External Chloride Stress Corrosion Cracking on uninsulated 316SS piping? 1

[Bazinga]

Hi all,

Has anyone heard of ECSCC being an issue on uninsulated SS process piping? SCC from the contents of the piping shouldn't be an issue as is carrying processed natural gas. However one of the customer engineers is concerned that the piping is operating above 60degC so wants all the pipework to be coated and all studs to be duplex instead of 316. The plant is within 20km of the ocean, but my understanding was that ECSCC was only an issue for insulated piping as it can cause chloride build up over time due to water build up and evaporation. Looking for guidance from anyone who has come across a similar scenario.

 

[SJones]

https://www.hse.gov.uk/safetybulletins/lokring-pipe-connectors.html

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[EdStainless]

There are many cases of external CSCC in bare 300 alloys.
If you visit plants closer to the coast it is common to see all of the piping coated.
I couldn't find it quickly, but I know that there have been serious incidents in US related to this.

the real concern about your temperature is that first it is hot enough to initiate SCC.
And secondly it is hot enough to encourage evaporation of any moisture. The result of that will be an accumulation of any trace salts on the surface.
Eventually you will have small spots with 26% salt content that will start pitting and/or cracking.

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P.E. Metallurgy, consulting work welcomed

 

[Bazinga]

Ok good to know. Thanks for your responses!