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SS304L Above Seawater Environment

September 25, 2008

We want to construct a SS304L pipeline which is to receive sodium hydroxide solution from a ship to our plant site. Because of the above-sea environment (pipe is about 2 meters above sea level), it is a highly corrosive environment.

1. Can you advice me what is the expected chloride corrosion that the SS304L will be facing?
2. What is the most suitable protection for the SS304L pipe? We are thinking of epoxy coating. Is it suitable?

Thank you.

Chan Ubol

Chan Ubol
chemical industry - Jurong Island, Singapore

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September 27, 2008

Hi Chan,

Yes, you will undoubtedly get corrosion of your stainless pipe particularly around the welds.

Yes, epoxy sounds OK but ensure that it is in a matrix of fibers, not just painted on.

Have you not considered uPVC for the pipe? Epoxy may be a good choice but what about a FRP laminate using a vinyl ester resin?

Cheers

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

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Dear Chan,

Why don't you use AISI 316L ? This performs much better in marine applications regarding corrosion resistance and the cost remains reasonable.

Anyway, for the finish in marine applications I would use electropolished parts/pipes, both with 316 or 304.
This finish realises a much better corrosion resistance than only passivated parts.

Kind regards,

Marc Quaghebeur.

Marc Quaghebeur
- Brugge, Belgium, Europe
November 15, 2008

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Hi Chan,

I'm with Marc.

Why use an inadequate material and then try to protect it, with on-going maintenance of the protection? Much better to start with a material that is suitable for the service environment. 304 would be a disaster. 316 would be borderline OK given your typical ambient temperatures in Singapore. 2205 would be excellent.

Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.
November 18, 2008