Having liaised directly with the Health and Safety Executive regarding the requirement for gas safety tightness tests, I have been advised of the following:
Whilst there is no actual requirement for routine gas tightness tests to be carried out, annual gas safety inspection tests do need to be carried out on commercial properties.
Annual industry safety tests would include testing flues and gas appliances to ensure that safety requirements are met. These tests would need to be conducted by engineers who are registered with the Gas Safety Register.
Instances where gas safety tightness tests are required:
In the event where the gas meter has either been replaced or damaged, gas safety tightness tests would need to be conducted by the provider.
In instances where there is evidence of a gas leak the Gas Emergency Service Provider would need to be contacted on 0800111999 where a gas safety tightness test would be conducted.
For further information regarding gas safety requirements, please find the relevant links below:
http://www.legislation.gov.uk/uksi/1998/2451/made