As i have mentioned earlier, the joint is a closing seam with no access from other side, hence can't be welded from inside.
Also the contractor does not want to take risk of any RT repairs with his qualified welders by welding a single sided FPW. However as the root run and hot pass are going to be welded with TIG , there will be no chances of slag entrapment in root run between metal backing strip and shell/dishend. Considering Spot radiography as per UW-12, the issue is now cleared. Regards Prem Nautiyal
--- On Tue, 3/20/12, gopunair5343@yahoo.com <gopunair5343@yahoo.com> wrote:
From: gopunair5343@yahoo.com <gopunair5343@yahoo.com>
Subject: Re: [MW:13943] Backing strip
To: materials-welding@googlegroups.com
Date: Tuesday, March 20, 2012, 2:03 PM
ASME Second VIII Div 1 permits use of backing strip for the type of joint in question. Please refer para UW-12 for joint efficiency. But why the contractor is not prefering a single side full penetration joint configuation or even a double welded butt joint. Welding from inside is not a big issue for 600 dia shell. RT with backing strip in position may be a bit tricky and interpretation problematic due to slag entrapment between shell and b/s. Gopu Sent from BlackBerry® on Airtel
From: prem nautiyal <prem_nautiyal26@yahoo.com> Sender: materials-welding@googlegroups.com Date: Tue, 20 Mar 2012 00:19:33 -0700 (PDT) To: <materials-welding@googlegroups.com> ReplyTo: materials-welding@googlegroups.com Subject: [MW:13932] Backing strip
| Hello friends Need expert opinion on the subject as follows.. A Heat exchanger is being fabricated as per ASME Sec VIII Div.1. The Channel Shell and dish end thickness is @ 10mm and dia. @ 600mm. The MOC is SA516 Gr.70. Now for the closing joint seam i.e. Channel Shell # Dish end (single V joint) can a "Permanent Backing strip" with 8mm root gap be used ? The permanent backing strip will be 6mm thicknes X 25mm wide and stich fillet welded from inside. Contractor has submitted WPS mentioning permanent backing strip for this joint. Can we accept this ? Is there any provision in code for non-usage of permanent backing strips in pressure parts ? The joint calls for full radiography. Contractor claims that upto 10mm thickness the RT will be cleared. Can we accept this case as per ASME Sec.VIII Div.1. Regards Prem Nautiyal | -- To post to this group, send email to materials-welding@googlegroups.com To unsubscribe from this group, send email to materials-welding+unsubscribe@googlegroups.com For more options, visit this group's bolg at http://materials-welding.blogspot.com/The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents. -- To post to this group, send email to materials-welding@googlegroups.com To unsubscribe from this group, send email to materials-welding+unsubscribe@googlegroups.com For more options, visit this group's bolg at http://materials-welding.blogspot.com/The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
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