[MW:4330] Re: AFFECT POLARITY IN HEAT INPUT

I think what is missing in the discussion is that the amps, volts and
travel speeds will need to be adjusted to run an acceptable bead in
either DCEP and DCEN. This change in variables will cause your heat
input to change. If you force the amps, volts and travel speed to be
the same for both polaritys, your heat input will be the same,
however, the quality of your weld may not be acceptable. That is also
why the code recognizes this change as an essential when impacts are
required. You will most likely need to change your amps, volts, and
travel to run acceptable beads in either polarity.

Any thoughts?

On Feb 15, 9:55 am, "John Henning" <jhenn...@deltak.com> wrote:
> The Code recognises that a change in polarity will affect heat input.
> Thats why Sc IX assigns a change in polarity, QW-409.4 is a
> supplementary essential variable, and any change in polarity must be
> requalified with a new PQR.  Without impacts QW-409.4 is a non-essential
> variable and must only be appropriately addressed on the WPS.
>
> John
>
> ________________________________
>
> From: materials-welding@googlegroups.com
> [mailto:materials-welding@googlegroups.com] On Behalf Of Singh Rishi
> (TIPO - QA/QC)
> Sent: Sunday, February 14, 2010 11:40 PM
> To: materials-welding@googlegroups.com
> Subject: RE: [MW:4314] AFFECT POLARITY IN HEAT INPUT
>
> If one checks the heat input formula, there is no variable for the
> polarity.
>
>  Therefore , as per standard,  Polarity  doesn't influence the H.I .
>
>  We all understand that actual H.I differs from calculated  H.I as
> current / voltage/ travel speed are never a single value ( specially in
> manual welding )
>
> Best Regards,
>
> Rishi Raj Singh
>
> ________________________________
>
> From: materials-welding@googlegroups.com
> [mailto:materials-welding@googlegroups.com] On Behalf Of ali asghari
> Sent: Saturday, February 13, 2010 9:59 AM
> To: materials-welding@googlegroups.com
> Subject: Re: [MW:4297] AFFECT POLARITY IN HEAT INPUT
>
> thank you
>
> but my inyention is distribution of heat is differed by polarity ,
> therefore H.I depend to polarity.is it true?
>
> regards
>
> On Sat, Feb 13, 2010 at 2:04 AM, <george.dilin...@gr.bureauveritas.com>
> wrote:
>
> It is because of the difference of the electrons flow I think
>
> ________________________________
>
>   From: Ali Asghari [asghari...@rocketmail.com]
>   Sent: 11/02/2010 23:44 PST
>   To: materials-welding@googlegroups.com
>   Subject: [MW:4291] AFFECT POLARITY IN HEAT INPUT
>
> Hi All
>
> all know that heat input is independent from polarity.but  i see in GTAW
> that in DCEN ,70%HEAT generated in arc concentrated in parent metal & in
> DCEP 30% HEAT concentrated in base metal.
>
> can anybody clarify it?
>
> regards.
>
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