What is a Gas Tightness Test and When is it Needed?

Gas and gas appliances are an essential part of every home or business in the UK. Gas is used to provide heating and hot water, as well as for cooking purposes. Whether it is natural gas or LPG, using gas for domestic or commercial purposes is generally considered safe. However, it cannot be termed a zero-risk energy. 

It is often said that gas is safe as long as it remains confined within the pipes. It means the risk starts when it starts leaking out of a damaged pipe or a faulty gas appliance. The common risks associated with gas are fire and explosions, which are directly related to gas leaks. Another risk related to gas is carbon monoxide poisoning. Incomplete combustion of gas in a faulty burner result in the emission of harmful gas, known as carbon monoxide.

The situation worsens when carbon monoxide accumulates within the building due to blockages in flues and chimneys. One of the most reliable ways to ensure the safety of your gas system is to conduct a gas tightness test, which a Gas Safe-registered engineer should perform. It includes testing and checking if a gas leak exists in your gas system.

This blog will guide you through everything you need to know about gas tightness tests, including how they are conducted, when and why they are needed.

Understanding Gas Tightness Test

A gas tightness test, as the name suggests, is a procedure carried out to check if all the gas connections and joints are tight enough to avoid gas leaks. This test is performed on all gas installations, including pipework and appliances, to check for gas leaks or sudden loss of gas pressure. This is the basic test that must be performed whenever new pipework or a gas appliance is installed on a premises. It can only be conducted by a Gas Safe Registered engineer, who is specifically trained to perform this task.

Typically, a gas tightness test is aimed at:

• Confirming that there is no gas leak in any of the gas appliances and related installations, including the entire gas pipe network.
• To ensure that the entire gas system is capable of safely containing the gas pressure.
• To identify if a fault exists in the pipework or other gas fittings. It is also designed to identify any weak points in the gas pipes that are prone to leaks.
• To confirm and verify the safety of the installations for safe use by the residents.

The gas tightness test must be carried out on the entire system, from the gas meter to the end point where the gas is practically used.

Remember!

Only a Gas Safe Registered Engineer is authorized to conduct a gas tightness test. The Gas Safe Register is an official body responsible for registering gas safety engineers and issuing them a license to work on gas appliances and installations. Under the provisions of the Gas Safety (Installation and Use) Regulations 1998, any work conducted by a non-registered gas safety engineer would be termed illegal. Therefore, it is highly important, if not mandatory, for landlords to have a gas tightness test conducted by a Gas Safe Registered Engineer.

Process of Conducting a Gas Tightness Test

The process of conducting a gas-tightness test appears to be straightforward, but it involves several steps that must be followed precisely. It can be done by a professionally trained, Gas Safe registered engineer. The steps to be followed can be summarized as follows:

Initial Preparations

• The first thing to ensure is that the landlord turns off all gas appliances. 
• Ensure that you shut down the appliances that cannot be safely isolated from the system. 
• Shut off all naked flames near or around the gas appliances. 
• Ensure that there are no sources of ignition near the gas appliances and fittings.

Connecting a Manometer and Pressurizing the System 

A manometer is a device used to measure gas pressure. It comes in two different types, U-tube and Digital manometer. It depends on the choice of the Gas Safe Registered engineer, which one they prefer to use for conducting a gas tightness test on your gas system. Whatever type of manometer they select, it needs to be properly and safely connected to the gas meter testing point. It is entirely a technical process, which can only be conducted by a qualified gas engineer. Never try to do it yourself.

Once the manometer is connected securely, the engineer will pressurize the gas system by opening the main gas supply valve. Sometimes, engineers prefer to use air to apply pressure to the system while disconnecting the natural gas supply.

After applying pressure, the engineer will record the pressure as displayed on the manometer. 

Stabilization Time and Tightness Testing

• When the system is pressurized correctly, the engineer allows it to settle for a specific period of time. This is a crucial step in the entire testing process. It depends on the size and length of the gas system. The engineer is trained to set a perfect stabilization time, based on the gas pipework in your premises. It also depends on the temperature variations as well as minor fluctuations in incoming gas pressure. The correct setting of the stabilization period is therefore highly important.
• Once the pressure is stabilized, the next step is to monitor the pressure for a preset time interval.
• The engineer will record the pressure after a specific time period.
• A significant reduction in pressure is a clear indication of a leak or fault in the gas system. 
• If the pressure drops within the permissible limits, based on the system size and gas safety regulations, it can be assumed that there is no gas leak or system fault. 
• If the pressure drops beyond the permissible limits, the engineer is required to locate the exact site of gas leakage to fix it.
• Once the gas leak is detected and fixed, the engineer will repeat the gas tightness test to make sure that the gas system is now safe for use.

