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GTAW Process limitation

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gkvengat

Mechanical
Oct 19, 2013
32
Dear Friends,
I qualified one PQR with GTAW+SMAW process as per ASME sec -9 for station piping work.In that Root & Hot pass with GTAW and remaining with SMAW. Please find given below PQR data
1. Test Coupon - 6 inch X 7.11 mm thick
2. GTAW Deposited weld metal in Root & Hot pass-4.22 mm
3.SMAW deposited weld metal thickness =7.11-4.22=2.89 mm
so in my WPS GTAW qualified weld metal thickness range is 8.44 mm as per ASME Sec-IX QW 451.1 and SMAW Weldmetal Qualified to weld 5.78 mm.


Please clarify,can i use this WPS to weld 2 inch X 5.54 mm thick pipe joints with full GTAW process?Its urgent.
 
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GTAW processis qualified to a DWMT of 8.44 mm and and a base metal thickness or 14.4 mm; therefoe, you may use the WPS to weld the 2" diameter x 5.54 mm pipe in question with the GTAW process.
 
Thanks weldstan,
Then why most of the company doing separate qualification for GTAW process,if codes permit to do weld.Is there any restriction in this?please clarify.
 
It has not been my experience in over 40 years that most companies (assume Owner/Engineers) require seperate qualifications. There may well be good reason to seperately qualify when impact test qualification is required.
 
Thanks Weldstan,
Means it is not specified in codes. Its only owner's requirement, I am correct weldstan?

My project also having impact test requirement, but I done welding in 2 inch X 5.54 mm thick pipe without doing separate qualification. If tomorrow they will not accepts this, what I will do? IS there any alternate solution to convince them?
Please give me any technical advice to convince them.
 
gkvengat,
Now you have a significant problem.
Did you perform impact tests on your PQR ?
Are you aware of minimum material thicknesses qualified as per QW 403.6 ?
What is your construction code ?
As per 403.6 your original PQR thickness of 7.11 mm WT is your minimum qualified WT so you cannot weld 5.54 mm WT when impact testing is required,
Regards,
DD
 
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