Pipeline Construction

Throughout the entire lifecycle of a pipeline – from the time planning for a new project begins to the day it is retired – safety and environmental protection are top priorities. The entire process is strictly regulated.

How are Pipelines Planned and Built?

From planning, through construction to operation, it takes years to build a major transmission pipeline. The pipeline construction process is divided into three phases: pre-construction, construction and post-construction.

The Construction Process


Pre-construction activities include: contact and engage landowners; survey and stake the route; prepare the right-of-way by removing and storing topsoil; dig the pipeline trench; ‘string’ the pipe (lay out individual lengths of pipe in the trench end-to-end).


Construction includes: weld the pipe pieces together (every weld is inspected using X-ray or ultrasound); lower the welded pipe into place in the trench; install valves and fittings, including remote sensors to monitor pipeline pressure, flow rate and temperature – valves can quickly shut down a pipeline in case of emergency; restore the right-of way by replacing soil.


In the post-construction phase, the pipeline is tested at operating pressure using nitrogen, air or water to ensure there are no leaks, and land remediation is completed, such as seeding. The right-of-way is monitored for three years to identify and correct any impacts from construction.

What are Pipelines Made Of?

Oil and natural gas pipelines are both made of coated steel pipe that is normally buried underground (except in the far North where pipelines are built above ground due to permafrost – these above-ground pipelines are insulated). Oil transmission pipelines operate at pressures from 600 to 1000 pounds per square inch (psi), while natural gas transmission pipelines operate at more than 1000 psi.

Special coatings are applied to the pipe during manufacturing to prevent corrosion. The coatings bond to the molecules in the steel, creating a powerful shield. The protective coatings are designed for specific conditions.

Natural gas pipelines have above-ground compressor stations at intervals along the route to maintain pressure inside the pipe. Crude oil or liquids pipelines have above-ground pump stations along the route to keep the pipeline’s contents moving.

Water Crossings

Specially designed pipes with thicker walls and corrosion-resistant coatings are used in water crossings. If there is a strong current or deep water, cables, bolts and weights may be installed for extra stability. The pipe is continuously checked during and after construction.

Biologists, environmentalists and other experts carefully study proposed pipeline routes to choose the safest place for the pipeline to cross a waterway. They consider bank stability, wildlife, vegetation and fish habitat.

Operators have options for building pipelines over, through or below water. Sometimes a tunnel is drilled underneath the water and the pipeline is threaded through. A pipeline can be suspended above a waterway, similar to a bridge. Pipes can also be laid on the lakebed or riverbed and anchored in place.

Canada’s Pipeline History

Some Canadian pipeline history highlights include:

  • Canada’s first pipeline, built in 1853, was a 25-kilometre cast-iron pipe that transported natural gas to Trois-Rivières, Quebec. It was the world’s longest pipeline at that time.
  • In 1862 Canada built one of the world’s first oil pipelines, which connected oil production at Petrolia, Ontario to Sarnia for refining.
  • By 1947, there were three crude oil pipelines in Canada. One transported oil from Turner Valley, Alberta to Calgary, the second moved imported crude from coastal Maine to Montreal, while the third brought American oil into Ontario.
  • Canada’s extensive pipeline grid began in the 1950s when major crude oil and natural gas finds in Western Canada led to the construction of large pipeline systems.
  • The Canada Energy Regulator (CER, formerly the National Energy Board) started regulating inter-provincial and international pipelines in 1959.

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