Prediction of the Service Life of Nickel Based Alloys UNS N06625 and UNS N06059 and Superaustenitic Stainless Steel UNS S31266 in Seawater using in-House Crevice Corrosion Tests

The successful use of Ni-based alloys and highly-alloyed stainless steels in seawater applications depends on their ability to resist localized corrosion and in particular crevice corrosion. An extensive programme has been conducted in recent years 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. The paper describes the in-house crevice corrosion tests and methods used. Results of an evaluation campaign performed on Ni-based alloys UNS N06625, UNS N06059 and superaustenitic stainless steel UNS S31266 are presented. The paper will also review the influence of several factors which impact crevice corrosion initiation and propagation, such as crevice geometry, nature of gaskets, temperature, surface cleanliness and use of passivation treatments.