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Re: [MW:4093] Magnetism in SS 304 & 321 after welding

By Materials & Welding
Hi All,
 
Can we know whether the joints started corroded after leaving to atmosphere?
 
Because we too faced similar type of problem, the weld joints after pickling and passivation started corroding.
 
We have observed this was due to the use of power brush (Buffing wheel- Iron frree) which the welders used to clean the joints after
 
welding. This is because of the heat generated (leads to generation of magnetism) due to the rpm of the brush.
 
Then we stopped using power brush for cleaning the welds and the problem is solved now.
 
 
Regards
Sudhakar
Welding Enigneer
 


 
On Thu, Jan 14, 2010 at 8:55 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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