1 Scope
NOTE This standard governs the procurement, fabrication, and installation of factory-built liquid fuel storage tanks and their integral appurtenances. (1.1)
NOTE The vessel, its integral secondary containment, overfill prevention, venting, leak detection, gauging, anchorage, cathodic protection (underground), and vessel pressure/leak testing are covered. The scope ends at the tank nozzle connections. (1.2)
NOTE Aboveground storage tanks (ASTs) listed to UL 142, UL 2080, or UL 2085, underground storage tanks (USTs) listed to UL 58 or UL 1316, sub-base (belly) tanks integral to packaged generator sets, and day/auxiliary tanks are included. (1.3)
NOTE Applicable project types are new construction and tank-replacement work for emergency generator plants, fuel-oil boiler plants, fleet fueling, industrial and process facilities, and data centers. (1.4)
NOTE Fuel-oil transfer pumps, supply and return piping, fuel polishing systems, and system-level controls are covered by
Fuel Oil Systems, which owns the complete fuel-oil system from the tank fill connection to the prime mover.
(1.5) NOTE Generator engine, alternator, controls, and exhaust are covered by
Generators; a sub-base tank factory-assembled as an integral part of a UL 2200-listed generator unit is selected under that standard, but the tank listing requirements of this standard still apply to it.
(1.6) NOTE Natural gas and LP/propane interior distribution piping is covered by
Fuel Gas Piping. Gasoline and aviation fuel retail dispensing stations, bulk propane siting per NFPA 58, and oil/water separator, process chemical, or water storage tanks are outside this scope.
(1.7) 1.8The Contractor shall coordinate the division of work between the tank vessel furnished under this standard and the fuel-system piping, pumps, and controls furnished under Fuel Oil Systems so that no interface item is left un-bid. 2 Referenced Standards
2.1Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
| Standard |
Title |
| NFPA 30 |
Flammable and Combustible Liquids Code |
| NFPA 30A |
Code for Motor Fuel Dispensing Facilities and Repair Garages |
| NFPA 37 |
Installation and Use of Stationary Combustion Engines and Gas Turbines |
| NFPA 110 |
Emergency and Standby Power Systems |
| UL 142 |
Steel Aboveground Tanks for Flammable and Combustible Liquids |
| UL 2080 |
Fire Resistant Tanks for Flammable and Combustible Liquids |
| UL 2085 |
Protected Aboveground Tanks for Flammable and Combustible Liquids |
| UL 58 |
Steel Underground Tanks for Flammable and Combustible Liquids |
| UL 1316 |
Glass-Fiber-Reinforced Plastic Underground Storage Tanks for Petroleum Products |
| UL 1746 |
External Corrosion Protection Systems for Steel Underground Storage Tanks |
| UL 2200 |
Stationary Engine Generator Assemblies |
| 40 CFR Part 280 |
Technical Standards for Owners and Operators of Underground Storage Tanks |
| 40 CFR Part 112 |
Oil Pollution Prevention (SPCC Rule) |
| IFC |
International Fire Code (Chapter 57) |
| API Std 2000 |
Venting Atmospheric and Low-Pressure Storage Tanks |
| PEI RP200 |
Installation of Aboveground Storage Systems for Motor Vehicle Fueling |
| ASTM D975 |
Standard Specification for Diesel Fuel Oils |
| ASCE 7 |
Minimum Design Loads and Associated Criteria for Buildings and Other Structures |
| NACE SP0169 |
Control of External Corrosion on Underground or Submerged Metallic Piping Systems |
| NACE SP0285 |
External Corrosion Control of Underground Storage Tank Systems by Cathodic Protection |
3 Submittals
3.1 Action Submittals
3.1.1The Contractor shall submit the following action submittals for review before fabrication:
- Product data for the tank, including the UL listing standard, listing mark, and listing file number.
- Shop drawings showing tank dimensions, nozzle schedule, lifting lugs, saddle or skid locations, and containment construction.
- Capacity calculation showing nominal, usable, and required runtime volumes with the served equipment fuel consumption rate.
- Secondary containment design showing interstitial space or dike volume against the 110% requirement.
- Vent sizing calculation for normal and emergency venting per API 2000 and NFPA 30.
- Anchorage and seismic restraint calculations, PE-stamped where required by ASCE 7.
- Buoyancy calculation and holddown design for underground tanks.
