DIRECTORATE OF ESTATES AND DEVELOPMENT

CONTROL OF GAS NETWORK OPERATIONS

Document Name: / HS0010 / Author: / Paul Richards
Issue Number: / 6 / Number of Pages: / 25
Issue Date: / 30May 2015 / Approved by: / Wilcock Consulting
Last revised: / 17/03/2017 / By - / Paul Richards
Current revision / 23/02/2018 / By / Phil Winnard/Paul Richards
REVISION HISTORY SHEET
Document Status / Checked by / Authorised by / Issued
17th March 2017. review of documentation and updating drawing information / Paul Richards / Keele Web site updated
23rd February 2018 , full review of documentation following Hawthorns decant, Barnes new build and G3 network alterations for Hydeploy project. / Phil Winnard , Wilcock consulting / Paul Richards

1

CONTENTS

1.FOREWORD

2.INTRODUCTION

3.DESCRIPTION OF THE OPERATION

4.GENERAL DESCRIPTION OF PLANT, PREMISES AND LOCATION

5.SITE GENERAL

6.OPERATION AND MAINTENANCE PROCEDURES

7.RISK ASSESSMENT

8.HEALTH AND SAFETY ARRANGEMENTS

9.MONITORING HEALTH AND SAFETY PERFORMANCE

10.COMPETENCE AND TRAINING

11.MANAGEMENT OF CONTRACTORS

12. AUDIT AND REVIEW OF MANAGEMENT SYSTEMS

13.CO-OPERATION WITH OTHER PARTIES

14.GAS ESCAPE AND INVESTIGATIONS

15. CONTENT AND OTHER CHARACTERISTICS OF GAS

16.CONTINUITY OF SUPPLY AND SUPPLY EMERGENCIES

17.OTHER INCIDENTS

18.GLOSSARY OF TERMS

19.APPENDICES

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1.FOREWORD

Purpose

This procedure details the operational arrangements to ensure the safety and integrity of the gas network, within the ownership and responsibility of Keele University.

Scope

These procedures are also designed to give guidance during emergency situations and supply interruptions.

2.INTRODUCTION

2.1For the purposes of the Gas Safety (Management) Regulations 1996, the Duty holder for the University of Keele gas distribution network is: Professor Trevor McMillan, Vice Chancellor.

The registered office of the University of Keele is: Keele University, Keele, ST5 5BG.

This Safety Case has been prepared by the University of Keele, as a Licensed Gas Transporter / Supplier within Great Britain, to demonstrate compliance with the Gas Safety (Management) Regulations 1996 (GS(M)R) in the construction, maintenance and operation of the Keele University Gas Distribution Network.

It sets out the arrangements for ensuring that the natural gas network, owned by the University of Keele, is operated and maintained safely and that the risk to site occupiers and visitors arising from its operation is as low as reasonably practicable.

The document includes a risk assessment and sets out the preventative measures in place to avoid incidents and the protective measures to be implemented in the event of an incident. It contains the essential elements of a gas safety management system. The document makes reference to Keele University standard procedures including the procedures to be followed in the event of a partial or total supply failure and the procedures for reporting and dealing with gas escapes and gas related incidents.

All gas supplies to the site are delivered under firm gas contracts, hence there are no issues arising from interruptible gas contracts.

3.DESCRIPTION OF THE OPERATION

3.1The University of Keele owns and maintains a gas distribution network which conveys natural gas from the outlet of 6 meters (i.e. primary meters located at points across the site) to student and staff houses and flats, places of assembly such as halls of residence, lecture theatres and other commercial buildings. Most of the staff housing and student flats take gas via secondary meters but supplies to the Halls of Residence and some of the other buildings are not metered and hence the gas flows directly into internal pipework and then on to appliances.

The primary meters are owned by National Grid plc (CADENT) and gas is delivered to them via the CADENT gas distribution system. It is CADENT’s responsibility to maintain adequate meter inlet pressures and gas quality.

Any new gas distribution infrastructure, extensions or alterations to the gas system are effected in accordance with procedure KU/Gas/11 – Gas site works process

4.GENERAL DESCRIPTION OF PLANT, PREMISES ANDLOCATION

4.1The University conveys the gas to consumers from the outlet of the primary meters via 9 km of below ground gas main. The gas mains are connected to the premises via gas service pipes. The site occupies an area of approximately 607 acres. The total peak instant gas load for the site is estimated at 20 MW.

