Raw seawater injection is an increasingly used technology in oil production. The injection of
water allows more oil to be retrieved from a well. A large advantage of using raw seawater compared to
treated seawater is that no surveillance is needed, and hence, the manning can be reduced. However,
raw seawater requires the use of more corrosion resistant alloys than treated seawater. UNS S33207 is
a newly developed hyperduplex stainless steel for umbilicals. It has a minimum PREN of 50. Recently,
large diameter tubing has been developed with minimum yield strength of 101 ksi in the solution
annealed condition, which results in a high strength material with a low level of anisotropy for the
mechanical properties. The crevice corrosion resistance was evaluated by laboratory testing. In
addition, crevice corrosion testing of UNS S33207 in natural seawater with severe crevices was
performed, demonstrating very good crevice corrosion resistance. Furthermore, no indications of stress
corrosion cracking in SSRT-testing in synthetic seawater at 80°C were found. The mechanical
properties of the large diameter tubing and the results from the corrosion testing show that UNS
S33207 is a good candidate tubing material for raw seawater injection.
Key words: Hyperduplex, Raw seawater injection, Crevice corrosion, Stress corrosion cracking, Tubing