- Cathodic protection design for steel underground tanks.
- Fuel-material compatibility statement for the specified fuel grade and biodiesel blend.
☑ Tank product data and UL listing
☑ Shop drawings (dimensions, nozzles, lifting)
☑ Capacity / runtime calculation
☑ Secondary containment volume calculation
☑ Vent sizing calculation (normal + emergency)
☑ Anchorage / seismic calculations
☐ Buoyancy / holddown design (USTs)
☐ Cathodic protection design (steel USTs)
☐ Fuel compatibility statement
3.2.1The Contractor shall submit the following informational submittals:
- Manufacturer factory pressure-test certificate for the vessel.
- Mill certificates for tank steel or resin certifications for fiberglass tanks.
- Welder qualifications and welding procedure specifications.
- Interstitial monitoring sensor product data and wiring interface documentation.
☑ Factory pressure-test certificate
☑ Mill / resin certifications
☐ Welder qualifications and WPS
☑ Leak-detection sensor data and wiring interface
3.3 Closeout Submittals
3.3.1The Contractor shall submit the following closeout submittals:
- Field acceptance test reports for the vessel and secondary containment.
- State UST registration confirmation, where applicable.
- SPCC Plan documentation or confirmation that the site is below threshold.
- Operation and maintenance manuals, including fuel-management and microbial-control guidance.
- Cathodic protection commissioning report with potential readings.
☑ Field acceptance test reports
☐ State UST registration confirmation
☐ SPCC Plan documentation / below-threshold confirmation
☑ Operation and maintenance manuals
☐ Cathodic protection commissioning report
4 Quality Assurance
NOTE The tank shall bear the listing mark of a Nationally Recognized Testing Laboratory for the applicable UL standard. (4.1)
NOTE A listing mark is the AHJ's primary evidence that the tank meets the construction, containment, and where applicable fire-rating requirements of the adopted code; an unlisted vessel cannot be permitted for combustible-liquid service. (4.2)
4.3The tank manufacturer shall be a firm regularly engaged in the fabrication of listed fuel storage tanks of the type and capacity specified.
4.4Welding of steel tanks shall be performed by welders qualified under a written welding procedure specification.
NOTE The selected UL listing standard shall be confirmed with the Authority Having Jurisdiction before procurement. (4.5)
NOTE UL 142 is adequate for many exterior ASTs, but local fire codes and occupancy type may mandate the 2-hour fire-rated UL 2085; confirming the requirement with the AHJ before purchase avoids costly field re-specification of an already-fabricated tank. (4.6)
5 Regulatory and Environmental Compliance
5.1The aggregate aboveground and underground oil storage volume on the site shall be summed across all oil-containing vessels, including generator sub-base tanks, to determine SPCC and registration applicability.
NOTE The Spill Prevention, Control, and Countermeasure (SPCC) Rule applies when aggregate aboveground oil storage exceeds 1,320 gallons or aggregate underground oil storage exceeds 42,000 gallons. A frequent omission is failing to count multiple generator sub-base tanks, which together commonly exceed the aboveground threshold on a multi-generator plant. (5.2)
5.3A facility that meets the SPCC threshold shall have an SPCC Plan prepared and certified before the tanks are placed in service.
5.4State UST registration shall be obtained before any underground tank is backfilled.
NOTE State UST programs authorized under RCRA Subtitle I require registration prior to burial; backfilling before the permit is issued can force mandatory excavation in some jurisdictions. (5.5)
5.6Underground tanks installed or replaced after April 11, 2016 shall provide secondary containment with interstitial monitoring per 40 CFR 280.
