Gas supply - Monitoring and reporting of Distribution Networks

Mains replacement programmes 2006 - 2013.
(December 2005)

Background

• In September 2001 the Health and Safety Executive (HSE) published its Enforcement Policy for the Replacement of Iron Gas Mains. This set out a national replacement programme so that all 'at risk' iron gas mains would be decommissioned by March 2032.
• HSE also published the arrangements for reporting and monitoring how Transco met the replacement programme over the first five years 2002 - 2007.
• This document revises the monitoring and reporting arrangements for the eight major distribution networks (the DNs) taking account of:
  • A revised HSE enforcement policy for 2006 - 2013;
  • Structural changes in the gas distribution industry in June 2005 when Transco sold four of its eight distribution networks;
  • New legislation concerning 'approved' mains replacement programmes;
  • Requirements for monitoring and reporting described in the DNs' safety cases under the Gas Safety (Management) Regulations 1996 (GSMR).

Objectives

• 4 The objectives of these arrangements are to:
  • Give HSE assurance that replacement targets are being met in line with its enforcement policy;
  • Provide information on the effectiveness of the replacement programme in removing risk;
  • Set out what reports HSE expects from the DN operators.

Changes in industry structure

• In June 2005 Transco plc sold four of their DNs followed by a change of its name to National Grid Gas plc. The eight major DNs are now operated by:

National Grid Gas plc	North West East of England West Midlands North London
Northern Gas Networks Ltd	North of England
Scotland Gas Networks plc	Scotland
Southern Gas Networks plc	South of England
Wales & West Utilities Ltd	Wales & West

Legislation

1. The Pipelines Safety Regulations 1996, regulation 13, require pipeline operators to ensure pipelines are maintained in good repair. Regulation 13A allows operators of iron gas distribution mains to submit a replacement programme to HSE for approval.
2. All the DNs have approved annual replacement programmes, giving the length of mains requiring replacement and how this will be prioritised. HSE will approve replacement programmes annually.

• Under GSMR the DNs have accepted safety cases describing how they maintain their gas mains and manage their replacement programmes. This includes compliance with the following monitoring and reporting arrangements.

Monitoring and reporting arrangements

• DNs are required to report quarterly and annually to HSE covering the periods:
  • April - June
  • July - September
  • October - December
  • January - March
• These are minimum reporting requirements and HSE may require further information where necessary.

Quarterly reports

• Each quarter for each network the DNs are required to report to HSE:
  • Mains decommissioned ('taken off risk'), by diameter (<=12", >12");
  • Replacement mains laid (including those by insertion), by diameter (<=12", >12");
  • Comparison of the mains decommissioned and laid against plan;
  • Mains decommissioned/laid for reasons of condition or diversion against plan^[1];
  • Exception reports where required.
• The quarterly reports should be submitted to HSE within one month of the end of the period to which they relate, including the final quarter so as to provide HSE with an early indication of annual performance. HSE notes that quarterly reports are likely to be provisional.

Annual reports

• Annually the DNs are required to report:
  • Annual replacement performance containing the information as required in the quarterly reports;
  • The risk band profile in each network. This includes the length of mains in risk bands 0 - 30, 30 - 60, ...210 - 240, > 240 by diameter (<=12", >12") and material (cast, ductile iron);
  • The number of 'gas in buildings' (GIB) events^[2] by diameter (<=12", >12") and material type (cast, spun, ductile iron);
  • Number of fractures by diameter (<=12", >12") and material (cast, spun, ductile iron);
  • Number of major mains and service related incidents (i.e. a gas explosion resulting in significant damage to property and/or injury);
  • An estimate on the risk reduction by network in incidents/annum;
  • The seed pipe risk score for the following programme;
  • The projected replacement by network for the following five years, by diameter (<=12", >12");
  • Where approved programmes have not been met, a report on the reasons and proposals for addressing any shortfall.
• The annual reports should be submitted to HSE by the end of July.

Exception reporting

• The DNs should provide detailed exception reports with each quarterly report where replacement performance falls below planned targets as below:
  • Quarter 1 20%
  • Quarter 2 15%
  • Quarter 3 10%
  • Quarter 4 0%
• The exception reports should give reasons for the shortfall and, for Q1, Q2 and Q3, details of the recovery plans.
• For Q4, where the DN has not met the annual 'approved' programme, HSE will require a detailed explanation and will consider what other action is necessary. For example, this may require the DN to address this shortfall in the following annual programme. HSE will also consider if further enforcement action is necessary.

Risk profiles

• Replacement programmes are developed using mains risk prioritisation system [MRPS] which gives a risk score, in incidents per km of main, for each mains unit.
• DNs can therefore give a risk profile for their networks and an estimate of the risk reduction. HSE and the DNs can then use this information to assess the effectiveness of the programme in removing risk from the network.

Auditing

• HSE have intervention plans for each DN which involve inspecting the DN's compliance with their replacement programmes. The inspections include looking at the procedures for prioritising replacement.

Enforcement action

• HSE may consider enforcement action throughout and following the annual programme where appropriate under its enforcement policy. This could involve:
  • Requiring an improvement plan where replacement rates fall below target, including issuing Improvement Notices;
  • Modifying the approved programme to address any shortfall in replacement targets;
  • Prosecution for serious failings to meet replacement targets.

HSE Hazardous Installations Directorate
Gas & Pipelines Unit, December 2005

---

[1] Mains replaced through condition and diversion policies do not contribute to the replacement targets under the approved programmes.

[2] A gas in buildings event is where gas from a leaking main has entered property and reached a concentration level of 20% of the lower explosive limit (LEL).