What is API 653? Storage Tank Inspection Protocol API 653

What is API 653?

  • API 653 is the standard for tanks over 50 feet tall or having diameter greater than 30 feet.
  • Covers the maintenance, inspection, alteration and repair of steel, field-erected aboveground storage tanks (ASTs) built to API 650 or API 12C standards.
  • API 653 inspections must be performed by a licensed inspector.
  • Brittle fracture assessment are covered under API 653.
  • API 653 includes welding requirements for field erected tanks.

Storage tank owners usually hear the term API 653 Standard in the context of aboveground storage tank inspections. This is rightly so, because API 653 is the internationally recognized standard for inspecting aboveground welded storage tanks storing products at atmospheric pressure.

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However, the API 653 Standard covers more than the requirements for an API 653 inspection. In addition to addressing inspection requirements, API 653 also addresses the repair, alteration, relocation, and reconstruction of existing aboveground storage tanks built to the API 650 Standard or its predecessor, API 12C.

Storage Tank Relocation and Reconstruction

As welded storage tanks increased in popularity between 1960 and 1990, many existing riveted tanks were cut down and reconstructed as welded tanks. After the catastrophic failure of a reconstructed tank in 1986, there was a clear need for guidance in safely relocating and reconstructing tanks. In 1991, API 653 was published and specifically addressed dismantling and reconstruction of aboveground storage tanks.

Section 10 of API 653 states “[a]ll reconstruction work must be authorized by the authorized (API certified) inspector or an engineer experienced in storage tank design” before commencement of the work. Section 10 provides guidance to the API 653 certified inspector or tank engineer as to methods of dismantling the various parts of a tank, using tank piece identification and alignment markings, reconstructing the tank, and testing dimensional tolerances on the reconstructed tank.

Repair or Alteration of a Storage Tank

Section 9, another important portion of API 653, addresses repair and alteration of aboveground storage tanks. Again, all repair work to an above ground storage tank must be authorized by an API certified inspector or an engineer experienced in storage tank design. Section 9 of API 653 details what requirements the certified inspector or tank engineer must follow when performing tasks such as removing or replacing shell plate material, installing a door sheet, repairing or installing a new tank bottom, and much more.

So whether you need an API 653 inspection, tank repair, or tank relocation, the API 653 Standard speaks to how these procedures should be safely completed.

4 Critical Components of an API 653 inspection

General Tank Information: Review tank description information including:

  • Tank Specifications
  • Tank Construction
  • Release Detection Methods
  • Spill Control

Tank Bottom, Tank Shell, and Tank Roof Inspections: API 653 allows different types of inspection to examine the aboveground tank components including:

  • Visual
  • Ultrasonic (spot)
  • Ultrasonic (Scan)
  • Liquid Penetrant
  • Penetrating Oil
  • Magnetic Particle
  • Radiography
  • Magnetic Flux Scan
  • Vacuum Box
  • Tracer Gas

Bottom, Shell and Roof: The structure of the tank is inspected to API 653 standards taking into account:

  • Minimum Remaining Thickness
  • Minimum Required Thickness
  • Maximum Corrosion Rate

Settlement Evaluations: Examine whether the tank is tilting or settling in the ground improperly. These factors are also assessed under API 653:

  • Out of plane
  • Rigid Body Tilting
  • Uniform
  • Dish Type
  • Edge Settlement
  • Localized Dispersions

Monthly Inspections Recommended Under API 653

  • Performed by site owner/operator’s inspector
  • Assess the overall tank condition as thoroughly as possible without removing the above ground tank from service.
  • Inspector performing monthly examination does not need to be certified, just knowledgeable.
  • Monthly records of inspections must be maintained for regulators.

API 653 External Inspections

Reaquired Every 5 Years

  • Depending on the initial inspection findings, an external inspection may be required more frequently.
  • External inspections are conducted by a certified API 653 inspector to assess the condition of the above ground tank and determine its suitability for continued service.
  • This inspection does not require entry into the tank’s interior. Tank can remain in service.

External Inspection 4 Critical Components

  • Inspector should review previous periodic inspection checklists and previous FEIs/FIIs
  • Inspection should include tank thickness testing
  • Must determine original shell thickness and establish current shell thickness
  • Ultrasonic thickness testing can lead to ultrasonic testing scan (UTS)

API 653 Internal Inspections

Required Every 10 Years

  • Depending on the initial assessment of the tank, internal inspections may be required more frequently.
  • API 653 internal inspections are conducted by a certified inspector
  • Internal inspection assesses the internal and external condition of the above ground tank and determine its suitability for continued service.

Avoid Penalties & Fines

  • Establish a formal internal & external inspection schedule
  • Routinely record your monthly inspection findings.

If you have any questions or need services such as an API 653 inspection, tank repair, or storage tank dismantle and reconstruction, for a free consultation and more advice on API 653 inspections please contacting me.

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