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Oil Pipelines and Elastomers – Compound Selection and Seal Design

Pipeline

Image source: cbc.ca

Clyde Sharpe President for International Sales of Elasto Proxy

What is the safest way to transport crude from the oil sands of Alberta to the petroleum refineries of Eastern Canada? After this summer’s tragic train derailment in Lac-Mégantic, TransCanada Corp. is promoting the Energy East Pipeline as safe, cost-effective, and efficient alternative to rail shipments. As the company’s CEO told CBC News, oil pipelines also promote job creation and energy independence.

Rail Shipments and Crude Oil

Just two months after residents of Lac-Mégantic awoke to the sounds of rail cars exploding, Canadians are still coping with this man-made disaster.  On the night of July 6, an unattended freight train with 72 oil tankers burned or spilled 5,630,000 liters of light crude near a scenic lakeside community in Québec. Buildings burned, residents were forced to flee their homes, and 47 people lost their lives.

Today, Canadians aren’t alone in wondering if oil tankers or oil pipelines are safer – or if any type of crude oil transport is truly “safe” at all.  In the United States, the fate of proposed Keystone XL Pipeline remains uncertain. Yet rail shipments of crude continue to rise across North America. The train that derailed in Lac-Mégantic was bound for New Brunswick, but began its journey in North Dakota.

Rubber Seals and Pipeline Safety

Could TransCanada’s proposed Energy East Pipeline, or Keystone XL for that matter, prove safer than the rail shipments that now crisscross the continent? As a supplier of high-quality sealing solutions to a wide range of industries, Elasto Proxy is watching this debate closely. Our Boisbriand, Québec company is also ready to join the conversation, sharing what we’ve learned over the course of our nearly 25-year history.

Elastomeric seals are just one of many components in railcars and pipelines, so they’re easy to overlook – at least to the casual observer. Failed seals can result in down-time and equipment damage, however, as when door seals on fuel tanks disintegrate and clog diesel engines. The stakes are higher with crude oil pipelines, even without fires and fatalities.

End Cap Seals and O-Rings

The oil and gas industry uses end cap seals and O-rings that are made of special elastomer grades and validated against international and industry standards such as ISO 01423 and API 6A PR2 F.1.11. Typical sealing duties include risers, riser bodies, riser joints, and riser joint connectors; wellheads and wellhead chokes;  and valves and pumps.

During seal selection, pipeline builders and technical buyers consider specifications such as temperature and pressure. Oilfield media is also important, and some compounds are better-suited for crude oil than sour crude. Today, most elastomeric oilfield seals made of nitrile, hydrogenated nitrile (HNBR), fluoroelastomers, tetrafluoroethylene and/or propylene polymers, and perfluoroelastomer.

Choosing Rubber Compounds

Nitrile is the most common oilfield elastomer. Cost-effective and resistant to hydrocarbons, this resilient rubber offers limited weathering resistance and modest temperature resistance. Hydrogenated nitrile (HNBR) provides better weathering resistance and a wider temperature range, but limited resistance to aromatics.  Fluoroelastomers offer excellent resistance to aromatics, ozone, and weathering.

Tetrafluoroethylene and/or propylene polymers also offer excellent weathering and ozone resistance, along with good heat resistance and good overall chemical resistance. Some grades are difficult to process, however. Perfluoroelastomers provide the ultimate heat and chemical resistance, but are very expensive and have modest mechanical properties at elevated temperatures.

How Can We Help You?

Do you need help sourcing rubber compounds for use with oils, fuels, and chemicals? Do you need help with seal design, or do you have questions about mechanical properties or resistance to temperature, chemicals, ozone, weathering and pressure? Regardless of your industry, it’s essential to specify and select the right seals for your application.

Next week, I’ll take a look at rubber parts used in railcars such as oil tankers. Until then, I hope you’ll comment on this blog entry, and connect with me on LinkedIn.