The gas mains and services across the site have been installed over a period between 1960 and 2017. There is no cast or ductile iron. All the medium pressure ductile iron main was de-commissioned in 2003 following a safety notice from the HSE dated February 2003.

In 1985 a major replacement programme was undertaken on the central campus to replace cast and ductile iron pipe with MDPE. Construction of the distribution network has been generally to IGE/TD/3 or TD/4 standards – edition current at the time of construction.

The majority of the gas main under the management of Keele University operates at low pressure (21mb – 30mb) and a small amount (0.68 km) operates at medium pressure (140mb). The MP mains are all MDPE and the LP mains are mostly of MDPE with 721metres of Steel pipe located in MZ1. The steel pipe ranges from 4 inch to 8 inch in diameter.

Service pipes, which connect the mains to the secondary meters (or to the internal pipework where there are no secondary meters), are MDPE, steel or MDPE/steel.

A survey has been carried out to check if external service isolation valves are fitted in accordance with IGE/TD/4 and installed as required.

A planned maintenance event takes place biannually to check service pipe condition. Any faults observed during the survey are rectified on a planned basis.

A gas service replacement policy has been developed as detailed in KU/Gas/8 – Gas Service Replacement Policy.

4.2The campus comprises four separate networks each supplied via a single primary meter and referred to as meter zones (A list of drawings can be found in Appendix 1 - Site Drawings.

The meter zones are zones are identified as follows: -

  • MZ1 comprising a medium pressure main from Clock House supplying twoseparate low-pressurenetworks as follows: -
  • Lyndsay Boiler House
  • Horwood accommodation and student’s union
  • Keele Hall
  • Horwood staff housing
  • Springpool
  • MZ3 comprises a low-pressure network serving the central academic campus
  • MZ7 comprises a low pressure main serving Barnes WX blocks
  • MZ8 comprises a low pressure main serving Barnes Halls

Note: -

MZ5 and MZ6 Networks were legally transferred to a third party in January 2018

A request made to CADENT seeking information on the standards to which the meters have been designed and a description of the maintenance regime being applied produced the following response:

“As there are a number of different types of installation on the campus there are as many maintenance regimes; rather than try to detail the exact regime associated with each site we have described what is done by type.

National Grid Metering and our predecessors have used internal documents for the design, construction and maintenance of metering equipment; over recent years these documents have been up dated and adopted by the Institution of Gas Engineers and Managers - these documents refer where possible to the relevant British and International standards - these are many and various.

All inspections and maintenance are carried out broadly in accordance with the appropriate recommendations and procedures published by the Institution of Gas Engineers and Managers. A long history of operating metering equipment and the application of Reliability Centered Maintenance techniques has led to the formulation of the maintenance procedures and frequencies employed.

All metering installations are subject to an inspection, usually carried out by the meter reading agency, on at least a two-year frequency.

4.3Low pressure supplies with diaphragm meters

No programmed maintenance is carried out, the performance of the installed population is monitored and policies to replace this type of equipment due to reliability or accuracy are formulated from the collected information.

4.4Low pressure rotary and turbine meter installations

All such installations are checked on a five-year cycle; the maintenance procedure includes general condition, pressure losses, noise, oil level and condition. Labelling and safety equipment is also checked.

4.5Medium pressure installations (such as Clock House)

There are 4 gas pressure control installations with an inlet pressure of greater than 75 mbar therefore attracting the designation ‘medium pressure installation’. The installations are located as follows: -

  • Walled Garden Station No 1 (GGS1)
  • Horwood Station No 2 (GGS2)
  • Horwood Station No 3 (GGS3)
  • Lyndsay Station No 4 (GGS4)

The Lyndsay installation has been upgraded which confirms all governor installations meet current standards.

The medium pressure regulator installations are subjected to a maintenance regime in accordance with the recommendations stipulated in IGEM/TD/13. The University maintenance policy is specified in document KU/Gas/9. The maintenance contract and results of the most recent maintenance inspection can be found in Appendix 7

The principal characteristics of each meter zone are as follows: -

4.6Meter Zone No. 1 - Drawing No. SG-MZ-1 – Meter No. G1 Clock House Main Meter

The gas to MZ1 is supplied from a 6” diameter, medium pressure; steel main owned by CADENT. Gas enters the network through CADENT’s twin stream meter rig ref no. G1. The rig operates at an inlet pressure up to 2 bar and an outlet pressure of 140mb. The slam shuts are set by CADENT to go off at 210 mbar.

