Preheating Requiremen​t for Tack Welding

[Amit Vishwakarma]

Dear Experts

 

If our WPS qualified with preheating say 200ºC then is it mandatory to preheat the job also as per WPS for tacking weld also? and if it is mandatory then where is mentioned in Code

 

Regards

Amit Vishwakarma

[mohd]

Dear Amit,

If Tack weld is going to be integral with weld (means not removed during) yes need preheating and it should be done by qualified welder.

But if tack welding is removed during welding and not integrated with weld then it is not necessary. 

Still in my opinion if 200C preheating is require material may produce hard zone during tacking so it is better you do preheating during tacking also to avoid any cracking problems.

Please share Materials and welding details for better answer from experts.

regards,

mohd.

[george....@gr.bureauveritas.com]

The only exemption that ASME Code Section give for tack welds is that they have to be grinded off in case they are performed by non qualified welders.
In no place it is written that they can be performed with a non qualified WPS.
So in case of tack welds, you have to apply a qualified WPS
 

best regards

Dr. Georgios Dilintas

Authorized Nuclear Inspector
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[MUNHOZ Sergio TECHINT]

Dear Amit;

 

 

All welds (including tack ones) SHALL be done according to the qualified WPS; no exceptions!

 

Best regards

 

Sérgio Munhós
Construção e Montagem
Techint Engenharia e Construção

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[Saravanan Sornam]

Dear Amit ,

This is just a friendly advice .

from next inquiry onwards, please mention the exact material spec. P No, thk , Filler datas, etc, to give 100% perfect reply, reasons behind, for any cases .

Anyway, you have to do Preheat and follow the WPS even for Tack welds, to avoid cracks...

Code has not given all the technical details directly which we are looking for , also we need to search the best Engg Practices , metallurgy aspects, preventive methods, including the recommendations given in code.

Experts, I think my opinion is right...

Cheers,

Saravanan,

Korea