not cause formation of any
  acetylides.

Note 7 to paragraph (a)(2): Specification 3HT cylinders for aircraft use only, having a maximum service life of
  24 years. Authorized only for nonflammable gases. Cylinders must be equipped with pressure relief devices of
  the frangible disc type that meet the requirements of Sec.   173.301(f). Each frangible disc must have a rated
  bursting pressure that does not exceed 90 percent of the minimum required test pressure of the cylinder. Discs
  with fusible metal backing are not permitted. Cylinders may be offered for transportation only when packaged
  in accordance with Sec.   173.301(a)(9).
Note 8 to paragraph (a)(2): See Sec.   173.301(a)(9).
Note 9 to paragraph (a)(2): When used for shipment of flammable gases, the internal volume of a specification 39
  cylinder must not exceed 75 cubic inches.
Note 10 to paragraph (a)(2): Each valve outlet must be sealed by a threaded cap or a threaded solid plug.
Note 11 to paragraph (a)(2): Must meet the valve and cleaning requirements in Sec.   173.302(b).
Note 12 to paragraph (a)(2): For an insecticide gas that is nontoxic and nonflammable, see Sec.   173.305(c).
Note 13 to paragraph (a)(2): For a refrigerant or dispersant gas that is nontoxic and nonflammable, see Sec.
  173.304(d).

    (3) A DOT 39 cylinder shall be equipped with a pressure relief
device as defined by the commodity in CGA S-1.1, excluding paragraph
9.1.1 (IBR; see Sec.  171.7 of this subchapter). If the commodity is
not listed in CGA S-1.1, a CG-7 pressure relief valve must be used.
* * * * *
    (d) * * *
    (3) * * *
    (i) DOT 3, 3A, 3AA, 3B, 3E, 3AL, 4B, 4BA, 4B240ET, 4BW, 4E, or 39
cylinders. The internal volume of a Specification 39 cylinder must not
exceed 75 cubic inches. Shipments of flammable gases in DOT 3AL
cylinders are authorized only when transported by motor vehicle, rail
car, or cargo-only aircraft.
* * * * *

0
14. In Sec.  173.306, revise paragraph (g) to read as follows:

Sec.  173.306   Limited quantities of compressed gases.

* * * * *
    (g) Water pump system tank. Water pump system tanks pre-charged at
time of manufacture with compressed air or limited quantities of
nitrogen or helium to not over 275.79 kPa gauge pressure (40 psig) for
single-trip shipment to installation sites are excepted from labeling,
and the specification packaging requirements of this subchapter when
shipped under the following conditions. In addition, shipments of these
tanks are not subject to the placarding requirements of subpart F of
part 172 of this subchapter, and not subject to parts 174 (except Sec.
174.24) and 177 (except Sec.  177.817) of this subchapter.
    (1) The tank must be of steel or composite construction, with heads
concave to pressure, having a rated water capacity not exceeding 455 L
(120 gallons) and with an outside diameter not exceeding 61 cm (24
inches). These tanks may be operated in ambient air temperatures of up
to 49 [deg]C (120 [deg]F) with a maximum working pressure not less than
75 psig and not greater than 150 psig. Safety relief devices are not
required.
    (2) Each tank must be pneumatically tested to the manufacturer's
specified maximum working pressure. The test pressure must be
permanently marked on the tank. In any case, the pneumatic test must
not be conducted to a pressure exceeding 150 psig.
    (3) The stress at prescribed pressure for steel tanks must not
exceed 20,000 psig (or 25,000 psig for deep-draw steel), using the
formula:

S = Pd/2t

Where:
S = wall stress in psi;
P = prescribed pressure for the tank is at least the manufacturer's
rated maximum working pressure or three (3) times the pre-charged
pressure at 21.1 [deg]C (70 [deg]F), whichever is greater;
d = inside diameter in inches; and
t = minimum wall thickness, in inches.

    (4) For steel and composite tanks, the burst pressure must be at
least six (6) times the pre-charge pressure at 21.1 [deg]C (70 [deg]F)
or three (3) times the manufacturer's specified maximum working
pressure, whichever is greater.
    (5) Each tank must be over-packed in a strong outer packaging in
conformance with Sec.  173.301(h).
    (6) Transportation is limited to motor vehicle, railcar, and
vessel. Transportation by aircraft is not authorized.
* * * * *

0
15. In Sec.  173.309, revise the introductory text to read as follows:

Sec.  173.309   Fire extinguishers.

    This section applies to portable fire extinguishers for manual
handling and operation, fire extinguishers for installation in
aircraft, fire extinguishers for installation as part of a fire
suppression system, and large fire extinguishers. Fire extinguishers
for installation as part of a fire suppression system include cylinders
charged with either a compressed gas and an extinguishing agent or a
gas which comprises the sole fire extinguishing agent in the system. A
fire extinguisher does not include cylinders pressurized with a gas for
purposes of expelling a separately stored extinguishing agent in the
fire suppression system. Large fire extinguishers include fire
extinguishers mounted on wheels for manual handling; fire extinguishing
equipment or machinery mounted on wheels or wheeled platforms or units
transported similar to (small) trailers; and fire extinguishers
composed of a non-rollable pressure drum and equipment, and handled,
for example, by fork lift or crane when loaded or unloaded. Cylinders
filled with a compressed gas whose purpose is to expel a separately
stored extinguishing agent may not be transported under this section
when offered for transportation or transported apart from a suppression
system.
* * * * *

0
16. In Sec.  173.312, revise paragraph (b)(1) to read as follows:

Sec.  173.312   Requirements for shipment of MEGCs.

* * * * *
    (b) * * *
    (1) A MEGC may not be filled above its marked maximum permissible
gross mass. Additionally, MEGCs must be filled in accordance with the
following:
    (i) A MEGC being filled with non-liquefied (permanent) compressed
gas may not be filled to a pressure greater than the lowest marked
working pressure of any cylinder (pressure receptacle).
    (ii) An MEGC being filled with a liquefied compressed gas must have
each pressure receptacle filled separately by weight and must be filled
by a means to ensure that only one pressure receptacle is filled at a
time.
    (iii) The filling density for UN pressure receptacles may not
exceed the values in accordance with Sec.  173.304b(b).
* * * * *

Sec.  173.323   [AMENDED]

0
17. In Sec.  173.323(b)(2), immediately following the words ``Pamphlet
C-14'' in the last sentence, add the phrase ``(IBR, see Sec.  171.7 of
this subchapter)''.

PART 178--SPECIFICATIONS FOR PACKAGINGS

0
18. The authority citation for part 178 continues to read as follows:

    Authority: 49 U.S.C. 5101-5128; 49 CFR 1.81 and 1.97.

0
19. In Sec.  178.35, add paragraph (f)(8) to read as follows:

Sec.  178.35   General requirements for specification cylinders.

* * * * *
    (f) * * *
    (8) Tare weight or mass weight, and water capacity marking. DOT-
specification 4B, 4BA, 4BW, and 4E cylinders used in liquefied
compressed gas service manufactured after December 28, 2022, must be
marked with the tare weight or mass weight. Additionally, the cylinder
must be permanently marked with the water capacity. The owner of the
cylinder must ensure it is marked with the following information, as
applicable:
    (i) Tare weight. The tare weight for a cylinder 25 pounds or less
at the time of manufacture, with a lower tolerance of 3 percent and an
upper tolerance of 1 percent; or for a cylinder exceeding 25 pounds at
the time of manufacture, with a lower tolerance of 2 percent and an
upper tolerance of 1 percent. The tare weight marking must be the
actual weight of the fully assembled cylinder, including the valve(s)
and other permanently affixed appurtenances. Removable protective
cap(s) or cover(s) must not be included in the cylinder tare weight.
Tare weight shall be abbreviated ``TW''; or
    (ii) Mass weight. The mass weight for a cylinder 25 pounds or less
at the time of manufacture, with a lower tolerance of 3 percent and an
upper tolerance of 1 percent; or the mass weight marking for a cylinder
exceeding 25 pounds at the time of manufacture, with a lower tolerance
of 2 percent and an upper tolerance of 1 percent. The mass weight
marking must be the actual weight of the fully assembled cylinder,
excluding valve(s) and removable protective cap(s) or cover(s). Mass
weight shall be abbreviated ``MW''; and
    (iii) Water capacity. The water capacity for a cylinder 25 pounds
water capacity or less, with a tolerance of minus 1 percent and no
upper tolerance; or for a cylinder exceeding 25 pounds water capacity,
with a tolerance of minus 0.5 percent and no upper tolerance. The
marked water capacity of the cylinder must be the capacity of the
cylinder at the time of manufacture. Water capacity shall be
abbreviated ``WC''.
* * * * *

0
20. In Sec.  178.36, revise paragraph (i) to read as follows:

Sec.  178.36   Specification 3A and 3AX seamless steel cylinders.

