QW 408.9 of ASME Sec IX Backing Gas / Purging Gas for P-No 41 and for P No-10I

[Ishack]

Dear Experts,

QW-408.9 states For groove welds in P‐No. 41 through P‐No. 49 and all welds of P‐No. 10I, P‐No. 10J, P‐No. 10K, P‐No. 51 through P‐No. 53, and P‐No. 61 through P‐No. 62 metals, the deletion of backing gas....is an essential variable for GTAW process.
The point I am getting confused is this variable is applicable for all welds (not only groove weld, but also fillet weld, partial groove weld etc...) a P-No 10I

1. if I have a WPS that was qualified using backing gas for groove weld for P-43 material, will I be able to use it for partial penetration weld without back purging or full penetration weld with backing plate without backing gas?.
2. if I have a WPS that was qualified using backing gas for groove weld for P-10I material, will I be able to use it for fillet weld without back purging or full penetration weld with backing plate without backing gas?.

With simple interpretation of QW-408.9, the above 2 points cannnot be done. But why ASME Sec IX restricted so?.

Even if u see the definition of backing gas in ASME Sec IX is backing gas: a gas, such as argon, helium, nitrogen, or reactive gas, which is employed to exclude oxygen from the
root side (opposite from the welding side) of weld joints.

Everyone opinion is most welcome here

regards
Isa

 

[DVWE]

Here is an interpretation on half of your question (fillet welds). My opinion is no for partial pen groove welds as well.


Standard Designation: BPV Section IX
Edition/Addenda: 2013
Para./Fig./Table No: QW-408.9
Subject Description: SC IX; QW-408.9
Date Issued: 02/02/2015
Record Number: 14-2025
Interpretation Number :
Question(s) and Reply(ies):
Question: Does QW-408.9 require backing gas (gas purge) to be applied for fillet (attachment) welds with P-No. 4X base metal and F-No. 4X weld filler metal when the WPS was qualified with a groove weld with backing gas?

Reply: No.

The devil is in the details; she also wears prada.

 

[Ishack]

thanks for the swift resonse DVWE.

But the interpretation is related to PNO.4 whereas QW 408.9 specific to P 10I for all welds and to P no.43 for groove weld.

 

[weldstan]

It's not P4 but P4X (P41, P42, P43, etc.).

 

[Ishack]

my apology for wrongly interpreted....but for P NO.4X 941, 42, 43 ETC....), code states for groove weld only..whereas p no.10I all welds mentioned in the same clause

 

[DVWE]

You may want to read QW-408.8 That answers your questions about backing bars, sort of.

The problem is, I cannot find where that variable is applied.

The devil is in the details; she also wears prada.

 

[DVWE]

That would be a good question to the code committees.

The devil is in the details; she also wears prada.

 

[DVWE]

See QW-356 for GTAW. Welder performance only.

The devil is in the details; she also wears prada.

 

[DekDee]

Hope this may help

Interpretation: IX-83-146
Subject: Section IX, QW-408.9
Date Issued: November 26, 1984
File: BC84-619
Question (1): May a GTAW PQR for P-No. 4X to P-No. 4X qualified with a backing strip and
without gas backing be used to support a WPS for a gas backed open butt joint?
Reply (1 1: No.
Question (2): May a GTAW PQR for P-No. 4X to P-No. 4X with an open butt gas backed joint be
used to support a WPS for a groove with a backing strip without gas backing?
Reply (2): No.

 

[Ishack]

Thanks DVWE and DEkDee,
But the original question remains unsolved. This interpretation is all about the butt weld with root. my point is why code has restricted or require re qualification even if I weld fillet weld or just fill and capping on groove weld without purging gas in fact there is no point in giving gas for those joints when my wps is w/purgng

The interpretation IX-83-146 was issued in 1986 and there are many changes in variables over the course of duration. The first question was answered as NO, but for the current edition is YES.

 

[DVWE]

That is why I suggested you contact the code committee. Do an interpretation.

The devil is in the details; she also wears prada.