By John Ekhtiar, VP Engineering

I have been getting calls from our sales organizations asking questions such as “What is the Flame Shield Standard?” “Do our tanks meet the standard?” and similar questions. It appears their clients and the Authorities Having Jurisdiction (AHJ) have been asking the same kinds of questions. The reason they are asking these questions is that the specifying engineers and contractors are requiring that the tanks meet the “Flame Shield Standard”.

I thought it would be helpful to members of the ConVault Network, the AHJs, the specifying engineers and customers to write and explain what the “Flame Shield Standard” is, and explain which fire codes accept this standard.

FlameShield

The short answer is that “FlameShield” is not a manufacturing standard, or a testing standard, but rather a trademark used by manufacturers for marketing a non-insulated doublewall steel tank that was originally listed by Southwest Research Institute (SwRI) as a “fire resistant” tank under SwRI 97-04.

None of the current national model fire codes such as National Fire Protection Association (NFPA 1 UFC, NFPA 30 & 30A), Uniform Fire Code (UFC) and International Fire Code (IFC) make any reference to SwRI 97-04. So, where did this standard come from, how was it developed and why do some specifying engineers make reference to it, requiring ASTs to meet this standard’s requirements? 

The following is a review of some standards for shop fabricated ASTs, current national model fire codes’ requirements and which standards meet them.

U.L. 2080 Fire Resistant Tank

In the 2003 editions, NFPA 30 and 30A recognize the UL 2080 Standard as a standard for Fire Resistant tanks. (See sections 4.2.3.1.1(1) in NFPA 30 and sections 3.3.15.2, 4.3.4 and D.1.2.5 in NFPA 30A.) However, when defining Fire Resistant tanks, the 2000 editions of NFPA 30, section 1.6.43.3 and NFPA 30A, section 3.1.19.2 (and prior editions) specified only that Fire-Resistive tanks provide “fire-resistive protection from exposure to a high intensity liquid pool fire”. The codes did not specifically determine the testing requirements and the temperature criteria needed for the fire test to meet the intent of the code. The NFPA code writers left it to the standards developing organizations such as Underwriters Laboratories (UL) to design a standard to satisfy the code’s intentions. In 1997, UL developed the UL 2080 Standard for Fire Resistant tanks to meet the code intent. Among other requirements, UL 2080 Standard for Fire Resistant tanks specifies that the tanks must be tested in a 2000 °F furnace for two hours. The temperature pass/fail criteria for the primary tank after 2 hours of fire test are:

1. The average maximum temperature rise recorded on the primary tank shall not exceed 800 °F and
2. The maximum temperature of any single thermocouple on the tank shall not exceed 1000 °F.

Even though the 2080 Standard for Fire Resistant tanks is inferior to UL 2085 (see criteria below), at least it has some temperature rise limitations and has the option for listing for resistance against vehicle and ballistic impacts.

SwRI 97-04 Fire Resistant Tank

Southwest Research Institute (SwRI) responded to the NFPA needs for a fire resistant tank by developing its SwRI 97-04 Standard for Fire Resistant tanks.>  Although the standard requires a two-hour fire test in a 2000 °F furnace, it has no temperature rise limitation criteria.  It allows the tank to pass the test if the tank itself survives the fire for two hours without falling apart. You may wonder what effect the red-hot tank will have on the product, but the question is not addressed in the criteria.

Another problem that intensifies the deficiency of SwRI 97-04 is the way the fire codes determine the size of a tank to be fire tested. The fire test requires the size of tank to be tested to have the maximum ratio of tank surface area to tank volume.  It so happens that the smallest size tank gives the highest surface area to volume ratio. Therefore, the smallest size tank gets tested.  If the tank with the largest span between tank supports were to be tested, one wonders if it would buckle between the legs due to high temperatures and weakened steel. Furthermore, the tanks are tested empty, so there is no product load/weight to stress the tank during the fire test.

The name FlameShield became synonymous with the SwRI 97-04 Standard because it was originally manufactured under that listing, and was heavily marketed.  However, according to documents on the SwRI website, only two products currently reference 97-04 on their SwRI label: SuperVault MH Tank/Pyrotector, and Pyrotector of Mexico. Tanks labeled FlameShield only state that the tank has been “built in accordance with UL 142 (1994) and complies with the requirements of Sections 2-4.5(a) of NFPA 30A, 1996 edition as a Fire Resistant Tank.”  However, NFPA 30A, 2003 edition (Section 3.3.15.2) defines a Fire Resistant Tank as a tank “…which is listed in accordance with the provisions contained in UL 2080, Standard for Fire Resistant Tanks for Flammable and Combustible Liquids, or an equivalent standard”. SwRI 97-04 does not appear to be an equivalent standard, mainly because it does not contain temperature criteria, as does UL 2080. Nor does FlameShield appear to meet the definition of Fire Resistant Tank according to the 2003 edition of NFPA 30A.

UL 2085 Protected Aboveground Storage Tank

Compare the SwRI 97-04 Standard and FlameShield with the UL 2085 Standard for Protected Aboveground Tanks. Among other requirements, UL 2085 specifies that the tanks must be tested in a 2000 °F furnace for two hours. The temperature pass/fail criteria for the primary tank after 2 hours of fire test are:

1. The average maximum temperature rise recorded on the primary tank shall not exceed 260 °F and
2. The maximum temperature of any single thermocouple on the tank shall not exceed 400 °F.

 The 400 °F temperature limit is based on the auto ignition temperature of Heptane. Heptane is one of the lightest petroleum product components in gasoline. The UL 2085 Standard limits the temperature of the tank after exposure to the 2-hour fire test so that the tank contents should not reach a point to automatically ignite the gasoline component in the tank. 

The UL 2085 Standard also provides criteria for resistance against vehicle impact, ballistic impact and fire hose impact.  It should be noted that UL 2085 is based on criteria designed to both prevent explosion inside the tank due to temperature rise and provide resistance against many kinds of external physical impacts.   

UL 2085 Standard for protected aboveground tanks is the most stringent standard for shop-fabricated atmospheric ASTs. Tanks meeting the requirements of UL 2085 also meet the requirements of UL 2080 and UL 142.  The preferred listing by all current national model fire codes is    UL 2085.  The Uniform Fire Code was the code that originally established the criteria for the protected above-ground tanks in its Appendix A-II-F-1, UFC Standard (79-7).  Underwriters Laboratories designed the UL 2085 Standard to meet the UFC requirements.  Once the standard was established, other fire codes such as the IFC and NFPA in its NFPA 30 & 30A codes made reference to UL 2085 and required the tanks to meet the standard.  NFPA 30, 2003 edition specifically refers to UL 2085 in sections 3.3.41.1.1 and 4.2.3.1.1(1). NFPA 30A, 2003 edition refers to UL 2085 in sections 2.3.3, 3.3.15.4 and 4.3.5. There is no mention or any reference to SwRI Standard 97-04 in any of the current model fire codes.

ConVault tanks are listed under UL 2085 Standard and meet or exceed all protected aboveground tank requirements.

For a better understanding of these standards, please see the following comparison table.