floating head cold crack
Thread Content
A floating-head heat exchanger with a diameter of 1600; the floating-head flange is made of 16MnIII with S32168 surfacing, and its thickness is 285 mm； The material of the arch cover is Q345R+S32168, with a thickness of 65+3 mm. Preheating, slow cooling, and heat treatment were all carried out, yet cracks still appeared. Does anyone have any good solutions?
I don’t understand; where did the cracks appear? Is there a weld connecting the floating head flange and the arch cover? Where do cracks occur in the weld?
It’s best to include pictures and test reports
The crack appeared at the junction of the weld and the floating head flange, as a circumferential crack.
Is it a multi-layer crack or a base layer crack?
The crack is in the base layer of the floating head flange; no transition layer welding material has been used yet.
How is current control? The method for welding?
Welding is no problem; use welding rods, weld alternately on both sides, and apply multiple passes with a low current. For welding work in the workshop, experienced welders are hired, and process control is very strict.
It looks like an old device from the picture? Cracks occur when 16Mn grade 3 forgings are welded to Q345R?
After the floating head and floating head flange are aligned, how is the control of the peripheral gaps? If it is uneven with large local gaps, it may cause local stress concentration
The cracks are circumferential, present all around; since two cracks have already occurred, strict control is applied to the third piece. The gap is strictly in accordance with the process. But it still cracked. The crack is very deep and long; it cannot be repaired and must be scrapped