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Corrosion on stainless stee pipe in water treatment plant


Hello To All.

OK , Here goes we have installed process piping into an existing water treatment plant ,all 316s/steel and we are experiencing rust on surface of piping . What could be the problem?, there is a small quantity of chlorine gas in the air and damp conditions. We have taken the usual procedures in the fabrication and installation ,To avoid cross contamination but the problem still persists.What can be done to correct the problem ?


Adrian Middleton
water treatment - Cambridge, Ontario, Canada


I assume that the pipe was passivated before installation. If not, that could be the culprit. The chlorine gas with moisture WILL give you some HCl on the surface which WILL cause some corrosion long term. HCl is one of the worst things you can put on stainless steel.

You can get rid of the rust and repassivate in situ, but it may take constant maintenance in this atmosphere. Washing the pipe with clean water regularly will help also. Let us know if you need help.

lee kremer
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Lee Kremer
Stellar Solutions, Inc.
supporting advertiser
McHenry, Illinois
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Hi Adrian,

My question is just WHY did you use stainless piping in an ordinary water treatment plant?

Why didn't you use PVC? ... ah, you may say, it's a question of temperature and PVC is only good for a rated pressure of 20% @ l40 degr. F .... ah, but a dual laminate can take you to around l75 degr. F at FULL pressure.

Dammit, Alcore Fabricating in Richmond Hill was doing this back in Ye Olden Days of the early 60's.

There are other plastics like the fusion joined hdPe pressure pipe (available to 5 feet diameter) plus some exotics.

... just plain curiosity ... and by the way, PVC doesn't rust either !

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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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