AS 4645-2005

1 - AS 4645-2005 GAS DISTRIBUTION NETWORK MANAGEMENT - GAS DISTRIBUTION NETWORK MANAGEMENT
4 - PREFACE
6 - CONTENTS
8 - SECTION 1 SCOPE AND GENERAL
8 - 1.1 SCOPE
8 - 1.2 EXCLUSIONS
10 - 1.3 RETROSPECTIVE APPLICATION OF STANDARD
11 - 1.4 REFERENCED DOCUMENTS
11 - 1.5 PRESSURE CLASSIFICATIONS
11 - 1.6 DEFINITIONS
11 - 1.6.1 Actual thickness
11 - 1.6.2 Approved
11 - 1.6.3 Authority
11 - 1.6.4 Casing
11 - 1.6.5 Consumer piping
11 - 1.6.6 Fuel gas
11 - 1.6.7 Inspector
11 - 1.6.8 Internal design pressure
12 - 1.6.9 Liquefied petroleum gas/LP Gas
12 - 1.6.10 Main
12 - 1.6.11 Maximum allowable operating pressure (MAOP)
12 - 1.6.12 Monitoring regulator
12 - 1.6.13 Network
12 - 1.6.14 Network operator
12 - 1.6.15 Nominal thickness
12 - 1.6.16 Odorization
12 - 1.6.17 Pressure
12 - 1.6.18 Pressure design thickness
12 - 1.6.19 Pressure-limiting station
12 - 1.6.20 Pressure-regulating station
13 - 1.6.21 Pressure-relief station
13 - 1.6.22 Regulator
13 - 1.6.23 Required thickness
13 - 1.6.24 Service
13 - 1.6.25 Service regulator
13 - 1.6.26 Shall
13 - 1.6.27 Should
13 - 1.6.28 Specified minimum yield stress (SMYS)
13 - 1.6.29 Statutory authority
13 - 1.6.30 Thickness
14 - SECTION 2 NETWORK SAFETY
14 - 2.1 GENERAL
14 - 2.2 SAFETY AND OPERATING PLAN
14 - 2.3 SYSTEM MANAGEMENT
14 - 2.4 COMPETENCIES
14 - 2.5 RECORDS
16 - SECTION 3 NETWORK PLANNING
16 - 3.1 GENERAL
16 - 3.2 FUNCTIONAL REQUIREMENTS
16 - 3.3 BASIS OF DESIGN
17 - SECTION 4 NETWORK DESIGN
17 - 4.1 GENERAL
17 - 4.2 DESIGN PRESSURES
17 - 4.3 NETWORK DESIGN DETAILS
17 - 4.3.1 Safety assessment of route
17 - 4.3.2 Materials and components
18 - 4.3.3 Pressure control
19 - 4.3.4 Meter/regulator specification
19 - 4.3.5 Pipe wall design thickness
20 - 4.3.6 Design of depth of cover and underground protection
20 - 4.3.7 Pipe identification and warning system, and contents identification
20 - 4.3.8 Design for natural hazards, and crossings
20 - 4.3.9 Additional requirements for LP Gas systems
21 - 4.4 DESIGN ELEMENTS OF MAINS AND SERVICES, AND ASSOCIATED PIPEWORK
21 - 4.4.1 Mains
21 - 4.4.2 General design of internal service lines and risers
22 - 4.4.3 Associated pipework
22 - 4.4.4 Corrosion mitigation of buried steel pipe
24 - SECTION 5 CONSTRUCTING, TESTING, COMMISSIONING
24 - 5.1 GENERAL AND DOCUMENTATION
24 - 5.2 SEPARATION FROM OTHER UNDERGROUND STRUCTURES
24 - 5.3 COATING FOR BURIED METAL PIPE
24 - 5.4 PIPE INSTALLATION METHODS
24 - 5.4.1 General
24 - 5.4.2 Trenched installation
25 - 5.4.3 Trenchless installation
25 - 5.4.4 Insertion
25 - 5.5 TESTING
25 - 5.5.1 Mains and Services
26 - 5.5.2 Over-pressure protection
26 - 5.6 COMMISSIONING OF GAS MAINS
26 - 5.6.1 General
26 - 5.6.2 Planning
27 - SECTION 6 OPERATING AND MONITORING
27 - 6.1 PRE-OPERATING REQUIREMENTS
27 - 6.1.1 Completion of preparations
27 - 6.1.2 Plans and procedures
27 - 6.1.3 Responsible personnel
27 - 6.1.4 Hazards, and safe practices
28 - 6.1.5 Venting procedures
28 - 6.2 OPERATING AND MONITORING
28 - 6.2.1 Maximum allowable operating pressure
28 - 6.2.2 Damaged pipe or component
28 - 6.2.3 Odour
29 - 6.2.4 Public reporting of leaks
29 - 6.2.5 Leakage surveys
29 - 6.2.6 Response to leak reports and surveys
29 - 6.2.7 Network pressure and flow control monitoring
29 - 6.2.8 Route monitoring
29 - 6.2.9 Locality monitoring, and asset location information
30 - 6.2.10 Valve operability monitoring
30 - 6.2.11 Monitoring of system performance, growth, pressures, flows and fringe points
30 - 6.2.12 Inspection of structures housing gas equipment
30 - 6.2.13 Special inspections
30 - 6.3 REVIEWS, REPORTS AND ANALYSIS
30 - 6.3.1 Leakage reports, review and analysis
30 - 6.3.2 Corrosion protection review
31 - 6.3.3 Incident reporting, review and analysis
31 - 6.3.4 Risk reviews
32 - SECTION 7 MAINTAINING AND REPAIRING
32 - 7.1 GENERAL
32 - 7.2 REPAIR OF COATING OF BURIED METAL PIPE
32 - 7.3 MAINTENANCE AND REPAIR OF COATING ON ABOVE-GROUND PIPEWORK
32 - 7.4 STEEL-CASED CROSSINGS
32 - 7.5 WORK ON GAS MAINS
32 - 7.5.1 General
32 - 7.5.2 Purging mains and services
34 - SECTION 8 MODIFYING
34 - 8.1 DESIGN OF MODIFICATIONS
34 - 8.2 CONSTRUCTION, TESTING AND COMMISSIONING OF MODIFICATIONS
35 - SECTION 9 DECOMMISSIONING
35 - 9.1 MAKING SAFE
36 - APPENDIX A - LIFE-CYCLE OF NETWORK
36 - A1 PLANNING
36 - A2 DESIGN
36 - A3 CONSTRUCT, TEST AND COMMISSION
36 - A4 OPERATE, MONITOR, MAINTAIN, REPAIR AND MODIFY
36 - A5 DECOMMISSION
37 - APPENDIX B - REFERENCED DOCUMENTS
38 - APPENDIX C - MATERIALS, COMPONENTS, AND DESIGN CONDITIONS GUIDELINES
38 - C1 GENERAL
38 - C2 MATTERS THAT SHOULD BE INCLUDED FOR CONSIDERATION
38 - C2.1 Materials comprising active metals
38 - C2.2 Materials in associations resulting in bi-metallic corrosion
38 - C2.3 Designs and configurations leading to crevice corrosion
38 - C2.4 Components in plastics
38 - C2.5 Materials adversely affected by solvents
38 - C2.6 Materials comprising passive alloys
38 - C2.7 Materials that are free machining alloys
38 - C2.8 Materials that are dezincification resistant alloys
39 - C2.9 Designs and configurations leading to stress concentrators
40 - APPENDIX D - CONTROL OF GAS PRESSURE
40 - D1 GENERAL
40 - D2 MAXIMUM ALLOWABLE OPERATING PRESSURE OF SYSTEM
40 - D3 PROTECTION FROM EXCEEDING MAOP
40 - D4 REGULATING CAPACITY
40 - D5 LOCATION OF PRESSURE CONTROL EQUIPMENT
41 - D6 DESIGN OF REGULATING DEVICES
41 - D7 DESIGN OF VENTS
41 - D8 NOISE CONTROL
42 - D9 PRECAUTIONS AGAINST FREEZING
42 - D10 PROTECTION OF REGULATORS FROM SOLID MATTER IN GAS
42 - D11 INTEGRAL OVER°PRESSURE SAFETY DEVICES
42 - D12 TYPES OF OVER-PRESSURE SAFETY DEVICE
43 - D13 PREVENTION OF UNAUTHORIZED OPERATION
43 - D14 SERVICE REGULATOR INSTALLATIONS
43 - D15 SERVICE REGULATORS
44 - D16 FAILURE OF EQUIPMENT
45 - APPENDIX E - MARKERS AND MARKING
46 - APPENDIX F - EMERGENCY PLANS
46 - F1 GENERAL
48 - APPENDIX G - CLASSIFICATION OF LEAKS
48 - G1 GENERAL
48 - G2 CLASSIFICATION
48 - G2.1 Class 1
48 - G2.2 Class 2
48 - G2.3 Class 3
50 - APPENDIX H - PIPE IDENTIFYING, LOCATING AND WARNING SYSTEM ELEMENTS

