When a major oil company needed an innovative fabricator to pioneer a brand new project, they called on Thermatech Ltd., a Bassett Mechanical Company, to get the job done.
Frustrated with the short service life of filters made out of carbon steel being used in the North Sea, the oil company investigated new materials that could withstand seawater corrosion and provide a longer service life. After considering several materials, the engineers chose a relatively new alloy from Norway and Sweden called super duplex stainless steel.
Super duplex steel features high chromium and molybdenum content, lending twice the strength compared to traditional stainless steels as well as improved resistance to localized corrosion. Traditional stainless steel vessels have an approximate six-month lifespan in seawater, while industry professionals expect super duplex to last more than 30 years.
Once the oil company selected super duplex, they were challenged to find a fabricator in the United States who could produce the vessel units. Thermatech has a history of taking on unique challenges and working with unique metals and was confident they could deliver quality results.
“We’re probably more adventurous than many fabricators. We didn’t know how the material would react to our forming, but we don’t mind taking jobs that nobody else has done,” said Chief Engineer Don Bredbeck.
Working with the client, Quality Assurance Manager Jim Forbes developed welding processes for super duplex, using new shielding gas, welding rod and a new welding recipe. Suppliers in Europe flew 30,000 pounds of material to the United States on cargo jets. Vessels were constructed to meet American Society of Mechanical Engineers (ASME) requirements and Norwegian standards (NORSOK).
The finished vessels ranged in size from 30 inches to 48 inches in diameter. When it came time to ship the product, Thermatech applied special efforts to clean and shrink wrap the vessels to prevent contamination during transport.
The project took six employees and just four months to complete—and was a resounding success. Since the initial order for two units, Thermatech Ltd., has built six more units for other drilling platforms. Bredbeck said Thermatech Ltd., can use the new techniques on any size project in the future.
“The project was a great achievement for Thermatech,” said Bredbeck. “We served the client’s needs and gained a skill set that very few fabricators in the United States have.”
