Sandvik SAF 3207 HD? - A New Hyper Duplex Stainless Steel forUmbilicals

摘要

Umbilicals are used for controlling wellhead functions using hydraulic lines and canrnalso be used for chemical injection. Since the steel umbilical were introduced to thernmarket superduplex stainless steels have been the most commonly used material. Inrnrecent years there has been a trend to exploring fields in deeper sea depths andrnhence longer and stronger umbilicals are required. Increasing the strength of thernmaterial decreases the weight of the umbilical which enables longer lengths. Therntrend is also that umbilicals are used in warmer water and developing conceptsrnwhere a riser is introduced in the umbilical. Hence, the demand on the corrosionrnresistance is increased. It is therefore a need for a new material with higher strengthrnand better corrosion resistance.rnSandvik SAF 3207 HD? is a new hyper duplex stainless steel with a nominal PRE ofrn51 that has been developed for use in umbilicals. Results from corrosion andrnmechanical testing show that Sandvik SAF 3207 HD has better corrosion resistancernand higher strength than superduplex stainless steel. The increase in strength isrnabout 20% compared to the superduplex Sandvik SAF 2507?. Further results fromrnlaboratory testing simulating the umbilicals indicate that maximum servicerntemperature in an umbilical has been increased compared to Sandvik SAF 2507. Norncrevice corrosion was found for Sandvik SAF 3207 HD at 90℃ in the simulatedrnumbilical testing.