Cracks in the welds between the cylinder and the head
Thread Content
There is leakage at the welds between the container cylinder and the head; a bolt was temporarily welded in place on the outside. After grinding the internal welds, longer cracks were found, with small cracks running through the entire weld. In the past, the solution involved cutting away the damaged area and then welding it again. What are some good heat treatment methods available after welding? The diameter of the container is 2.8 meters, its thickness is 62 mm, and it is made of 16Mn material.
A heating strip is used to carry out local heat treatment
Are cracks present on the straight edges of the head? No
How to carry out heat treatment after repair is a minor issue; for such cracks, the key is to determine the cause of their formation – whether it arose during the manufacturing process or as a result of equipment operation, whether it is a material issue or a corrosion problem, and whether similar conditions exist in other parts of the container. . . . . .
This device has been in use for eight or nine years; the medium used is a slurry containing strong alkalis. The material itself should be fine, but it’s likely that proper heat treatment was not applied at the time, and stress corrosion is the cause of the problem
The image is not clear enough; it’s difficult to see the characteristics, location, and direction of the cracks: how many cracks are there? Does it span the weld and the base metal? Is it on the tube section? If stress is suspected to be high, measure the hardness after heat treatment.
It makes sense; it is possible that forced assembly occurred during the manufacturing process in this area. Welding-induced heat treatment alone is insufficient to eliminate the stresses resulting from forced assembly, and the risk of stress corrosion cracking due to prolonged operation is very high.
Stress corrosion has occurred, the material properties have changed, and there is a high risk of continued use after patch welding.
I’ve learned it; I agree with the person above. For stress corrosion, it is best not to use Q345R
This crack is perpendicular to the direction of the circumferential stress, and it is located at the weld. Agree with the views on stress corrosion expressed by those above