* * * * *
    (i) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) The test must be by water-jacket or direct expansion method as
prescribed in CGA C-1 (IBR; see Sec.  171.7 of this subchapter). The
testing equipment must be calibrated as prescribed in CGA C-1. All
testing equipment and pressure indicating devices must be accurate
within the parameters defined in CGA C-1.
    (2) Each cylinder must be tested to a minimum of \5/3\ times
service pressure.
    (3) The minimum test pressure must be maintained for at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and previous to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (4) Permanent, volumetric expansion may not exceed 10 percent of
the total volumetric expansion at test pressure.
* * * * *

0
21. In Sec.  178.37, revise paragraph (i) to read as follows:

Sec.  178.37   Specification 3AA and 3AAX seamless steel cylinders.

* * * * *
    (i) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) The test must be by water-jacket or direct expansion method as
prescribed in CGA C-1 (IBR; see Sec.  171.7 of this subchapter). The
testing equipment must be calibrated as prescribed in CGA C-1. All
testing equipment and pressure indicating devices must be accurate
within the parameters defined in CGA C-1.
    (2) Each cylinder must be tested to a minimum of \5/3\ times
service pressure.
    (3) The minimum test pressure must be maintained for at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and previous to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (4) Permanent, volumetric expansion may not exceed 10 percent of
the total volumetric expansion at test pressure.
* * * * *

0
22. In Sec.  178.38, revise paragraph (i) to read as follows:

Sec.  178.38   Specification 3B seamless steel cylinders.

* * * * *
    (i) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) The test must be by water-jacket or direct expansion method as
defined in CGA C-1 (IBR; see Sec.  171.7 of this subchapter). The
testing equipment must be calibrated as prescribed in CGA C-1. All
testing equipment and pressure indicating devices must be accurate
within the parameters defined in CGA C-1.
    (2) Cylinders must be tested as follows:
    (i) Each cylinder to at least two (2) times its service pressure;
or
    (ii) One (1) cylinder out of each lot of 200 or fewer to at least
three (3) times its service pressure. When one (1) cylinder out of each
lot of 200 or less is tested to at least 3 times service pressure, the
balance of the lot must be pressure tested by the proof pressure,
water-jacket or direct expansion test method as prescribed in CGA C-1.
The cylinders must be subjected to at least 2 times service pressure
and show no defect. If, due to failure of the test apparatus or
operator error, the test pressure cannot be maintained, the test may be
repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as appropriate.
Determination of expansion properties is not required.
    (3) When each cylinder is tested to the minimum test pressure, the
minimum test pressure must be maintained at least 30 seconds and
sufficiently longer to ensure complete expansion. Any internal pressure
applied after heat-treatment and previous to the official test may not
exceed 90 percent of the test pressure. If, due to failure of the test
apparatus or operator error, the test pressure cannot be maintained,
the test may be repeated in accordance with CGA C-1, section 5.7.2.
    (4) Permanent volumetric expansion may not exceed 10 percent of
total volumetric expansion at test pressure.
* * * * *

0
23. In Sec.  178.39, revise paragraph (i) to read as follows:

Sec.  178.39   Specification 3BN seamless nickel cylinders.

* * * * *
    (i) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) The test must be by water-jacket or direct expansion method as
prescribed in CGA C-1 (IBR; see Sec.  171.7 of this subchapter). The
testing equipment must be calibrated as prescribed in CGA C-1. All
testing equipment and pressure

indicating devices must be accurate within the parameters defined in
CGA C-1.
    (2) Each cylinder must be tested to a minimum of at least two (2)
times its service pressure.
    (3) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and previous to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (4) Permanent volumetric expansion may not exceed 10 percent of
total volumetric expansion at test pressure.
* * * * *

0
24. In Sec.  178.42, revise paragraph (f) to read as follows:

Sec.  178.42   Specification 3E seamless steel cylinders.

* * * * *
    (f) Pressure testing. Cylinders must be tested as follows:
    (1) One cylinder out of each lot of 500 or fewer must be subjected
to a hydrostatic test pressure of 6,000 psig or higher.
    (2) The cylinder referred to in paragraph (f)(1) of this section
must burst at a pressure higher than 6,000 psig without fragmenting or
otherwise showing lack of ductility, or must hold a pressure of 12,000
psig for 30 seconds without bursting. In which case, it must be
subjected to a flattening test without cracking to six times wall
thickness between knife edges, wedge shaped 60 degree angle, rounded
out to a \1/2\ inch radius. The inspector's report must be suitably
changed to show results of latter alternate and flattening test. The
testing equipment must be calibrated as prescribed in CGA C-1 (IBR, see
Sec.  171.7 of this subchapter). All testing equipment and pressure
indicating devices must be accurate within the parameters defined in
CGA C-1.
    (3) The remaining cylinders of the lot must be pressure tested by
the proof pressure water-jacket or direct expansion test method as
prescribed in CGA C-1. Cylinders must be examined under pressure of at
least 3,000 psig and not to exceed 4,500 psig and show no defect.
Cylinders tested at a pressure in excess of 3,600 psig must burst at a
pressure higher than 7,500 psig when tested as specified in paragraph
(f)(2) of this section. The pressure must be maintained for at least 30
seconds and sufficiently longer to ensure complete examination. The
testing equipment must be calibrated as prescribed in CGA C-1. All
testing equipment and pressure indicating devices must be accurate
within the parameters defined in CGA C-1. If, due to failure of the
test apparatus or operator error, the test pressure cannot be
maintained, the test may be repeated in accordance with CGA C-1 5.7.2
or 7.1.2, as appropriate. Determination of expansion properties is not
required.
* * * * *

0
25. In Sec.  178.44, revise paragraph (i) to read as follows:

Sec.  178.44   Specification 3HT seamless steel cylinders for aircraft
use.

* * * * *
    (i) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) The test must be by water-jacket or direct expansion method as
prescribed in CGA C-1 (IBR; see Sec.  171.7 of this subchapter). The
testing equipment must be calibrated as prescribed in CGA C-1. All
testing equipment and pressure indicating devices must be accurate
within the parameters defined in CGA C-1.
    (2) Each cylinder must be tested to minimum of \5/3\ times service
pressure.
    (3) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and previous to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (4) Permanent volumetric expansion may not exceed 10 percent of
total volumetric expansion at test pressure.
* * * * *

0
26. In Sec.  178.45, revise paragraph (g) to read as follows:

Sec.  178.45   Specification 3T seamless steel cylinder.

* * * * *
    (g) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) The test must be by water-jacket or direct expansion method as
prescribed in CGA C-1 (IBR; see Sec.  171.7 of this subchapter). The
testing equipment must be calibrated as prescribed in CGA C-1. All
testing equipment and pressure indicating devices must be accurate
within the parameters defined in CGA C-1.
    (2) Each cylinder must be tested to minimum of \5/3\ times service
pressure.
    (3) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and prior to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (4) Permanent volumetric expansion may not exceed 10 percent of
total volumetric expansion at test pressure.
* * * * *

0
27. In Sec.  178.46, revise paragraph (g) to read as follows:

Sec.  178.46   Specification 3AL seamless aluminum cylinders.

* * * * *
    (g) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) The test must be by water-jacket or direct expansion method as
prescribed in CGA C-1 (IBR; see Sec.  171.7 of this subchapter). The
testing equipment must be calibrated as prescribed in CGA C-1. All
testing equipment and pressure indicating devices must be accurate
within the parameters defined in CGA C-1.
    (2) The minimum test pressure must be the greater of the following:
    (i) 450 psig regardless of service pressure;
    (ii) Two (2) times the service pressure for cylinders having
service pressure less than 500 psig; or
    (iii) \5/3\ times the service pressure for cylinders having a
service pressure of 500 psig or greater.
    (3) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat treatment and prior to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2, however, if a second failure to maintain the test
pressure occurs the cylinder being tested must be rejected.
    (4) Permanent volumetric expansion may not exceed 10 percent of
total volumetric expansion at test pressure.
* * * * *

0
28. In Sec.  178.47, revise paragraph (j) to read as follows:

Sec.  178.47   Specification 4DS welded stainless steel cylinders for
aircraft use.

* * * * *

    (j) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) The test must be by water-jacket or direct expansion method as
prescribed in CGA C-1 (IBR; see Sec.  171.7 of this subchapter). The
testing equipment must be calibrated as prescribed in CGA C-1. All
testing equipment and pressure indicating devices must be accurate
within the parameters defined in CGA C-1.
    (2) Each cylinder must be tested to a minimum of at least two (2)
times its service pressure.
    (3) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and prior to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (4) Permanent volumetric expansion may not exceed 10 percent of the
total volumetric expansion at test pressure.
    (5) The cylinder must then be inspected. Any wall thickness lower
than that required by paragraph (f) of this section must be cause for
rejection. Bulges and cracks must be cause for rejection. Welded joint
defects exceeding requirements of paragraph (k) of this section are
cause for rejection.
* * * * *

0
29. Revise Sec.  178.50 to read as follows:

Sec.  178.50  Specification 4B welded or brazed steel cylinders.

