Backing Gas for SS Pipe Welding

[pras ari]

Dear Experts,

I have read WPS/PQR and I found that on PQR mentioned use backing gas (argon) with argon but on WPS without backing gas (argon).

Please advise to me, this WPS/PQR approved or not?

Thanks & Regards

Winarko

win...@pp-epc.com

[navnitkumar parikh]

Dear

Deletion of backing gas is an essential varible so if PQR qualified with backing gas then mention backing gas in WPS.

Regards,
Navnitkumar Parikh
Asst. Manager-Welding
Thermax Limited

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[John Henning]

Depends on the Code and the process.

 

For Section IX, GTAW:  addition or deletion of backing gas or a change in flow rate of the backing gas is a non-essential variable.  It must be addressed on the WPS but can be changed without any requalification.

 

 

If you are unfamiliar with ASME IX, first column are essential variables (changes require requalification), 2^nd column are supplementary essential variables (apply if impact qualification is required), and third column are nonessential – variables that must be addressed on the WPS but can be changed.

 

So, technically, the WPS meets Sc IX if addressed as none.  But, stainless steel should be gas backed or back gouged and welded (except in very specific instances) to prevent oxidation of chromium at the root of the weld.

 

Hope this helps.

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[Jim Price]

Very well put

 

Jim Price | Welding Engineer, CWI

Direct:  320.7463439 | Fax: 417-862-5564

jimp...@polarcorp.com

 

 

 

 

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[navnitkumar parikh]

If material P No. is not falling as mentioned in QW-408.9 then backing gas is non essential variable as per ASME SEC.IX so it doesn't require requalification

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