Specifies the requirements for safe management of a fuel gas distribution network throughout the life cycle of all elements of that network. The requirements apply to the life cycle of new assets in new or existing systems, but the Sections on operations, maintenance, repair and decommissioning are suitable for application to existing assets in existing systems.

This Standard specifies requirements for safe management of a fuel gas distribution network throughout the life cycle of all elements of that network.AppendixA describes life-cycle phases.The requirements apply to the life cycle of new assets in new or existing systems, but the Sections on operations, maintenance, repair and decommissioning are suitable for application to existing assets in existing systems.Gas distribution networks within the scope of this Standard comprise of all facilities between the outlets of all city gate supply points or equivalent (being wherever pressure is reduced to below 1050kPa), or for an LP Gas network the point of entry to the network operator’s facility, and the outlet of the consumer’s meter assemblies, as detailed in Figure1.2.Detailed requirements for design and materials, construction, testing and commissioning of steel and plastic mains and services within a network, are specified by reference to—AS1697 for steel mains and services; andAS3723 for plastic mains and services.Details for design and maintenance of gas control plant and equipment associated with the distribution network are specified by reference to—AS4041 for design of above ground steel pipework and facilities; andAS3873 for maintenance of above ground facilities.Some requirements of this Standard are suitable for consumer piping operating at >200kPa, being not otherwise provided in AS5601. The operator of such piping should decide which requirements are appropriate, and should obtain any necessary agreement from the regulator having jurisdiction over the operation of that piping.The relevant technical regulator may regard this Standard as appropriate for other than fuel gas.AG606 (to be AS 4568) provides guidance for preparation of a Safety and Operating Plan for gas networks.

First published November 1978.This edition April 1982 (incorporates amendments to June 2003) .Revised and redesignated as AS 4645-2005. Originated as AG 603-1978. Previous edition 1982. Revised and redesignated as AS 4645-2005.