    (a) Type, size, pressure, and application. A DOT 4B is a welded or
brazed steel cylinder with longitudinal seams that are forged lap-
welded or brazed and with water capacity (nominal) not over 1,000
pounds and a service pressure of at least 150 but not over 500 psig.
Cylinders closed in by spinning process are not authorized.
    (b) Steel. Open-hearth, electric or basic oxygen process steel of
uniform quality must be used. Content percent may not exceed the
following: Carbon, 0.25; phosphorus, 0.045; sulphur, 0.050. The
cylinder manufacturer must maintain a record of intentionally added
alloying elements.
    (c) Identification of material. Pressure-retaining materials must
be identified by any suitable method that does not compromise the
integrity of the cylinder. Plates and billets for hotdrawn cylinders
must be marked with the heat number.
    (d) Manufacture. Cylinders must be manufactured using equipment and
processes adequate to ensure that each cylinder produced conforms to
the requirements of this subpart. No defect is permitted that is likely
to weaken the finished cylinder appreciably. A reasonably smooth and
uniform surface finish is required. Exposed bottom welds on cylinders
over 18 inches long must be protected by footrings. Welding procedures
and operators must be qualified in conformance with CGA C-3 (IBR, see
Sec.  171.7 of this subchapter). Seams must be made as follows:
    (1) Brazing materials. Brazing materials must be by copper brazing,
by copper alloy brazing, or by silver alloy brazing. Copper alloy
composition must be: Copper, 95 percent minimum; Silicon, 1.5 percent
to 3.85 percent; Manganese, 0.25 percent to 1.10 percent.
    (2) Brazed circumferential seams. Heads attached by brazing must
have a driving fit with the shell, unless the shell is crimped,
swedged, or curled over the skirt or flange of the head, and be
thoroughly brazed until complete penetration by the brazing material of
the brazed joint is secured. Depth of brazing of the joint must be at
least four (4) times the minimum thickness of shell metal.
    (3) Welded circumferential seams. Circumferential seams are
permitted by the welding process.
    (4) Longitudinal seams in shells. Longitudinal seams must be a
forged lap joint design. When brazed, the plate edge must be lapped at
least eight (8) times the thickness of the plate, laps being held in
position, substantially metal to metal, by riveting or electric spot-
welding; brazing must be done by using a suitable flux and by placing
brazing material on one side of seam and applying heat until this
material shows uniformly along the seam of the other side.
    (e) Welding or brazing. Only the attachment of neckrings,
footrings, handles, bosses, pads, and valve protection rings to the
tops and bottoms of cylinders by welding or brazing is authorized.
Attachments and the portion of the cylinder to which they are attached
must be made of weldable steel, the carbon content of which may not
exceed 0.25 percent except in the case of 4130X steel, which may be
used with proper welding procedure.
    (f) Wall thickness. The wall thickness of the cylinder must comply
with the following requirements:
    (1) For cylinders with outside diameters over 6 inches, the minimum
wall thickness must be 0.090 inch. In any case, the minimum wall
thickness must be such that calculated wall stress at minimum test
pressure (paragraph (i)(4) of this section) may not exceed the
following values:
    (i) 24,000 psig for cylinders without longitudinal seam.
    (ii) 22,800 psig for cylinders having copper brazed or silver alloy
brazed longitudinal seam.
    (iii) 18,000 psig for cylinders having forged lapped welded
longitudinal seam.
    (2) Calculation must be made by the formula:

S = [P(1.3D\2\ + 0.4d\2\)]/(D\2\ - d\2\)

Where:
S = wall stress in psig;
P = minimum test pressure prescribed for water jacket test or 450
psig whichever is the greater;
D = outside diameter in inches; and
d = inside diameter in inches.

    (g) Heat treatment. Cylinder heads, bodies or the completed
cylinder, formed by drawing or pressing, must be uniformly and properly
heat treated by an applicable method shown in table 1 of appendix A of
this part before tests.
    (h) Opening in cylinders. Openings in cylinders must comply with
the following:
    (1) Any opening must be placed on other than a cylindrical surface.
    (2) Each opening in a spherical type of cylinder must be provided
with a fitting, boss, or pad of weldable steel securely attached to the
cylinder by fusion welding.
    (3) Each opening in a cylindrical type cylinder, except those for
pressure relief devices, must be provided with a fitting, boss, or pad,
securely attached to container by brazing or by welding.
    (4) If threads are used, they must comply with the following:
    (i) Threads must be clean cut, even without checks, and tapped to
gauge.
    (ii) Taper threads must be of a length not less than as specified
for American Standard taper pipe threads.
    (iii) Straight threads, must have at least four (4) engaged
threads, must have tight fit and a calculated shear strength at least
ten (10) times the test pressure of the cylinder; gaskets are required
for straight threads and must be of sufficient quality to prevent
leakage.
    (iv) A brass fitting may be brazed to the steel boss or flange on
cylinders used as component parts of handheld fire extinguishers.
    (5) The closure of a fitting, boss, or pad must be adequate to
prevent leakage.
    (i) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows: (1) Lot testing. (i) At least one (1)
cylinder randomly selected out of each lot of 200 or fewer must be

tested by the water jacket or direct expansion method as prescribed in
CGA C-1 (IBR; see Sec.  171.7 of this subchapter). The testing
equipment must be calibrated as prescribed in CGA C-1. All testing
equipment and pressure indicating devices must be accurate within the
parameters defined in CGA C-1.
    (ii) Each cylinder must be tested to a minimum of 2 times service
pressure.
    (iii) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and prior to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (iv) Permanent volumetric expansion may not exceed 10 percent of
the total volumetric expansion at test pressure.
    (2) Pressure testing. (i) The remaining cylinders in the lot must
be tested by the proof pressure, water-jacket, or direct expansion test
method as prescribed in CGA C-1. The minimum test pressure must be
maintained for the specific timeframe and the testing equipment must be
calibrated as prescribed in CGA C-1. Further, all testing equipment and
pressure indicating devices must be accurate within the parameters
defined in CGA C-1. If, due to failure of the test apparatus or
operator error, the test pressure cannot be maintained, the test may be
repeated in accordance with CGA C-1, sections 5.7.2 or 7.1.2, as
appropriate. Determination of expansion properties is not required.
    (ii) Each cylinder must be tested to a minimum of at least two (2)
times service pressure and show no defect.
    (j) Mechanical test. A mechanical test must be conducted to
determine yield strength, tensile strength, elongation as a percentage,
and reduction of area of material as a percentage as follows:
    (1) Testing is required on two (2) specimens removed from one (1)
cylinder, or part thereof, heat-treated as required, as illustrated in
appendix A to this subpart. For lots of 30 or fewer, mechanical tests
are authorized to be made on a ring at least 8 inches long removed from
each cylinder and subjected to the same heat treatment as the finished
cylinder.
    (2) Specimens must comply with the following:
    (i) When a cylinder wall is \3/16\ inch thick or less, one the
following gauge lengths is authorized: A gauge length of 8 inches with
a width not over 1\1/2\ inches, a gauge length of 2 inches with a width
not over 1\1/2\ inches, or a gauge length at least twenty-four (24)
times the thickness with a width not over six (6) times the thickness.
    (ii) The specimen, exclusive of grip ends, may not be flattened.
Grip ends may be flattened to within one inch of each end of the
reduced section.
    (iii) When the size of a cylinder does not permit securing straight
specimens, the specimens may be taken in any location or direction and
may be straightened or flattened cold, by pressure only, not by blows.
When specimens are taken and prepared using this method, the
inspector's report must show detailed information regarding such
specimens in connection with the record of mechanical tests.
    (iv) Heating of a specimen for any purpose is not authorized.
    (3) The yield strength in tension must be the stress corresponding
to a permanent strain of 0.2 percent of the gauge length. The following
conditions apply:
    (i) The yield strength must be determined by either the ``offset''
method or the ``extension under load'' method as prescribed in ASTM E 8
(IBR, see Sec.  171.7 of this subchapter).
    (ii) In using the ``extension under load'' method, the total strain
(or ``extension under load'') corresponding to the stress at which the
0.2 percent permanent strain occurs may be determined with sufficient
accuracy by calculating the elastic extension of the gauge length under
appropriate load and adding thereto 0.2 percent of the gauge length.
Elastic extension calculations must be based on an elastic modulus of
30,000,000. In the event of controversy, the entire stress-strain
diagram must be plotted and the yield strength determined from the 0.2
percent offset.
    (iii) For strain measurement, the initial strain reference must be
set while the specimen is under a stress of 12,000 psig, and strain
indicator reading must be set at the calculated corresponding strain.
    (iv) Cross-head speed of the testing machine may not exceed \1/8\
inch per minute during yield strength determination.
    (v) The yield strength must not exceed 73 percent of the tensile
strength.
    (k) Elongation. Mechanical test specimens must show at least a 40
percent elongation for a 2-inch gauge length or at least 20 percent in
other cases. However, elongation percentages may be reduced numerically
by 2 percent for 2-inch specimens, and by 1 percent in other cases, for
each 7,500 psig increase of tensile strength above 50,000 psig. The
tensile strength may be incrementally increased by four increments of
7,500 psig for a maximum total of 30,000 psig.
    (l) Flattening test--(1) Cylinders. After pressure testing, a
flattening test must be performed on one cylinder taken at random out
of each lot of 200 or fewer by placing the cylinder between wedge-
shaped knife edges having a 60 degree included angle, rounded to a
half-inch radius. The longitudinal axis of the cylinder must be at a
90-degree angle to knife edges during the test. For lots of 30 or
fewer, flattening tests are authorized to be performed on a ring of at
least 8 inches long removed from each cylinder and subjected to the
same heat treatment as the finished cylinder.
    (2) Pipes. When cylinders are constructed of lap welded pipe, an
additional flattening test is required, without evidence of cracking,
up to six (6) times the wall thickness. In such case, the rings (crop
ends) removed from each end of the pipe, must be tested with the weld
45 [deg]F or less from the point of greatest stress.
    (m) Acceptable results for flattening tests. There must be no
evidence of cracking of the sample when it is flattened between flat
plates to no more than six (6) times the wall thickness. If this test
fails, one additional sample from the same lot may be taken. If this
second sample fails, the entire lot must be rejected.
    (n) Rejected cylinders. Reheat treatment is authorized for a
rejected cylinder in accordance with this paragraph (n). After reheat
treatment, a cylinder must pass all prescribed tests in this section to
be considered acceptable. Repair of brazed seams by brazing and welded
seams by welding is authorized. For cylinders with an outside diameter
of less than or equal to six (6) inches, welded seam repairs greater
than one (1) inch in length shall require reheat treatment of the
cylinder. For cylinders greater than an outside diameter of 6 inches,
welded seam repairs greater than three (3) inches in length shall
require reheat treatment.
    (o) Markings. (1) Markings must be as required as in Sec.  178.35
and in addition must be stamped plainly and permanently in any of the
following locations on the cylinder:
    (i) On shoulders and top heads whose wall thickness is not less
than 0.087-inch thick;
    (ii) On side wall adjacent to top head for side walls which are not
less than 0.090 inch thick;
    (iii) On a cylindrical portion of the shell that extends beyond the
recessed bottom of the cylinder, constituting an integral and non-
pressure part of the cylinder;

