De-commission gas systems, installations and components in industrial properties

Business Sectors (Suites): Industrial and Commercial Gas Utilisation
Developed by: Energy & Utility Skills
Approved on: 30 Mar 2020


This standard is about de-commissioning gas systems, installations and components.  This could apply to temporary or permanent decommissioning.   It is for the industrial property part of the non-residential downstream gas industry.  It can apply to gas systems, installations and components for any type of fuel gas or combinations of fuel gas.   

It includes checking systems are safe for de-commissioning, identifying and resolving problems with gas systems, installations and components, liaising with people from other trades and carrying out temporary or permanent de-commissioning. Any person carrying out this role must have site specific competence relevant to the level of risk.

This standard is for those who de-commission gas systems, installations or components in non-residential downstream, industrial properties.

Performance criteria

You must be able to:

1. ensure that isolation is carried out by appropriate people before starting work
2. work in line with plans, safe systems of work and risk assessments
3. make sure appropriate permissions from relevant people and authorities are in place before starting de-commissioning activities
4. check that conditions within gas systems will permit safe de- commissioning
5. confirm with input services personnel that the integrity and conditions in associated electricity, water, ventilation and flue/extraction systems will permit safe de-commissioning
6. select and use tools and equipment that are appropriate for de-commissioning activities
7. use designated safe isolation methods, tests, and procedures to de- commission gas systems, installations and components
8. verify that associated electricity, water, ventilation and flue/extraction systems and components have been de-commissioned and removed in line with safety requirements
9. ensure that temporarily and permanently de-commissioned gas-fired plant and equipment, systems, and components do not present safety hazards
10. remove and disconnect gas systems, installations and components in line with job requirements
11. remove, dispose of and recycle waste materials and system contents in line with safety and environmental requirements
12. liaise with responsible person(s) and other people who will be affected by the work to minimise disruption to work
13. comply with authorisation and verification processes that ensure correct working practices on other input services
14. liaise and cooperate with people from other trades at appropriate points in the work 
15. advise all people who are affected by work about any delays as soon as they occur
16. report any delays in work schedules to job supervisors in line with agreed reporting procedures
17. advise responsible person(s) of any unsafe situations, and actions required to remedy those situations, without delay
18. complete required records and documentation for de-commissioning
19. rectify any deficiencies in gas input services, reporting those you cannot rectify to appropriate person(s)
20. verify and report deficiencies in electricity, water, waste water, ventilation, flue/extraction and fresh air systems in line with procedures
21. ensure that isolation is lifted by appropriate people once work is completed
22. interact with customers at appropriate times during your work

Knowledge and Understanding

You need to know and understand:

1. regulations and guidance governing health and safety in the workplace, environmental protection and the use of risk assessments
2. the implications on the environment of large amounts of hazardous waste from de-commissioning activities including gas clouds 
3. who to seek permission for de-commissioning work from including the people losing supply, health and safety executive, environment agency, aviation authority 
4. legislation covering the general responsibilities for own safety and that of others
5. the industry standards and stages involved in de-commissioning gas systems, installations and components 
6. how to use plans, safe systems of work and risk assessments
7. hazard operability standards, failure mode, deficit analysis and hazard identification for industrial plant
8. the implications of your work on industrial processes
9. the impact of gas systems on industrial processes
10. the use of dynamic risk assessment in emergency situations
11. the tools and equipment necessary to provide safe access to work at heights, or in restricted or confined spaces
12. methods of working which protect building décor, customer property and existing systems and components
13. care and maintenance requirements of tools and equipment, and checks for safe condition
14. tools, equipment, materials and components required for de- commissioning
15. how to secure and store tools, equipment, materials and components to meet safety requirements and minimise loss or wastage
16. potential hazards that could arise from all de-commissioning, activities and the checks to be carried out before work takes place
17. authorisation and verification processes, roles and responsibilities which apply to working with other input services and personnel
18. steps to take should materials, components, tools and equipment not be available on site 
19. how to access and interpret required information including statutory and normative documents, industry standards, guidance documents and manufacturers’ instructions 
20. the range and operation of gas systems, installations and components
21. who should carry out isolation of industrial gas systems, installations and components
22. the procedures for temporary and permanent de-commissioning of gas-fired plant and equipment and gas systems including use of temporary continuity bonds
23. the precautions and measures used to prevent de-commissioned gas-fired plant and equipment or gas systems being brought into operation, use of temporary locking devices, safety and warning notices
24. the need to liaise with others whose procedures or routines may be affected by the suspension of gas-fired plant and equipment and gas system operation
25. the points in the de-commissioning process where co-operation and liaison with other trades and affected people may be required
26. steps to take when problems arise in work activities
27. job management structures and methods of reporting and recording job progress or problems delaying progress
28. how to safely collect and dispose of waste products that may be hazardous to health or the environment asbestos, insulation, electrical/electronic items and those containing fluorinated gases
29. how access and interpret industry regulations regarding the safe disposal of system contents that may be hazardous to health or the environment
30. how to isolate unsafe gas-fired plant and equipment, gas systems and components 
31. procedures for completing de- commissioning records
32. how to communicate with customers and when it is appropriate to do so


Scope Performance

Scope Knowledge





Links To Other NOS

External Links

Version Number


Indicative Review Date

30 Mar 2025





Originating Organisation

Energy & Utility Skills

Original URN


Relevant Occupations

Building and Civil Engineering Technicians, Design and Development Engineers, Electrical Engineer, Engineering Professionals, Engineering Technicians, Heating and Ventilating Engineer, Mechanical Engineer, Plumbers, Planning and Quality Control Engineers

SOC Code



De-commission; gas; systems; installations; components; industrial properties; industrial; de-commissioning; resolve problems; de-commissioning checks; temporary de-commissioning; permanent de-commissioning; plant; equipment;