commercial gas pipework - excavation site with visible pipes

How To Make your Commercial Demolition Project Gas Safe

There is a legal obligation to carefully plan and carry out all demolition and dismantling projects in a way that minimises hazards and risks. There are multiple dangers including falls from height, uncontrolled collapse and injuries from falling materials. One of the biggest risks is posed by connected services such as water, electricity and gas.

Wherever possible, these services should be isolated and disconnected from the mains before the demolition begins. Here’s a look at what to consider when the building has a gas supply and gas-powered appliances. 

Carry out a risk assessment

A full risk assessment should be carried out beforehand to identify all potential supply lines. This should be done by a professional commercial gas pipework engineering company who have the correct knowledge and detection equipment. Contact the gas distribution network operator to discuss disconnection from the mains supply.

A failure to carry out a full risk assessment can lead to leak of toxic chemicals that pollute the environment and are harmful or even fatal to humans. Gas leaks can also cause explosions or fires that have serious consequences in terms of injuries, loss of life, and damage and disruption to businesses and communities. 

Carry out testing and purging

When gas lines are being decommissioned, it’s important to follow the correct testing and purging procedures. This will ensure that there is no gas or other combustibles remaining in the pipes that may present a leak hazard before they are removed or capped. Gas is a highly flammable substance when mixed with air and exposed to an ignition source.

Therefore, gas supply pipework or storage tanks that have not been purge tested during the decommissioning process are at a high risk of causing leaks, fires, or explosions. Purge testing involves introducing an inert gas such as nitrogen into the system to decrease the concentration of flammable gases. 

It’s highly recommended that this process is carried out by qualified gas safe engineers, because they will have the most accurate and up to date detection equipment to ensure that no unsafe levels of gas are left in the system. Standard gas detection systems are not considered to be reliable or sensitive enough for this purpose. 

There are two main methods of purging, usually referred to as direct and indirect purging. However they may also be referred to as displacement and dilution purging. Direct purging involves inserting inert gas (non-combustible) directly into a closed system. This flushes out the flammable gases to safe levels that will not cause an explosion when exposed to air. 

Indirect purging involves injecting an inert gas to dilute the levels of flammable gases in the system. Once the gas has been tested and is deemed to present no risk of fire or explosion when it comes into contact with an ignition source, it is discharged into the atmosphere. 

Purging is considered to be a very safe and effective method of removing unsafe levels of natural gas from the system during decommissioning or dismantling. The pipes, storage containers and other gas infrastructure should not be removed until this process has been carried out.

Inform suppliers and local authorities

You should always inform gas suppliers and local authorities about the work you intend to carry out. This will ensure that you comply with all the necessary legal requirements and guidelines, and that any relevant permits are in place.

Develop an emergency response plan

There should be an emergency response plan in place should any serious gas-related incidents or accidents occur during the demolition phase. The plan should include everyone who may be potentially affected by an incident, including all workers and visitors at the site, and surrounding businesses, shops, schools, hospitals, homes, and so on.

A risk assessment should be made prior to the work commencing to identify the most high-risk areas. All these areas should be flagged up with warning signs and wayfinding markers to the nearest emergency exits and outdoor meeting points. There should be a clear chain of command so that everyone is clear about their roles and responsibilities.

The plan should be communicated to all workers and visitors to the site through emails, notice boards, and in-person training sessions, and practice drills should be carried out to ensure that everyone knows what is expected of them. 

The plan should also be rolled out to the wider community, including neighbouring commercial premises, housing areas, schools, and emergency services. The site should have gas safety equipment including leak detectors, smoke alarms, and fire extinguishers that are in full working order and close to hand.

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