Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
---
title: Fuel Storage Tanks
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### 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. {note}
+### Whether the fuel storage tank is aboveground or underground shall be specified based on available site area, setbacks, soil, water-table conditions, and zoning constraints.
+
```datasheet
label: Tank Location
…7 unchanged lines
### 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. {note}
+### The fire-protection listing standard for the aboveground storage tank shall be specified based on occupancy, AHJ requirements, and proximity to occupied structures.
+
```datasheet
label: AST Listing Standard
…8 unchanged lines
### 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. {note}
+### The underground storage tank material and listing standard shall be specified based on the corrosivity and moisture condition of the surrounding soil.
+
```datasheet
label: UST Material and Listing
…9 unchanged lines
### 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. {note}
+### The tank orientation shall be specified based on the available site footprint and the tank's intended service.
+
```datasheet
label: Tank Orientation
…12 unchanged lines
### Where the tank serves an emergency or standby power system under NFPA 110, the fuel grade and quality shall be compatible with the served equipment.
−### Tank coatings, gaskets, and sealants shall be compatible with the specified fuel grade, including any biodiesel blend. {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. {note}
−
```datasheet
label: Stored Fuel Grade
…7 unchanged lines
```
+### Tank coatings, gaskets, and sealants shall be compatible with the specified fuel grade, including any biodiesel blend. {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. {note}
+
## Capacity and Runtime {toc}
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### 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. {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. {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.
```datasheet
…20 unchanged lines
## 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. {note}
+## The secondary containment type shall be specified based on the desired footprint, monitoring approach, and level of fire and impact protection required.
+
```datasheet
label: Secondary Containment Type
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## Secondary containment shall provide a volume of at least 110% of the largest single tank's capacity per NFPA 30.
−## 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. {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.
## The secondary containment shall be of the same listing as the primary tank where factory double-wall construction is used.
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## 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. {note}
+## The level of overfill protection shall be specified based on the delivery method and applicable AHJ requirements.
+
```datasheet
label: Overfill Protection
…8 unchanged lines
## Each fill connection shall be provided with a spill containment bucket (catchment basin) to capture drips and disconnect spillage during delivery.
−## Where a bulk tank feeds a day tank through a transfer pump, the day tank high-level sensor shall shut off the transfer pump. {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. {note}
−
```datasheet
label: Spill Containment Bucket
…6 unchanged lines
```
+## Where a bulk tank feeds a day tank through a transfer pump, the day tank high-level sensor shall shut off the transfer pump.
+
+## 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. {note}
+
# Venting {toc}
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## Each tank shall be provided with a normal vent sized per API 2000 for the maximum fill and withdrawal rates.
+```datasheet
+label: Normal Vent Configuration
+type: radio
+options:
+ - Atmospheric (open) vent
+ - Pressure-vacuum vent
+default: Atmospheric (open) vent
+```
+
## Each tank shall be provided with emergency venting sized to relieve the fire-exposure vapor-generation rate per NFPA 30.
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## 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: [[drawing: tank vent routing and termination]]. {note}
−```datasheet
−label: Normal Vent Configuration
−type: radio
−options:
− - Atmospheric (open) vent
− - Pressure-vacuum vent
−default: Atmospheric (open) vent
−```
−
# Leak Detection and Gauging {toc}
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### 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. {note}
+### The leak detection method shall be specified based on the tank's containment configuration and, for underground tanks, the feasibility of interstitial monitoring.
+
```datasheet
label: Leak Detection Method
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### 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. {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. {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.
## Level Gauging {toc}
### 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. {note}
+### The level gauging method shall be specified, including whether integration with the building monitoring system for remote indication is required.
+
```datasheet
label: Level Gauging
…38 unchanged lines
### Steel underground tanks shall be provided with external corrosion protection per UL 1746 and cathodic protection per NACE SP0285.
−### 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. {note}
−
```datasheet
label: Cathodic Protection (Steel USTs)
…6 unchanged lines
```
+### 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. {note}
+
# Testing {toc}
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## Underground tanks shall be set on and surrounded by clean, non-corrosive backfill of the gradation required by the tank listing.
−## Tank-area surface drainage shall be graded so that a containment release or spill is directed away from storm inlets and coordinated with [[sync/stormwater-management-systems]]. {note}
+## Tank-area surface drainage shall be graded so that a containment release or spill is directed away from storm inlets and coordinated with [[sync/stormwater-management-systems]].
## Tank fill, vent, and gauge connections shall be terminated and capped pending connection of the fuel system furnished under [[sync/fuel-oil-systems]].
…21 unchanged lines
## The manufacturer shall warrant the tank against defects in materials and workmanship, including perforation of the primary and secondary walls, for the period specified.
−## 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. {note}
−
```datasheet
label: Tank Warranty Period
…7 unchanged lines
```
+## 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. {note}
+
# Spare Parts {toc}
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- Spare fill-cap and spill-bucket gaskets
```