Back gouging on Stainless steel with carbon arc gouging

[voleti Satish kumar]

Hello Experts we are building the stainless steel above ground storage tank's. The issue is that i found the production using the carbon arc gouging method for back gouging , i know that we cannot perform this on stainless steel and i stopped them by doing this now the construction engineer is asking on what reference you are saying this . So please kindly give me the code reference that we cannot perform carbon arc gouging on stainless steel's.  

[george....@gr.bureauveritas.com]

The Code does not prohibit back-gouging on stainless steel.
However Section VIII-1 in UG-76 sets some requirements and  in UW-32 requires  cleaning and removal of detrimental oxides.
Furthermore, since the back-gouging is a non essential variable of the applicable WPS and therefore integral part of it, during back-gouging with arc-air the other variables of the WPS have to be respected during back-gouging which are:

• Preheat temperature
• Maximum Interpass temperature

best regards

Dr. Georgios Dilintas

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voleti Satish kumar ---17/09/2013 11:58:00---Hello Experts we are building the stainless steel above ground storage  tank's. The issue is that i

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[voleti Satish kumar]

Dear Dr. Georgios Dilintas,

Thank you very much for your reply.I thought it was not allowed. I think i rode some where  that back gouging with carbon arc on stainless steel but i forgot whether it was a client spec or international code. 

[navanee kumar]

Dear Mr.Satish,

Read below emails &you will get answer:

Already answer is there in google groups

Dear  Friends

 

What is the best method of back gouging of SS weld of heavy thickness plate?

Do you prefer

i)                    Back Gouging by Carbon Arc rod

ii)                   By Plsama gouging with hand torch

 

Ia)If By Carbon Arc rod – How much gouged surface you prefer to grind ? to remove carbon contamination

Iia) Is there any special plasma torch available for back gouging

 

Regards

 

Hegde P.b.

3/31/10

  Dear Friend.

 

You should use Plasma Gouging with Hand Torch and use the Flapper disc for cleaning. 
 

ibratech

3/31/10

Hi,

 

You can use GTAW Twin welders for welding from both side simultaniously to avoid back gouging. Minor back grinding touch up is only required if you use twin weldes. If back gouging un avodable, use plasma arc gouging.

 

Regards,

Ibrahim

3/31/10

Are you looking for long term solution or temporary solution to complete the project ?

I have used both the methods and found acceptable. If your requirement is temporary and you have facility of in-house testing you can choose Carbon arc gouging. 

For carbon are gouging you have to grind 3mm after carbon arc gouging To be assured how much carbon deposition / dilution from the carbon rod occurred, you can do mock up at different depth (after removal of surface layers) and carry out PMI to check carbon % and other main elements and establish the data. The same can be witnessed by client. In my experience there is not much carbon pick up observed and you can get the chemistry at 0.5 to 1.0 mm depth (no need to remove 3mm from the gouged surface). 

In plasma hand held torch you need very skill full operators and getting that torch may affect the Project Cost.

You have not mentioned what type of joints and shape & size of the product. 
  
Regards.

4/1/10

We can even use Farros Blatter for backgouging from a min. ø of 800 mm upwards and it will have following advantages:


1)assured gouging of the weld root, preventing weld faults

2)no hardness increase in the edge zone

3)clean and reproducible tulip shape in the weld root area

4)no carbonisation

5)high rates of material removal:- removal rates:up to approx 600 gr/min with grinding wheel, up to approx 800 gr/min with grinding belt

Regards

Prem Nautiyal


On Wed, 31 Mar 2010 11:22:16 +0530 wrote

PB,

 

1) It is oserved that if one use carbon arc gouging the carbonpick up is observed upto the depth of mm so it is better to griding upto 3 mm  thk from the gouged surface.

 

2) Chip back grinding using farros blattor is another option for good productivity but ihs the limitations to be used in L/seam & circ seam joints not in nozzle implant chip back.

 

3) yes, chip back using plasma arc is another option for SS chip back in all type of joints but its torch availability is an issue. You can try hypertherm for plasme arc gouging torch.

 

regards,

Amarjit singh 

TEMA INDIA LTD

4/5/10

April 05, 2010

 

Dear Mr Hegde,

 

Attached herewith are 2 articles relating to your requirement. In my opinion Plasma Gouging

is thebest alternativen You can ask for demo from any Hypertherm dealer, if you do not

possess the Plasma Cutting Machine

Regards

Ashok Rai

 

HyperthermGouging-2.pdf

204 KB   View   Download

Click here to Reply

Dick Overkleeft

4/7/10

Dear Mr. Hegde,

 

In  1994 we tested carbon arc rod gouging for back gouging on duplex stainless steel, and tested the sample welds . At that time we did not discover any contamination of the ss with carbon. We did grind the gouged groove to such extent, that a smooth bevel was arranged.

 

best regards,

 

Dick Overkleeft

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Navaneethakumar.D.
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