California State Fire Marshal Information Bulletin 14-005 Addendum

Underground Storage Tanks Being Sold as Aboveground Storage Tanks

Issued: January 29, 2015


This Information Bulletin (IB) is an addendum to IB 14-005 regarding the prohibited use of underground storage tanks (UST) as aboveground storage tanks (AST).

Information reported to the Office of the State Fire Marshal indicates that former single wall, steel and fiberglass, USTs are being sold as ASTs for the storage of fuel. This IB has been developed to provide information and notice to consumers when buying ASTs. Aboveground storage tanks should have an Underwriter’s Laboratory (UL) listing plate mounted on the exterior side of the tank that indicates what they have been listed for use as. For example, steel AST will have a UL 142 listing plate; whereas, steel USTs will have a UL 58 listing plate.

Underground storage tanks are not designed to operate as aboveground storage tanks. While in the process of buying or obtaining a used tank, never obtain a tank that has not been approved for aboveground flammable or combustible liquid storage. Refer to the Information Bulletin 14-005 for California Fire Code and National Fire Protection Association specifications and for more detailed information.

Identifying factors that an AST may have been an UST include, but are not limited to, the following:

  • The tanks are usually a large volume (greater than 1,100 gallons) tank and will not have a mounted UL listing plate on the tank.
  • If there is a mounted UL plate, check the listing number on the plate (see above).
  • Pitting on the external side of the entire shell of the tank, which indicates soil and rock contact while in use as an UST.  
  • Corrosion, which at times, will appear as “worm like” tunneling marks. This corrosion occurred when the tank was utilized underground. This is usually an indicator of a weak area within the steel shell. These marks can still be seen under a new coat of paint.
  • Check for new or field fabricated welding marks on the entire tank, including the top and side shell walls. For example, some of these tanks have been cut down to make into smaller tanks. The bulkheads of the tank are completely removed. After the desired tank size is achieved, the same bulkheads are welded back onto the tank.
  • If in doubt, it may be good practice to check with a Professional Engineer (PE) for certification of the tank you plan to purchase. The PE will aid in checking for various indicators on the tank, such as the size ratio of the emergency vent (if there is one) with the size of the tank.


  • NONE – There are no specific exemptions for using an AST from a recycled UST. The California Fire Code contains provisions for Alternate Means and Methods which are subject to approval by the enforcing agency.



Please contact your local fire department and other enforcing agencies for additional guidance and information.

The following information relating to these tanks, as well as the IB 14-005, can be found in the article below.

UL 142 Aboveground Flammable Liquid Tanks, Ten things to know about these Listed products -

Questions or comments regarding this Information Bulletin should be directed to Senior Environmental Scientist Denise Gibson, Code Development and Analysis Division at (916) 445-8289, or by electronic mail to



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