SS 316 L Thru weld corrosion
SS 316 L Thru weld corrosion
(OP)
We have the second of our Ozone plants on line. The plants are processing / using the same source water.
This is all well and good but on the second plant on - stream we seem to be experiencing through the weld leaks.
The pipes in question operate at ~ ~ 4 p H.
We have not had problems with the first plant and this has
been a real curve ball -
We have about 40 joints leaking and this is totally new to
my experience as I have worked with austenitic stainless
in ASME Section VIII and Piping and have not experienced this since 1968 -
Has anyone experienced anything similar ? ? ?
This is all well and good but on the second plant on - stream we seem to be experiencing through the weld leaks.
The pipes in question operate at ~ ~ 4 p H.
We have not had problems with the first plant and this has
been a real curve ball -
We have about 40 joints leaking and this is totally new to
my experience as I have worked with austenitic stainless
in ASME Section VIII and Piping and have not experienced this since 1968 -
Has anyone experienced anything similar ? ? ?





RE: SS 316 L Thru weld corrosion
I figure that you can handle about 10 ppm Cl before pitting kills you.
A heat of material with a bit lower Nitrogen, or welds that have a bit more oxidation and maybe 5ppm Cl would be the limit.
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Still trying to help you stop corrosion.
formerly Trent Tube, now Plymouth Tube
eblessman@plymouth.com
or edstainless@earthlink.net
RE: SS 316 L Thru weld corrosion
Mark Hutton
RE: SS 316 L Thru weld corrosion
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdoweb/
RE: SS 316 L Thru weld corrosion
S.
http://www.corrosionist.com
RE: SS 316 L Thru weld corrosion
You should have some standard metallographic work done. Base metal and weld filler chemistries are easy. Looking at the degree of coring (segregation) in the welds would be my next step.
= = = = = = = = = = = = = = = = = = = =
Still trying to help you stop corrosion.
formerly Trent Tube, now Plymouth Tube
eblessman@plymouth.com
or edstainless@earthlink.net
RE: SS 316 L Thru weld corrosion
We all really need to move away from 316 to lean duplex, such as 2101 and 2003. We don't need to make Norilsk richer than they are already. The 10% nickel in 316 is a tremendous waste of money and of a scarce resource. It takes end users, such as the members of this forum, to make this happen.
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/
RE: SS 316 L Thru weld corrosion
I have never seen pitting in the welds on this line. The corrosion rate in this system is very low < 0.005 ipy, measured.
I would suspect that you have a problem with weld contamination that is causing your problem. I have seen SS welds diluted with about every alloy around.
One other problem I've seen is where you have water line, in our case cooling tower water, where there is considerable downtime creating stagnate conditions where MIC has preferentially attacked the welds.
RE: SS 316 L Thru weld corrosion
Remove a section of the failed line w/a butt weld and have it analyzed by a competent metallurgical lab.
RE: SS 316 L Thru weld corrosion
Syd, 316 can be very unpredictable, there are so many environments that are so close to depassivating that minor details can push you over. With constant flow and no deposits you can run seawater in 316L, but stop the flow for a few hours and you will destroy the lines. Local oxygen levels and pH are everything.
You are fortunate with your system. It is well beyond a reasonable application for 316L. I would consider 2205 suitable, but nothing lower.
Minor variations in weld practice can be a killer. Poor back shielding, too high or low of delta ferrite levels, too high of heat input, and about 10 other things can all cause significant reductions in pitting resistance in the welds or weld HAZs.
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Plymouth Tube
RE: SS 316 L Thru weld corrosion
HEAT TINTS ON STAINLESS STEELS CAN CAUSE CORROSION PROBLEMS
http://
S
http://www.corrosionist.com