Industrial Services

Any industry dealing with Aboveground Storage Tanks must stay in compliance with the inspection standards laid down by the U.S Environment Protection Agency. The EPA is responsible for creating rules for Spill Prevention Control and Countermeasure or SPCC. Further, the Steel Tank Institute released the first edition of the STI inspections standards that guide the aboveground tank owners on how to comply with the EPA mandates. Since its first release in the year 2000, the standards are constantly updated.

In this blog, we answered a few frequently asked questions regarding the updated STI testing standards.

• Why is there a need for internal tank inspection of a shop-fabricated tank if the tank’s inside is not easily accessible?

According to the STI SP001, there is no need to enter into the tank that has the capacity of 30,000 gallons or less. While inspecting such tanks, internal inspections are not mandatory. Other alternative tank testing methods can be used to look for defects or leakage. Similarly, tanks that are larger than 30,000 gallons have dedicated entryway for inspectors to enter into the tank for inspection.

• Is any requirement for the inspection of fiberglass or plastic tanks?

The STI inspection standard revolves around the inspection of field-erected tanks, and stainless steel shop fabricated tanks and welded tanks. The STI standards also have separate provisions for the assessment of portable or small-sized containers. However, the standards do not mention the inspection of fiberglass tanks or shop-fabricate d plastic tanks.

• What are the provisions for UT reading included in the latest edition of the STI inspection standards?

Earlier, there were no provisions for a risk-based approach in STI inspection standards. However, the standard made it mandatory for the inspectors to conduct UT testing on all the tanks. While conducting tests on tanks with specific capacities, one has to run thousands of readings.

In the 3rd and 4th editions of the revised STI inspection standards, much emphasis on a risk-based inspection approach has been given. The standard has mentioned the number of UT readings taken per square foot of tank surface area in the newer edition. However, the standard does not mention the areas for reading.

According to the STI standards, the certified inspector should use his judgment to identify the area where the corrosion is most likely to be present.

• What are the STI inspection standards for insulated tanks?

It is challenging to detect corrosion present underneath the insulated tank. Undetected moisture or water inside the tank can leak to corrosion or contamination of the stored fuel.

According to the STI inspection standards, one must remove the insulation from the area where moisture or mold is most likely to accumulate. Once the insulation is removed, the inspectors can conduct the further examination.

• Who can conduct an STI inspection?

The STI inspection standards clearly describe the two basic types of AST inspections. Monthly inspections can be performed by a qualified inspector hired by the tank owner. On the other hand, certified tank inspectors should perform external and internal checks with appropriate training.…