    (iv) On a metal plate attached to the top of the cylinder or
permanent part thereof; sufficient space must be left on the plate to
provide for stamping at least six retest dates; the plate must be at
least \1/16\-inch thick and must be attached by welding, or by brazing.
The brazing rod must melt at a temperature of 1100 [deg]F. Welding or
brazing must be along all the edges of the plate;
    (v) On the neck, neckring, valve boss, valve protection sleeve, or
similar part permanently attached to the top of the cylinder; or
    (vi) On the footring permanently attached to the cylinder, provided
the water capacity of the cylinder does not exceed 30 pounds.
    (2) Embossing the cylinder head or sidewall is not permitted.

0
30. Revise Sec.  178.51 to read as follows:

Sec.  178.51   Specification 4BA welded or brazed steel cylinders.

    (a) Type, size, pressure, and application. A DOT 4BA cylinder is a
cylinder, either spherical or cylindrical design, with a water capacity
of 1,000 pounds or less and a service pressure range of 225 to 500
psig. Closures made by the spinning process are not authorized.
    (1) Spherical type cylinder designs are permitted to have only one
circumferentially welded seam.
    (2) Cylindrical type cylinder designs must be of circumferentially
welded or brazed construction; longitudinally brazed or silver-soldered
seams are also permitted.
    (b) Steel. The steel used in the construction of the cylinder must
be as specified in table 1 of appendix A to this part. The cylinder
manufacturer must maintain a record of intentionally added alloying
elements.
    (c) Identification of material. Pressure-retaining material must be
identified by any suitable method that does not compromise the
integrity of the cylinder. Plates and billets for hotdrawn cylinders
must be marked with the heat number.
    (d) Manufacture. Cylinders must be manufactured using equipment and
processes adequate to ensure that each cylinder produced conforms to
the requirements of this subpart. No defect is permitted that is likely
to weaken the finished cylinder appreciably. A reasonably smooth and
uniform surface finish is required. Exposed bottom welds on cylinders
over 18 inches long must be protected by footrings.
    (1) Seams must be made as follows:
    (i) Minimum thickness of heads and bottoms must be not less than 90
percent of the required thickness of the side wall.
    (ii) Circumferential seams must be made by welding or by brazing.
Heads attached by brazing must have a driving fit with the shell unless
the shell is crimped, swedged, or curled over the skirt or flange of
the head and must be thoroughly brazed until complete penetration by
the brazing material of the brazed joint is secured. Depth of brazing
from end of the shell must be at least four (4) times the thickness of
shell metal.
    (iii) Longitudinal seams in shells must be made by copper brazing,
copper alloy brazing, or by silver alloy brazing. Copper alloy
composition must be: Copper 95 percent minimum, Silicon 1.5 percent to
3.85 percent, Manganese 0.25 percent to 1.10 percent. The melting point
of the silver alloy brazing material must be in excess of 1,000 [deg]F.
The plate edge must be lapped at least eight times the thickness of
plate, laps being held in position, substantially metal to metal, by
riveting or by electric spot-welding. Brazing must be done by using a
suitable flux and by placing brazing material on one side of seam and
applying heat until this material shows uniformly along the seam of the
other side. Strength of longitudinal seam: Copper brazed longitudinal
seam must have strength at least \3/2\ times the strength of the steel
wall.
    (2) Welding procedures and operators must be qualified in
conformance with CGA C-3 (IBR, see Sec.  171.7 of this subchapter).
    (e) Welding or brazing. Welding or brazing of any attachment or
opening to the heads of cylinders is permitted provided the carbon
content of the steel does not exceed 0.25 percent except in the case of
4130 x steel, which may be used with proper welding procedure.
    (f) Wall thickness. The minimum wall thickness of the cylinder must
meet the following conditions:
    (1) For any cylinder with an outside diameter of greater than 6
inches, the minimum wall thickness is 0.078 inch. In any case, the
minimum wall thickness must be such that the calculated wall stress at
the minimum test pressure may not exceed the lesser value of any of the
following:
    (i) The value shown in table 1 of appendix A to this part, for the
material under consideration;
    (ii) One-half of the minimum tensile strength of the material
determined as required in paragraph (j) of this section;
    (iii) 35,000 psig; or
    (iv) Further provided that wall stress for cylinders having copper
brazed longitudinal seams may not exceed 95 percent of any of the above
values. Measured wall thickness may not include galvanizing or other
protective coating.
    (2) Cylinders that are cylindrical in shape must have the wall
stress calculated by the formula:

S = [P(1.3D\2\ + 0.4d\2\)]/(D\2\ - d\2\)

Where:
S = wall stress in psig;
P = minimum test pressure prescribed for water jacket test;
D = outside diameter in inches; and
d = inside diameter in inches.

    (3) Cylinders that are spherical in shape must have the wall stress
calculated by the formula:

S = PD/4tE
Where:
S = wall stress in psig;
P = minimum test pressure prescribed for water jacket test;
D = outside diameter in inches;
t = minimum wall thickness in inches;
E = 0.85 (provides 85 percent weld efficiency factor which must be
applied in the circumferential weld area and heat affected zones
which zone must extend a distance of 6 times wall thickness from
center line of weld); and
E = 1.0 (for all other areas).

