Presently I have established zero gap butt welding with direct SAW for following type of joint:
Double V Joint with both equal V, i.e bevel in centre only.Included angle=60degrees(both).
0-0.5mm root gap,1mm root face.
Long seam joint of 50mm thick SA516Gr.70 shells.
SAW wire dia.=3.15mm.
Parameters for root run is most important:430A,28V,T.S=300mm/min.Preheat=150degrees celcius.
Then 430A,30V for subsequent passes.
With these parameters we are able to minimize chipback to a mere depth of 2mm only.
UT=100% clear.
Benefits of zero gap welding:
Less skilled fitter is required for setup.
Productivity increases as setup time is less (no need to maintain rootgap.)
Less distortion due to less shrinkage stresses.
Ovality can be better controlled.
Regards
Prem S Nautiyal
Godrej,Vikhroli,Mumbai.
On Fri, 08 May 2009 12:33:51 +0530 wrote
>Hi!
>
>We have been using this practice of zero gap butt joint for shell thk of 12
>mm to 20mm , and above 75mm thk joint.
>
>We keep the zero gap with tolerance of 0-1mm and root face should be of
>3-4mm for smaller thk and 5-6mm for thicker shell
>
>To avoid any burn through, we require to increase the speed of weld with
>lower side current of WPS for root pass. This parameters are require to be
>established at each place
>
>
>
>Regards
>
>
>
>Hegde P.B.
>
>
>
>From: materials-welding@googlegroups.com
>[mailto:materials-welding@googlegroups.com] On Behalf Of Muhammed Ibrahim
>Sent: Thursday, May 07, 2009 4:47 PM
>To: materials-welding@googlegroups.com
>Subject: [MW:2122] Zero gap butt welding
>
>
>
>Hi Gents,
>
>
>
>Anybody having experience with zero gap butt welding (V- groove with more
>root face) with direct SAW in pressure vessels. Is it possible in circular
>seam?. If possible how much root face should be maintained?.
>
>Thanks & Regards
>Muhammed Ibrahim PK
>
>
>
>
>>
>
PREM S NAUTIYAL
CELL : 9820313278
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