API 653 storage tank inspection services

Storage tanks hold large volumes of liquids in petroleum, agricultural and food-processing industries. Examples include fuels, bitumen, edible oils, molasses, alcohol, beer and treated water. LPG and LNG facilities also use specialised storage systems; their inspection requirements must be selected for their particular design and service.

Scope of API 653

The American Petroleum Institute (API) publishes API 653 for inspection, repair, alteration and reconstruction of in-service steel storage tanks.

API 653 covers steel tanks built to API 650 and its predecessor API 12C, with requirements for maintaining their integrity in service. Applicability is determined from the tank design and service; it is not defined by a general threshold of 15 m height or 10 m diameter.

API — API 653 scope summary

Tank inspection service activities

1. Review documents and collect general tank information: design drawings, specifications, condition, maintenance and repair history.
2. Visually inspect the shell, roof, welds, coatings and foundation.
3. Measure the thickness of bottom, shell and roof plates using ultrasonic equipment and assess corrosion rates.
4. Vacuum-box leak testing of the tank bottom, where applicable.
5. Assess settlement, tilt and local deformation using appropriate survey methods, including laser/electronic total-station measurements.
6. Assess the remaining service life of the tank.
7. Recommend the next inspection interval.

Inspection records from the source article