Backing by gas/Back purging is not essential for P.No 8 - Austentic stainless steel? - ASME Sec 9

[Srinivas Engr]

Dear All,

As per QW 256, GTAW process,
QW 408 Gas, There is no essential variable for gas Backing for P.No.
-8. Austentic Stainless Steel. A312 & others.
So we can qualify WPS without gas backing/Bsckpurging.
Am i right or not?
Pl clear me

Regards
Srinivas

[Zakaria ghrab]

Dear Sir,

As i know & as per QW 256 & QW408.9 ,  only deletion and chnage in backing gas composition is essentiel variable, so we can qualify WPS without backing but we will have sure problem in penetration. The best is to do one PQR with backing gas and use it to qualify all your WPS's in production.


Regards.

  

2011/2/10 Srinivas Engr <srinivas...@gmail.com>

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GHRAB Zakaria

[Engineer Mech]

Dear All,

 

BY Asme sec 9, QW 408.9 & .10, does n't applies to P No.8, Austentis SS

So.. he may be right. I think we can.

 

 

Regards

[Prakash Hegde]

Hi!

From qualty point of view, the gas backing /purging for groove welding of SS  is essential . Failure to backing will cause Oxidation of weld which is not acceptable

 

Regards

 

Hegde P.B.

---

From: Zakaria ghrab <zakari...@gmail.com>
To: material...@googlegroups.com
Sent: Thu, 10 February, 2011 1:04:39 PM
Subject: Re: [MW:9799] Backing by gas/Back purging is not essential for P.No 8 - Austentic stainless steel? - ASME Sec 9

[Vinod Kataria]

No for Austenitic Steel it is must to do back purging so that oxygen does
not come in contact with molten Chromium as SS is having Cr and during
welding if it is coming in contact with oxygen it will become chromium oxide
and the same is very brittle and lead to weld crack.

With kind regards,
Vinod Kumar Kataria
GM - Operations
Bliss Anand Private Limited,
92B/93B Sector 5
IMT Manesar,Gurgaon,
National Capital Region Delhi.
India .
Phone : +91-124-4366000 (9 Lines)
Mobile Phone : +91-9560199004
Fax : +91-124-2290884

-----Original Message-----
From: material...@googlegroups.com
[mailto:material...@googlegroups.com] On Behalf Of Srinivas Engr
Sent: Thursday, February 10, 2011 12:03 PM
To: Materials & Welding
Subject: [MW:9798] Backing by gas/Back purging is not essential for P.No 8 -
Austentic stainless steel? - ASME Sec 9

Dear All,

Regards
Srinivas

--

[james gerald]

Srinivas,

AS per ASME Sec.IX, Backing Gas is not an essential variable for P.No.8 materials but the applicable Client specification will cover this aspect and make it mandatory to use Backing Gas for stainless steel.

Basically you cannot weld materials greater than 5% Chromium and Non ferrous metals without Backing Gas. The entire weld will be Blackish with lot of porosities and it will not pass Radiography testing.

Hence it is always good engineering practice to use Backing Gas for single sided welds of P.No:8 stainless steels.

J.GERALD JAYAKUMAR 00919344954677  

--- On Thu, 2/10/11, Srinivas Engr <srinivas...@gmail.com> wrote:

> From: Srinivas Engr <srinivas...@gmail.com>
> Subject: [MW:9798] Backing by gas/Back purging is not essential for P.No 8 - Austentic stainless steel? - ASME Sec 9

[Eduardo Calva]

Dears, could you please tell me what this statement of API RP-2201 mean?

 

6.8 WELDING AND HOT TAP CONNECTION DESIGN

Welding or hot tapping should not be permitted closer than

18 in. (46 cm) to a flange or threaded connection, or approxi-

Mately 3 in. (8 cm) to a welded seam (including a longitudi-

nal seam of welded piping) unless determined by an

engineering review to be acceptable.

 

 

Eduardo Calva

[AGUSTIN JIMENEZ]

Hi.

If you instaling a split tee with welding this should not be permitted closer than

18 in. (46 cm) to a flange or threaded connection, or approxi-

Mately 3 in. (8 cm) to a welded seam (including a longitudi-

nal seam of welded piping)

 

Agustin

---

De: Eduardo Calva <eduard...@hotmail.com>
Para: material...@googlegroups.com
Enviado: jue, febrero 10, 2011 9:34:45 PM
Asunto: [MW:9805] Hot-tap hole

[Pedro Alvarez]

Dear Mr. Calva

The statement means that you are not allowed to weld or to hot tap
(drill a hole in the pipe under pressure conditions) unless these
operations are performed at distances farther than specified values
from flanges, threaded connectiosn of welds.

A Hot Tap is defined as using a drilling machine to cut a hole into an
in-service, under-pressure piping system. This is done without service
interruption or product leakage.

Regards.

Pedro Alvarez
Materials Science PhD.
LORTEK-Joining Research Center
Ordizia-Spain
palv...@lortek.es

[Eduardo Calva]

Thanks Pedro.
 
Could someone please tell me the origin of that restriction?
 
Is it not acceptable making the drill on a longitudinal seam on the carrier pipe?

Eduardo Calva

 
> Date: Sat, 12 Feb 2011 01:26:46 -0800
> Subject: [MW:9837] Re: Hot-tap hole
> From: palvar...@gmail.com
> To: material...@googlegroups.com

[DWGCWICWENDE]

ASME IX Paragraph QW-408.9 is called out on table QW-256 under gas QW-408. The definitive answer is there, all the exotics in that paragraph Backing Gas is essential for them only. All other groups that are not there Backing gas is not a Essential Variable for WPSs. A Welder Performance Qualification done using Backing Gas or not using Backing Gas it is Essential on those material groups not called out in QW-408.9. Is using Argon backing gas the best welding practice for welding P8 materials, absolutely. I would not remove backing gas from any process per a customers request as it is a quality and application issue. People don't choose stainless steel by spinning the wheel of material to use on this job as it is typically applied because of applications or environment that have corrosive potential and that property is diminished if Backing Gas is not used.