A New Underwriters Laboratory (UL) Listing Service covers entire aboveground storage tank systems.

Oil Storage Tank Standards for Tank Construction & Tank Testing

Subject 2244, Aboveground Flammable Liquid Tank Systems

For years, factory-fabricated aboveground liquid storage tanks such as those used to store home heating oil were shipped to job sites where dispensers, flame arrestors, vents and other accessories were added. Installers verified that the proper components were selected for compliance with fire and environmental codes.

[Click to enlarge any image]

Unfortunately, code authorities still might find that requirements were not met. Sketch of an above ground outdoor oil storage tank is courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

During the past five years, manufacturers have introduced complete aboveground storage tank (AST) systems with related accessories, such as dispensers, siphon valves, overfill protection systems and emergency venting devices, installed on the tank at the factory.

Authorities Having Jurisdiction (AHJs) and manufacturers have requested that UL investigate entire factory-fabricated AST systems, to streamline the field-approval process and minimize problems associated with incompatible tank accessories.

UL has established a new product category and continues outlining requirements for Subject 2244, Aboveground Flammable Liquid Tank Systems. UL has already completed its first product Listings to Subject 2244, and work on a proposed Standard was expected to begin in 1998.

Subject 2244 identifies four AST installations: aviation-fuel storage, motor-vehicle fuel dispensing, motor-oil storage, and generator-base tank systems.

AST systems include a primary tank with integral secondary containment, provided by a double-wall tank or an integral tank and dike. Required and optional components are assembled prior to shipping.

However, some components may require limited field assembly detailed in the installation instructions provided with each AST system.Sketch of an indoor above ground oil storage tank is courtesy of Carson Dunlop Associates, a Toronto home inspection, education & report writing tool company [ carsondunlop.com ].

To assist code authorities in facilitating the field evaluation process, UL has developed a Code Compliance Verification List (CCVL) for UL Listed AST systems.

The CCVL documents how the tank complies with U.S. model codes, including National Fire Protection Association (NFPA) 30, Flammable and Combustible Liquids, and NFPA 30A, Automotive and Marine Service Stations, and the Uniform Fire Code (UFC). The CCVI, is included with UL Listed AST systems, and will be provided in the guide card information for Aboveground Flammable Liquid Tanks (ECRU) in the 1998 edition of ULs Gas and Oil Directory (gray book).

The CCVL identifies the model code requirements for AST installations, including: supports, venting, piping and fittings, tank construction and openings, electrical installations, spill-control dispensers, and other accessories. The CCVL also documents installed components, including manufacturers' names, model numbers, ratings and UL Listing information.

For example, motor-vehicle fuel-dispensing tank systems have requirements for sizing emergency vents in accordance with the exposed side walls and top of tank. The CCVL documents the required emergency venting for the tank, and identifies that the appropriately sized UL Listed emergency vent was installed.

The UL Listing markings on a tank system will identify the primary tank construction, For example, UL 142 and Subject 2244 indicate a steel tank; UL 2085 and Subject 2244 indicate a protected-tank system.

UL markings affixed to ASTs that have been evaluated to Subject 2244 will also include the AST system type, such as motor-vehicle fuel dispensing, generator-base, aviation-fuel storage and motor-oil storage.

For more information regarding UL requirements for aboveground flammable liquid tank systems, contact UL engineer Shari Duzac in Santa Clara, Calif., by telephone at (408) 985-2400, ext. 32550; by fax at (408) 556-6036; or by e-mail at duzacs@ul.com.

Source: The Code Authority, Underwriters Laboratories -- December 1997

UL-142 Standard as Amended in July 1998

UL-142 oil storage tank standard Amendment 1 1998 - Steel Aboveground Tanks for Flammable and Combustible Liquids, 7th Ed, was released on 22 July 1998 and replaced or amended older versions of UL Standard 142. UL's comments about the new standard included these remarks:

These requirements cover steel atmospheric tanks intended for aboveground storage of noncorrosive, stable flammable, and combustible liquids that have a specific gravity not exceeding that of water.

These tanks are intended for installation and use in accordance with the Flammable and Combustible Liquids Code, NFPA 30; the Standard for Installation of Oil Burning Equipment, NFPA 31; and the Automotive and Marine Service Station Code, NFPA 30A.

Tanks covered by these requirements are fabricated, inspected and tested for leakage before shipment from the factory as completely assembled vessels.

These requirements do not cover seismic loading.

Geometries or special constructions not specifically covered in these requirements shall be investigated on an individual basis.

A product that contains features, characteristics, components, materials, or systems new or different from those in use when the Standard was developed, and that involves a risk of fire, electric shock, or injury to persons, shall be evaluated using the appropriate additional component and end-product requirements as determined necessary to mai ntain the level of safety for the user of the product as originally anticipated by the intent of this Standard.

Pressure Testing Guidelines for Oil Storage Tanks

UL-142 oil storage tank standard calls for pressure testing oil storage tanks (that fall under this standard) at 3-5 psi for cylindrical oil storage tanks.

UL-142 calls for pressure testing oil storage tanks (that fall under this standard) at 1.5-2 psi for rectangular welded-construction storage tanks.

Bench top above ground storage tanks for flammable and combustible liquids (Standard UL 142) also must meet NFPA setions 30, 30A, 31 and the Uniform Fire Code UFC Article 79. These benchtop atmospheric tanks are typically tested to 1 psi but may have to have passed a design hydrostatic pressure tes of 25 psi.

Other types of tanks such as double wall generator base tanks might be tested to 25 psi and at four times load pressure test.

These complete text of these oil storage tank codes and standards are available from UL, NFPA, and ASTM directly.

Oil Tank Construction and Testing Standards

UL-142 Standard for Steel Aboveground Tanks for Flammable and Combustible Liquids

This standard whose roots date to 1922, covers steel atmospheric pressure tanks used above ground to store non-corrosive, stable flammable, and combustible liquids which are no more dense than water. For example this would include No2. heating oil used at residential properties.

These tanks are required to be installed in accordance with:

• NFPA 30 - the Flammable and Combustible Liquids Code
• NFPA-31 - the Standard for Installation of Oil-Burning Equipment
• NFPA 30A - the Motor Fuel Dispensing Facilities and Repair garages code
• The Uniform Fire Code - published by IFCI the International Fire Code Institute

These complete text of these oil storage tank codes and standards are available from UL, NFPA, and ASTM directly.

Other tank codes that do not pertain to oil tanks built to UL-142 include:

• Seismic loading effects on oil storage tanks are not considered by UL-142
• Specially-constructed oil storage tanks are not considered by UL-142
• API-650 - standard for Welded Steel Tanks for Oil Storage
• API-12D - Specification for Field-Welded Tanks for Storage of Production Liquids
• API-12F - Specification for Shop-Welded Tanks for Storage of Production Liquids

U.S. Environmental Protection Agency EPA Underground Oil Storage Tank Regulations include - Complete 40 CFR part 280 Technical Standards and Corrective Action Requirements for Owners and Operators of Underground Storage Tanks (UST) (454K byte PDF). This document defines dielectric material (coatings) used to protect underground oil storage tanks from corrosion:

More about the galvanic scale and corrosion between dissimilar metals is at GALVANIC SCALE & METAL CORROSION.

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Continue reading at OIL TANK CODES & STANDARDS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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