[MW:881] clarification reg root gap

It appears that the problem is with the mismatch / ovality and not with the root gap, with 1.5 or 2.0mm root gap or equal to dia of filler wire used (which normally we recommend on paper) you can achieve a good weld penetration, but practically, when you start welding with a 2mm root gap and finishes 180° the root gap will close to zero due to distortion during welding the other half.

That is why most welders prefer wider root gap than recommended, and it should left to welder judiciously (of course all welders can’t be same and depends on their skill), you can try out few joints with various root gaps.

You can overcome with it by using pipe clamps for fit up.

 

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From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Bathula Anil Kumar
Sent: Sunday, June 22, 2008 3:17 PM
To: materials-welding@googlegroups.com
Subject: [MW:880] clarification reg root gap

 

Dear Friends, My Name is Anil Kumar working as a Quality Control Inspector in Qatar, for Decon for an Oil Refinery project. I Joined the company recently and during my regular visits to site and also reviewing various data sheets I found that most of the defects are Root undercut, LOP and LOF, the welding used for the production is TIG welding with 2.4mm filler wires for all SS, CS and LTCS materials the Dia of the pipes ranges from 2inch to 24 inch and yeah there is lot of problem with the material reg the mismatch and ovality in the pipe apart from this another prob I observe that the root gap used for the welding is mostly 4+ mm for all the joints , I strongly recommended for 2.5 to 3.5 mm at the max for the Root gap but some of the welders complaining that they are finding difficulty in moving the electrode. I request you to kindly suggest me what is the root gap for the above said materials and what are the other possibilities for the above said repairs and the corrective action required to be taken for the same. I thank you one and all very much for creating such a beautiful group   Thanking you,   Regards Bathula Anil Kumar Visakhapatnam

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