The successful use of Ni-based alloys and highly-alloyed stainless in seawater applications
depends on their ability to resist localized corrosion and in particular crevice corrosion. An extensive
programme has been conducted by DCNS Cherbourg to optimise the use of such alloys for
seawater pipings, identify their resistance to crevice corrosion and predict their performance under
specific service conditions. This paper describes the in-house corrosion tests and methods used.
The influence of several factors which are known to impact crevice corrosion initiation and
propagation, such as crevice geometry, the nature of gaskets, temperature, the cleanliness of the
surfaces and passivation treatments, are reviewed using these tests. The results of an evaluation
campaign performed on Ni-based alloys A625 (UNS N06625), A59 (UNS N06059) and superaustenitic
stainless steel B66 (UNS S31266) are presented.
Keywords: crevice corrosion, seawater, nickel based alloys, superaustenitic stainless steel