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Re: [MW:4084] Magnetism in SS 304 & 321 after welding

By Materials & Welding
The use carbon steel root to weld SS to save on purging completely undermines the whole point of using SS? The cost of relpacement would be far higher.
 
Anyway, often a weld consumable used with a low susceptibility to hot cracking in the
weld metal, e.g. a weld metal with 3-8% ferrite. Have you checked the welding consumble? This could be the source of magnetism.
 
But if is a fully austenitic filler then it should not be and cant see how it has become magnetic and you have a big problem.
 
SK
On Thu, Jan 14, 2010 at 10:55 PM, Singh Rishi (TIPO - QA/QC) <R.Singh@panipat.ticb.com> wrote:

One of my friend is facing a problem, which I'm putting to the group as I'm not sure about the solution..

SS joints after welding has becoming magnetic ( Ferrite number is not a criteria for these joints) and hence attracted by magnet ( including Socket Joints )- mostly pipe to fitting joints , but his Client is doubting that they are becoming magnetic because it's root has been welded by CS filler wire- rest passes by SS filler wire.

 This , he insists is done by welder to do the job faster and save purging- as per his past experience in some Gulf project.

There are some thousand of SS joints ( 304, 321 ) in his plant, which is ready.

What can be done, apart from PMI & Ferrite ( on which he doesn't have much faith as they show the reading of the Final pass ) , to convince him about the integrity of the joint without cutting/ drilling / damaging  the joint.

Please share any literature which relates Magnetism to the Welding/ Ferrite percentage.

Welding Processes involved are GTAW (mandatory for all root welding ) and SMAW ( for above 8mm thk )

Thanks & Best Regards,
 
Rishi Raj Singh


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