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Re: [MW:4885] Ar purge for Low Alloy steel

dear all

according to API 582 CLAUSE 7.3 see the following

 

"Back purging is required for the GTAW and GMAW

processes for welding materials having a nominal chromium

content greater than 2l/4% unless the joint is ground or back

gouged to sound metal."
the cause  is

"back purging gas is selected to prevent oxidation

or scale formation on the underside of the weld"


--- On Mon, 4/19/10, kannayeram gnanapandithan <kgpandithan@gmail.com> wrote:

From: kannayeram gnanapandithan <kgpandithan@gmail.com>
Subject: Re: [MW:4883] Ar purge for Low Alloy steel
To: materials-welding@googlegroups.com
Date: Monday, April 19, 2010, 3:20 PM

For Cr>3%, it is always better go for purging, if customer insist for all low alloy, pl do it because it will better and uniform root penetration
KGP

On Wed, Apr 14, 2010 at 10:57 PM, qaqcmpm <mamujeebali@gmail.com> wrote:
One of our client specn asks for argon purging of root pass (pressure
retaining welds) for GTAW for Low alloy Cr-Mo steel? why it is
required any idea?

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