The periodic inspection of storage tank includes external inspection, internal and external inspection and comprehensive inspection. The inspection cycle shall be determined according to the technical conditions and application conditions of the equipment, but the external inspection shall be conducted at least once a year, the internal and external inspection shall be conducted at least once every three years, and the comprehensive inspection shall be conducted at least once every six years. If the service life of the tank has reached 15 years, the internal and external inspection shall be carried out every two years; if the service life has reached 20 years, the internal and external inspection shall be carried out at least once a year. For tanks subject to regular inspection, inspection personnel shall put forward inspection statement to indicate whether the tanks can be used continuously or special monitoring methods shall be adopted. The inspection statement shall be stored in the tank technical file.

Preparation before inspection:

1. Refer to the relevant technical data to understand the defects found in the production, installation and application of the tank.

2. Clean the medium inside the storage tank, use blind plate to block the equipment and pipes connected with it, and there should be a significant separation symbol.

3. The residual gas in the tank shall be replaced and cleaned, and the sampling analysis shall meet the safety standard.

4. Open all manholes of the tank, remove the inner parts of the tank and remove the dirt on the inner wall.

5. Cut off the power supply associated with the tank. When entering the tank for inspection, the low-voltage explosion-proof lamp with voltage no more than 12V or 24V shall be used, and there must be a special person outside the tank for supervision. When the power supply voltage of the inspection instrument and repair tool exceeds 36V, the flexible wire with good insulation and solid ground wire must be used.

6. The tank farm shall be equipped with fire fighting, safety and rescue equipment. If hot work is required, hot work approval procedures must be handled according to the rules.