Hi Shadab,
If you do not have the machnning capacity for Narrow Gap joints ( 2-5 deg included angle), then this joint should be fine. I would like to suggst some fine points based on my past experiences in shop welding for thick walled pressure vessels:-
- Long Seams-Remove the backing strip altogether. Rolling the backing strip to shell contour and making perfect fit up is quite difficult in adouble vee weld. Moreover when backing strip gets fused while welding, one has to do immense gouging to remove it completely.Hence a conventional double vee joint, 2/3Vee Outside(45 -50 deg included angle) and 1/3 Vee inside (55-60 deg included angle) may be a good option.Such joints may be prepared by high power gas cutting and grinding. Weld metal deposition may be more,however if welding heas and powe are equipped with Tandem or Twin Arc SAW, one can make up for the fabriction time.
- For C Seams-- you may adopt a quasi narrow gap bevel to start with.A sample bevel is shown in the attachment.The included angle may be chosen to be anything between 10-20 deg and the edge preparation be done with gas cut followed by machinning.Placing a backing strip would be the joint fit up easy.
For welding of thickwalled plates, Narrow Gap welding(2-5 de included angle) is the best choice, due to less distortion, better weld and HAZ properties,considerabe savings on weld metal, fabrication time etc.But without good machning facilities,this process ia almost difficult to implement.An alternative may be edge prep and rolling in outside shops, then perfom welding at fabricator's workplace, busometimes thatmay not e a realistic solution.
Thanks
Pradip Goswami,P.Eng.IWE
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Shadab Alam Ansari
Sent: Wednesday, November 03, 2010 6:05 AM
To: materials-welding@googlegroups.com
Subject: [MW:8050] Weld Joint Preparation for Thk=146mm
Dear All,
We are having 146mmthk shell welding for P1 material with PWHT & Impact as per ASME SEC-VIII Div.2
Please give me best possible weld configuration. We don't have facility to make J grooves.
Is there any portable machines available in the market to make J grooves on such high thick plates.
I have prepared one sample Bevel edges as attached below.
Waiting for reply.
Thanks!!!!!!!!
Regards
Shadab
Welding Engineer
--
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.
No comments:
Post a Comment