Root Cracking in carbon steel buttweld

[jessecwi]

I am having issues with the root cracking in sa 105 flange buttweld, 14" schedule 80,we welded root,ground root and pt root and cracks are showing up,we have preheated it and are still having issues.the original weld was welded at our fabrication facility with saw process, and we have had to cut this weld due to dimension bust. any ideas on why this root was cracking???? we cut it off and bought a whole new flange and are in the process of fitting the new flange up.

 

[metengr]

Either the wrong filler metal was used by your fabrication facility, or preheat is not adequate or your joint fit-up is poor resulting in a small width to depth weld bead ratio.

 

[stanweld]

In addition to metengr's comments, the actual flange material may not be SA-105. May be a mixed steel.

 

[jessecwi]

after replacing the flange, new 6010 electrodes ,the welder even got another welding machine. as he was swapping leads out he realized his ground was loose. so apparantly this may have been the root cause. we had no problems after all of this was done. the weld was pt'd all the way out and x rayed and accepted.

 

[metengr]

I had seen this once before. The welder picked up on it because the arc was unstable during welding.