API 653 

Aboveground Storage Tank Inspection,
Repair, Alterations, and Reconstruction

API 653 Tank Inspections

What is an API 653 storage tank inspection?

API 653 is the American Petroleum Institute Standard that provides inspection, repair, alteration, and reconstruction criteria for above ground atmospheric and low pressure storage tanks.  API 653 inspections are periodic assessments to ensure the safety of these tanks, as well as compliance with applicable codes and standards from API and government organizations that recognize this standard.

Why do you need an API 653 inspection?

These inspections are necessary to detect any structural problems with the tank, such as corrosion or weak points in the walls, base, or roof. Additionally, regular inspections and repairs to the API 653 standard are required by the DOT and by some state regulations for many storage tanks.

API 653 certified personnel can evaluate the structural fitness of a tank based on precise measurements taken on various areas of the tank's surfaces. By regularly obtaining API 653 storage tank inspections, bulk storage facilities can take proactive measures to prevent potential catastrophes due to unsound storage tanks, minimizing risk and ultimately protecting personnel, property, and operations.

While the document was initially designed for and updated by the petroleum industry, the high quality of the document means that the standard is applied to tanks in a wide range of services.  

There are other standards provided by organizations such as STI and AWWA, but the API 653 standard is currently the best standard for ensuring the safe storage of hazardous substances in atmospheric and low-pressure aboveground bulk storage tanks.



Types of Storage Tanks Inspected

What are the different types of storage tanks that can be inspected?

There are a variety of different types of storage tanks that can be inspected, with the standard.   Several appendices are included with the standard to help address a wide range of designs and product conditions such as:

  • Atmospheric and low pressure tanks
  • Tanks made from carbon steel, stainless steel, aluminum, and certain specialty metals
  • Tanks with floating roofs and without floating roofs
  • Open top, cone roof, self supporting, and geodesic dome tanks
  • Tanks in heated, ambient, and cooled service

The exact inspection process required for each type may vary depending on its size and construction material.  The inspection primarily focuses on the structural integrity of the storage tank and leaves operational design issues to the customers discretion whenever possible.

The API 653 standard is not an appropriate inspection standard for the following type of tanks:

  • Underground tanks
  • High pressure tanks
  • Mobile storage containers (rail cars, tankers, totes, etc.)
  • Boilers and pressure vessel
  • Elevated tanks such as water towers.

These tanks are covered by different standards from API and other industry trade organizations such as ASME, STI, and AWWA.



API 653 Inspection Process

What does the API 653 inspection process entail?

API 653 inspections involve a thorough examination of the interior and exterior of any tanks along with a foundation evaluation.   The standard requires and recommends several different levels of inspection from routine inspections that can be completed by terminal personnel to more detailed inspections that must be completed by a certified API 653 certified inspector.

While on site the API 653 inspector will take thickness measurements, settlement data, and complete a full visual inspection of the tank.  Detailed checklists are used to ensure all the information required is collected during the on site portion of the inspection.

After completing their on-site  inspection, API 653 inspectors usually issue a field report that identifies potential integrity issues.   This followed up by a detailed formal report with additional calculations and evaluations required by API 653.   While API 653 inspections may require extra time, they can prevent costly repairs down the line while keeping industrial processes running smoothly and safely.



API 653 Inspection Frequency

How often should storage tanks be inspected?

When it comes to storage tanks, internal and external inspections are a necessity. To ensure your tanks are running smoothly and safely, regular inspections should be scheduled each month according to API 653 guidelines. 

With regular inspections, any potential problems can be identified quickly so that necessary action can be taken promptly to avoid any catastrophe or further damage from occurring.   Exact requirements vary based on local government requirements and your company’s record keeping practices and policies.

External API 653 Inspection Frequency

External inspections are an essential component of storage tank maintenance. The inspections must be conducted at a minimum every five years by a licensed API 653 inspector.  With no need for entry into the interior of the tank, this inspection can be completed without disrupting operations.

Internal API Inspection Frequency

Internal inspections are an important part of tank maintenance and play a vital role in prolonging the life of a tank and helping to protect against any form of failure.  Most tanks require an inspection every ten years.  However, the tank’s condition, service, location, and past records can shorten or extend this period between required internal inspection.  This inspection must be completed by a licensed API 653 inspector. 

For most chemical products the tank will need to be removed from service and cleaned for this inspection to be completed to API 653 standards.  However, modern robotic inspection technologies are able to inspect some tanks in-service drastically reducing your project turnaround time.



API 653 Inspector

Why should you use a licensed API 653 inspector?

API 653 inspectors are the best way to ensure that the maintenance, repair, and inspection of API 653 tanks are done properly. Licensed API 653 inspectors have received extensive training in API standards and all related safety requirements, giving them the knowledge necessary to identify potential problems with your  tanks. They can perform thorough inspections of aboveground storage tanks that proactively identify issues before they lead to catastrophic failure or unexpected operational issues.

Employing a licensed API 653 inspector can eliminate many potential risks and help keep your facility in compliance with state and federal requirements.  Using a certified API 653 inspector and qualified inspection company can reduce risk, protect the environment,  improve safety, and help avoid last minute unexpected problems and expenses.



API 653 Repairs

What are API 653 repairs?

In addition to providing detailed inspection requirements the API 653 standard provides detailed requirements for tank repairs, alterations, and reconstructions.  Employing a contract like Concord Tank who is familiar with this standard is an essential part of any tank integrity program guided by the requirements of API 653.

The API 653 standard and its sister document API 650 provide detailed material, weld spacing, weld process, and testing requirements for any repair work.  The standard also provides clear guidelines for when additional engineering design and review is required for your tank repairs.

Repairing your storage tank to the API 653 standard ensures that you avoid catastrophic failures and will greatly reduce the chances of an unexpected failure before the next out of service inspection.

We've Got You Covered

API 653 Tank Inspections


Ensuring the proper inspection and repair of your aboveground storage tanks is a critical step to making sure your business runs smoothly and safely.  

Our experienced team can help you ensure that your tank is inspected and repaired to the requirements of the API 653 standards. Contact us today with your API 653 repair and inspection needs.

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To avoid conflicts of interest with our API 653 repair work, our API 653 certified inspectors only provide limited inspection services.  We are happy to connect you with, coordinate, or subcontract a full-service third-party inspection company if that will simplify your tank project.