A study for possible replacement of martensitic stainless steel with duplex stainless steel with duplex stainless steel castings used in refinery valve trim

Abstract:

In the petroleum industry, the corrosion of metallic equipment and structures is very important. Consequently, there is a constant search for highly resistant metallic alloys. Such corrosion problems are due to the presence of water in petroleum and in its derivatives, because there is no corrosion in the absence of water for electrochemical type corrosion mechanics. Within the equipment used in a petroleum industry, one can emphasize the valves which are made of carbon steel with internal pieces made of martensitic stainless steel. In refineries, for example, the number of valves is especially high, reaching almost 1000 valves per refinery unit. It seems that the choice of material is based on its mechanical properties more than on its corrosion resistance although many valve failures are observed due to general or localized corrosion. This normally occurs in the sealed region of the drawer type valves. This type of valves usually presents premature leakage as a consequence of the corrosion of internal pieces made of martensitic steel due to the presence of sour water. Therefore valves lose their retention function and they must be repaired or disposed of. The internal pieces of valves used in the exploitation of crude oil are already made of duplex stainless steel which is known as high chloride resistant material. Consequently, the number of valve failures is decreasing contrary to the refinery valves where duplex stainless steel is not used.


Reference:

PANOSSIAN, Zehbour; SILVA, Carlos Alberto da. A study for possible replacement of martensitic stainless steel with duplex stainless steel with duplex stainless steel castings used in refinery valve trim. In: INTERNATIONAL CORROSION CONGRESS, 17., 2008, Las Vegas, Nevada. Proceedings… 20 p.

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