GTAW Process limitation

[gkvengat]

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.

 

[weldstan]

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.

 

[gkvengat]

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.

 

[weldstan]

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.

 

[gkvengat]

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.

 

[DekDee]

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