    (4) For a cylinder with a wall thickness less than 0.100 inch, the
ratio of tangential length to outside diameter may not exceed 4.1.
    (g) Heat treatment. Cylinders must be heat treated in accordance
with the following requirements:
    (1) Each cylinder must be uniformly and properly heat treated prior
to test by the applicable method shown in table 1 of appendix A to this
part. Heat treatment must be accomplished after all forming and welding
operations, except that when brazed joints are used, heat treatment
must follow any forming and welding operations, but may be done before,
during or after the brazing operations (see paragraph (m) of this
section for weld repairs).
    (2) Heat treatment is not required after the welding or brazing of
weldable low carbon parts to attachments of similar material which have
been previously welded or brazed to the top or bottom of cylinders and
properly heat treated, provided such subsequent welding or brazing does
not produce a temperature in excess of 400 [deg]F in any part of the
top or bottom material.
    (h) Openings in cylinders. Openings in cylinders must comply with
the following requirements:
    (1) Any opening must be placed on other than a cylindrical surface.
    (2) Each opening in a spherical type cylinder must be provided with
a fitting, boss, or pad of weldable steel securely attached to the
container by fusion welding.
    (3) Each opening in a cylindrical type cylinder must be provided
with a fitting,

boss, or pad, securely attached to container by brazing or by welding.
    (4) If threads are used, they must comply with the following:
    (i) Threads must be clean-cut, even, without checks and tapped to
gauge.
    (ii) Taper threads must be of a length not less than that specified
for American Standard taper pipe threads.
    (iii) Straight threads, having at least 4 engaged threads, must
have a tight fit and a calculated shear strength of at least 10 times
the test pressure of the cylinder. Gaskets, adequate to prevent
leakage, are required.
    (i) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) Lot testing. (i) At least one (1) cylinder randomly selected
out of each lot of 200 or fewer must be tested by water jacket or
direct expansion method as prescribed in CGA C-1 (IBR, see Sec.  171.7
of this subchapter). The testing equipment must be calibrated as
prescribed in CGA C-1. All testing equipment and pressure indicating
devices must be accurate within the parameters defined in CGA C-1.
    (ii) The selected cylinder must be tested to a minimum of two (2)
times service pressure.
    (iii) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and prior to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (iv) Permanent volumetric expansion may not exceed 10 percent of
the total volumetric expansion at test pressure.
    (2) Pressure testing. (i) The remaining cylinders in the lot must
be tested by the proof pressure, water-jacket, or direct expansion test
method as prescribed in CGA C-1. The minimum test pressure must be
maintained for the specific timeframe and the testing equipment must be
calibrated as prescribed in CGA C-1. Further, all testing equipment and
pressure indicating devices must be accurate within the parameters
defined in CGA C-1.
    (ii) Each cylinder must be tested to a minimum of two (2) times
service pressure and show no defect. If, due to failure of the test
apparatus or operator error, the test pressure cannot be maintained,
the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as
appropriate. Determination of expansion properties is not required.
    (j) Mechanical test. (1) A mechanical test must be conducted to
determine yield strength, tensile strength, elongation as a percentage,
and reduction of area of material as a percentage, as follows:
    (i) Cylinders. Testing is required on two (2) specimens removed
from one cylinder or part thereof taken at random out of each lot of
200 or fewer. Samples must be removed after heat treatment as
illustrated in appendix A to this subpart.
    (ii) Spheres. Testing is required on two (2) specimens removed from
the sphere or flat representative sample plates of the same heat of
material taken at random from the steel used to produce the spheres.
Samples (including plates) must be taken from each lot of 200 or fewer.
The flat steel from which two specimens are to be removed must receive
the same heat treatment as the spheres themselves. Samples must be
removed after heat treatment as illustrated in appendix A to this
subpart.
    (2) Specimens must comply with the following:
    (i) When a cylinder wall is \3/16\ inch thick or less, one the
following gauge lengths is authorized: A gauge length of 8 inches with
a width not over 1\1/2\ inches, a gauge length of 2 inches with a width
not over 1\1/2\ inches, or a gauge length at least twenty-four (24)
times the thickness with a width not over six (6) times the thickness.
    (ii) The specimen, exclusive of grip ends, may not be flattened.
Grip ends may be flattened to within one inch of each end of the
reduced section.
    (iii) When size of the cylinder does not permit securing straight
specimens, the specimens may be taken in any location or direction and
may be straightened or flattened cold, by pressure only, not by blows.
When specimens are so taken and prepared, the inspector's report must
show with the record of physical tests detailed information in regard
to such specimens.
    (iv) Heating of a specimen for any purpose is not authorized.
    (3) The yield strength in tension must be the stress corresponding
to a permanent strain of 0.2 percent of the gauge length. The following
conditions apply:
    (i) The yield strength must be determined by either the ``offset''
method or the ``extension under load'' method as prescribed in ASTM E 8
(IBR, see Sec.  171.7 of this subchapter).
    (ii) In using the ``extension under load'' method, the total strain
(or ``extension under load''), corresponding to the stress at which the
0.2 percent permanent strain occurs may be determined with sufficient
accuracy by calculating the elastic extension of the gauge length under
appropriate load and adding thereto 0.2 percent of the gauge length.
Elastic extension calculations must be based on an elastic modulus of
30,000,000. In the event of controversy, the entire stress-strain
diagram must be plotted and the yield strength determined from the 0.2
percent offset.
    (iii) For strain measurement, the initial strain reference must be
set while the specimen is under a stress of 12,000 psig, and the strain
indicator reading must be set at the calculated corresponding strain.
    (k) Elongation. Mechanical test specimens must show at least a 40
percent elongation for a 2-inch gauge length or at least 20 percent in
other cases. However, elongation percentages may be reduced numerically
by 2 percent for 2-inch specimens, and by 1 percent in other cases, for
each 7,500 psig increase of tensile strength above 50,000 psig. The
tensile strength may be incrementally increased by four increments of
7,500 psig for a maximum total of 30,000 psig.
    (l) Tests of welds. Except for brazed seams, welds must be tested
as follows:
    (1) Tensile test. A specimen must be removed from one cylinder of
each lot of 200 or fewer, or welded test plate. The welded test plate
must be of one of the heats in the lot of 200 or fewer which it
represents, in the same condition and approximately the same thickness
as the cylinder wall except that in no case must it be of a lesser
thickness than that required for a quarter size Charpy impact specimen.
The weld must be made by the same procedures and subjected to the same
heat treatment as the major weld on the cylinder. The specimen must be
taken from across the major seam and must be prepared and tested in
conformance with and must meet the requirements of CGA C-3. Should this
specimen fail to meet the requirements, one additional specimen must be
taken from two additional cylinders or welded test plates from the same
lot and tested. If either of these latter two specimens fail to meet
the requirements, the entire lot represented must be rejected.
    (2) Guided bend test. A root bend test specimen must be removed
from the cylinder or welded test plate that was used for the tensile
test specified in paragraph (l)(1) of this section. The specimen must
be taken from across the circumferential seam and must be prepared and
tested in conformance with and must meet the requirements of CGA C-3.
Should this specimen fail to meet the requirements, one additional

specimen must be taken from two additional cylinders or welded test
plates from the same lot and tested. If either of these latter two
specimens fail to meet the requirements, the entire lot represented
must be rejected.
    (3) Alternate guided-bend test. This test may be used and must be
as required by CGA C-3. The specimen must be bent until the elongation
at the outer surface, adjacent to the root of the weld, between the
lightly scribed gage lines a to b, must be at least 20 percent, except
that this percentage may be reduced for steels having a tensile
strength in excess of 50,000 psig, as provided in paragraph (k) of this
section. Should the specimen fail to meet the requirements, one
additional specimen must be taken from two additional cylinders or
welded test plates from the same lot and tested. If any of these latter
two specimens fail to meet the requirements, the entire lot represented
must be rejected.
    (m) Rejected cylinders. Reheat treatment is authorized for a
rejected cylinder in accordance with this paragraph (m). After reheat,
a cylinder must pass all prescribed tests in this section to be
acceptable. Repair of brazed seams by brazing and welded seams by
welding is considered authorized. For cylinders with an outside
diameter of less than or equal to six (6) inches, welded seam repairs
greater than one (1) inch in length shall require reheat treatment of
the cylinder. For cylinders greater than an outside diameter of six (6)
inches, welded seam repairs greater than three (3) inches in length
shall require reheat treatment.
    (n) Markings. (1) Markings must be as required in Sec.  178.35 and
in addition must be stamped plainly and permanently in one of the
following locations on the cylinder:
    (i) On shoulders and top heads whose wall thickness is not less
than 0.087 inch thick;
    (ii) On side wall adjacent to top head for side walls not less than
0.090 inch thick;
    (iii) On a cylindrical portion of the shell that extends beyond the
recessed bottom of the cylinder constituting an integral and non-
pressure part of the cylinder;
    (iv) On a plate attached to the top of the cylinder or permanent
part thereof; sufficient space must be left on the plate to provide for
stamping at least six retest dates; the plate must be at least \1/16\
inch thick and must be attached by welding, or by brazing at a
temperature of at least 1100 [deg]F., throughout all edges of the
plate;
    (v) On the neck, neckring, valve boss, valve protection sleeve, or
similar part permanently attached to the top of the cylinder; or
    (vi) On the footring permanently attached to the cylinder, provided
the water capacity of the cylinder does not exceed 30 pounds.
    (2) [Reserved]

0
31. In Sec.  178.53, revise paragraph (h) to read as follows:

Sec.  178.53   Specification 4D welded steel cylinders for aircraft
use.