When a Gas Tightness Test is Needed

A gas tightness test is not a routine matter; it is needed when one or more of the following happens in your property:

When New Appliances are Installed 

A gas tightness test is mandatory whenever a new gas appliance is installed. It is also required if there is an alteration in the current installations, such as an addition or extension to the existing pipe network. Once a new appliance is installed or any alteration is made to the pipework, the system must not be used without conducting a gas-tightness test.

When Repair Work is Conducted

In the event of detecting any fault in any of the gas appliances or pipework, a Gas Safe-registered engineer must be engaged to rectify it. It also involves any fault detected in the performance of safety valves or any other related fittings. Once the repair work is complete, the system can only be used after a gas-tightness test has been conducted by a Gas Safe registered engineer.

When an Annual Gas Safety Check is in Process

Under the provisions of the Gas Safety (Installation and Use) Regulations 1998, landlords are legally required to conduct an annual gas safety inspection on the entire gas system installed in their rented properties. It is a prerequisite for getting a gas safety certificate. A Gas Safe-registered engineer also conducts this inspection. A gas tightness test is usually a part of this inspection. If not, ensure the engineer performs this test on gas appliances and pipework in your property during the annual gas safety inspection.

When You Suspect a Gas Leak 

Gas itself is odorless and colorless, hence it cannot be detected. To make it detectable, a chemical, mostly mercaptan, is mixed in it by the gas suppliers. It gives a smell similar to rotten eggs. If such a smell is noticed in your property, it is a clear indication of a gas leak. To handle this situation, you need to call a Gas Safe-registered engineer, who will perform a gas tightness test to detect and fix the gas leak. Don't use your gas appliances until the fault is fixed and the property is declared gas safe by the engineer.

Important

• A gas tightness test is essential before recommissioning the gas system. It is often necessary when a gas system remains turned off for an extended period.
• For commercial or industrial units, a gas-tightness test must be performed after regular intervals. It applies explicitly to catering businesses, factories, and other high-risk industrial setups.

Importance of Gas Tightness Test

• It prevents a gas leak. Whether it is a natural gas or an LPG cylinder, leaks pose a serious threat, including the risk of fire, explosions, and carbon monoxide poisoning. Therefore, conducting a gas tightness test may save you from potential damage or loss.
• For all landlords of rented properties, whether residential or commercial, a gas tightness test is a mandatory requirement under the Gas Safety (Installation and Use) Regulations. Therefore, the performance of a gas tightness test is also crucial for compliance with regulatory requirements.
• It brings peace of mind for landlords and homeowners. Knowing that your property is free from any threat of gas leaks is a reassuring and satisfying feeling. 
• A leak-free gas system is more energy-efficient, which has a direct impact on your annual energy consumption, thereby keeping your energy bills within reasonable limits.

Cost and Duration of Gas Tightness Test

• A gas tightness test typically takes around 30 minutes for a standard residential unit. The time duration may vary depending on the property's size and the length of the gas system. 
• The cost of a gas tightness test may vary on a case-by-case basis. Typically, the price ranges between £50 and £100 for a residential property.
• The cost may be slightly higher for commercial properties, starting at £100, based on the property's nature and size.
• If a gas leak is detected, an additional cost will be applied for fixing the problem.

Conclusion

Gas is safe when it remains confined within the pipework. It becomes dangerous when it starts leaking. Leaks may occur at any time, mostly from loose joints and connections, and more frequently from a damaged, corroded, or weakened part of a gas pipe. Gas tightness test is the only and best way to detect a gas leak. Although it is a simple test, it must be conducted only by a qualified Gas Safe-registered engineer, as it involves critical procedures. Gas is highly flammable; hence, it is essential to detect it in time, before it results in a significant accident, such as a fire or explosion.

A gas tightness test is compulsory if you suspect a gas leakage in your premises. Otherwise, it should be made part of the annual gas safety inspection. It is also essential when installing a new gas appliance or making alterations to existing pipework. Although it may incur a certain cost, it is crucial for the safety of your property and its occupants. Don't miss it, whenever it becomes due.