Regarding pits on the inner wall of the steam drum
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Our unit is ready to start operating. After the cooking furnace was connected to the steam drum (with a diameter of 1400 mm and a wall thickness of 40 mm), cleaning it revealed small dents on both the bottom and sides of the drum; their dimensions are approximately 8 mm in length, 5 mm in width, and 2–3 mm in depth. I would like to ask the experts in the boiler technology forum: how were such dents formed, and what impact do they have on the operation of the boiler? Thank you all, fellow sailors, for sharing your valuable advice!
The analysis may point to the following reasons: 1. Defects in the equipment itself, present from the time of manufacture; 2. Local corrosion; 3. Defects that occur during the steel plate rolling process
I wonder if the boiler in the original post is newly installed or already in use. If it’s a new furnace, I agree with what was said on the 2nd floor. If it is an old furnace that has been idle for a long time and is now being put into use again. These corrosions are likely caused by hydrogen corrosion. The cause of hydrogen corrosion is poor circulation of the boiler water in this area, along with the deposition of sludge formed as a result of the continuous concentration of the boiler water. The water beneath the scale undergoes hydrolysis to release hydrogen gas. It is caused by hydrogen-induced intergranular c-corrosion. The thinning of the corroded metal thickness primarily affects the pressure-bearing capacity of the body. The corrosion caused by the poster, being less than 0.1 of the tube wall thickness, should have little impact. In the future, it’s important to pay attention to regular waste discharge and improving the quality of water added. (My personal opinion, for your reference)
Thank you very much to the helpful members on floors 2 and 3; I express my sincere gratitude! :Handshake!
I think it’s a defect in the equipment manufacturing: 1. Improper material selection； ⒉It is due to inadequate manufacturing supervision.
As you said, it should be a new boiler; it has a manufacturing defect, and it can be repaired by surfacing welding.
The materials are defective, and manufacturing and supervision are inadequate. It can be repaired by welding, but it is important to note that first, a detailed welding procedure must be developed, and second, heat treatment is required after welding.