Carry out gas tightness testing and check system safety in small settings

Business Sectors (Suites): Downstream Domestic Gas Installation and Maintenance
Developed by: Energy & Utility Skills
Approved on: 01 Jan 2022


This standard is about carrying out gas tightness testing and checking system safety in small (including domestic) settings.  A small setting would have:
a maximum rated capacity through the primary meter of 16m3/h (U16), 
a maximum installation volume (IV) supplying an individual dwelling or non domestic premises of 0.035m3

It can apply to any type of fuel gas or combinations of fuel gas including, but not restricted to, natural gas, LPG, biogas, blended or 100% hydrogen. Methods of checking system safety will be by direct purging for natural gas but other techniques may be more appropriate for other types or combinations of fuel gas.

This standard should be used alongside any of the standards listed below:
EUSDSG6 Upgrade, modify and convert systems to alternative fuel sources in the gas industry
EUSDSG8 Install, service, repair and remove gas water heating and wet central heating
EUSDSG9 Install, service, repair and remove gas space heating appliances
EUSDSG10 Install, service, repair and remove gas fired ducted air heaters
EUSDSG12 Install and remove gas pipework in domestic settings
EUSDSG13 Install and remove gas meters and regulators in domestic settings
EUSDSG14 Install and remove positive displacement gas meters and regulators 

This standard is for gas engineers who work in small settings and for emergency first responders.

Performance criteria

You must be able to:

1. Confirm the entire pipework installation complies with manufacturers’ specifications and industry standards
2. Check that conditions within systems are safe to carry out required work activities
3. Use the correct tools, test equipment and other equipment for required work activities
4. Measure, calculate and record system installation volumes for required work activities
5. Ensure ventilation for required work activities meet industry standards’ requirements
6. Ensure existing systems are clean and free of debris
7. Minimise damage to customer property and building features whilst carrying out required processes
8. Use tightness testing procedures and appropriate test equipment to confirm the integrity of systems to industry standards
9. Use appropriate procedures to confirm the safe supply of fuel gas to installed systems and appliances
10. Resolve problems in accordance with approved procedures during required work activities 
11. Instruct property occupiers on the correct operation of systems, valves and components and appropriate actions to take during emergency situations, providing them with their copy of any literature
12. Use designated safe isolation procedures and warning notices to prevent the unauthorised use of un-commissioned or de-commissioned appliances, systems, electrical systems and components 
13. Liaise with property occupiers and other people who will be affected by the work to minimise disturbance to the job
14. Advise of any delays to the work, unsafe situations and required remedial actions to those who require the information
15. Check that customers are satisfied with the finished job
16. Complete required records and documentation 

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. Legislation covering your general responsibilities for your own safety and that of others
3. The limits of your own autonomy and responsibility
4. Gas industry unsafe situations procedures and how to isolate unsafe gas appliances, gas systems and components 
5. Potential hazards that could arise from all required work activities and checks to be carried out before work takes place
6. How to access and interpret normative documents, guidance documents, manufacturers’ instructions, industry standards, safety schemes and regulations
7. Industry practices, work standards, routines and sequences for gas tightness testing and checking system safety including appropriate test equipment 
8. How to measure, calculate and record gas system installation volumes 
9. The tools, test equipment, other equipment, materials and components required for the work and how to secure and store them
10. The test equipment and legislative requirements for applying tightness testing to gas systems, appliances and components
11. Safe isolation methods, tests, and procedures for gas and electricity systems, components and appliances including use of temporary continuity bonds, non-contact voltage detectors, voltage indicators, proving units, multimeters
12. Tightness testing procedures to confirm the integrity of newly installed gas system and, where applicable, new and existing appliances
13. Tightness testing procedures to confirm the integrity of existing installed gas systems and, where applicable, new and existing appliances to ensure installations don’t exceed the maximum permissible pressure drops
14. How to recognise medium pressure regulator sets and, whether or not a meter inlet valve (MIV) is fitted
15. Tightness testing procedures to confirm the integrity of gas systems including when a meter inlet valve (MIV) is fitted and is not fitted
16. Industry practices and procedures for tracing and repairing gas escapes
17. Process, procedures, routines, sequences, equipment and legislative requirements for checking safety of gas systems, appliances and components for the type or combination of fuel gas in use
18. Measures to prevent un-commissioned gas systems being brought into operation utilising safety and warning notices
19. Required records and documentation for the work activities
20. The system handover procedures and how to demonstrate the operation of gas systems and components to end users
21. Approved procedures for resolving problems during required work activities including system or component defects, systems and components do not meet design requirements and systems and components cannot be restored to full performance
22. Job management structures and methods of reporting and recording job progress or problems delaying progress
23. How to safely collect and dispose of system contents that may be hazardous to health or the environment
24. How to isolate unsafe gas appliances, gas systems and components and application of the gas industry unsafe situations procedure


Scope Performance

Scope Knowledge





Links To Other NOS

External Links

Version Number


Indicative Review Date

01 Jan 2025





Originating Organisation

Energy & Utility Skills

Original URN


Relevant Occupations

Domestic Gas Engineers, Emergency First Responders

SOC Code



strength, testing, gas, tightness, direct purging, utility, utilities