Comprehensive API-653 Inspection


A potential consequence of doing an API 653 – tank inspection is dealing with a tank that does not comply with its requirements. Some owners may be reluctant to incorporate API 653 into their tank inspection program. Reluctance occurs due to the cost of potential repairs to bring a tank into compliance or perceived liability of having an inspection report that includes a noncompliance statement. Unfortunately, this approach is like sticking one’s head in the sand. It is always better to be aware of a potential problem and the options for rectifying it, than to risk a failure.


An API -653 inspection program addresses four main tank components: the roof and it structure, shell, bottom and the tank foundation. These components directly affect the tank’s structural integrity and liquid storage capability. API – 653 does not specify exact inspection procedures nor quantities of data that must be collected. It only specifies what must be inspected, when to inspect it, in order to detect leaks & structural integrity discrepancies due to corrosion, settlement and previous repair operations.

Engineering Evaluation:

API-653 goes beyond merely requiring that the main tank components be inspected. An engineering evaluation of inspection data is required to ensure that the tank’s structural condition meets specified acceptance criteria for the purpose to:

  1. Determine if the tank is structurally sound at inspection
  2. Determine what repairs, if any should be made to be in compliance.
  3. Project the safe useful life of the tank for the intended service.
  4. confirms that the tank structural & leak integrity will remain sound until the next inspection
Benefits Of Compliance To API-653:
  • Ensure operator safety.
  • Minimize product losses.
  • Comply with state regulations.
  • Prevent environmental damage and litigation.
  • Document tank maintenance and inspection activities.

Qualitech Engineering is fully equipped to provide API 653 Suitability for Service Inspections and Evaluations. Qualitech has inspected hundreds of individual tanks from 3 meter diameter to 60 meter diameter. Bellow is a breakdown of some of the inspection packages we provide:

Our full scope of NDT methods to perform Tank Inspection include:
  • A-scan ultrasonic thickness measurements.
  • B-scan Advanced ultrasonic imaging for tank bottom plate
  • Magnetic Flux Leakage technique for tank bottoms.
  • Vacuum box testing for bottom plate lap welds and shell to bottom weld.
  • Magnetic Particle for shell to bottom welds.
  • Visual inspections are performed by experienced API 653 qualified inspectors.
  • Geometric Optical Measurements.
  • Pit Gauging.
Our Engineering evaluations include:
  • Repair recommendations
  • Next Inspection Interval calculations
  • Shell & Bottom Settlement evaluations.
  • Shell Out of Roundness
  • Remaining life for Bottom, Shell, & Roof
  • Shell Safe fill height calculations
  • Other evaluations as per API 653 guidance
  • Evaporative Loss calculations as per API- Chapter 19
  • Floating roof primary & secondary seals inspection as per 40 CFR part 60

To view a document about the TMI-150 Scanning System, pleace click here

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