ASME IX - Ar Gas Purity 5

[SuPeR9981]

Hi All, for GTAW process, Argon purity is an essential variable in ASME IX? If my WPS qualified with 99.997% purity of argon but now I want to weld by using 99.95% purity of Argon for both purging and shielding gas do I need requalified my WPS ?

 

[david339933]

You won't have to requalify, but you may need to revise your WPS. Does your WPS state 99.997% Argon, or just Argon? There is no requirement to state the purity of Argon (99.997% Argon) on the WPS....just Argon is sufficient. If you have 99.997% on the WPS and use 99.95%, you are not following the WPS.

Standard Designation: BPV Section IX
Edition/Addenda: 2013
Para./Fig./Table No: QW-408.2
Subject Description: SC IX; QW-408.2, Shielding Gas Variable
Date Issued: 12/01/2014
Record Number: 14-1943
Interpretation Number : IX-15-21
Question(s) and Reply(ies):
Question: For a single shielding gas or combination of shielding gases, is a change in the purity of the shielding gas an essential variable?
Reply: No

 

[SuPeR9981]

Thank you david339933 for your explanation. My WPS did mention about the argon purity, and there is no requalified needed if I revised my WPS to lower argon purity however I need bear the risk on quality of weld right?

 

[david339933]

There is no increase or decrease in risk...you are using a qualified WPS. The revised WPS is as valid as the original which stated purity.

 

[weldstan]

There is considerable risk in decreasing purity levels in Argon shielding when welding reactive materials like Ti, Zr and some other high alloy materials.

 

[Dhurjati Sen]

In continuation to Weldstan.

This is where the recommended practices come in. So, changing the purity of Argon would surely affect the weld for the service for which the original WPS was made.

Regards

 

[gtaw]

If you are in the US, order your shielding gas(es) to AWS A5.32. The purity is specified as is the dew point and moisture in terms of ppm.

It just makes life easier.

Al

Best regards - Al