HISC and SSC 1

[JT100]

During subsea pipeline design I have come across hydrogen induced stress cracking and sulphide stress cracking. i think i understand what these are, however I am unsure of the difference between them. Is SSC not caused by the hydrogen in H2S, and therefore a result of hydrogen as well? I have read that HISC affects duplex materials and can make them more susceptible when cathodic protection is applied. Is this the only difference? Thanks

 

[CoryPad]

SSC is caused by hydrogen from hydrogen sulfide.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[SJones]

Try sticking to a recognised vocabulary document which will help communication and understanding. From your question, the NACE Glossary Of Corrosion Terms would have the description 'hydrogen induced stress cracking' as "hydrogen embrittlement" or "hydrogen stress cracking" which is what it is. SSC is sulphide stress cracking and requires a corrosion process to be occurring that involves hydrogen sulphide. Clearly, when cathodic protection is applied, a corrosion (wastage) process will not be occurring.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdoweb/