Umbilicals are used for controlling wellhead functions using hydraulic lines and can also be used for chemical injection. Since the steel umbilical were introduced to the market superduplex stainless steels have been the most commonly used material. In recent years there has been a trend to explore fields at deeper sea depths and longer umbilicals are required. Increasing the strength of the material decreases the weight of the umbilical which enables longer lengths. The trend is also that umbilicals are used in warmer water and that concepts where a riser is introduced in the umbilical are developed. Hence, the demand on the corrosion resistance and mechanical strength is increased. UNS S33207 is a new hyper duplex stainless steel with a minimum PRE of 50 that has been developed for use in umbilicals. Results from corrosion and mechanical testing show that UNS S33207 has better corrosion resistance and higher strength than superduplex stainless steels. The increase in strength is about 20% compared to UNS S32750. Further the results from both crevice corrosion testing in laboratory simulating conditions inside an umbilical as well as in seawater testing show that the operation window is larger for UNS S33207 compared to UNS S32750.
UNS S33207 - A new hyper duplex stainless steel for umbilicals
2009
8 Seiten, 11 Quellen
Conference paper
English
Duplex-Stahl , elektrochemische Korrosion , Grübchenbildung , Hydraulikleitung , Hyperfeinstruktur , Korrosionsbeständigkeit , korrosionsfeste Legierung , Korrosionsprüfung , Laborversuch , mechanische Festigkeit , mechanische Prüfung , Meerwasser , nichtrostender Stahl , Seewasserkorrosion , Spaltkorrosion
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