Monday, December 6, 2010

Re: [MW:8536] Re: cracks in tacking

We also had the same problem but material was different (SA387 GR11 CL1) and thickness was higher (24~54).

So, we found cracks in tack welding.

Solution adopted was quite opposite than mentioned in trailing mail in terms of PREHEATING. We reduced preheating temperature, which reduced EXPANSION-CONTRACTION effect, of-course it gives some bad effect to material chemistry, but the same followed with back chipping.

1 handy option was also to use restrains to avoid movement of material, say restrict EXPANSION-CONTRACTION, which will not restrict cracks.

Another thing is to remove the tack welding completely during back chipping.

and yes, increase tack welding dimensions, say, 100 mm long tacking for every meter or less.


Suggestions on above view points are welcome.


Thanks and Regards,

Ashish Soni.

On Mon, Dec 6, 2010 at 4:57 PM, joshi jaydeep <jaydeep.p.joshi@gmail.com> wrote:
I am not sure whether you have done post heating or not. If not, then go for it.
 
Increasing preheat is good option.
 
Moreover you can increase the weld deposition of tack weld.
 
Also do some mechanical restraining till the sufficient weld is deposited.
 
One more improvement is to do electrical preheating which provides you the uniform heating over a wide area and reduces the thermal stress.
 
 

Jaydeep Joshi | Welding Engineer. TDW India Limited

Plot No 16 | Phase –III | Alindra – Savli G.I.D.C | Taluka : Savli | Vadodara – 391 775

Board : +91-2667- 619900 | Fax : +91- 2667- 619501| Extension : 7845

E-Mail : jaydeep.joshi@tdwilliamson.com  | www.tdwilliamson.com

Cell: +91 9978959626

P    Before printing, Think about ENVIRONMENTAL responsibility

 


 
On Mon, Dec 6, 2010 at 2:04 PM, marcelo <marcelopsoriano_1925@yahoo.com.ph> wrote:
vasu,

we are also have the same problem before, i am suggesting you to put a
tacking bridge same material as base metal and to be tack in bevel
face and increase the preaheat temp. up to 177-180 deg. celcius

marcelo p. soriano
qa/qc eng'r

On Dec 3, 7:37 am, srinivas rao <ksrv...@gmail.com> wrote:
> Dear All,
>
> we are using  FILLER WIRE ER 90SB3 FOR SA387GR22 CL-2 thk 6mm...we are are
> pre-heating to 150 with  torch....after doing tacking, about 95% of tacks
> are found to have cracks .We have not released for Welding.The filler
> material is checked and ok. pls give your sugestions.
>
> Regards
>
> Vasu

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