Answer: Wall thickness measurement is an important part of the regular inspection of pressure vessels. Wall thickness measurement is not only convenient to use, but also can find many problems, provide a basis for in-depth analysis, and is also the basis for strength verification.
(1) The measurement location should be representative and have enough measurement points. After the measurement, the map should be marked and recorded. The location of the measurement point should generally be selected from the following parts:
1) The location where the liquid level often fluctuates;
2) The location that is prone to corrosion and erosion;
3) The location where the wall thickness is thinned during manufacturing and the location where deformation occurs during use;
4) The suspicious location found during surface defect inspection.
The purpose of thickness measurement: ① Provide the minimum remaining wall thickness for strength calculation; ② Find suspicious locations in the parent material; ③ Analyze the impact of working conditions on pressure vessels based on the remaining wall thickness. Provide preventive measures for the use of pressure vessels. To this end, the selection of points must be representative, and it is necessary to specify the number and location of wall thickness measurement points.
（2）When using an ultrasonic thickness gauge to measure the wall thickness, if there are interlayer defects in the parent material, additional measuring points should be added, or an ultrasonic flaw detector should be used to determine the distribution of the interlayer and the inclination with the parent material surface.
