Welding Carbon Steel Caustic Piping

[JasonLouie]

Hello,
Is SMAW an acceptable welding process for caustic piping? Will the slag on the ID affect the corrosion resistance of carbon steel in caustic service or will the effect be negligible?

Thanks in advance.

 

[metengr]

Is SMAW an acceptable welding process for caustic piping? Will the slag on the ID affect the corrosion resistance of carbon steel in caustic service or will the effect be negligible?

What you really mean is the SMAW process permitted for joining carbon steel piping exposed to caustic solution?

Yes.

As a side note, I would verify the caustic concentration to decide if post weld heat treatment is required.

 

[MJCronin]

I agree with "met"... carbon steel has been used successfully for these systems, but will periodically need replacement.

If your caustic concentration is ~73% or greater, a generous corrosion allowance for carbon steel is a good idea.

More information from the Chlorine Institute....

http://www.dow.com/causticsoda/safety/piping.htm

 

[JasonLouie]

Thank you both very much for your response.

Yes, we will have 50% caustic solution with a limit on our design temperature to allow for the use of carbon steel. All our lines will be PWHT'd as well.