1. Uneven wall thickness of pipe fittings
The wall thickness unevenness mainly occurs in the most severely deformed parts of the pipe. For example, the rear part of the elbow is thinner than other parts, and the wall thickness of the nozzle is different from the wall thickness of the pipe body. Relevant national standards stipulate that the wall thickness reduction of pipe fittings must not exceed 12 or 5 of the nominal thickness. However, field measurements have shown that some wall thickness reductions amount to 2o-30. For the detection of such problems, it is often difficult to find them with measuring tools such as ordinary calipers. At this time, only ultrasonic thickness gauges can be used.
2. Hardness exceeds the standard
The problem of excessive hardness is mainly due to the heat treatment process after forming. The solution is to use the correct heat treatment process and heat treatment once. This problem can generally be solved.
3. Defects in materials and processing
This kind of problem is a safety hazard to the equipment, and it is more troublesome to check. The causes of defects are various and complicated, including defects in the materials themselves, problems in the manufacturing process and defects caused by improper heat treatment processes.