Re: Re: [MW:29249] Re: FW: 29173] TIG Tandem Welding qualification as per ASME-IX

Yes as said tandem is not a TIG process, regardless of TWI where do u find word tandem from code to ensure in your WPS? even TWI and miller reflects for MIG / MAG.

How you know by that picture one welder is with filler and oppsite is with autogenous? what if both autogenous or what is both filler?

Anyhow check your Procedure as per below

PQR:

*Backing with what? root backing? hot pass weld metal state clearly. 

* test coupon thk 10 mm / deposited also 10 mm? how?

*on what basis preheat 20 deg C for SS?

*Plate?

*AR-99.997 minmum purity? so how 995?

*How thickness 10.22 and 20 in tensile?

1G what?

WPS:

Welding process- Tandem - remove you do not have any rights to place tandem there, where do u find the definitions from code?

Thk n dep- why 6mm to 10mm why not 2T or 2t?

Group no - all?

2G what and how?

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Regards,

MOHAMED MUNEEB MAHABOOB

 

From: Kannayeram Gnanapandithan

Date: 2019-03-10 11:21

To: materials-welding

Subject: Re: [MW:29245] Re: FW: 29173] TIG Tandem Welding qualification as per ASME-IX

What is the advantages. Since you are giving more heatinput, have u  checked machanial properties including impact and also. Micro and macro  . If possible, pl upload the outcome

On Sun, 10 Mar 2019 9:02 am , <anamulqc@gmail.com> wrote:

Dear Sir,

Thank you for valuable comments. Please see the attached WPS and PQR which I have prepared for production and welder qualification. 

On Friday, March 1, 2019 at 9:51:24 PM UTC+6, pgoswami wrote:

This technique is NOT  "Tandem GTAW". This term applies to machine or  automatic welding processes, when one electrode is the lead electrode and the other is the trail.

The picture depicted here is a modification of the GTAW welding technique, where 2 welders are welding in the same welding puddle at the same time. In shop floor coinage the technique is called, "Double Operator TIG (DOT process)" to avoid costly back chipping in Stainless welds. I know in the 1980; L &T used to adopt this technique a lot and when it was convenient.

 

What's required:-

·         Qualify a PQR, with the identical welding condition for the root, followed by rest of the process by other welding techniques. For GTAW the heat input is doubled. Hence corrosion properties may be affected.

·         Qualify welders to Sec-IX, with identifiable pairs and document The same.

·         Use these pairs only in production welds

·         Both welders should use filler metals, or else chances of crater crack would exist ( due to the fact,  more volume is melted but less filler wire is added).

 

Duplex SS calls for severe restriction of heat input, hence this technique may not be advisable. However if trials yield good results then it may be thought of  at the discretion of the welding engineer and the AI.

 

Thanks.

 

P.Goswami.P.Eng, IWE.

Independent Welding & Metallurgical Specialist

Linkedin: https://www.linkedin.com/in/pradip-goswami-2999855/

Email:p...@quickclic.net,pradip.goswami@gmail.com

Whatsapp:1-905-9793232

 

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of anam...@gmail.com
Sent: February 28, 2019 11:39 PM
To: Materials & Welding <material...@googlegroups.com>
Subject: [MW:29173] TIG Tandem Welding qualification as per ASME-IX

 

Dear expert,

How I can write a WPS and qualify welder as per the following picture. In this picture, one welder will weld with filler metal opposite welder without filler. Please need your valuable suggestions.    

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