Rust in caustic tank

[NickHorne]

I have a few sub par welds in my keg washer caustic tank.
I am wondering how to treat these rust spots and with what.
Would a coating of something (epoxy? ) work?
How does this bit of rust affect the cleaner?
Should i stop using it?

Any advise would be appreciated.

[gitchegumee]

Rust could be caused by many things, including weld preparation, electrode composition, post-weld finishing, and caustic makeup. The most common seems to me to be that folks use a carbon steel wire wheel to buff the weld, or use a stainless wire wheel or a grinding wheel that has been used on carbon steel before. This will cause rust as bits of residual carbon gets smeared into the stainless substrate. Use only stainless steel dedicated tools to work on stainless. Another possibility is heated chlorinated caustic causing corrosion. This is most often accompanied by pitting--not so much rust--and high stress points--like welds--are attacked first. My suggestion is that you use a new stainless steel wire brush to buff out any rust. This may require you to buff several times before the rust goes away. Another option is to passivate the stainless with strong, warm acid--careful here! Good luck!

[dick murton]

Don't forget - not hydrochloric acid.

Contact your local SS welder to reweld if necessary, passivate with commercial paste, rinse off and then ideally polish off to 150 / 180 grit

Cheers

[matt]

What you have is what you have....


If S.S., to try and preserve what you have, I would clean the "rust" spots with the lightest abrasive possible. ( IF YOU NOTICE WERE YOU POLISHED; THEN TOO MUCH) Try the green scotch brite pads.(used) CIP and, rinse, then a good pasification with Nitric acid.

If Green scotch brite pads and the above do not work, you have more then a few "sub par welds". Clorides, metal contamination, unsat tank manufactuer! and ......

Other then gross contamination, should not effect you caustic cleaner.. too much.