Offshore oil rigs

Use of duplex grades in offshore applications: an expanding trend

Joanne McIntyre - 5 November 2015

Duplexes have proven their worth in this sector: is it time for these to be pushed even further and for new duplex grades to take centre stage?

About the author

Mrs Joanne McIntyre
Joanne McIntyre is the Editor in Chief of Stainless Steel World magazine, and Conference Coordinator for the Duplex Seminar & Summit.
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A recent article by Babak Bahar, Material Specialist at Kvaerner Engineering, Norway looks at the valuable role that duplex stainless steels play in the offshore industry and how use of the material could develop in the future.

Corrosion has been an important issue for the offshore oil and gas industry since its very beginning. The production processes used here are complicated and demanding for materials and take place in a marine environment highly restricted by legislations to any kind of pollution. As a direct result, the safety and longevity requirements for the platforms are high in order to ensure the environmental aspects. These are normally guaranteed by robust material selection and continuous preventive maintenance.

“From my professional perspective duplex stainless steel grades have played an important role within offshore process efficiency since their introduction in the market,” says Babak.

Today very little carbon steel is used in this application in the North Sea.

“Materials are mainly selected in stainless steels based on weight saving potential, long design life expectations and more corrosive process media than before due to e.g. higher pressure and temperature. The expected lifetime for the new platforms is up to 50 years in the North Sea with minimum requirements for costly maintenance,” Babak explains.

“The main question is: can we push the offshore process efficiency even further via considering higher duplex grades than 25Cr super duplex? If yes, further activities within standardisation, price establishment, and offshore application development are important for the new duplex grades.” Babak goes on to look at this point in further detail, bearing in mind that from a customer procurement point of view, it is preferable to have several sources for each duplex grade. Read the full article to learn more.

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