A
AHJ — Authority Having Jurisdiction
The organization or official responsible for enforcing code requirements and issuing permits in a specific geographic area. For residential propane tank installations, the AHJ is typically your county building department or city building department (if inside city limits), or the county fire marshal's office. The AHJ has final say on permit approval, inspection requirements, and code interpretation — including the right to require more than NFPA 58 minimums.
Above-Ground Container
A propane tank installed on the surface — sitting on a pad, compacted gravel, or firm ground. Visible from the exterior of the property. Subject to size-based permit thresholds (often 125 gallons in jurisdictions that have adopted NFPA 58). Contrast with underground container.
Anode Bag
A canvas or mesh bag filled with magnesium granules attached to underground propane tanks as part of the cathodic protection system. The magnesium corrodes preferentially (sacrificially), protecting the tank's steel from underground corrosion. Must be tested periodically per NFPA 58 and state LP gas regulations.
B
BTU — British Thermal Unit
The standard unit of heat energy used to rate gas appliances and calculate fuel demand. One BTU is the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit. Propane contains approximately 91,500 BTUs per gallon. Your home's total BTU demand (all appliances combined) determines the minimum gas supply capacity needed from your tank and piping system.
Building Department
The local government office that issues building permits and conducts building inspections. For LP gas tank installations, the building department typically issues the LP tank installation permit and the gas piping permit, and schedules the required inspections. In some jurisdictions, fire marshal oversight overlaps with building department functions for LP gas.
C
Cathodic Protection
A corrosion prevention method required for all underground propane tanks. Uses electrochemical principles to prevent the tank's steel from oxidizing (rusting) in contact with soil. The most common residential method is a sacrificial anode system — magnesium or zinc anode bags attached to the tank that corrode instead of the tank. Required by NFPA 58 for all underground LP gas containers. Must be tested every 3 years (varies by state).
Container
NFPA 58 terminology for a propane tank. The code uses "container" rather than "tank" to cover cylinders (portable) and tanks (stationary) under the same framework. In common usage, "tank" and "container" are used interchangeably for stationary residential installations.
F
First-Stage Regulator
The pressure-reducing valve attached to the propane tank outlet that reduces the high pressure inside the tank (up to 200 PSI) to an intermediate working pressure (typically 10 PSI) for delivery through the supply line to the home. Most residential systems also have a second-stage regulator near the home's meter or first appliance that further reduces pressure to the appliance operating level (typically 11 inches water column). Regulators are installed and sized by the licensed LP gas contractor.
G
Gas Piping Permit
A separate permit from the LP tank installation permit, authorizing the installation of the supply line from the tank to the home's gas distribution system. Almost universally required even when no tank installation permit is needed. Covers pipe material, sizing, burial depth, pressure testing, and appliance connections.
I
IFGC — International Fuel Gas Code
Published by the International Code Council (ICC), the IFGC is adopted by states and counties that use the "I-codes" building code family. It incorporates NFPA 58 by reference for LP gas installations, so the practical LP gas requirements under the IFGC and NFPA 58 are essentially the same. Many states that have adopted the IFGC for building code purposes use NFPA 58 terminology in their LP gas permit processes.
L
Licensed LP Gas Contractor
A company or individual licensed by the state LP gas regulatory agency to install, service, and deliver LP gas systems. Most states require a separate LP gas contractor license (beyond a general contractor or plumber's license). For residential propane tank installations, you must use a licensed LP gas contractor in virtually every state. Always verify the license number through your state agency's online lookup before signing a contract.
LP Gas / LPG
Liquefied petroleum gas — primarily propane (C3H8) and butane (C4H10). Stored as a liquid under pressure; vaporizes to gas for use. Propane is the dominant LP gas used in U.S. residential applications due to its lower boiling point (effective in cold climates). Heavier than air, so releases and leaks accumulate in low-lying spaces. This property drives most of the safety regulations around tank placement and enclosure prohibition.
N
NFPA — National Fire Protection Association
A non-profit organization that publishes fire, electrical, and building safety codes and standards used throughout the United States and many other countries. For LP gas, the key publication is NFPA 58. NFPA standards are developed through a consensus process involving industry experts, fire safety professionals, and regulators.
NFPA 58
The Liquefied Petroleum Gas Code published by NFPA. The primary national standard governing LP gas storage, installation, and distribution systems. Sets minimum setback distances, container installation requirements, piping standards, and installer qualification requirements. Most U.S. jurisdictions have adopted NFPA 58 either directly or through the IFGC. Full guide →
P
Pre-Backfill Inspection
An inspection required for all underground propane tank installations, conducted before the excavation is filled in. The inspector visits the site to verify tank placement, depth, cathodic protection installation, setback distances, and vent pipe routing while the tank is still fully visible and accessible. Backfilling before this inspection passes is a permit violation and can require excavation to expose the tank again.
Pressure Test
A test of the gas piping system that introduces compressed air or inert gas at a specified pressure and verifies the system holds that pressure for a specified duration without drop. Required before first fill and final inspection. A pressure drop indicates a leak. The licensed contractor performs the pressure test; the inspector may require a witnessed test or documentation of the test results.
R
Regulator
See First-Stage Regulator. In residential LP gas systems, the regulator reduces the high-pressure gas from the tank to a safe working pressure for delivery to appliances.
S
Setback
The minimum required horizontal distance between a propane tank and a specific feature — building wall, window, door, property line, ignition source, etc. Setbacks under NFPA 58 are measured from the nearest point of the tank shell to the nearest point of the feature. See the complete setback table in our Setback Requirements guide.
U
Underground Container
A propane tank installed below grade — buried in the ground. Always requires a permit regardless of size, jurisdiction, or ownership arrangement. Requires cathodic protection, pre-backfill inspection, vent pipe above grade, and additional setbacks from wells and water features. Full guide →
V
Vent Pipe
For underground propane tanks: a pipe that allows the pressure relief valve to vent propane gas above grade rather than into the soil. Must terminate at least 5 feet above grade (some jurisdictions require 7 feet), at least 5 feet from any building opening or ignition source, capped with a rain-cap fitting, and clearly labeled "LP GAS VENT." Inspected during both the pre-backfill and final inspections.