* * * * *
    (h) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) Lot testing. (i) At least one cylinder selected at random out
of each lot of 200 or fewer must be tested by water-jacket or direct
expansion as prescribed in CGA C-1 (IBR; see Sec.  171.7 of this
subchapter). The testing equipment must be calibrated as prescribed in
CGA C-1. All testing equipment and pressure indicating devices must be
accurate within the parameters defined in CGA C-1.
    (ii) The selected cylinder must be tested to a minimum of three (3)
times service pressure.
    (iii) The minimum test pressure must be maintained be maintained at
least 30 seconds and sufficiently longer to ensure complete expansion.
Any internal pressure applied after heat-treatment and prior to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (iv) Permanent volumetric expansion may not exceed 10 percent of
the total volumetric expansion at test pressure.
    (2) Pressure testing. (i) The remaining cylinders in each lot must
be tested by the proof pressure water-jacket or direct expansion test
method as prescribed in CGA C-1. The minimum test pressure must be
maintained for the specific timeframe and the testing equipment must be
calibrated as prescribed in CGA C-1. Further, all testing equipment and
pressure indicating devices must be accurate within the parameters
defined in CGA C-1. Determination of expansion properties is not
required.
    (ii) Each cylinder must be tested to a minimum of two (2) times
service pressure and show no defect. If, due to failure of the test
apparatus or operator error, the test pressure cannot be maintained,
the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as
appropriate.
    (3) Alternative volumetric expansion testing. As an alternative to
the testing prescribed in paragraphs (h)(1) and (2) of this section,
every cylinder may be volumetrically expansion tested by the water
jacket or direct expansion test method. The testing equipment must be
calibrated as prescribed in CGA C-1. All testing equipment and pressure
indicating devices must be accurate within the parameters defined in
CGA C-1.
    (i) Each cylinder must be tested to a minimum of at least two (2)
times its service pressure.
    (ii) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and previous to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (iii) Permanent volumetric expansion may not exceed 10 percent of
total volumetric expansion at test pressure.
* * * * *

0
32. In Sec.  178.55, revise paragraph (i) to read as follows:

Sec.  178.55  Specification 4B240ET welded or brazed cylinders.

* * * * *
    (i) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) Lot testing. (i) At least one (1) cylinder selected at random
out of each lot of 200 or fewer must be tested by water-jacket or
direct expansion method as prescribed in CGA C-1 (IBR; see Sec.  171.7
of this subchapter). The testing equipment must be calibrated as
prescribed in CGA C-1. All testing equipment and pressure indicating
devices must be accurate within the parameters defined in CGA C-1.
    (ii) Each cylinder must be tested to a minimum of two (2) times
service pressure.
    (iii) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and prior to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (iv) Permanent volumetric expansion may not exceed 10 percent of
the total volumetric expansion at test pressure.
    (2) Pressure testing. (i) The remaining cylinders in each lot must
be tested by the proof pressure water-jacket or direct expansion test
method as prescribed in

CGA C-1. The minimum test pressure must be maintained for the specific
timeframe and the testing equipment must be calibrated as prescribed in
CGA C-1. All testing equipment and pressure indicating devices must be
accurate within the parameters defined in CGA C-1.
    (ii) Each cylinder must be tested to a minimum of two (2) times
service pressure and show no defect. If, due to failure of the test
apparatus or operator error, the test pressure cannot be maintained,
the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2.
Determination of expansion properties is not required.
    (3) Burst testing. (i) For purposes of burst testing, each 1,000
cylinders or fewer successively produced each day constitutes a lot.
All cylinders of a lot must be of identical size, construction heat
treatment, finish, and quality.
    (ii) One cylinder must be selected from each lot and be
hydrostatically pressure tested to destruction. If this cylinder bursts
below five (5) times the service pressure, then two additional
cylinders from the same lot as the previously tested cylinder must be
selected and subjected to this test. If either of these cylinders fails
by bursting below five (5) times the service pressure then the entire
lot must be rejected. All testing equipment and pressure indicating
devices must be accurate within the parameters defined in CGA C-1.
* * * * *

0
33. In Sec.  178.56, revise paragraph (i) to read as follows:

Sec.  178.56  Specification 4AA480 welded steel cylinders.

* * * * *
    (i) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) Lot testing. (i) At least one (1) cylinder selected at random
out of each lot of 200 or fewer must be tested by water-jacket or
direct expansion method as prescribed in CGA C-1 (IBR; see Sec.  171.7
of this subchapter). The testing equipment must be calibrated as
prescribed in CGA C-1. All testing equipment and pressure indicating
devices must be accurate within the parameters defined in CGA C-1.
    (ii) The selected cylinder must be tested to a minimum of two (2)
times service pressure.
    (iii) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and prior to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (iv) Permanent volumetric expansion may not exceed 10 percent of
the total volumetric expansion at test pressure.
    (v) If the selected cylinder fails, then two (2) additional
specimens must be selected at random from the same lot and subjected to
the prescribed testing. If either of these fails the test, then each
cylinder in that lot must be tested as prescribed in paragraph (i)(l)
of this section.
    (2) Pressure testing. (i) The remaining cylinders in each lot must
be tested by the proof pressure, water-jacket, or direct expansion test
method as prescribed in CGA C-1. The minimum test pressure must be
maintained for the specific timeframe and the testing equipment must be
calibrated as prescribed in CGA C-1. Further, all testing equipment and
pressure indicating devices must be accurate within the parameters
defined in CGA C-1.
    (ii) Each cylinder must be tested to a minimum of two (2) times
service pressure and show no defect. A cylinder showing a defect must
be rejected unless it may be requalified under paragraph (m) of this
section. If, due to failure of the test apparatus or operator error,
the test pressure cannot be maintained, the test may be repeated in
accordance with CGA C-1 5.7.2 or 7.1.2, as appropriate. Determination
of expansion properties is not required.
* * * * *

0
34. In Sec.  178.57, revise paragraph (i) to read as follows:

Sec.  178.57  Specification 4L welded insulated cylinders.

* * * * *
    (i) Pressure testing. Each cylinder, before insulating and
jacketing, must successfully withstand a pressure test as follows:
    (1) The cylinder must be tested by the proof pressure, water-
jacket, or direct expansion test method as prescribed in CGA C-1 (IBR;
see Sec.  171.7 of this subchapter). The testing equipment must be
calibrated as prescribed in CGA C-1. All testing equipment and pressure
indicating devices must be accurate within the parameters defined in
CGA C-1.
    (2) Each cylinder must be tested to a minimum of two (2) times
service pressure.
    (3) The minimum test pressure must be maintained at least 30
seconds. Any internal pressure applied after heat-treatment and prior
to the official test may not exceed 90 percent of the test pressure.
If, due to failure of the test apparatus or operator error, the test
pressure cannot be maintained, the test may be repeated in accordance
with CGA C-1 5.7.2 or 7.1.2. Determination of expansion properties is
not required.
    (4) There must be no evidence of leakage, visible distortion or
other defect.
* * * * *

0
35. In Sec.  178.58, revise paragraph (i) to read as follows:

Sec.  178.58  Specification 4DA welded steel cylinders for aircraft
use.

* * * * *
    (i) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) The test must be by water-jacket or direct expansion method as
prescribed in CGA C-1 (IBR; see Sec.  171.7 of this subchapter). The
testing equipment must be calibrated as prescribed in CGA C-1. All
testing equipment and pressure indicating devices must be accurate
within the parameters defined in CGA C-1.
    (2) Each cylinder must be tested to a minimum of two (2) times
service pressure.
    (3) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and prior to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (4) Permanent volumetric expansion may not exceed 10 percent of the
total volumetric expansion at test pressure.
* * * * *

0
36. In Sec.  178.59, revise paragraph (h) to read as follows:

Sec.  178.59  Specification 8 steel cylinders with porous fillings for
acetylene.

* * * * *
    (h) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) Lot testing. (i) At least one (1) cylinder selected at random
out of each lot of 200 or fewer must be tested by water-jacket or
direct expansion method as prescribed in CGA C-1 (IBR; see Sec.  171.7
of this subchapter). The testing equipment must be calibrated as
prescribed in CGA C-1. All testing equipment and pressure indicating
devices must be accurate within the parameters defined in CGA C-1.
    (ii) The selected cylinder must be tested to a minimum of 750 psig.

