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Pipeline Construction

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Construction Processes
Petroleum Processes

Pipelines are constructed to allow the transportation of liquid, usually oil, from its point of origin to a refinery tank. Their construction involves the use of a broad range of machines from the construction industry, including hydraulic excavators, pipelayers, bulldozers, tractors, and weld tractors. Among the most famous pipeline construction is the Trans Alaska Pipeline System (TAPS), a pipeline stretching 800 miles (1,287 km) through permafrost sections, crossing 800 rivers and streams, animal crossings, highways, and more. Another famous pipeline is the Langeled Pipeline, the longest underwater pipeline at 746 miles (1,200 km) from Norway to England.


[edit] History

Crews Lay Pipe in 1899
Pipelines in the U.S. date back as far as the 1800s. Pipelines were primarily used for transporting water in the 1830s but their usage extended to transporting oil in 1859. The first person to commercially drill for oil was “Colonel” Edwin Drake, from Titusville, Pennsylvania.

The first pipes were made from wood or iron and transported across shorter distances than are demonstrated in today’s pipelines. With the oil industry collecting speed, the business of constructing pipelines grew as well.

After the 1860s, pipeline construction saw advancements that left the old day of wooden and iron pipes behind. Oil drilling companies needed a metal they could rely on and steel was the answer. Steel pipes are always being experimented with to ensure better protection, insulation, and prevention from corrosion.[1]

Pipe installation is also continuously being advanced. Where and how the pipes are being laid has played a precedent for new methods. Pipelines lain under the seabed and in permafrost conditions, for example, were the result of unique projects that required contractors to think outside the conventional tunnel in the ground.

[edit] Process

Before pipelines can be constructed, a lot of planning is put into the project. Planning can delay the process for years while companies assess the market demand for pipelines, assess costs, and obtain permits. This can be affected by a number of factors, including whether the pipelines will cross highways or other private dwellings and whether the pipeline will be constructed above ground, below ground, or in the ocean. Researchers have to sample the soil in order to determine what types of pipes are required to withstand certain, possibly harrowing, conditions that will befall the pipes. If the pipes are to contain oil, researchers have to assess whether the heat generated by the oil will lead to disastrous results. Furthermore, pipes need to be tested to ensure that there is little probability of combustion, leaks, and corrosion by the various materials that pipes encounter (soil, bitumen, and other rocks).

Pipeline projects must follow strict guidelines imposed by federal and state governments. Land or Right-of-Way (ROW) agents take on the responsibility to establish the routes of the pipeline in a manner that is agreed to by landowners. The ROW is the area designated for the construction and cannot usually come within close proximity—defined as 50-feet (15 m)—with private or public dwellings, buildings. If they do come within this proximity, pipelines must contain a 12-inch (30-cm) covering.

Once the design, permit, and Right-of-Way plans have been assessed, assigned and completed, the process of constructing pipelines can begin. Incidentally, it is the construction process that usually takes the least amount of time to complete. Contractors begin this by removing any objects or materials that obstruct the route of the pipeline, such as trees and rocks.[2]

Pads are sometimes placed adjacent to the digging site to allow for the easy movement of equipment. Once this is prepared the digging begins. The trenches where the pipes are to be laid can be accomplished with a number of different construction machines: hydraulic excavators, bulldozers, tractors, trenchers, ditcher, bucket wheel excavators, and tunnel boring machines. The type of equipment used for digging usually depends on the size of the trench being dug and the type of materials being excavated.

Caterpillar 330C Lifts Pipe for Oil Pipeline
Pipes undergo preparation before they are installed into the ground, and in most cases, they have to be welded together with other pipes, usually by pipe welding trucks, or welding rig trucks. Some welding can also be done manually. During this process, workers come upon occasions when pipes need to be bent in order to follow the designated route. Bending pipes is achieved by a pipe-bending machine called a pipe bending mandrel. This machine bends steel in a manner that enables it to retain its strength and durability. Workers have to be careful that the pipes do not experience a wrinkle-bend, and that the pipes remain circular with smooth contours

A group of workers known as a pipe gang aligns the pipes in the trenches and welds the finishing touches. The firing line completes the other final touches, such as installing the cap bead and filler for the pipes.

When the pipes are ready, a tractor, pipelayer, or sideboom lowers the pipe into the trench. Sometimes, the complexity of lowering the pipe in a careful manner calls for the use of further equipment. Rollers, cradles, and pipe tongs assist the tractor in this process. As the pipes are lowered, any leaks are detected by an apparatus called a jeep. As well, valves for controlling the pipeline are inserted. Pipes that need to cross areas such as rivers and railway crossings undergo work from a directional drill or horizontal directional drill. Directional drills are used when pipes need to be adjusted to suit railway or other type crossings. Horizontal directional drills are used for large rivers.

Before the trenches are refilled with soil, numerous tests are conducted on the pipes to ensure good conditions. The trenches are covered with backfill to provide cover and protection for the pipes, as well as enabling the environment to run its normal course.[3]

[edit] Equipment Used

[edit] References

  1. History of Pipelines. Pipeline 101, 2008-09-29.
  2. Design and Construction. Pipeline 101, 2008-09-29.
  3. Pipeline Design and Construction, 2008-09-29.