Friday, April 15, 2011

[MW:10681] Re: GMAW short circuit Welders Qualification

GMAW process changes the characteristics as the voltage and current
are varied. When the voltage is in the 17-18 volt range, the mode of
transfer is short circuit. This is a very low heat input process that
is used for very thin materials and root pass on pipe. The concern is
that you can have non-fusion. As the voltage is raised the mode of
transfer changes to globular which generates an abnormal amount of
spatter. When you get to the 26-28 volt range the mode of tranfer
becomes spray arc. The concern of non-fusion goes away with GMAW
spray transfer. This is why the codes (ASME and AWS) require bend
tests for GMAW short circuit. X-ray does not do a good job of picking
up non-fusion where as bend test will definately identify it.

I hope this helps.

David Landon
Vermeer Corporation

On Apr 14, 11:50 am, Zakaria ghrab <zakaria.gh...@gmail.com> wrote:
> Hi all,
>
> According ASME section IX, in case of welders Qualification of GMAW process
> - short circuit transfer mode, Radiography is not applicable and we must do
> Mechanical tests.
>
> Need just to know what's exactly Short circuit transfert mode and how it can
> defferenciate of others ! by current range ?
>
> Regards.
>
> --
> *زكرياء غراب
> **GHRAB Zakaria** *
> مسؤول عن الجودة
> QA/QC SENAD
> مشروع المحطة الحرارية ـ الوحدة الرابعة
> المحمدية ـ المغرب

--
To post to this group, send email to materials-welding@googlegroups.com
To unsubscribe from this group, send email to materials-welding+unsubscribe@googlegroups.com
For more options, visit this group's bolg at http://materials-welding.blogspot.com/
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

No comments:

Re: [MW:34832] Inquiry about Single Bevel with Back Grinding

Dear Uday, As per your question that one is called with backing only,Simple both side you are welding it is backing with strip or without st...