NOTE Carrying forward a pre-2016 single-wall UST specification on a replacement project is a common error; the federal rule now requires double-wall construction with interstitial monitoring for new and replacement underground tanks. (5.7)
6 Tank Selection and Configuration
6.1 Location and Listing
NOTE Aboveground tanks (ASTs) avoid excavation, buoyancy, and corrosion concerns and simplify leak detection and inspection, but consume site area and are subject to fire-code setbacks. Underground tanks (USTs) free the site surface and reduce fire exposure but add excavation, buoyancy, corrosion, and registration obligations. The choice is driven by available area, setbacks, soil and water-table conditions, and zoning or visual constraints. (6.1.1)
● Aboveground (AST)
○ Underground (UST)
NOTE The fire-protection listing class is driven by the IFC occupancy, AHJ requirements, and the tank's proximity to occupied structures or high-exposure locations. UL 142 is the standard steel AST; UL 2080 adds a fire-resistant rating; UL 2085 adds a full 2-hour fire endurance plus vehicle-impact resistance and is often required where a tank is in or near an occupied building. (6.1.2)
● UL 142 (standard steel AST)
○ UL 2080 (fire-resistant)
○ UL 2085 (protected, 2-hour fire-rated)
NOTE Underground tank material is steel (UL 58, most common) or fiberglass-reinforced plastic (UL 1316). Fiberglass is corrosion-immune and preferred in corrosive or high-moisture soils; steel requires external corrosion protection per UL 1746. (6.1.3)
● Steel (UL 58 with UL 1746 corrosion protection)
○ Fiberglass / FRP (UL 1316)
6.2 Orientation and Construction
NOTE Horizontal cylindrical is the most common form for facility ASTs and USTs; vertical cylindrical is selected where footprint is constrained; rectangular construction is typical of sub-base and day tanks built onto a generator base rail. (6.2.1)
● Horizontal cylindrical
○ Vertical cylindrical
○ Rectangular (sub-base / day tank)
6.2.2Tank steel and wall thickness shall comply with the minimums of the applicable listing standard for the tank capacity.
NOTE UL 142 sets minimum steel wall thickness by capacity: 10 gauge (0.135 in) for tanks up to 1,200 gallons, 7 gauge (0.179 in) for 1,201 to 12,000 gallons, and 1/4 in for tanks over 12,000 gallons. UL 58 underground tanks have a minimum primary-wall thickness of 0.123 in and a minimum secondary-wall thickness of 0.093 in. (6.2.3)
6.2.4Where the tank serves an emergency or standby power system under NFPA 110, the fuel grade and quality shall be compatible with the served equipment.
NOTE Tank coatings, gaskets, and sealants shall be compatible with the specified fuel grade, including any biodiesel blend. (6.2.5)
NOTE Biodiesel blends of B20 and higher degrade nitrile rubber gaskets, seals, and some interior coatings used in steel tanks. When the project is in a biodiesel-supply region, B5 or B20 compatibility must be specified explicitly so the manufacturer selects compatible elastomers and linings. (6.2.6)
● No. 2 diesel (ULSD)
○ Biodiesel blend B5
○ Biodiesel blend B20
○ No. 2 fuel oil (heating)
6.3 Capacity and Runtime
6.3.1The tank capacity shall be sized for the required runtime at the served equipment's full-load fuel consumption rate plus the planned delivery interval.
NOTE NFPA 110 Level 1 requires a minimum of 8 hours of on-site fuel at 100% rated load; critical facilities such as hospitals and data centers commonly design for 24 to 96 hours. Only 80 to 85% of the rated tank volume is operationally usable once ullage for thermal expansion and the dead leg at the suction connection are subtracted. (6.3.2)
NOTE Specifying a tank to its nameplate runtime without subtracting the 15 to 20% unusable volume results in insufficient runtime. The runtime calculation shall be based on usable volume, not nameplate volume. (6.3.3)
7 Secondary Containment
NOTE Double-wall (interstitial) containment is factory-built into the tank and is the default for new work, giving the smallest footprint and the cleanest interstitial-monitoring path. A single-wall tank within a diked enclosure relies on a separate bund; an above-ground containment vault encloses a tank inside a concrete enclosure that also provides fire and impact resistance. (7.1)
● Double-wall interstitial (factory-built)
○ Single-wall with diked enclosure
○ Containment vault (concrete enclosure)
7.2Secondary containment shall provide a volume of at least 110% of the largest single tank's capacity per NFPA 30.
NOTE For open diked enclosures exposed to weather, 40 CFR 112 requires the containment to hold the largest tank's full capacity plus accumulated precipitation; the dike must be sized for both. (7.3)
7.4The secondary containment shall be of the same listing as the primary tank where factory double-wall construction is used.
7.5Underground secondary containment shall comply with the 40 CFR 280 interstitial monitoring requirement for new and replacement tanks.
