Gas Pipelines: Inspecting Polyethylene (PE) Natural Gas Installations


This guidance outlines the key areas to include and ratings to apply in HSE polyethylene (PE) natural gas installation inspections carried out on distribution mains and services operated by gas conveyors such as gas distribution network operators (GDNs), independent gas transporters (IGTs) and other small network operators.


This guidance provides inspectors with a framework to judge compliance, assign performance ratings and decide what enforcement action is necessary should legislative breaches exist.  It complements and supports HSE's Enforcement Management Model (EMM) and Enforcement Policy Statement.

The majority of new natural gas distribution mains and service are made from PE. Ensuring the safe installation of PE natural gas pipes is of critical importance because of the risk of gas escapes from poorly installed pipes leading to the potential for major incidents and loss of network pressure. The consequence of PE pipe or joint failure is likely to be more serious for medium pressure systems where the volume of gas released is greater than from low pressure systems.


The purpose of PE natural gas installation inspections is to check issues relevant to the control of major hazards across the gas distribution networks.

When undertaking inspections covered by this guidance, inspectors should:

  • Check the issues against their success criteria in Appendix 1
  • Use the generic performance descriptors in Appendix 2 to:
    • determine the appropriate performance rating and
    • the initial enforcement expectation to use alongside the EMM
  • Where in doubt, compare the standard of PE pipe installation found on site with the examples of poor practice shown in Appendix 3
  • Consider how and when the issues raised during an inspection are to be closed out and recorded using the COIN issues tab
  • Where enforcement action is indicated by the EMM, identify the relevant dutyholder and applicable legislation using Appendix 4


The installation of safe PE natural gas pipes is achieved by competent and adequately supervised personnel correctly following operational procedures. However, the integrity of a PE pipe joint can be significantly affected by its cleanliness, alignment and compliance with the correct fusion cycle at the time of installation.  Damage to the pipe near the joint can also affect joint integrity.

The GDNs, the IGTs and/or their contractors carry out most PE natural gas pipe installation. The GDNs, IGTs and small network operators also adopt pipes installed by Utility Infrastructure Providers (UIPs) who install pipes for new-build projects.

Natural gas network activities giving rise to PE pipe installation are:

  • Iron mains decommissioning and replacement
  • New gas mains and service pipes laying
  • New consumer connections
  • Network maintenance and repair work



PE natural gas installation inspections should be carried out in accordance with dutyholder intervention plans. The risk ranking arrangements used by Energy Division Gas & Pipelines (ED5) may also be used to assist inspectors when deciding intervention frequency and targeting of dutyholders.


The installation of PE gas pipes is transient. Gas conveyors either employ direct labour to install PE pipes or use contractors. Inspectors should request work schedules from the relevant gas conveyor in order to carry out inspections. Inspectors may also arrange with the gas conveyor to either jointly or independently visit newly adopted or soon-to-be adopted pipes installed by UIPs.

Rating and recording

PE natural gas installation inspection ratings recorded on COIN will be based upon the major hazard risks associated with work on, to, or around the network. Ratings should be recorded on the Inspection Rating Form (IRF) tab of the Intervention Plan Service Orders (IPSOs) for the relevant gas conveyor.

The following topics may also be encountered during an inspection and should be rated separately:

  • Safe Control of (live gas) Operations SCO inspection - separate guidance covers this topic.  Where SCO issues are encountered this guidance should be consulted and an appropriate performance rating entered in the SCO line on the IRF tab.
  • Mains replacement - this is only relevant to the GDN operators whose iron mains risk reduction programmes are approved by HSE under Regulation 13A of the Pipelines Safety Regulations 1996 (PSR).  Further information on this topic is available on the HSE website's iron mains replacement pages.


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Updated 2020-12-15