solidifiction crack and lower impct value 1

[vks1986]

Hello all, now i have facing problem of solidiction crack and lower impact value. we have pipe order of 36inch dia and 44mm thickness . our process of sawpipe welding is first doing gmaw on od longitudinaly then three wire tandam saw welding in inside and then outside of pipe longitudinally and impact requirment at -20c avg 105 in api 5l x65m grade pipe. we are facing problem of solidifiction crack and lower impact about 40j. and we are weld same grade pipe with same consumable of thick 23mm we geting 164j impact at -20c and no solidification crack. how it possible?..

 

[metengr]

What is your preheat temperature and interpass temperature for the thicker (43mm) base material?

 

[vks1986]

preheat 100c and interpass 130c. we are getting depth to width ratio less than 1.

 

[metengr]

I would increase the preheat to 125 deg C and the interpass to 200 deg C.

 

[vks1986]

we can do preheat at 125 deg c but interpass I can not achieve 200c.
Because we prepare double v bevel groov so first we done inside saw three wir tandam welding and then we do outside of pipe. distance between inside and outside welding machine is 36meter.
so max I can achieve is 130c.

 

[SJones]

Check the alloying content of the plate. Going from 23 mm to 43 mm will inevitably bring about an adjustment in alloying to achieve the required properties and the results of dilution in the weld metal could be negative. The first people to contact for advice should be the consumable supplier.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[stanweld]

Check pipe chemistry as per Steve's recommendations. Also you may need to change your flux to a more basic chemistry.

 

[vks1986]

Dear all,
thanks for ur guidances.