What Is UL 1316 ?

October 28, 2022 · English

UL 1316
Glass-Fiber-Reinforced Plastic Underground Storage Tanks for Petroleum Products, Alcohols, and Alcohol-Gasoline Mixtures

First published in July 1983, UL 1316 covers both single- and double-wall FRP tanks. It addresses safety issues regarding protection from leakage; buckling due to external pressure; the ability of the tank to withstand internal pressures that may develop in the tank during testing; and the compatibility of the materials with the intended fluids and ground soil conditions.

The Standard requirements include the location of openings and minimum vent size. The test program includes the following:

1. Leakage test—The tank is pressurized and checked for leaks.

2. Strength-of-pipe fittings tests
• Torque—A length of pipe is threaded into fittings for pipe connections and a torque is applied based on the thread size. The fitting shall not crack or split, and the threads shall not strip.
• Bending Moment—A length of schedule 40 steel pipe is threaded into the fitting and a force is applied perpendicu-lar to the pipe axis. The fitting and the tank shall not be damaged.
• Leakage—After each of the above tests, the tank and fit-tings shall not leak when subjected to the leakage test.

3. Strength-of-lifting fittings test—A lift fitting shall be sub-jected to a load equal to twice the weight of the empty tank. Neither the fitting nor the tank shall be damaged. The tank is subjected to the leakage test after this test is conducted.

4. Water-load test—The tank shall be placed in a sand bed so that one-eighth of the tank is buried and then filled with water. The tank shall not be damaged.

5. External pressure test—The tank is placed in a pit and back-filled according to the manufacturer’s instructions. The pit is then filled with water so that the tank is submerged to its max-imum burial depth. The tank is to remain submerged for 24 hours. Then, while still submerged, the tank is subjected to an internal vacuum. The tank shall not be damaged or implode.

6. Internal pressure test—A tank shall withstand without rup-ture an internal pressure test for one minute. The test pres-sure is 25 psi for tanks with diameter of 10 feet or less and 15 psi for tanks greater than ten feet in diameter.

7. Physical properties of materials tests— Coupons cut from the tank shall be subjected to air oven aging, immersion in liquids representing the actual product, and immersion in liquids representing outside soil. A coupon is a sample cut from the nonmetallic tank that is as flat as possible. Coupons are used for conducting physical tests on the materials both before and after conditioning (again, fluid immersions and light and water exposure). The physical tests include tensile strength, Izod impact, cold impact and flexural strength tests. Physical tests conducted after the conditioning will be com-pared to results of tests conducted on “as received” coupons.

• Impact and cold exposures—Coupons are subjected to impact from a steel ball dropped from a height of six feet at both room temperature and at -29 degrees C. The coupons shall not crack or rupture, but surface crazing is permitted.
• Light and water exposure—Coupons shall maintain at least 80% of their “as received” properties after 180 and 360 hours of light and water exposure. The test is con-ducted according to ASTM G23-90.

8. Earth-load test—The tank shall not implode or be otherwise damaged during this test. The tank is installed in a pit and backfilled according to the manufacturer’s installation instruc-tions. The tank is to be covered so that it is 3 feet below the surface of the fill, and the tank shall remain buried for one hour. After this test, the tank is subjected to the leakage test.

9. Annulus proof-pressure test—The annulus of a double-wall tank is to be subjected to its maximum rated pressure or vacuum for 24 hours. For a positive pressure tank, the annu-lus pressure is then increased to twice the rated value for one minute. For a negative pressure tank, the annulus vacuum is then increased by 5.3 inches of mercury and held for one minute. There shall be no rupture of the tank.

As part of normal production, each tank shall be subjected to the leakage test, an internal vacuum test and a surface cure test. The surface cure test verifies that the hardness of the lam-inate is within the resin manufacturer’s specified tolerances.

Conclusion

It is important to note UL’s standard development process gives interested parties the chance to comment before a new or revised standard becomes final. Interested parties include manu-facturers and trade associations, such as the Steel Tank Institute, the Petroleum Equipment Institute, the Fiberglass Tank & Pipe Institute, NFPA and building code officials, just to name a few.

Working with these interested parties helps UL to develop stan-dards that are practical for manufacturers, compatible with other standards and installation codes and effective in addressing public safety issues. UL also works with standards writing and certifica-tion organizations in other counties to harmonize requirements.

What is UL 1316?

