A Guide to Gas Tightness Testing

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A Guide to Gas Tightness Testing

(In accordance with IGE/UP/1:2003 with 2004 amendments & IGE/UP/1A: 2003)

This guide is designed to give an overview of the legal maintenance requirements of pipework installations, what's involved in gas tightness testing and the services Maintenance by Global offers.

Your legal obligations

The Gas Safety (Installation and Use) Regulations 1998 state:

"It shall be the duty of every employer or self-employed person to ensure that any gas appliance or installation pipework installed at any place of work under his control is maintained in a safe condition so as to prevent risk of injury to any person."

To ensure pipework is maintained in 'a safe condition', the Institution of Gas Engineers recommends that pipework systems be inspected at least every five years. Transco monitor correct gas pressures going into your premises but beyond the meter you have responsibility for the safety of pipework. Gas tightness testing can prevent the potentially disastrous effects of leaks, preventing injury, saving lives and greatly reducing the risk to property from explosion and fire. In 2003/4, 136 dangerous incidents involving incorrect pressures in internal gas pipework systems were reported to the Health & Safety Executive. Gas tightness testing doesn't occur very often, but it should be considered an essential part of every company's health & safety policy.

What Happens during a Gas Tightness test?

Gas tightness testing will:

  • reveal any leaks in the system;
  • find any potential risks from incorrect pressures;
  • spot wear and tear before it becomes a hazard.

In order to correctly calculate the leakage rate for your gas installation, you need to provide the engineer with a plan of the system, including the pipe sizing and lengths of pipes.

The Service offered by Maintenance by Global

Maintenance by Global's gas engineers are Gas Safe registered and qualified to work on industrial and commercial pipework and appliances. The procedures they follow during a gas tightness test are carried out in accordance with the strict guidelines set by the Institute of Gas Engineers.

To prepare a system for gas tightness testing the engineer will:

  • Undertake a thorough survey of the pipe work to detect any major defect. The environment in which the pipe work is installed and other appropriate safety considerations will also be noted.
  • Check the accuracy of any plans, any other information provided and the mechanical integrity of installations.
  • Calculate the installation volume, which involves surveying the whole of the installation to be tested including pipe work and other components.
  • Determine the test pressure, which should be at least the maximum operating pressure, in order to detect leaks and to check safe operation at pressures which may occur in the installation.
  • Select an appropriate pressure test gauge before calculating the permitted leak rate.
  • Calculate the test period taking into account that a large installation may need to be sectioned.
  • Plug, cap or spade off all valves to and from the section and leave in the open position, so that the test will be made against the sealed ends.
  • Ensure that there are no major leaks on the installation pipe work by using a gas detector or a leak detection fluid.
  • Close any appliance isolation valves.
  • Close the isolation valve upstream from the section under test.

To test a system, the engineer will then undertake the following routine:

  • Set the pressure in the test section to 50 per cent of the maximum operating pressure. It is important to ensure that test pressure does not exceed the design pressure of any particular component.
  • Observe the pressure gauge for the first test period. Provided the pressure does not rise to more than the minimum gauge reading during the test period the upstream isolation valve may be assumed to be satisfactory for the purposes of this test only. If the valve is unsatisfactory it should be capped or plugged and consideration given to valve repair or replacement.
  • Raise the pressure in the test section gradually to the final test pressure.
  • Allow the temperature to stabilize for the test period or for 15 minutes, whichever is the longer. The source of the pressure should now be isolated.
  • Observe the pressure gauge for the test period.
  • De-pressurize any sections where spades and caps have been fitted. Remove the spades and test any reconnections with a suitable detection fluid.
  • As a precautionary measure, on completion of the test, all joints situated in potentially hazardous areas will be tested for leaks with a suitable detection fluid.
  • Calculate the leak rate and if this exceeds the permitted rate the User should be notified and any leaks isolated and rectified.
  • A gas safety inspection certificate will be completed and issued to the User, ensuring the correct type for the premises inspected. The inspection shall prove and record the integrity of the pipework system.

Maintenance by Global recommends that testing only takes place when temperature conditions or, in the case of exposed pipe work, weather conditions remain stable.

Other Gas Services offered by Maintenance by Global

Maintenance by Global also offers a number of other services for gas installations, including boiler strip-downs, replacements, servicing and breakdown response, commissioning, ventilation and flue arrangement checks and all statutory requirements under the Gas Safety Installation & Use Regulations 1998.

Our engineers are fully qualified to work on all kinds of direct and indirect fired gas units and our combustion analysis equipment allows accurate adjustments for optimum performance and operating pressures on atmospheric or packaged (blown) units.

Fault Finding

We offer a full breakdown and fault finding service for all types of process equipment covering boilers, radiant heaters, gas pipe-work, digester boilers, control systems and burners.

For customers with a maintenance plan with Maintenance by Global our response to breakdowns is normally the same day, and within 2-4 hours of receiving a call for gas leaks.


We can undertake the on-site commissioning of all types of boilers and process equipment in industrial and commercial premises.

Our special areas of expertise are:-

  • Boiler house plant
  • Legionella control systems for large domestic hot water circuits
  • Pipe-work systems (gas, oil, compressed air, steam condensate).
  • Planned maintenance.

A whole series of Guides to... are available on request, covering all aspects of our building services and outlining the recommendations for testing and maintenance according to the legal regulations and industry-approved codes of practice. For copies, or a free, no-obligation quotation, contact us