- 2-5 deg total included bevel angle NGSAW. 10-20 deg total included angle quasi narrow gap.
- My experience tells it's good to start with quasi narrow gap details then to move real narrow gap weld. This gives the necessary confidence to welders. If NGSAW bevel and welding is a regular feature in your shop then welders would not need any quasi narrow gap to develop the confidence.
- Good Wire and Flux combination is a must for NGSAW. More than the wire it's the flux. Generally all basic high quality SAW fluxes. such as OK-10.62, OP-41TT or UV421TT/421TTR/421TTRC or Kobelco PF-200 are proven fluxes for NGSAW. While selecting a flux wire combination consumable manufacturers' opinion also may considered.
- NGSAW would require more careful monitoring of welding parameters.Defects, removal & repair could be painstaking and costly. Often a defect or a suspected defect shall be removed/ repaired before proceeding for the rest of the weld.
- Common techniques are 1-2-3 pass/layer technique. 2 pass /layer technique is more tolerant to defects and offer more flexibility to welders. Typically the fillet shall be flat and bead shall be thin typically ( form factor less than 3 ). Thick and bulky beads (often termed as peaky beads) could cause solidification cracks due to shape/form factors.
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Vanchinath S.A.
Sent: Friday, November 19, 2010 10:29 AM
To: materials-welding@googlegroups.com
Subject: Re: [MW:8327] RE: 8242] FW: 8050] Weld Joint Preparation for Thk=146mm
--Dear Sir,
If we are going for Narrow groove welding with only single bevel and less degree, For SAW welding, there will be solidification cracking problem since the depth to width ratio will not be maintained as 3:1.
Please suggest.
Thanking you,
Best regards,
Shadab Alam Ansari
Welding Engineer
For Gulf Heavy Industries Co
One of Al-Bassam Group of Companies
Cell Phone No: 00966502090165, Fax No:0096633410105
Telephone No: 0096633400098 (5 Lines) Ext: 232Email: ansari@ghi.com.sa
Web: "www.ghi.com.sa"
Save paper, don't print any emails unnecessarily. Let's save environment for future generation....
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of pgoswami@sympatico.ca
Sent: Sunday, November 14, 2010 12:19 AM
To: materials-welding@googlegroups.com
Subject: [MW:8242] FW: 8050] Weld Joint Preparation for Thk=146mm
Hi Shadab,
If you do not have the machining capacity for Narrow Gap joints ( 2-5 deg included angle), then this joint should be fine. I would like to suggest 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 double 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 has and power are equipped with Tandem or Twin Arc SAW, one can make up for the fabrication 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
Welding & Metallurgical Specialist & Consultant
Email-pgoswami@sympatico.ca,
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=146mmDear 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.
Error! Filename not specified.
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.--
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.
--
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