Technology
corner

A Roadmap of AST Codes and Standards

Audio version
Posted / Last update: 01-01-1997
Publication: Petroleum Equipment & Technology Archive
Issued: January 1997
Author: Geyer Wayne B. , PE, POE

What you don’t know can hurt you

AST codes and standards can make or break an AST purchase. Wayne B. Geyer reports on the major code requirements that impact AST purchasing decisions, and tells PE&T readers how to determine out which ones could apply to them.

 

Imagine spending thousands of dollars on an aboveground storage (AST) system, and finding out too late that you can’t install it because of certain local fire regulations. Could this nightmare come true? The answer is “yes.” The old saying “What you don’t know won’t hurt you” is completely untrue about many things, including AST codes and standards.

In order to make informed decisions, tank buyers, engineers, architects and local fire marshals need to familiarize themselves with the evolving technology of ASTs, as well as the various national, state and local fire codes that govern AST installation. Such an understanding will dictate whether a tank can, or should, be installed underground or aboveground.

In the Nov./Dec. issue, I discussed AST technology (“AST Fuel Dispensing Systems Today”). In this article I will discuss code organizations and their requirements for the installation of AST systems as the subject affects our industry, and thus our wallets.

An explosive subject
Fire prevention authorities contend that storing large quantities of flammable and combustible liquids in ASTs carries more risk than storing these liquids in underground tanks, since ASTs are more accessible to the public than USTs. This concern has been the impetus for many codes for ASTs and AST fuel dispensing systems.

Hard experience, however, does not entirely bear out this concern, particularly in terms of shop fabricated (less than 50,000 gallon) ASTs. It has been nearly 30 years since the last recorded US fatalities occurred from an AST fuel dispensing system fire caused by a shop-fabricated AST. On July 31, 1968, an explosion of a 10,000 gallon aboveground gasoline tank caused three deaths in Kennedale, Texas. The AST was a factory built skid tank, common at self-service stations of the time, with a baffle in the tank, dividing it into two compartments: 7,000 gallons at one end and 3,000 gallons at the opposite end. The tank had one two-inch vent, which should have been at least four inches to handle any discharge overflow, and no emergency vent. (Over pressurization will not occur if it has a properly installed and maintained emergency vent.)

Large AST process pressure vessels pose more of a threat than factory made ASTs, because of their larger size and pressurized containment. However, there is always a greater potential for risk with any ASTs because, in most cases (except with vaulted tanks), the tanks are out in the open. Therefore, fire codes seek to reduce the possibility of hazardous or catastrophic incidents. System fleet fueling applications, for example, place perhaps hundreds of people near an AST.

Major players
In the March/April 1996 issue of PE&T, columnist Marshall Klein looked at the major code options for ASTs. He notes:

  “There are four national codes enforced in different parts of the United States—three of them model fire codes (see Table): the Standard Fire Prevention Code (SFC); the BOCA National Fire Prevention Code (BOCA); and the Uniform Fire Code (UFC). The fourth code is the National Fire Protection Association’s Automotive & Marine Service Station Code (NFPA 30A).”

Taken out of context, Marshall’s statement might seem to indicate that by looking at a map of the United States, you will be able to determine which state is regulated by which code. However, this is hardly the case. For instance, in Texas, where some big cities have adopted UFC (the Uniform Fire Code); some small cities have adopted SBCCI (the Southern Building Code Congress International); and rural areas often use NFPA (the National Fire Protection Association). See Marshall Klein’s table above for AST options for service stations.

Here is a brief description of the four national code organizations that provide AST codes:

• The National Fire Protection Association (NFPA) oversees two of the more widely known codes for ASTs. The NFPA 30 Code is the Flammable and Combustible Liquids Code. The NFPA 30A code is the Automotive and Marine Service Station Code, for the dispensing of motor fuels for vehicles at service stations. Both codes refer to a number of construction and installation standards, such as those developed by Underwriters Laboratories (UL), the Steel Tank Institute (STI), the Petroleum Equipment Institute (PEI) and the American Petroleum Institute (API). NFPA 30 and 30A are predominantly used in the midwest and eastern US, yet are often referenced overseas as well.   

NFPA has a different structure than other model code organizations, which permit only code officials and enforcers to vote upon changes in codes. Instead, NFPA uses consensus committees to develop codes, and no more than one-third of any single interest group is allowed to vote. These interest groups—which include manufacturers, fire enforcers, insurance representatives, engineers and end users—provide a balance to the code process.

• The Uniform Fire Code, published by the International Fire Code Institute (IFCI), is predominant in the western half of the US. Until recently, the UFC prohibited aboveground tanks at any type of service station, whether a fleet or a retail operation. In 1991, the IFCI changed this rule by adopting Appendix II-F, which provides requirements for any type of aboveground fueling facility and in 1994, Appendix A-II-F-1, the testing requirements for protected tanks. The rule required all tanks to be secondarily contained and to have two hour fire ratings. Qualification requirements of this tank were added to another appendix and eventually formed the basis of a portion of UL 2085, Insulated Aboveground Tanks for Flammable and Combustible Liquids.   

The UFC held a hearing in December 1996. Its committee will recommend to the IFCI membership that:

 1. Appendix II-F be incorporated into the main body of the UFC code.
 2. UL 2085 be added as an approved standard.
 3. Emergency venting be required for all confined/enclosed spaces.
 4. An exception be allowed for diking of ASTs with “listed” integral secondary containment.

• ASTs are also regulated by the National Fire Prevention Code for the Building Officials and Code Administrators (BOCA). Chapter 23 applies to the storage, handling and processing of all hazardous liquids, while Chapter 32 contains flammable and combustible liquid requirements. BOCA oversees many of the building codes in the US.

• Yet another code-making body is the Southern Building Code Congress International (SBCCI). In 1994, the SBCCI adopted NFPA 30A nearly verbatim for its fuel dispensing requirements at non-retail facilities throughout the Standard Fire Prevention Code. Like BOCA, SBCCI oversees many US building codes.

Normally, national model fire codes (UFC, BOCA, SFPC) are revised to a minor extent every year, and these revisions are published in annual supplements. The local Authority Having Jurisdiction (AHJ) must then decide whether to incorporate these revisions into their existing codes. The model fire code agencies will typically publish the entire code every three years, as does NFPA.

Service Station Layout: Minimum Property Size
UL 2085

This figure illustrates the minimum property size for 3/6000 fire resistant or vaulted tanks with dispensers mounted atop tanks.

 

 

 

UL 2085
Minimum property size  
130 feet by 230 feet = 15,080 square feet = 0.35 acres

Post a comment

Please login or register to post comments.

Subscribe for weekly newsletter