Aboveground Tanks API Inspection Standards Are Complex

API Sets The Inspection Standard For The Oil & Natural Gas Industry

  1. API 653:  What is API 653?  Learn when it’s needed and what’s involved with an API 653 inspection.
  2. API 653 Inspector – 5 helpful tips in finding an API inspector.
  3. Different standards for shop fabricated tanks- STI inspections, specifically SP001.

Background on API Standards

American Petroleum Institute (API) is an association that promulgates manufacturing standards for oil and natural gas tanks, piping and equipment.  In addition to these standards, API also publishes processes for maintaining equipment and establishes standards for inspections of tanks and piping.

  • Following API protocols saves money: When the API inspection and maintenance protocols are followed, the facility owner can expect to significantly extend the useful life of the equipment.
  • An API inspection can prevent catastrophic failures and oil spills:  In this economy, many facility owners are forced to operate outdated and aging equipment.  A proper API inspection will identify areas of concern and recommend a course of treatment & repair.

API Inspection – Other Types Pertaining To Our Customers’ Industries.

API 570 inspection for pipelines:

  • This section provides the standards for testing, inspecting and monitoring of the integrity of petroleum and chemical pipelines. In practice, the standard is often applied to evaluate any piping system. The goal of the API 570 is to determine whether conditions exist in the piping that could compromise the piping integrity.  API inspection code 570 requires periodic thickness measurements by ultrasonic thickness testing (UTT) to determine the corrosion rate and describes methods for welding and hot tapping.  API 570 also discusses a system for maintaining inspection records.

API inspection 510 for pressure vessels:

  • API 510 inspection code applies to chemical & refining process pressure vessels. The code covers the pressure vessels and the relief devices protecting them. Standards are given for inspection, corrosion and thickness testing. The section also gives a way to calculate the remaining life of the vessel.


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API Inspection Identifies Corrosion In High Risk Areas

  • Fuel by itself does not cause corrosion. Any inspection will identify the areas on the structure with the highest probability of a corrosion issue. When these areas are discovered, any API inspection should focus on these high risk areas first.
  • Water level: If water is present in the tank, the point at which the water is resting is an area where corrosion is likely to occur.
  • API inspections determine the corrosion rate using an ultrasonic thickness (UT) test.  Here’s the process:
    • Determine what the shell thickness was when the tank was built.
    • Identify the current shell thickness using a UT.
    • Compare these two figures against the age of the tank.
    • This will yield the rate of corrosion.
  • After areas of concern are identified, the inspection should determine whether it’s a pit or a corroded area.
    • UT scans are necessary to determine if the area is one random spot of corrosion or an entire area.
    • The API inspection should take into account the surrounding areas that may impact the test.  For example, a radio tower may interfere with a UT scan.
    • If the thickness readings are cut in half in an area, this is a potential sign for a gap in the metal plate not necessarily delamination.  Even if there’s delamination, it doesn’t mean the tank is damaged.
    • If there are manholes, the inspection should concentrate on the thickness manhole’s neck.
    • The biggest concern is after work has been performed on the tank.  If new metals are used in adding components or repairing a tank, you could have galvanic series caused by the dissimilar metals.

Contact one of our specialists to find out what kind of inspection and how often you need one at your facility.