Designing and engineering a pipeline is a lengthy and detailed process. Pipeline construction consists of a number of distinct activities that each contribute to the long-term integrity of the pipeline as well as minimize the impact to the environment and to the landowner.
Pipeline integrity begins with sourcing the materials – oil pipelines are generally constructed from steel with an inner diameter typically ranging from 100 mm to 1,200 mm (four to 48 inches). The steel used is of the highest quality and manufactured to stringent Canadian Standard Association (CSA) specifications, which include chemistry and material properties. Through production, transportation to the job site and installation, quality management processes are in place to ensure the pipe fully meets the requirements.
Pipeline operations include multiple controls and monitoring systems to ensure it operates safely. The latest technological advancements are incorporated, along with trained personnel, to ensure the pipeline is operated safely. With a strong focus on regular maintenance, the application of the latest technology and sound operating practices, the Trans Mountain Pipeline has an indefinite lifespan — as safe in the future as the day it was installed.
The Pipeline Installation Process
Surveying and Staking
Once a pipeline is approved and a route is finalized, crews survey and stake the right-of-way and any temporary working space required for construction.
Trees and vegetation are removed from the right-of-way (ROW) and the topsoil is removed and stockpiled and protected for future reclamation. The crew installs silt fences along edges of streams and wetlands to prevent erosion of disturbed soil and for protection of the water courses. The ROW is then leveled and graded to provide a safe working space.
Excavators dig the trench to the required depth and place the excavated soil to the side.
Individual lengths of pipe ranging from 12 to 24 metres long are brought in from stockpile sites and laid out end-to-end along the right-of-way.
Individual joints of pipe are bent using a hydraulic bending machine for directional changes and to fit the terrain.
Welders join the pipes together using either manual or automated welding processes. Both manual and automatic welds are of the highest quality, with every weld inspected and certified using non-destructive examinations including X-ray or ultrasound methods.
Coating on the outside of the pipeline is used to prevent it from corrosion or rusting. The new pipe (and any repairs to the existing pipe) will typically be coated with fusion bond epoxy. In rockier areas, enhanced external coatings such as concrete, abrasive resistant fusion bond epoxy or polyethylene will be used to mitigate the impact from abrasives or stress-concentrating conditions (such as rocks or backfill) and to provide additional mechanical protection. Prior to lowering the pipe section into the trench, the integrity of the coating is checked by means of a high voltage tool that will detect even the smallest defect in the coating. If a defect is noted, an epoxy repair coating is applied.
The welded pipeline is lowered into the trench using heavy lifting machines called sidebooms.
Valves and Fittings
Valves and other fittings are installed at intermediate locations as required by the Canadian Standards Association pipeline code. The valves are used once the line is operational to shut off or isolate part of the pipeline. There are generally two types of valves used: Check Valves and Block Valves.
- Check Valves are mechanical devices, which only permit flow in one direction. If upstream pipeline pressure reduces, the valve closes and stops the flow.
- Block Valves are typically automated and can be controlled remotely. They feature an electric actuator that is connected via satellite or other communications system. If a problem is detected and sent to the Control Centre as an alarm, the operator will follow written procedures, which may include stopping the pipeline and closing the Block Valves to isolate the area until the condition can be investigated and resolved.
Once the pipeline is in place, select backfill may be used to protect the pipe. Following this, subsoil and topsoil are replaced in the sequence in which they were removed.
The pipeline is pressure tested to 125 per cent of its anticipated maximum operating pressure for a minimum of eight hours. This process tests the integrity of the complete system of the pipe, welds, fittings and all other appurtenances such as valves. A successful test is required to obtain certification for the pipeline to operate.
The final step is to reclaim the pipeline right-of-way, removing any temporary facilities, re-seeding and restoring the land.