8 Overfill Prevention and Spill Control
NOTE Overfill protection ranges from a high-level alarm only, to a high-high alarm that shuts off the fill pump, to an automatic overfill prevention valve that mechanically restricts flow as the tank approaches full. The level of protection is driven by the delivery method and AHJ requirements. (8.1)
○ High-level alarm only
● High-high alarm with fill pump shutoff
○ Automatic overfill prevention valve
8.2Each fill connection shall be provided with a spill containment bucket (catchment basin) to capture drips and disconnect spillage during delivery.
NOTE Where a bulk tank feeds a day tank through a transfer pump, the day tank high-level sensor shall shut off the transfer pump. (8.3)
NOTE The day-tank overflow interlock is a frequent gap: if neither the tank specification nor the pump specification claims it, it goes unaddressed until startup. This standard assigns the day-tank high-level shutoff interlock to the tank package so the wiring path is defined. (8.4)
5 gal cast-iron spill bucket
15 gal spill bucket
5 gal poly spill bucket
9 Venting
NOTE Normal venting relieves the pressure and vacuum produced during filling, withdrawal, and thermal breathing and is sized per API 2000. Emergency venting relieves the much larger vapor-generation rate produced when the tank is exposed to fire and is sized per NFPA 30 Table 22.7.3.2 or API 2000. Both are required; the emergency vent is not a substitute for the normal vent. (9.1)
9.2Each tank shall be provided with a normal vent sized per API 2000 for the maximum fill and withdrawal rates.
9.3Each tank shall be provided with emergency venting sized to relieve the fire-exposure vapor-generation rate per NFPA 30.
9.4The normal vent line shall be not smaller than 1.25 in for aboveground tanks per NFPA 30.
9.5The fill line shall be not smaller than 2 in for aboveground tanks per NFPA 30.
9.6Vent outlets shall terminate at least 12 ft above finished grade, at least 5 ft above the fill point, and away from building openings per NFPA 30.
NOTE Vent termination conflicts are best resolved early: NFPA 30 keeps the outlet high and clear of openings, so coordinate vent routing against the building facade, HVAC intakes, and overhead structure before fabrication. Vent routing locations are shown on the drawings:
tank vent routing and termination.
(9.7) ● Atmospheric (open) vent
○ Pressure-vacuum vent
10 Leak Detection and Gauging
10.1 Leak Detection
NOTE Interstitial monitoring with a liquid-sensing or hydrostatic sensor is standard for double-wall tanks. Vacuum and pressure monitoring continuously verify interstitial integrity. A groundwater monitoring well is an underground-only method used where interstitial monitoring is not feasible. (10.1.1)
● Interstitial sensor (electronic)
○ Vacuum monitoring
○ Pressure monitoring
○ Groundwater monitoring well (UST only)
10.1.2The leak-detection system shall alarm a confirmed leak within the response time required by 40 CFR 280.43 for underground tanks.
NOTE Continuous electronic interstitial monitoring achieves near-real-time leak response and is preferred over the 30-day maximum allowed by 40 CFR 280.43. (10.1.3)
NOTE The interstitial monitoring sensor is furnished under this tank standard, but the monitoring panel and home-run wiring are often carried in the electrical specification. (10.1.4)
NOTE The Contractor shall coordinate the monitoring panel and home-run wiring so the interstitial sensor is connected and supervised; if neither the tank nor the electrical scope claims it, it goes un-bid. (10.1.5)
10.2 Level Gauging
NOTE Level gauging ranges from a mechanical float gauge for local indication, to an electronic level transmitter, to a continuous ultrasonic gauge; the electronic and ultrasonic options integrate with the building monitoring system for remote indication and alarming. (10.2.1)
○ Mechanical float gauge (local)
● Electronic level transmitter
○ Continuous ultrasonic gauge
10.2.2A level transmitter that reports to the building monitoring system shall interface per Pressure Instrumentation signal conventions where an analog output is provided. 11 Anchorage and Corrosion Protection
11.1 Seismic Anchorage
11.1.1Aboveground tanks in Seismic Design Categories C through F shall be anchored and restrained per ASCE 7 Chapter 15 for nonbuilding structures.
NOTE Aboveground tanks exceeding 50,000 lb operating weight require PE-stamped seismic anchorage calculations in SDC C and above. The anchorage interfaces with the supporting concrete or steel per
Structural Steel Anchor Bolts and
Grouted Base Plates.
(11.1.2) 11.1.3Tank anchorage to the foundation shall be designed for the seismic and wind reactions delivered to the saddles or skid.
