Re: [MW:34237] SS GTAW Welding without Back purging.

For GTAW welding  -Single Vee - 33.4 OD, Full GTAW welding  - 

SS TO SS Welding   or Cr > 3 %  , backing gas is required to get sound root without any Oxidation.

The Oxygen is excluded by  purging Argon/Helium or other Inert mixtures  at root side to avoid Oxidation .

The root side is inaccessible  due to small diameter in your above case.

Backing gas shall be continued till 6mm deposit is welded . This is not a Code requirement but followed  as a good engineering practice across industries 

Thanks 

Vishwas 

On Monday, May 22, 2023 at 4:51:37 PM UTC+5:30 Anand Elankumaran wrote:

Hi Mr. Vishwas Keskar,

Single Vee butt weld  - Root/Hot/fill/cap-  full GTAW

pipe OD -33.4 mm

On Mon, May 22, 2023 at 7:47 AM Vishwas Keskar <vvkes...@gmail.com> wrote:

Are you intending to qualify PQR in 

Single Vee butt weld - No welding from Root side ?

Double Side Weld with back grinding DPT from root side ?

This will decide the PQR  purging requirement

Thanks

Vishwas

IWE 

Sent from my iPhone

On 22-May-2023, at 8:40 AM, Anand Elankumaran <email2...@gmail.com> wrote:



Dear experts,

Could you please check and advise the below query.

• Whether the back purging is a quality requirement or the ASME code is insisting on back purging on SS material while doing the GTAW process.
• Whether we can qualify SS -GTAW PQR without back purging or the ASME code does not allow doing PQR for austenitic steels without a back purge?
• Kindly advise how to do it without purging in SS GTAW Welding . Planning for PQR as well 

--

Thanks and Regards,

E. Anand,

Lead QA-QC,

Sohar,

Oman.

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Thanks and Regards,

E. Anand,

Lead QA-QC,

Sohar,

Oman.

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