Re: [MW:29146] RE: 28982] Backing gas as per API RP 582

To be specific, as you know purging purpose in SS is mainly for shield against oxidation which took place when molten metal kiss the oxygen from atmosphere. Now when you welding a fillet weld the amount of oxidation is corresponding to the amount of heat supplied vs. encounter of molten weld metal to the atmosphere without shielding. 

A fillet weld having a configuration without any gap and zero flow of molten metal to the back side will defiantly not require any purging. Its recommended to use a optimized low heat input. I advise you although to put gas backing upto 2 mm thickness as the low heat dissipation in SS can melt through thickness during welding.

Thanks & regards

Sandeep Kumar

On Friday, February 22, 2019 at 6:19:06 AM UTC+3, John Manoj wrote:

Thanks for the reply, Is back purging is required when we do fillet welding on a thin (2mm to 5mm) SS base material, for example some cleat welding or pad welding or socket welding with GTAW or SMAW process.

Expecting a reply.

Thanks,

Manoj

Dear Mr. Goswami,

In 2016 editions of API RP 582 the purging gas requirement given in subcluases (a) (b) (c) but in previous editions purging requirement given in clause 

On Mon, Jan 28, 2019 at 9:53 AM PGoswami <pgos...@quickclic.net> wrote:

Manoj,

 

SMAW never requires back purging. It's the "slag" generated by the process, which protects the weld root. This is just back to basic scenario.

Thanks.

 

P.Goswami.P.Eng, IWE.

Independent Welding & Metallurgical Specialist

Saudi Aramco: Designated Project Welding Engineer(DPWR)& Quality Management Personnel

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

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

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Manoj John
Sent: January 27, 2019 8:04 PM
To: material...@googlegroups.com
Subject: [MW:28982] Backing gas as per API RP 582

 

Dear Experts,

 

As per clause 7.3 of API RP 582 Ed. 2016 back purging required for GTAW & GMAW process but no where I could found for other process like SMAW.  Is it mean that if we do welding with SMAW process back purging is not required?

 

Please share your interpretation.

 

Thanks and regards

 

Manoj.

 

 

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