Within MZ 1 there are a number of halls of residence and a range of commercial buildings housing the Students Union and a café bar (See drawing MZ 1 for details).

This is the only MZ that comprises sections of medium pressure mains.

The MP main carries supplies to the following gas governors which supply student flats, boilers or commercial buildings.

  1. Approximately 680m of 250 mm diameter MDPE medium pressure main supplying Horwood complex. This gas main supplies two regulator module as follows: -
  2. Twin stream active slam shut pressure reduction module (GGS2) with outlet pressure set at 28 mbar supplying Horwood flats and, Students Union Catering, Keel Hall, Horwood Staff Housing and Springpool. The low-pressure network comprises the following: -
  3. Approximately 750m of low pressure MDPE main of varying sizes at Horwood flats and Students Union.
  4. Approximately 160 metres of low pressure 8 steel main and 311 meters of varying sizes of MDPE main supplying Keel Hall, Horwood Staff Housing and Springpool.
  5. Twin stream active slam shut module (GGS3) with outlet pressure set at 70 mbar supplying Horwood main boilers and a newly installed CHP
  1. Approximately 200 metres of 180mm diameter MDPE medium pressure main supplying Lindsay boiler house – The pressure regulator and meter installation (GGS4) has been upgraded to supply the existing boiler house and make provision for a future CHP
  2. A pressure regulator installation (GGS1) supplying the Green house boiler, Clock house kitchen, Music Department and Firshill. The outlet pipework comprises approximately 175 metres of 90mm, 63mm and 32mm PE pipe. This system operates at a pressure of approximately 30 mbar

There are no industrial processes and the supply is via a firm gas contract. It is an all plastic system,

4.7Meter Zone No.3 - Main Campus – drawing no. SG-MZ-3 – Meter No. G3 Main Campus

This is by far the largest network on the site. It is a low-pressure system. The gas is supplied from a 6” diameter, medium pressure, steel main (owned by CADENT) and enters the network through CADENT’s twin stream meter rig ref no. G3. The CADENT rig operates at an inlet pressure up to 2 bar and an outlet pressure of 28mb. The slam shuts are set by CADENT to trigger at 70 mbar.

The total length of the MZ 3 network is 4381 meters and is constructed of MDPE of varying sizes

MZ 3 comprises domestic type dwellings including staff houses, a number of halls of residence and a range of commercial buildings housing lecture theatres, science laboratories, a leisure centre and administration staff offices.

All supplies to domestic type dwellings and commercial buildings are separately metered via the University-owned secondary meters.

There are no industrial processes and the supply is via firm gas contracts.

4.08Meter Zone No. 7 – Drawing No. SG-MZ-7 – Meter No. G340(Barnes W & X )

This is an all LP system. There is 103 metres of 125mm MDPE main operating at a pressure of 27mb.

The gas is supplied from a 4” diameter medium pressure, steel main owned by CADENT and enters the network throughCADENT’s single stream meter rig ref no. G340.

The system supplies two halls of residence, both of which are separately metered via the University -owned secondary meters. These residences are designated blocks X and W

4.09Meter Zone No.8 - Main Campus – drawing no. SG-MZ-8 – Meter No. G360 Barnes

This is a low-pressure distribution system. The gas is supplied from a 180mm diameter, medium pressure, PE main (owned by CADENT) and enters the network through CADENT’s twin stream meter rig ref no. G360. This rig was replaced with one of larger capacity in 2017 to accommodate new developments. The CADENT rig operates at an inlet pressure up to 2 bar and an outlet pressure of 28mb. The slam shuts are set by CADENT to trigger at 70 mbar. The MZ 8 network comprises 734meters of MDPE. MZ 8 suppliesthe Barnes Halls of Residences, blocks A-V and social space, bar and launderette. Two additional blocks were added to this network in 2017 and designated blocks Y and Z

All supplies to domestic type dwellings and commercial buildings are separately metered via the University-owned secondary meters

5.SITE GENERAL

5.1There are no interruptible customers on the site and no industrial processes and there are no single, very large volume consumers on site. The largest (downstream) consumer is meter G041A372,000 cubic meters per annum. It is in MZ 1.