September 9, 2021 · English

UL 1316 is the UL standard for Glass-Fiber-Reinforced Plastic (FRP) Underground Storage Tanks for petroleum products, alcohols, and alcohol-gasoline mixtures. First published in July 1983, it covers both single-wall and double-wall FRP tanks, addressing safety requirements for leakage protection, structural integrity under external pressure, internal pressure resistance, and material compatibility with stored fluids and soil conditions.

What Does UL 1316 Cover?

UL 1316 applies to non-metallic (FRP/fiberglass) underground storage tanks intended for:

Petroleum products (gasoline, diesel, oil)
Alcohols and ethanol blends
Alcohol-gasoline mixtures (up to E85)
Both single-wall and double-wall tank designs

Key Specifications at a Glance

Parameter	Requirement
Standard Title	Glass-Fiber-Reinforced Plastic Underground Storage Tanks
First Published	July 1983
Tank Types	Single-wall and double-wall
Internal Pressure (≤10 ft dia)	25 psi for 1 minute
Internal Pressure (>10 ft dia)	15 psi for 1 minute
External Pressure	Submerged to max burial depth + internal vacuum for 24 hours
Impact Test	6 ft steel ball drop at room temp and -29°C
Light/Water Exposure	≥80% property retention after 360 hours (ASTM G23-90)
Burial Depth	3 feet minimum cover for earth-load test

UL 1316 Required Tests (Complete Checklist)

Every UL 1316 certified tank must pass the following 9-test program:

1. Leakage Test

The tank is pressurized and checked for leaks. This is the baseline test repeated after other tests.

2. Strength-of-Pipe Fittings Tests

Torque test: Pipe threaded into fittings — fitting must not crack or strip threads
Bending moment test: Force applied perpendicular to pipe axis — fitting and tank must not be damaged
Leakage test repeated after each sub-test

3. Strength-of-Lifting Fittings Test

Lift fitting subjected to 2× the empty tank weight. Neither fitting nor tank shall be damaged.

4. Water-Load Test

Tank placed in sand bed with 1/8th burial, then filled with water. No damage permitted.

5. External Pressure Test

Tank buried to maximum depth and submerged in water for 24 hours, then subjected to internal vacuum while still submerged. No damage or implosion permitted.

6. Internal Pressure Test

Tank must withstand internal pressure for 1 minute: 25 psi (≤10 ft diameter) or 15 psi (>10 ft diameter).

7. Physical Properties of Materials Tests

Coupons cut from the tank undergo:

Air oven aging
Fluid immersion (representing stored product)
Soil liquid immersion (representing outside soil conditions)
Impact and cold exposure: Steel ball drop from 6 ft at room temp and -29°C. No cracking or rupture (surface crazing allowed)
Light and water exposure: ≥80% property retention after 180/360 hours per ASTM G23-90

Tested properties: tensile strength, Izod impact, cold impact, and flexural strength — compared before and after conditioning.

8. Earth-Load Test

Tank buried under 3 ft of fill for 1 hour per manufacturer’s installation instructions. No implosion or damage permitted.

9. Annulus Proof-Pressure Test (Double-Wall Tanks)

The annulus (interstitial space) of double-wall tanks undergoes:

Positive pressure tanks: Max rated pressure for 24 hours, then 2× rated pressure for 1 minute
Negative pressure tanks: Max vacuum for 24 hours, then increased by 5.3 inHg for 1 minute
No rupture permitted

Production Quality Control

As part of normal production, every tank must undergo:

Leakage test
Internal vacuum test
Surface cure test (verifying laminate hardness within resin manufacturer’s tolerances)

Why UL 1316 Matters for Your Project

UL 1316 certification is critical for:

Gas station owners: Required by most U.S. jurisdictions for underground fuel storage
Environmental compliance: Double-wall tanks with annulus monitoring provide leak detection required by EPA 40 CFR 280
Insurance requirements: Many insurers require UL-listed tanks for coverage
Longevity: FRP tanks certified to UL 1316 resist corrosion indefinitely — no sacrificial anodes or cathodic protection needed

IFGS and UL 1316 Certified Tanks

IFGS manufactures FRP underground storage tanks that meet or exceed UL 1316 requirements. Our tanks are built with:

ISO 9001 certified manufacturing process
Custom sizes and configurations available (up to 35,000 m³ capacity)
Double-wall designs with integrated leak detection systems
Global shipping with installation supervision available

Note: UL’s standard development process allows interested parties — manufacturers, trade associations (Steel Tank Institute, Petroleum Equipment Institute, Fiberglass Tank & Pipe Institute), NFPA, and code officials — to review and comment before new or revised standards become final. UL also collaborates with international standards organizations to harmonize requirements.

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