Preventing Pipeline Corrosion
Posted on February 13, 2019
Transmission pipelines cover 119,000 kilometers of Canada, going through different types of terrains (farmland, rivers, wetlands, mountains and urban areas). A pipeline operator’s job is to safely deliver the oil and gas products that Canadians rely on, and that means that pipelines need to be properly protected from potential threats like corrosion.
MYTH VS. FACT Pipeline corrosion
Myth: All pipelines corrode.
FACT: With proper maintenance and monitoring, a pipeline can be safely operated for many decades.
Myth: diluted bitumen causes pipeline corrosion.
FACT: Diluted bitumen doesn’t have characteristics that cause more corrosion – it’s virtually the same as conventional crude oil.
Myth: Retired pipelines are left to rust.
FACT: Retired transmission pipelines are subject to specific regulatory requirements to make sure they remain safe.
Corrosion is a naturally-occurring phenomenon that happens when metal is exposed to air and the environment it’s in, such as water or soil. It’s a gradual process – one common example of corroded metal is rust. Left untreated, corrosion will impact the strength and appearance of metal.
But corrosion is preventable, and pipeline operators are committed to protecting pipelines from corroding using different techniques, including cathodic protection.
A layer of protection
Pipelines are made of high-quality steel, and one of the most effective ways to prevent pipelines from corroding is to prevent the steel itself from having direct contact with the water or soil that can cause corrosion. That’s why pipeline operators apply a protective coating on the pipes when they are being manufactured or during construction.
The most common type of coating is an epoxy coating, which is a paint-like substance that seals the surface of the pipeline. The epoxy prevents the metal pipeline from being in direct contact with the environment.
Because pipelines go through such diverse terrain, operators will use different coatings for different environments. For instance, if a pipeline is going through a river, a pipeline operator may use a cement coating that prevents corrosion from occurring, while also weighing the pipe down and protecting against mechanical damage during installation.
With the current
Pipeline operators also prevent corrosion from occurring using a technique called cathodic protection. Corrosion is an electrochemical process, and cathodic protection basically drains the electrons out of the metal to inhibit its potential to corrode.
A clean sweep
Corrosion is more likely to occur on the outside of the pipeline than the inside of the pipeline because the outside is exposed to a corrosive environment, such as soil or water. Pipeline failures caused by corrosion are extremely rare because pipeline operators thoroughly monitor and maintain their pipelines, using tools and
Scrapers – Large wire brushes rotate through the pipeline, cleaning the pipe and preventing product build-up. As extra protection, sometimes a substance called a corrosion inhibitor will be used during this process.
In-line inspection tools (smart pigs) – Inserted into the pipeline, these large plunger-like devices have digital sensors. As they move through the pipe, they detect cracks, deformations and metal loss on the pipe’s surface. If an irregularity is detected, the operator will take action to repair or replace that section of the pipe.
Visual surveillance – Pipeline operators have employees who walk the pipeline right-of-ways, looking for signs that something is out of the ordinary, like changes in the environment or leaking product. Aerial inspections also give operators a birds’ eye view of the right-of-way. If there are any signs that the pipeline’s integrity is at risk, the operator will immediately investigate the situation and repair the affected pipe.