The main items of safety critical plant are the pressure regulators and slam-shut valves owned and maintained by CADENT and located at the primary meter installations. Meter No. G007 is owned by CADENT and embedded in system.

In addition, there are low pressure meter regulators at the inlet of the secondary meters. These are owned by the University and maintained by the Director of Estates and Development (see Management Organisation section 7.1).

Note: Some secondary meters may not have pressure regulators. A survey of secondary meters is proposed and this will include a check for meter regulators. The University metering standard is set out in KU/Gas/14 – University gas Metering Policy.

There are no control centers required to ensure the safe flow of gas since CADENT is responsible for maintaining inlet pressures to the primary meter installations and any reports of low pressure on the network will immediately be reported to the NG gas emergency service on 0800 111 999.

Safe gas flow from the primary to the secondary meters is maintained by ensuring there is sufficient capacity within the network to meet peak demand. A Network Analysis exercise has been completed by Wilcock Consultants Ltd using the Small Network Analysis Programme (SNAP) to assess how the University-operated systems meet peak demand; no reduction in demand to allow for diversity was built in to this exercise. Validation of Network Pressures has been carried out.Loggers have been installed at the lowest pressure points predicted in the network analysis. A list of logger locations and an example of the plots from the loggers is included in Appendix 11. The data from the loggers is used to validate the network analysis findings to ensure adequate pressures are maintained.

The minimum design pressure for the system at peak demand is 19mbar.

The following table shows the minimum pressures calculated for the system using network analysis. It is demonstrated that pressures in the networks are greater than the minimum design pressure at all locations.

Min Pressure Summary
Meter Zone / Node / Min Pressure
MZ1 - MP / 5 / 138.60
MZ1 – Clock House / 29 / 39.00
MZ1 – Horwood / 22 / 34.01
MZ3 / 407 / 27.54
MZ7 / 704 / 27.86
MZ8 / 829 / 26.88

Note: - MZ5 and MZ6 have been legally transferred to a third party and are not now included in the table above.

The results of the network analysis are tabulated in Appendix 5 and the node references are shown on drawing numbers:

S-G-MZ1

S-G-MZ3

S-G-MZ7

S-G-MZ8

There are no other technical specifications, procedures or arrangements relating to the management of the safe flow of gas or safety critical plant on the site.

It should be noted that the network analysis model is to be updated in 2018 to reflect the recent changes to the system.

6.OPERATION AND MAINTENANCE PROCEDURES

6.1Operational Procedures

Gas flows are managed by the pressure regulation equipment at the primary meter installations and these are owned and maintained by CADENT. There is no other associated plant on either the CADENT or the University systems that is likely to affect the safe flow of gas through the network. The University has installed its own Pressure Reduction Equipment in certain instances and this equipment is inspected and maintained in accordance with procedure KU/Gas/9 – Gas Governor Maintenance Policy

In the event of a plant failure onequipment affecting gas flows (e.g. a slam-shut failure or loss of pressure on CADENT’s system) an attempt will be made to maintain positive pressure within the affected section/s of the University network in the first instance by appealing to consumers to stop using gas.

Where there is a general requirement to reduce gas demand on the Campus then load shedding will be carried out in accordance with the schedule listed in KU/Gas/10 – Load shedding data sheets

If, after doing this, pressures fall below 19mb consumers, supplies will be turned off at the secondary meter emergency control valves.

If this is necessary, the University’s Gas Safe registered plumbers will be dispatched to turn off meter control valves. The University does not have a census of gas users but there are no at-risk institutions such as care homes and there are believed to be few elderly consumers on the site. (Please note the nursery is on CADENT supply)

If pressure falls to zero mbar, the section/s of the network affected will be isolated by closing the appropriate valves, disconnecting or squeezing off the mains concerned.

Before restoring gas flows, the isolated sections of the network will be tested, reconnected and then purged before restoring supplies to consumers (see Document KU/Gas/4 - Procedure for restoring gas supplies This work will be undertaken using competent contractors working to approved codes of practice (see section 10 Management of Contractors).