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
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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 |
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