Working Near Gas Mains

Gas mains carry natural gas under pressure through a network of pipes beneath roads, footpaths, and open ground.
Striking a gas main during excavation can cause an immediate explosion, fire, or release of toxic and flammable gas.
Gas pipes may be made of cast iron, steel, or polyethylene — PE pipes cannot be detected by a CAT scanner.
The minimum safe approach distance for machine excavation near a known gas main is 500mm on each side.
Within 500mm of a gas main, only hand digging with non-sparking tools such as insulated hand tools is permitted.
Gas mains are typically marked on utility plans but their actual position and depth may differ from recorded locations.
The smell of gas, hissing sounds, or discoloured vegetation are indicators of a possible gas leak nearby.
If you suspect a gas leak, evacuate the immediate area, do not use phones or create ignition sources, and call the National Gas Emergency Service.
SGN, Cadent, NGN, and Wales & West Utilities are the four gas distribution networks that own gas mains in the UK.
All excavation workers must be trained in gas main emergency procedures before working in areas with known gas infrastructure.

Prevent explosion	A ruptured gas main can cause a fireball and explosion that kills workers and members of the public in the immediate area.
Invisible danger	Natural gas is colourless and can accumulate in excavations and confined spaces, creating an explosive atmosphere without warning.
Legal duty	HSG47 and the gas network operator's requirements mandate safe digging practices and emergency procedures near gas mains.

Do

Don't

Obtain gas main locations from the network operator before any excavation begins.
Scan with CAT and Genny, but remember PE gas pipes will not be detected.
Hand dig with care within 500mm of any known or suspected gas main location.
Use non-sparking hand tools when excavating near gas pipework.
Know the emergency procedure and the National Gas Emergency number: 0800 111 999.
Look for warning tape, marker posts, and coloured pipe indicating gas infrastructure.
Brief all excavation workers on gas main locations and emergency procedures daily.
Monitor for the smell of gas, hissing sounds, or bubbling in standing water.
Support exposed gas mains immediately to prevent damage from ground movement.
Report any damage to gas pipework, however minor, to the gas network operator.

DON'T machine dig within 500mm of a known or suspected gas main position.
DON'T rely on CAT scans alone — PE gas pipes produce no electromagnetic signal.
DON'T use metal picks, forks, or striking tools that could spark near gas pipework.
DON'T ignore the smell of gas — evacuate the area and call the emergency number immediately.
DON'T use mobile phones, radios, or create any ignition source near a suspected gas leak.
DON'T assume gas main records are accurate — actual positions may differ from plans.
DON'T work near gas mains without being trained in the gas emergency procedure.
DON'T backfill around exposed gas mains without supporting them to prevent damage.
DON'T attempt to repair a damaged gas main yourself — only the network operator may do this.
DON'T continue excavation if you see coloured pipe or warning tape — stop and investigate.

See also: CAT & Genny Safe Use | Service Strike Emergency Procedure

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