    (iii) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and prior to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (iv) Permanent volumetric expansion may not exceed 10 percent of
the total volumetric expansion at test pressure.
    (v) If the selected cylinder passes the volumetric expansion test,
each remaining cylinder in the lot must be pressure tested in
accordance with paragraph (h)(2) of this section. If the selected
cylinder fails, each cylinder in the lot must be tested by water-jacket
or direct expansion method as prescribed in CGA C-1 at 750 psig. Each
cylinder with a permanent expansion that does not exceed 10% is
acceptable.
    (2) Pressure testing. (i) If the selected cylinder passes the
water-jacket or direct expansion test, the remaining cylinders in each
lot must be pressure tested by the proof pressure, water-jacket or
direct expansion test method as prescribed in CGA C-1. The minimum test
pressure must be maintained for the specific timeframe and the testing
equipment must be calibrated as prescribed in CGA C-1. Further, all
testing equipment and pressure indicating devices must be accurate
within the parameters defined in CGA C-1.
    (ii) Each cylinder must be tested between 500 and 600 psig and show
no defect. If, due to failure of the test apparatus or operator error,
the test pressure cannot be maintained, the test may be repeated in
accordance with CGA C-1 section 5.7.2 or 7.1.2, as appropriate.
Determination of expansion properties is not required.
* * * * *

0
37. In Sec.  178.60, revise paragraph (j) to read as follows:

Sec.  178.60  Specification 8AL steel cylinders with porous fillings
for acetylene.

* * * * *
    (j) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) Lot testing. (i) At least one (1) cylinder selected at random
out of each lot of 200 or less must be tested by water-jacket or direct
expansion method as prescribed in CGA C-1 (IBR; see Sec.  171.7 of this
subchapter). The testing equipment must be calibrated as prescribed in
CGA C-1. All testing equipment and pressure indicating devices must be
accurate within the parameters defined in CGA C-1.
    (ii) The selected cylinder must be tested to a minimum of 750 psig.
    (iii) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and prior to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (iv) Permanent volumetric expansion may not exceed 10 percent of
the total volumetric expansion at test pressure.
    (v) If the selected cylinder passes the volumetric expansion test,
each remaining cylinder in the lot must be pressure tested in
accordance with paragraph (h)(2) of this section. If the selected
cylinder fails, each cylinder in the lot must be tested by water-jacket
or direct expansion method as prescribed in CGA C-1 at 750 psig. Each
cylinder with a permanent expansion that does not exceed 10% is
acceptable.
    (2) Pressure testing. (i) If the selected cylinder passes the
water-jacket or direct expansion test, the remaining cylinders in each
lot must be pressure tested by the proof pressure water-jacket or
direct expansion test method as prescribed in CGA C-1. The minimum test
pressure must be maintained for the specific timeframe and the testing
equipment must be calibrated as prescribed in CGA C-1. Further, all
testing equipment and pressure indicating devices must be accurate
within the parameters defined in CGA C-1.
    (ii) Each cylinder must be tested between 500 and 600 psig and show
no defect. If, due to failure of the test apparatus or operator error,
the test pressure cannot be maintained, the test may be repeated in
accordance with CGA C-1 section 5.7.2 or 7.1.2, as appropriate.
Determination of expansion properties is not required.
* * * * *

0
38. Revise Sec.  178.61 to read as follows:

Sec.  178.61  Specification 4BW welded steel cylinders with electric-
arc welded seam.

    (a) Type, size, pressure, and application. A DOT 4BW cylinder has a
spherical or cylindrical design, a water capacity of 1,000 pounds or
less, and a service pressure range of 225 to 500 psig. Closures made by
the spinning process are not authorized.
    (1) Spherical designs are permitted to have only one
circumferentially electric-arc welded seam.
    (2) Cylindrical designs must be of circumferentially welded
electric-arc construction; longitudinally electric-arc welded seams are
permitted.
    (b) Steel. (1) The steel used in the construction of the cylinder
must be as specified in table 1 of appendix A to this part. The
cylinder manufacturer must maintain a record of intentionally added
alloying elements.
    (2) Material for heads must meet the requirements of paragraph
(b)(1) of this section or be open hearth, electric or basic oxygen
carbon steel of uniform quality. Content percent may not exceed the
following: Carbon 0.25, Manganese 0.60, Phosphorus 0.045, Sulfur 0.050.
Heads must be hemispherical or ellipsoidal in shape with a maximum
ratio of 2:1. If low carbon steel is used, the thickness of such heads
must be determined by using a maximum wall stress of 24,000 psi in the
formula described in paragraph (f)(2) of this section.
    (c) Identification of material. Pressure-retaining materials must
be identified by any suitable method that does not compromise the
integrity of the cylinder. Plates and billets for hotdrawn cylinders
must be marked with the heat number.
    (d) Manufacture. Cylinders must be manufactured using equipment and
processes adequate to ensure that each cylinder produced conforms to
the requirements of this subpart and the following:
    (1) No defect is permitted that is likely to weaken the finished
cylinder appreciably. A reasonably smooth and uniform surface is
required. Exposed bottom welds on cylinders over 18 inches long must be
protected by footrings. Minimum thickness of heads may not be less than
90 percent of the required thickness of the sidewall. Heads must be
concave to pressure.
    (2) Circumferential seams must be by electric-arc welding. Joints
must be butt with one member offset (joggle butt) or with a lap joint.
Joints must have a minimum overlap of at least four (4) times nominal
sheet thickness.
    (3) Longitudinal electric-arc welded seams (in shells) must be of
the butt welded type. Welds must be made by a machine process including
automatic feed and welding guidance mechanisms. Longitudinal seams must
have complete joint penetration, and must be free from undercuts,
overlaps or abrupt ridges or valleys. Misalignment of mating butt edges
may not exceed \1/6\ inch of nominal sheet thickness or \1/32\ inch
whichever is less. All joints with nominal sheet thickness up to and
including \1/8\ inch must be tightly butted. When nominal sheet
thickness is

greater than \1/8\ inch, the joint must be gapped with maximum distance
equal to one-half the nominal sheet thickness or \1/32\ inch whichever
is less. Joint design, preparation, and fit-up must be such that
requirements of this paragraph (d) are satisfied.
    (4) Welding procedures and operators must be qualified in
accordance with CGA C-3 (IBR, see Sec.  171.7 of this subchapter).
    (5)(i) Welds of the cylinders must be subjected to radioscopic or
radiographic examination as follows:
    (ii) Radioscopy or radiography must be in conformance with CGA C-3
(IBR; see Sec.  171.7 of this subchapter). Maximum joint efficiency
will be 1.0 when each longitudinal seam is examined completely. Maximum
joint efficiency will be 0.90 when one cylinder from each lot of 50
consecutively welded cylinders is spot examined. In addition, one out
of the first five cylinders welded following a shutdown of welding
operations exceeding four hours must be spot examined. Spot
radiographs, when required, must be made of a finished welded cylinder
and must include the circumferential weld for 2 inches in both
directions from the intersection of the longitudinal and
circumferential welds and include at least 6 inches of the longitudinal
weld. Maximum joint efficiency of 0.75 will be permissible without
radiography or radioscopy. When fluoroscopic examination is used,
permanent film records need not be retained. Circumferential welds need
not be examined, except as part of spot examination.
    (e) Welding of attachments. The attachment to the tops and bottoms
only of cylinders by welding of neckrings, footrings, handles, bosses,
pads and valve protection rings is authorized provided that such
attachments and the portion of the container to which they are attached
are made of weldable steel, the carbon content of which may not exceed
0.25 percent.
    (f) Wall thickness. (1) For outside diameters over 6 inches the
minimum wall thickness must be 0.078 inch. In any case, the minimum
wall thickness must be such that the wall stress calculated by the
formula listed in paragraph (f)(2) of this section may not exceed the
lesser value of any of the following:
    (i) The value referenced in paragraph (b) of this section for the
particular material under consideration.
    (ii) One-half of the minimum tensile strength of the material
determined as required in paragraph (j) of this section.
    (iii) 35,000 psig.
    (2) Stress must be calculated by the following formula:

S = [2P(1.3D\2\ + 0.4d\2\)]/[E(D\2\ - d\2\)]

Where:
S = wall stress, psig;
P = service pressure, psig;
D = outside diameter, inches;
d = inside diameter, inches; and
E = joint efficiency of the longitudinal seam (from paragraph (d) of
this section).

