UTL/Gas/TBT-UTL-008

Gas Mains Replacement (PE Pipe)

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Gas Mains Replacement (PE Pipe)

Toolbox Talk Record

Ref: TBT-UTL-008  |  Issue: 1  |  Date: March 2026
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What?

  • Gas mains replacement involves decommissioning old iron or steel mains and installing new PE (polyethylene) pipe.
  • PE pipe is the standard replacement material for gas distribution networks operating at low and medium pressure.
  • The old metallic main may still contain live gas during the replacement works until transfer is completed.
  • Electrofusion and butt fusion are the primary jointing methods for PE gas pipe on site.
  • Gas escapes from old mains or new connections create immediate explosion and asphyxiation risks.
  • All gas operatives must hold current gas competency cards registered on the relevant industry scheme.
  • Live gas working requires strict compliance with safe working practices and permit systems.
  • Pipe squeeze-off equipment is used to control gas flow in PE pipes during connections and repairs.
  • Excavations for gas mains must comply with HSG47 and include measures to prevent third-party damage.
  • The Gas Safety (Management) Regulations 1996 and IGEM standards govern all gas network work.

Why?

Explosion riskGas leaks from damaged mains or poor joints can cause explosions that kill workers and members of the public.
AsphyxiationNatural gas displaces oxygen in excavations and confined spaces, creating immediate suffocation risk for anyone below ground.
Legal complianceThe Gas Safety (Management) Regulations 1996 and HSE enforcement require strict controls on all gas network operations.
Do Don't
  • Confirm all operatives hold current gas competency cards before work starts.
  • Follow the approved safe working practice for every live gas procedure.
  • Monitor for gas continuously using calibrated portable gas detectors in excavations.
  • Use only approved PE pipe, fittings, and fusion equipment for gas installations.
  • Squeeze off PE pipe using approved equipment before making cuts or connections.
  • Ensure electrofusion joints are made in clean, dry conditions per IGEM standards.
  • Purge and test all new pipework before commissioning and putting it into service.
  • Maintain fire extinguishers and no-smoking zones around all gas working areas.
  • Report any gas escape immediately and follow the gas escape emergency procedure.
  • Protect completed PE pipe from UV exposure and mechanical damage during backfill.
  • DON'T allow unqualified personnel to work on live or decommissioned gas mains.
  • DON'T make electrofusion joints in wet or contaminated conditions on PE pipe.
  • DON'T use any ignition source within the gas safety zone around open pipework.
  • DON'T enter an excavation with a gas reading above the lower explosive limit.
  • DON'T squeeze off PE pipe without approved equipment and trained operators.
  • DON'T leave exposed PE gas pipe unprotected from UV sunlight on site.
  • DON'T backfill over gas pipe without confirming joint integrity test results.
  • DON'T bypass the permit system for any live gas working operation.
  • DON'T use metallic tools that could create sparks near open gas pipework.
  • DON'T assume old mains are gas-free; treat all pipework as live until proven.

See also: Gas Main Installation Safety | Gas Escape and Emergency Procedures
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