Colleagues,
I have been ignoring this one because it is not my field of expertise. I have however burned my fingers very severely using stainless pipe in the past and avoid it like the plague these days. Generally the problem has proved to be stress corrosion cracking and it is always a surprise how little it takes to get it going. All you normally need is a residual stress from welding or forming of the steel, and the very smallest exposure to chlorides or sulfide's. This is all black magic stuff however and definitely not the reviler of the amateur. I strongly recommend you consult a qualified and practising metallurgist.
Regards,
Gordon
Gordon Reddek
Specialist Mechanical Engineer
Alcan Engineering, Level 3, 443 Queen St, Brisbane, Qld 4001, Australia.
Tel: +61 7 3328 6424
Fax: +61 7 3328 6990
Email: gordon.reddek@alcan.com
"Vijayan Raja" <rajamv@igcar.ernet.in>
14/07/2004 04:43 PM
Please respond to
PipingDesign@yahoogroups.com
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Subject
Re: [PipingDesign] water leak at welded connection
I think the assembly might have been left with some water inside for quite
some time..most of the austenitic steels are vulnerable to stress
corrosion
cracking in the presence of aqueous atmosphere...may be an investigation
on
these lines may throw some light..
Regards,
V.Raja
> Someone had suggested that the characteristics of DM water be checked
wih
respect to the pipe material. That seems to be the cause of the problem.
> Regards,
> Rajendra Bajikar.
>
> RICK <rickb_jp@yahoo.com> wrote:
> Bruce and Al,
>
> The pipe material is A312 TP312L sch40 and its size is 6 inches. The
joints are butt-welded. Furthermore, its a part of a piping system of a
petrochemical plant and of all the piping systems in that particular plant
its the only system which manifested that kind of problem. I ruled out the
possibility of defects in workmanship since a Welding Procedure
Specification is in place, the welders are duly qualified by ASME, and the
welding engineer in-charge is an experienced guy who has a Masteral Degree
in Welding Engineering from an American University. The piping system
mentioned above is a newly-constructed piping system and
hydrostatically-tested and retested after rectification of leaks but the
problem is recurring. The test media is demineralized water.
>
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> Rajendra Bajikar.
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[Non-text portions of this message have been removed] Received on Wed Jul 14 19:23:00 2004
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