About Pipelines 101: What are pipelines made of?

For energy pipelines, manufacturers use high-quality steel that’s carefully produced using sophisticated manufacturing and testing processes. Each pipe is built with the strength to withstand pressure beyond what it will be operated at, achieving (and in many cases exceeding) the CSA Z245.1 standards (or the U.S. equivalent, API 5L).

Important facts about the pipes used to construct pipelines

1. For pipelines in Canada, the Canadian Standards Association’s (CSA) ‘pipe material’ standards dictate the properties required for manufacturing steel that will eventually be used to build pipelines. Over and above that, most pipeline companies have proprietary specifications that exceed CSA standards. Those standards and specifications usually dictate stricter requirements on a number of items, including chemistry, yield strength, and the grades of steel used for building pipelines. To meet industry standards, before the pipe leaves the mill manufacturers must test the steel and the completed pipes using three types of testing processes.

   1. Destructive tests

      break apart samples of the pipe steel to measure the maximum stress, or force, the material can withstand before it breaks. Other similar tests determine the maximum cold temperature the pipe can withstand, which is especially critical for pipelines installed in some Canadian climates.

   2. Non-destructive tests

      (NDT) examine the completed pipes before they leave the pipe mill, using x-ray and ultrasound technologies similar to the ones used for medical tests on humans. These inspections look for any defects in the pipe. Every section of pipe must undergo ultrasonic testing before it leaves the mill. And, each pipe section is marked so it can be traced back to the original steel batch number.

   3. Hydrostatic testing

      is the final test before the pipe leaves the mill. This test is done to verify that the pipeline meets CSA specifications to withstand the pressure it will experience during operation. The test uses water to simulate a pressure that’s higher than the pipe will encounter in normal pipeline operation. The pressure is held for periods specified by the CSA – five seconds for pipes that are 16 inches or less in diameter, and 10 seconds for pipe diameters of 18 inches and above.

    

2. The pipe goes to a coating plant once testing is done. There, a polymer coating is bonded to the pipe metal for corrosion control. Additional measures, undertaken during construction, protect the buried pipeline from external corrosion. They include the coating that’s applied to individual welds and cathodic protection.

Research contributes to continuous improvement in pipe manufacturing

Even with the rigorous testing that’s routinely applied, pipe manufacturers are always looking for ways to improve their products. EVRAZ, which is the only fully integrated pipe manufacturer in North America, has their own research and development facility in Saskatchewan. They, and other pipe manufacturers, also routinely partner with multiple universities and research institutions to conduct research and improve testing.

About Pipelines Blog thanks Dave Coffin of EVRAZ North America and David Milmine of DM Professional Services Ltd. for their contributions to this blog post.