UNS S33207 – A New Hyper Duplex Stainless Steel for Umbilicals

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 umbilcals are used in warmer water and developing concepts where a riser is introduced in the umbilical. Hence, the demand on the corrosion resistance and mechanical strength is increased.
Sandvik SAF 3207 HD^®, 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 steel. The increase in strength is about 20% compared to UNS S32750. Further the results both crevice corrosion testing both in laboratory simulating conditions inside an umbilical and in seawater testing show that the operation window is larger for UNS S33207 compared to UNS S32750.