Gas Distribution Networks Operators' approved risk reduction programmes: 2013 - 2017 and 2013 - 2021


Under the Pipelines Safety Regulations 1996, regulation 13A, HSE approves iron mains risk reduction programmes submitted by the Gas Distribution Network operators (GDNs).

In 2011 HSE reviewed its approach to the management of risk from iron mains within 30 meters of occupied buildings (known as 'at risk' iron pipes). This resulted in the publication of a new Enforcement Policy for the iron mains risk reduction programme 2013 - 2021. The principal changes to the Enforcement Policy are:

  • HSE will approve iron mains risk reduction programmes for periods of up to 8 years where they are assessed to be 'suitable and sufficient'.
  • Decommissioning targets submitted by the GDNs should include only iron pipes with an external diameter 8 inches and below (Tier 1).
  • Tier 1 pipes decommissioned on the basis of their condition, or those selected for reasons of reliability or joint leakage, may be counted towards the approved programme target.
  • The GDNs must manage the risk from iron pipes with an external diameter greater than 8 inches (Tiers 2 and 3) in accordance with the Enforcement Policy. The GDNs are not required to submit decommissioning targets for Tier 2 and 3 pipes.

Approved programme targets

The approved programme targets for the period 1 April 2013 to 31 March 2017 and 31 March 2021 are shown in Table 1.

Table 1 – Approved iron mains risk reduction programmes from 2013

Gas Distribution Network Operator Geographical Network Approval Period (years) Tier 1 Approved Target (km) Tier 1 Indicative Annual Target (km)
National Grid Gas plc North West England 8 12742.00 1592.75
East of England
West Midlands
North London
Northern Gas Networks Ltd North of England 4 1760.00 440.00
Scotland Gas Networks plc Scotland 8 1736.80 217.10
Southern Gas Networks plc South of England 8 4944.80 618.10
Wales & West Utilities Ltd Wales and the West of England 8 2537.80 317.23
Total indicative annual target
(all Great Britain)

The Enforcement Policy permits the GDNs to adopt flexible approaches to their decommissioning programmes to accommodate large or complex projects and maximise efficiency. As a result, the GDNs are not bound by annual targets. However, HSE will query large deviations from the GDNs' indicative annual targets (calculated by dividing the whole programme target by the duration of the approval period) to ensure that they remain on course to deliver their final approved programme decommissioning targets.

Monitoring progress

Over the period of each approved programme HSE requires the GDNs to provide the following information quarterly and also, in summary, annually:

  • Length of 'at risk' Tier 1 pipes decommissioned.
  • Length of 'at risk' Tier 2 pipes scoring above the risk action threshold subjected to appropriate attention*.
  • Length of 'at risk' Tier 2 pipes scoring above the risk action threshold and decommissioned.
  • Length of 'at risk' Tier 2 pipes scoring below the risk action threshold decommissioned.
  • Length of all 'at risk' Tier 3 pipes decommissioned.

* (Appropriate attention means that Tier 2 pipes scoring above the risk-action threshold will either be decommissioned or, where a suitable and sufficient technique exists, assessed for continued use if found to be in good condition or remediated to allow for lifetime extension).

The GDNs should submit quarterly reports to HSE within one month of the end of the period to which they relate (Apr-June, Jul-Sep, Oct-Dec, Jan-Mar), including the final quarter, to provide an early indication of annual performance. HSE notes that quarterly reports are likely to be provisional.

Final annual reports should be submitted to HSE by the end of July.

Exception reporting

Where a significant shortfall in planned decommissioning has occurred, either within an approved programme period or at the end of that period, HSE will require the GDN to report the reasons for this. In addition, HSE will require the GDN to submit proposals for addressing the shortfall.

Inspection and enforcement

As part of its intervention plans HSE will carry out inspections to verify that the GDNs manage 'at risk' iron mains in accordance with the Enforcement Policy and the policies and procedures included in their Gas Safety (Management) Regulations 1996 safety cases.

In the event of a serious shortfall in planned decommissioning delivery by a GDN HSE will consider enforcement action in accordance with HSE's Enforcement Policy Statement during and/or following the period of an approved programme. This may involve any or all of the following measures:

  • Requiring the GDN to submit a recovery plan. This may include issuing Improvement Notices.
  • Modifying the GDN's approved programme.
  • Requiring the GDN to address a decommissioning shortfall during a subsequent approval period where it has not been practicable for the GDN to address it during the approval period in which it occurred.
  • Prosecution of the GDN.

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