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Inspection methods: 1. Visual inspection and dimensional inspection; 2. Non-destructive testing: Detecting internal defects in the workpiece without damaging it. 3. Pressure resistance test: namely hydraulic test and pneumatic test. 4. Mechanical property tests. 5. Chemical analysis, metallographic inspection. Purpose of chemical analysis: To determine whether the material meets the standards and whether it undergoes any changes after being in use for a period of time. Purpose of metallographic inspection: To determine whether there have been any changes in the microstructure of the material. 6. Stress-strain testing: Stress analysis is often carried out using theoretical analysis and experimental stress analysis methods. The purpose is to conduct strength verification or create stress distribution graphs. Experimental methods can determine the actual stress state at various points on the surface or inside a container under load: these include resistance strain measurement, photoelasticity, strain-sensitive brittle coating methods, and dense grating interferometry. Currently widely used methods include: resistive strain measurement, and fracture analysis: observing the fracture surface of materials or metal components after damage with the naked eye or instruments. Repair – General Principles: The handling of defects in pressure vessels in use should comply with the principle of being \"suitable for use\". Repair method 1: Use grinding to remove defects such as surface cracks. 2. Welding. Defects such as cracks in the welds or vessel walls, as well as issues like incomplete welding or lack of penetration, should be addressed by gouging and repair or replacement; patching or direct rewelding should not be used. After the defects are removed, surface non-destructive testing should be carried out to confirm that they have been completely eliminated; non-destructive testing is performed again after welding is completed. The welded area of the base material must be ground smooth. Pressure vessels whose main stressed components have a welding depth greater than 1/2 of the wall thickness shall also undergo pressure testing. 3. For lined containers, if the lining has cracks, pores, inclusions, etc., it can be repaired by welding or the lining can be replaced. 4. For containers under low pressure with severe local corrosion, patching or replacing the cylinder sections and heads can be employed. 5. If the sealing surface of the container is damaged, it can be repaired using a laser cutter or by welding. The metal sealing elements of high-pressure containers can be repaired through grinding. 6. Repair of heat exchanger tubes—tube-to-tube sheet joints. Remove the welded metal from the joint and weld it again.