Welding of B7 bolts
Welding of B7 bolts
(OP)
During a recent activity on one of our equipment, one of its head bolt M100 X 4 broke in the middle. The bolt one side is in the tapped hole of the channel head , whereas nut is applied on the other side. We had a spare bolt, so cut the spare bolt from the length where the bolt stuck in the channel heads broken,made a V-joint and welded with 8018 B2 electrode. Please note that the equipment has total 26 bolts. Proper PWHT was done after welding (applicable to P11 material, as the B7 composition is nearest to it). Is it safe procedure?





RE: Welding of B7 bolts
At least provide a drawing.
Mike Halloran
Pembroke Pines, FL, USA
RE: Welding of B7 bolts
RE: Welding of B7 bolts
RE: Welding of B7 bolts
If not, no.
Regards,
Mike
RE: Welding of B7 bolts
Dont be too quick to criticize "on the spot repairs" if you dont know all the circumstances.
RE: Welding of B7 bolts
RE: Welding of B7 bolts
... but you had one on hand. I guess you couldn't remove the damaged one?
It's an odd assembly, in that the female thread of the housing or whatever is not very deep, so maybe the working pressure is not super high. ... but you haven't given us a clue about that.
The flange closure plate (retained by all those studs) is also a bit odd, in that one edge, adjacent what might be a gasket face, is chamfered so far that the stud shanks are exposed. ... which may be why the stud threads were damaged, e.g. by corrosion or by impact of something falling on the flange.
Whether it's safe for continued operation, well that's not what we do here, and even if it were, nobody here has enough information to answer a question like that.
Mike Halloran
Pembroke Pines, FL, USA
RE: Welding of B7 bolts
Well I don't think its a good idea, but as someone calculated the strength of the weld in tension?
Once the stud is loaded via the nut, the weld needs to transfer the tensile load to the female threads and in addition are the studs subject to cyclic loading?
What caused the stud to fail in the first place?
desertfox
RE: Welding of B7 bolts
If you are assured of the weld properties and quality, and they then meet the required strength, you should be OK.
If not, no. Welding B7 (or any high-strength fastener material) is generally a bad idea.
Regards,
Mike
RE: Welding of B7 bolts
As a failure analyst, including numerous fractured fasteners - I especially don't like it.
How straight is that 'new' bolt?
RE: Welding of B7 bolts
RE: Welding of B7 bolts
The picture did not illuminate anything for me.
RE: Welding of B7 bolts
RE: Welding of B7 bolts
By the way, why ask such an obvious question? You did what you needed to do. Except if I was the client I would make you jump through so many hoops - weld mock-up and demonstration test for procedure qualification and NDT is required.