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
- 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.
- 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.
- 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.
- 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).