11.2 Underground Buoyancy
NOTE An empty underground tank in a high-water-table soil will float; anchor straps and a holddown slab or deadman must be sized for the buoyant force of the empty tank. This calculation is frequently omitted in preliminary design and must be completed before the tank is set. (11.2.1)
11.2.2Underground tank anchorage shall be designed for the buoyant uplift of the empty tank at the maximum design water table.
● Anchor straps to holddown slab
○ Concrete holddown slab (ballast)
○ Deadman anchors
11.3 Cathodic Protection
11.3.1Steel underground tanks shall be provided with external corrosion protection per UL 1746 and cathodic protection per NACE SP0285.
NOTE Cathodic protection uses either sacrificial magnesium anodes sized per NACE SP0285, or an impressed-current system meeting the -850 mV protective-potential criterion of NACE SP0169. Sacrificial systems are simpler and need no external power; impressed-current systems suit larger or higher-resistivity installations. (11.3.2)
● Sacrificial magnesium anode
○ Impressed-current system
○ Not required (fiberglass tank)
12 Testing
12.1Each tank shall be factory pressure-tested and certified before shipment.
NOTE UL 142 requires a pneumatic factory test at 3 to 5 psi held for 30 minutes with all welds inspected. The certificate accompanies the tank as an informational submittal. (12.2)
12.3The Contractor shall field-acceptance-test the tank vessel and secondary containment after installation per NFPA 30.
NOTE The field acceptance test shall be pneumatic or hydrostatic at the pressure and duration required by NFPA 30 and the AHJ. (12.4)
12.5The interstitial space of a double-wall tank shall be tested for integrity, by vacuum or pressure, before the tank is placed in service.
12.6The cathodic protection system shall be commissioned and protective potentials recorded before backfill is completed over the tank connections.
● Pneumatic (air) test
○ Hydrostatic test
13 Installation
13.1Tanks shall be installed in accordance with the manufacturer's instructions, NFPA 30, IFC Chapter 57, and PEI RP200 for aboveground systems.
13.2Aboveground tanks shall maintain the separation distances from buildings, property lines, and ignition sources required by NFPA 30 and the IFC.
13.3Tanks serving stationary engine-generators shall maintain the fuel-storage clearances of NFPA 37.
13.4Underground tanks shall be set on and surrounded by clean, non-corrosive backfill of the gradation required by the tank listing.
NOTE Tank-area surface drainage shall be graded so that a containment release or spill is directed away from storm inlets and coordinated with
Stormwater Management Systems.
(13.5) 13.6Tank fill, vent, and gauge connections shall be terminated and capped pending connection of the fuel system furnished under Fuel Oil Systems. 14 Long-Term Fuel Quality
NOTE Ultra-low-sulfur diesel stored more than 6 to 12 months without biocide treatment or fuel polishing promotes microbial growth and filter plugging. NFPA 110 reliability intent is met by a fuel-management program, not by tank sizing alone. (14.1)
14.2The operation and maintenance manual shall include a fuel-management program covering periodic fuel testing, biocide treatment, and the polishing interval recommended for the stored fuel grade.
15 Delivery, Storage, and Handling
15.1Tanks shall be delivered with all nozzles plugged or capped and lifting lugs protected.
15.2Tanks shall be handled only at the manufacturer's designated lifting points; slings shall not be passed around the shell of a coated tank in a way that damages the coating.
15.3Tanks shall be stored level and supported to prevent shell distortion.
15.4Tanks shall be protected from standing water in the interstitial space prior to installation.
16 Warranty
16.1The manufacturer shall warrant the tank against defects in materials and workmanship, including perforation of the primary and secondary walls, for the period specified.
NOTE Fiberglass underground tanks are commonly available with an extended corrosion warranty reflecting their corrosion-immune construction; steel underground tank warranties are tied to the integrity of the external corrosion protection system. (16.2)
1 year
5 years
10 years
30 years (FRP corrosion)
17 Spare Parts
17.1The Contractor shall furnish the following spare parts and consumables to the Owner:
- One spare interstitial leak-detection sensor of each type installed.
- One spare set of fill-cap and spill-bucket gaskets.
- One spare overfill alarm float or sensor where a float type is used.
☑ Spare interstitial leak-detection sensor
☑ Spare fill-cap and spill-bucket gaskets
☐ Spare overfill alarm float / sensor