    (3) For a cylinder with a wall thickness less than 0.100 inch, the
ratio of tangential length to outside diameter may not exceed 4 to 1
(4:1).
    (g) Heat treatment. Cylinders must be heat treated in accordance
with the following requirements:
    (1) Each cylinder must be uniformly and properly heat treated prior
to test by the applicable method referenced in table 1 of appendix A to
this part. Heat treatment must be accomplished after all forming and
welding operations, except that when brazed joints are used, heat
treatment must follow any forming and welding operations, but may be
done before, during or after the brazing operations (see paragraph (n)
of this section for weld repairs).
    (2) Heat treatment is not required after welding of weldable low-
carbon parts to attachments of similar material which have been
previously welded to the top or bottom of cylinders and properly heat
treated, provided such subsequent welding does not produce a
temperature in excess of 400 [deg]F in any part of the top or bottom
material.
    (h) Openings in cylinders. Openings in cylinders must comply with
the following requirements:
    (1) All openings must be in heads or bases.
    (2) Each opening in a spherical-type cylinder must be provided with
a fitting, boss, or pad of weldable steel securely attached to the
cylinder by fusion welding.
    (3) Each opening in a cylindrical-type cylinder must be provided
with a fitting, boss, or pad securely attached to the cylinder by
welding.
    (4) If threads are used, they must comply with the following:
    (i) Threads must be clean cut, even, without checks, and tapped to
gauge.
    (ii) Taper threads must be of length not less than as specified for
American Standard Taper Pipe Threads.
    (iii) Straight threads, having at least four (4) engaged threads,
must have a tight fit and calculated shear strength at least ten (10)
times the test pressure of the cylinder. Gaskets, adequate to prevent
leakage, are required.
    (iv) A brass fitting may be brazed to the steel boss or flange on
cylinders used as component parts of handheld fire extinguishers.
    (i) Pressure testing. Each cylinder must successfully withstand a
pressure test as follows:
    (1) Lot testing. (i) At least one (1) cylinder randomly selected
out of each lot of 200 or fewer must be tested by the water-jacket or
direct expansion method as prescribed in CGA C-1 (IBR, see Sec.  171.7
of this subchapter). The testing equipment must be calibrated as
prescribed in CGA C-1. All testing equipment and pressure indicating
devices must be accurate within the parameters defined in CGA C-1.
    (ii) Each selected cylinder must be tested to a minimum of two (2)
times service pressure.
    (iii) The minimum test pressure must be maintained at least 30
seconds and sufficiently longer to ensure complete expansion. Any
internal pressure applied after heat-treatment and prior to the
official test may not exceed 90 percent of the test pressure. If, due
to failure of the test apparatus or operator error, the test pressure
cannot be maintained, the test may be repeated in accordance with CGA
C-1, section 5.7.2.
    (iv) Permanent volumetric expansion may not exceed 10 percent of
the total volumetric expansion at test pressure.
    (2) Pressure testing. (i) The remaining cylinders in each lot must
be pressure tested by the proof pressure, water-jacket or direct
expansion test method as prescribed in CGA C-1. The minimum test
pressure must be maintained for the specific timeframe and the testing
equipment must be calibrated as prescribed in CGA C-1. Further, all
testing equipment and pressure indicating devices must be accurate
within the parameters defined in CGA C-1.
    (ii) Each cylinder must be tested to a minimum of two (2) times
service pressure and show no defect. If, due to failure of the test
apparatus or operator error, the test pressure cannot be maintained,
the test may be repeated in accordance with CGA C-1 5.7.2 or 7.1.2, as
appropriate. Determination of expansion properties is not required.
    (3) Burst testing. One finished cylinder selected at random out of
each lot of 500 or less successively produced must be hydrostatically
tested to four (4) times service pressure without bursting. All testing
equipment and pressure indicating devices must be accurate within the
parameters defined in CGA C-1.
    (j) Mechanical tests. Mechanical tests must be conducted to
determine yield strength, tensile strength, elongation as a percentage,
and reduction of area of material as a percentage, as follows:
    (1) Specimens must be taken from one cylinder after heat treatment
as

illustrated in appendix A to this subpart, chosen at random from each
lot of 200 or fewer, as follows:
    (i) One specimen must be taken longitudinally from the body section
at least 90 degrees away from the weld.
    (ii) One specimen must be taken from either head on a cylinder when
both heads are made of the same material. However, if the two heads are
made of differing materials, a specimen must be taken from each head.
    (iii) If due to welded attachments on the top head there is
insufficient surface from which to take a specimen, it may be taken
from a representative head of the same heat treatment as the test
cylinder.
    (2) Specimens must conform to the following:
    (i) When a cylinder wall is \3/16\ inch thick or less, one the
following gauge lengths is authorized: A gauge length of 8 inches with
a width not over 1\1/2\ inches, a gauge length of 2 inches with a width
not over 1\1/2\ inches, or a gauge length at least twenty-four (24)
times the thickness with a width not over six (6) times the thickness.
    (ii) The specimen, exclusive of grip ends, may not be flattened.
Grip ends may be flattened to within 1 inch of each end of the reduced
section.
    (iii) When size of the cylinder does not permit securing straight
specimens, the specimens may be taken in any location or direction and
may be straightened or flattened cold, by pressure only, not by blows.
When specimens are taken, and prepared in this manner, the inspector's
report must show, in connection with the record of physical tests,
detailed information in regard to such specimens.
    (iv) Heating of a specimen for any purpose is not authorized.
    (3) The yield strength in tension must be the stress corresponding
to a permanent strain of 0.2 percent of the gauge length. The following
conditions apply:
    (i) The yield strength must be determined by either the ``off-set''
method or the ``extension under load'' method as prescribed in ASTM E 8
(IBR, see Sec.  171.7 of this subchapter).
    (ii) In using the ``extension under load'' method, the total strain
(or ``extension under load''), corresponding to the stress at which the
0.2-percent permanent strain occurs may be determined with sufficient
accuracy by calculating the elastic extension of the gauge length under
appropriate load and adding thereto 0.2 percent of the gauge length.
Elastic extension calculations must be based on an elastic modulus of
30,000,000. In the event of controversy, the entire stress-strain
diagram must be plotted and the yield strength determined from the 0.2-
percent offset.
    (iii) For strain measurement, the initial strain reference must be
set while the specimen is under a stress of 12,000 psig, and the strain
indicator reading must be set at the calculated corresponding strain.
    (iv) Cross-head speed of the testing machine may not exceed \1/8\
inch per minute during yield strength determination.
    (k) Elongation. Mechanical test specimens must show at least a 40
percent elongation for a 2-inch gauge length or at least 20 percent in
other cases. However, elongation percentages may be reduced numerically
by 2 percent for 2-inch specimens, and by 1 percent in other cases, for
each 7,500 psi increase of tensile strength above 50,000 psig. The
tensile strength may be incrementally increased by four increments of
7,500 psig for a maximum total of 30,000 psig.
    (l) Tests of welds. Welds must be subjected to the following tests:
    (1) Tensile test. A specimen must be removed from one cylinder of
each lot of 200 or fewer. The specimen must be taken from across the
longitudinal seam and must be prepared and tested in conformance with
the requirements of CGA C-3 (IBR, see Sec.  171.7 of this subchapter).
    (2) Guided bend test. A root bend test specimen must be removed
from the cylinder or welded test plate used for the tensile test
specified in paragraph (m)(1) of this section. Specimens must be taken
from across the longitudinal seam and must be prepared and tested in
conformance with the requirements of CGA C-3. If the specimen fails to
meet the requirements, one specimen each must be taken from two
additional cylinders or welded test plates from the same lot as the
previously tested cylinder or added test plate and tested. If either of
these latter two specimens fails to meet the requirements, the entire
lot represented must be rejected.
    (3) Alternate guided bend test. This test may be used and must be
as required by CGA C-3. The specimen must be bent until the elongation
at the outer surface, adjacent to the root of the weld, between the
lightly scribed gauge lines a to b, must be at least 20 percent, except
that this percentage may be reduced for steels having a tensile
strength in excess of 50,000 psig, as provided in paragraph (k) of this
section. Should this specimen fail to meet the requirements, one
additional specimen must be taken from two additional cylinders or
welded test plates from the same lot and tested as the previously
tested cylinder or added test plate. If either of these latter two
specimens fails to meet the requirements, the entire lot represented
must be rejected.
    (m) Rejected cylinders. (1) Unless otherwise stated, if a sample
cylinder or specimen taken from a lot of cylinders fails the prescribed
test, then two additional specimens must be selected from the same lot
and subjected to the prescribed test. If either of these fails the
test, then the entire lot must be rejected.
    (2) Reheat treatment of rejected cylinders. Reheat treatment is
authorized for a rejected cylinder in accordance with this paragraph
(m)(2). After reheat treatment, a cylinder must pass all prescribed
tests in this section to be considered acceptable. Repair of welded
seams by welding is authorized. For cylinders less than or equal to an
outside diameter of 6 inches, welded seam repairs greater than 1 inch
in length shall require reheat treatment of the cylinder. For cylinders
greater than an outside diameter of 6 inches, welded seam repairs
greater than 3 inches in length shall require reheat treatment.
    (n) Markings. (1) Markings must be as required in Sec.  178.35 and
in addition must be stamped plainly and permanently in one of the
following locations on the cylinder:
    (i) On shoulders and top heads whose wall thickness is not less
than 0.087 inch thick.
    (ii) On side wall adjacent to top head for side walls not less than
0.090 inch thick.