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• July 19, 2022

Are You Inspecting Your Above Ground Storage Tanks as Required by Code?

If you own aboveground storage tanks, you should be aware of your need to inspect them once they are put into use in order to preserve their integrity. Leaks can be prevented, your asset may be preserved, and you can avoid expensive repairs and environmental harm with a strong inspection and maintenance program.

The API 653 Inspection

API 653 inspections are required for aboveground storage tanks that were constructed in accordance with the American Petroleum Institute (API) 650 standard. API 653 is based on the concepts of API 650 for inspection and repair, but it can be used with any steel tank made in accordance with a tank specification. State or local statutes may occasionally impose stricter standards. To ensure adherence to the standards for scheduling and inspections, knowledge of such regulations is required.

A foundation, bottom, shell, structure, roof, attached accessories, and nozzles to the face of the first flange, first threaded connection, or first welding-end connection from the tank are all subject to an API 653 inspection.

How Frequently Should an Aboveground Storage Tank Be Inspected?

The frequency of storage tank inspections must be determined by taking into account a number of parameters. According to API 653, 6.2.1, the full list of variables includes, to name a few, jurisdictional requirements, the type of product being stored, corrosion allowances and prevention systems, the outcomes of visual maintenance checks, and variations in operation modes.

The following inspection intervals apply generally:

• A Routine In-Service Inspection must be carried out each month, during which employees familiar with the facility, the tank, and the properties of the product being stored visually inspect the exterior of the tank.

• Staining: Visually inspect the above-ground storage tank each month for stains that can indicate leaks. Make sure there is no product inside the secondary containment and the spill collection sites.

• Valves: Check the connected piping and valves visually for leaks, cracks, or corrosion.

• Foundation: Check the foundation visually for signs of wear and tear, wash-out, settling, leaks, or other changes since the last inspection. Tanks change with time, therefore it’s critical to document observations to help identify patterns.

• Type and quantity: Keep a record of every product kind and quantity that was put into the tank.

• Internal: Every few years, undertake a visual inspection by opening the tank roof access to check for corrosion, the state of the coatings, and the interior parts.

• An in-service external inspection must be performed every five years.An ultrasonic thickness inspection of the shell is part of this inspection.

• Unless the tank contains safeguards mentioned in API 653 Table 6.1, which extends this initial period, an Internal Inspection must be carried out 10 years following the tank’s original date of in-service.

• The data from the last internal inspection and API 653 procedures to calculate corrosion rates or Risk Based Inspection (RBI) evaluation shall be used to estimate subsequent internal inspection intervals.

You should thoroughly clean the interior of the tank in advance of the internal examination to make it easier to inspect the tank’s internal parts and structure. It means that all products, water, and dirt must be completely removed.