Stainless steel storage tank inspection is divided into external inspection, internal inspection, and inspection. The periodic inspection of stainless steel storage tanks should be determined based on the technical usage conditions of the tanks.

Generally speaking, external inspections should be conducted at least once a year, internal inspections should be conducted at least once every 3 years, and inspections should be conducted at least once every 6 years. If the service life of stainless steel storage tanks exceeds 15 years, internal and external inspections must be conducted every two years. If the service life reaches 20 years, internal and external inspections must be conducted at least once a year.

1、 Internal inspection

1. Whether there is corrosion agent wear on the inner surface and manhole connection of the storage tank, and whether there are cracks in the weld, head transition zone or other stress concentration areas;

2. When there is corrosion or other phenomena on the inner and outer surfaces of the tank, multiple wall thickness measurements should be taken at suspected locations. If the measured wall thickness is less than the designed small wall thickness, the strength should be re evaluated and suggestions should be made on whether it can continue to be used and whether high working pressure is allowed;

3. When there are defects such as decarburization, stress corrosion, intergranular corrosion, and fatigue cracks on the inner wall of the tank, metallographic examination and surface hardness measurement should be carried out, and an inspection report should be submitted.

2、 External inspection

1. Check whether the anti-corrosion layer, insulation layer, and equipment nameplate of the storage tank are intact, and whether the safety accessories and control devices are complete, sensitive, and reliable;

2. Whether there are cracks, deformations, local overheating and other phenomena on the outer surface;

3. Check for leaks in the weld seams and pressure components, integrity of fastening bolts, and any abnormal conditions such as sinking or tilting of the foundation.

3、 Check

1. Perform non-destructive inspection on the main welds or shells, with a spot check length of 20% of the total weld length;

2. After passing the internal and external inspections, a water pressure test shall be conducted at 1.25 times the design pressure of the storage tank, and an air tightness test shall be conducted at the design pressure of the storage tank. During the above inspection process, if there is no leakage or visible abnormal deformation in the tank and its welds, it is considered qualified;

After the inspection of the stainless steel storage tank is completed, a report should be made on the tank inspection, indicating the problems and reasons why it can continue to be used or can continue to be used but needs to be repaired or cannot be used. The inspection report should be kept on file for future maintenance and reference.