Understanding the requirement for Tank Inspections According to the STI SP001

Did you know? According to the EPA portal, around 14,000 oil spills happen each year. In the United States, there are approximately 618,000 establishments controlled by the EPA SPCC. Additionally, there are more authorized aboveground storage tanks than subterranean storage tanks. Ninety percent of the total tank units in service are tanks under 300,000 gallons.

Since the mid-1960s, STI predicts that up to 4 million shop-fabricated oil storage facilities have been constructed. It’s hard to say how many of these containers are still in operation today, but based on anecdotal data, tanks are frequently utilized for four decades or more.

It’s no surprise that the Steel Tank Institute/Steel Plate Fabricators Association (STI/SPFA) is constantly reviewing and updating regulations, researching new technologies, and providing public and industry experts with knowledge and awareness about STI inspections. STI/SPFA is a trade group that represents steel construction product manufacturers and their vendors. Steel storages, field-erected water tanks, containers, and heat exchangers, and pipes and pipelines are all manufactured by member businesses. The petrochemical, power generating, food, pharmacy, fuels, sewage, and water transport sectors are among its clients.


The Spill Prevention, Control, and Countermeasure (SPCC) Rule was first issued by the United States Environmental Protection Agency (EPA) in 1973, mandating specified non-transportation establishments to design and execute an SPCC Plan. The SPCC regulation’s goal is to prevent oil from entering navigable waterways in the United States. The SPCC Plan for a facility explains the preventative measures put in place to keep a spill at the plant confined. It also explains how to prevent a spill from accessing navigable waterways in the case of a leak.

Suppose a facility has an elevated rail oil storage space of more than 1,320 gallons or a buried subterranean oil storage capacity of more than 42,000 gallons. In that case, it must have a Spill Plan certified by a registered Professional Engineer.

In 2002, the EPA formally revised the SPCC Rule to make it primarily performance-based after numerous interim revisions. Following that, the EPA released the Final Revised SPCC Rule, which governs the storage and management of gasoline and non-petroleum oils (40 CFR Part 112).

Facilities affected: This Rule applies to a wide range of facilities that hold oil in various types and sizes of containers. Facilities having a total aboveground (i.e., not entirely underground) oil storage potential of more than 1,320 gallons are impacted. Tanks of oil, both petroleum and non-petroleum, with a volume of 55 gallons or more must be considered when calculating a facility’s overall oil storage capacity. Before 2002, the lowest container eligible for inclusion in a facility’s total oil capacity was 660 gallons.

Importance of Industry Standards

Only the American Petroleum Institute (API) Standard 653, “Tank Inspection, Repair, Alteration, and Reconstruction,” included terrestrial storage tank examination standards prior to 2000. Massive, field-erected tanks manufactured to API Standard 650 are the emphasis of API 653. API 650 contains formulae for determining the steel thickness required for a certain tank. The pressure faced, the quality steel and weld joints utilized, and the weld maintenance tests performed are all factored into these calculations. Because of the huge volumes and hydrostatic pressures experienced in these bigger tanks, API 653 has stringent criteria.

In the year 2000, STI/SPFA published the first version of Standard SP001. STI/SPFA employed a consensus procedure further to amend SP001 with the help of the EPA. Participants from significant oil corporations, petroleum marketers, federal and state governing authorities, tank manufacturers, examiners, and tank vendors served on the team that established the 3rd Edition and future versions of STI SP001.

Inspection criteria for forged metal, shop-fabricated, and compact field-erected containers are included in SP001. Examination of smaller, transportable containers, such as 55-gallon barrels, medium bulk cartons, and other containers of plastic or metal composition, is also covered.