Gas Jargon Buster

Gas Jargon and Industry Terminology Explained

At Crown Energy, we’re passionate about making utility connections simple. But within the energy industry, sometimes there’s no escaping the jargon! We’ve put together a handy “Gas Jargon Buster” to help you sail through the minefield of complicated terms and energy acronyms, so you’re never left in the dark.

Air test

A pressure test is carried out using air to check for leaks in newly installed gas pipework before gas is introduced.

Annual quantity (AQ)

An estimate of the amount of gas (measured in kWh) a property will use in a year. Used by suppliers to forecast demand.

Apex or riser

The vertical section of a gas service pipe that runs above ground into the property or meter box.

As-laid drawing

A diagram produced after installation, showing the exact location and depth of buried gas pipes and other utilities.

Capping off

Sealing the end of a gas pipe when the meter or service has been removed to make it safe.

Commissioning

The process of testing, purging, and setting up new gas pipework or meters so that the system is safe and ready for use.

Cross-connection

When gas pipework becomes incorrectly connected to another utility or property. This is dangerous and must be rectified immediately.

Decommissioning

Safely isolating and removing a redundant gas supply or section of pipework.

Downstream / upstream

“Upstream” refers to the gas supply side before the meter; “downstream” refers to the pipework and appliances after the meter.

Emergency control valve (ECV)

The valve (usually located before the gas meter) that shuts off the gas supply to a property in case of emergency or for maintenance.

Flue

A pipe or duct that removes combustion gases from boilers or heaters to the outside atmosphere.

Gas distribution network (GDN)

Regional networks that own and operate the pipes delivering gas from the National Transmission System to homes and businesses.

Gas Safe Register

The official register of engineers legally permitted to work on gas appliances and installations in the UK. Replaced CORGI in 2009. (See the Gas Safe Register to find a gas engineer)

Gas meter

A device that measures how much gas passes into your property, allowing your supplier to calculate your energy usage.

Gas transporter (GT)

A licensed company responsible for owning and maintaining gas pipes in a particular area. The largest is National Grid Gas, but there are also smaller Independent Gas Transporters (IGTs).

Institution of gas engineers and managers (IGEM)

The UK’s professional body for gas engineering, producing technical standards for safe gas design, installation, and operation. (See IGEM to learn more)

Independent gas transporter (IGT)

A company other than National Grid that owns and operates local gas pipes. Common in new housing developments.

Interruption

A planned or unplanned suspension of gas supply, usually for maintenance or emergency works.

Live/dead check

A safety check to confirm whether a gas supply is active (live) or disconnected (dead).

Load

The total amount of gas required by all appliances connected to a property, measured in kW.

Main

A large-diameter pipe forming part of the gas distribution network that carries gas along streets or through developments.

Meter box

An enclosure (often white or brown) that houses the gas meter and emergency control valve, usually on an outside wall or boundary.

Meter exchange

Replacing an existing gas meter, typically due to size changes, age, or the move to a smart meter.

Meter point reference number (MPRN)

The unique number that identifies your gas supply point. Found on your gas bill, it’s essential when arranging new connections, disconnections or meter installations.

Meter point administration service (MPAS)

The system that manages and tracks all Meter Point Reference Numbers (MPRNs) across the UK gas market. It supports suppliers and transporters by maintaining accurate supply point data used for switching and billing.

National transmission system (NTS)

The high-pressure gas pipeline network that transports gas across the UK before it enters the regional distribution networks.

Natural gas

A fossil fuel composed mainly of methane, used for heating, cooking, and power generation.

Outlet pipework

Pipework that carries gas from the meter to internal appliances such as boilers, cookers, and heaters.

PE pipe (polyethylene)

A flexible yellow plastic pipe that is commonly used for new underground gas service installations.

Pressure tiers (LP / MP / IP / HP)

Gas networks are divided into pressure levels:

• Low Pressure (LP) – Standard domestic properties
• Medium Pressure (MP) – Larger residential or small commercial developments
• Intermediate Pressure (IP) – Industrial or commercial premises
• High Pressure (HP) – Large industrial sites and power generation

Purge and decommissioning

The process of safely removing any residual gas from pipework once a supply is disconnected, ensuring no gas is left trapped in pipes that could pose a risk.

Riser

Vertical pipework carrying gas up through multi-storey buildings, typically between floors in flats or office blocks.

Service alteration

Work carried out to move or modify an existing gas service pipe or meter position.

Service pipe

The pipe that connects a property to the mains gas network, running from the boundary into the building.

Service pipe entry

The point at which the underground service pipe enters the building or meter box.

Smart gas meter

A modern gas meter that automatically sends readings to your supplier and provides real-time information on gas usage.

Supply pipe

A general term sometimes used to describe the full pipe run from the gas main in the street to the emergency control valve (ECV) inside your property. It includes both the underground service pipe and the internal pipework up to the ECV.

Testing and commissioning

Procedures are carried out to verify that newly installed gas systems are leak-free, correctly purged, and operating safely.

Third-party damage

When a gas pipe is accidentally damaged by external works, for example, during excavation or building activity.

U-gauge / manometer

A simple pressure-measuring device used by engineers to check for gas leaks during tests.

Underground service

A section of buried gas pipework between the gas main and the building’s entry point.

Utility infrastructure provider (UIP)

A company (like Crown Energy) accredited to design and install gas infrastructure and connections, often working alongside GDNs and IGTs.