Fact Sheet: Valves on a Pipeline
Why are valves used?
Valves are primarily used to allow for maintenance activities. When located appropriately, and maintained and operated properly, valves can reduce the volume of product released in the event of a pipeline failure. They are an important element to the safe operation of a pipeline. Each valve is incorporated into the company’s control system to ensure safe operation.
However, valves increase system complexity and have inherent risks. The installation of a valve can create an impact to the environment, and the valve itself can have issues related to reliability, leakage, and susceptibility to accidental damage or vandalism.
It is important to assess the engineering and environmental impacts of valves holistically, in the context of the entire pipeline system and landscape. Placing a valve in a sensitive area may create a risk that could outweigh the benefit.
What do valves look like?
Valves in oil and gas pipelines are much larger than the pipe and protrude above ground. In fact, for a 36 inch diameter pipeline project they may take up several tens of square meters of space, stand over 5 meters tall and weigh approximately 8 metric tons.
Where to place valves?
The NEB requires the companies we regulate to locate and place valves for pipeline control and to potentially reduce the impact of a pipeline failure. Valves are placed where they make sense; the terrain has to be taken into account. Oil, as a liquid, will always flow downhill and can therefore be blocked by rising terrain.
Illustrations of how the natural environment plays a role in valve placement
If the pipe failure occurs in the river, valves at location A provide protection to this water crossing.
A valve at location A provides protection to the water crossing from failures outside of the crossing.
A valve at location B would provide no protection to the crossing.
As well as crossing waterways, pipelines must sometimes be laid out parallel to rivers. In these instances, the objective of valve placement is to limit the worst-case quantity of product moving downhill to the waterway. The pipeline system as a whole must be considered, as the location of a potential failure cannot be known in advance. Pipe failure is a very rare event, but the design and construction of the pipe will always consider worst-case scenario.
Illustration of how valve placement may occur when pipe runs parallel to a river
Valves have been placed, after considering the entire pipeline system, at the points where they can best reduce the impact of a pipeline failure.
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