This is the second post in CEPA’s “Pipeline innovations” blog series, which explores technologies and innovations that are helping pipeline companies continuously improve safety and environmental protection.
Ever wondered how a ship’s hull withstands corrosion when it’s always in water? The hull is covered with a coating that’s chemically designed to protect against the elements.
Similarly, pipeline companies use special coatings to stop oxygen and water found in the ground from corroding the steel on their pipelines. (PDF)
Matt Alliston, Canadian vice president of domestic markets with Specialty Polymer Coatings, a company that makes high-performance coatings for pipelines, marine vessels and other industrial projects, shared his expertise on how external pipeline coatings work.
External pipeline coatings are substances applied to the outside of pipelines. These coatings are so sophisticated that they become a kind of armor protecting the pipeline from damage. (PDF)
Alliston explained that coatings offer a corrosion barrier as well as abrasion protection for the pipeline (due to land movement, rocks and other abrasive forces in the soil can be a risk to pipelines).
Specialized coatings are applied to a pipe when it is manufactured and are also applied in the field where sections of pipe are welded together prior to installation.
“Every surface coated is inspected multiple times before being buried,” explained Alliston. “Once buried, these coating systems can be inspected while in service through a multitude of devices and techniques.”
The type of coating used on a pipeline is determined based on a number of factors, including environment and the pipeline-installation method. However, Alliston explained that epoxy-based coatings are the most commonly used in North America.
“These easy-to-apply epoxy mainline and girth-weld coatings have dramatically increased a pipeline’s ability to maintain its integrity,” he said.
Epoxy coatings protect against water permeation (to prevent corrosion) and against abrasion from materials in the soil. The coatings bond to steel pipe through a mechanism commonly referred to as polar bonding. This basically means molecules in the steel bond to corresponding molecules in the epoxy.
“This polar bond allows for excellent adhesion of the pipeline coating, thus offering superior protection for the life of the pipeline,” Alliston said.
Formulating pipeline coatings is a science, and like any good field of study, the science is always improving.
Companies like Specialty Polymer Coatings are finding ways to make some coatings more environmentally friendly by removing volatile organic compounds (VOCs) that can be released into the atmosphere when coatings are curing.
Also, technology is helping to improve the way coatings are applied in the field. Alliston explained that the use of automated mechanical-application equipment is allowing for a “consistent, repeatable and reliable protective field weld coating process.”
Pipeline coatings are just one of many tools pipeline companies use to maintain the integrity of their pipelines. Through continuous improvement of technologies and processes, Canadian pipeline operators are constantly striving to increase pipeline safety and environmental protection.
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The Canadian Energy Pipeline Association represents Canada’s transmission pipeline companies who operate approximately 115,000 kilometres of pipelines in Canada. In 2013, these energy highways moved approximately 1.2 billion barrels of liquid petroleum products and 5.3 trillion cubic feet of natural gas. Our members transport 97 per cent of Canada’s daily natural gas and onshore crude oil from producing regions to markets throughout North America.