General precautions: what GSIUR Parts A and B require

Parts A and B of the Gas Safety (Installation and Use) Regulations apply to gas work of every kind: who may do it, and the precautions that go with it.

Where the regulations apply

• Excluded places, with one exception. Factories, mines, quarries, agricultural premises, temporary construction installations such as site huts, test premises and sewage works are outside GSIUR. Any part used as a home or for sleeping is still covered, such as a caretaker's flat at a factory. Gas work in excluded places still needs competence under the Health and Safety at Work etc Act.
• Caravans and boats. A touring caravan is outside GSIUR unless it is hired out by a business. Static caravans and park homes, a caravan used as a granny annexe and caravans housing staff are covered. A boat that needs no load line is covered when it is hired out, used for a business serving the public, or lived on, such as a houseboat; private leisure boats, waterway workboats, sea-going ships and hovercraft are not.
• Vehicles. Self-propelled vehicles are outside GSIUR unless hired out or used for a business serving the public from them, so a burger van or other mobile food stall serving the public is covered. Gas supplied to a vehicle's engine is outside it.
• What counts as work. Connecting or disconnecting a bayonet or other self-sealing connector is not gas work, so pulling a freestanding cooker out to clean behind it is not; installing the cooker is. Replacing a consumer control, such as an electric time switch or thermostat, is outside GSIUR if no gasway is broken into, but it must still be done competently.

Relighting a burner or pilot with the normal user controls is not gas work. Purging, repairs or other gas work needed to get the supply back still are. If the supply may have stopped because of a fault, find the fault: relighting again and again does not fix it.

The training-centre exceptions apply only in the training or assessment setting the regulations describe. A trainee working on a customer's installation comes under the full regulations, and needs the right competence, instruction and supervision.

Who may do the work

• Competence applies to everyone. No person may carry out work on a gas fitting unless competent to do it (regulation 3(1)). That includes a householder working on their own home.
• Registration applies to business work. An employer's staff and self-employed people may do gas work only if they belong to the class of persons approved by HSE, which is Gas Safe registration (3(3)).
• Two named exemptions from registration, not from competence: replacing a hose or regulator on a portable or mobile space heater, and replacing a hose that connects a refillable cylinder to installation pipework (3(4)).
• Registration is category-specific. ACS certificates show competence in the categories held; they do not let a business do gas work. If a job falls outside your registered scope, decline it and refer it to someone registered for that work, even if it looks simple, the customer presses you or you want to help.
• Private work needs its own registration. An engineer employed by a registered firm who also takes jobs on their own account must be Gas Safe registered in their own right.
• LPG storage. Changing cylinders, filling a tank or setting a tank in position needs competence but not registration; connecting a tank to its service pipework is registered work.
• Checking a contractor. A business that has gas work done at a workplace it controls must take reasonable steps to check the contractor is Gas Safe registered (regulation 4).

Materials

• Every part of a gas fitting must be of sound material and construction, adequate strength and size, and suited to the gas it carries.
• No new lead or lead-alloy gas pipe may be installed in a building (5(2)). Existing lead pipe in a safe condition may stay, and appliances or meters may be connected to it with suitable fittings.
• Non-metallic pipe normally stays outside the building. Regulation 5(2) allows two exceptions: a connection to a readily movable appliance made for use without a flue, and the indoor length of a pipe entering from outside inside a correctly made and fitted metal sheath. If that pipe fails, the sheath must stop gas getting into the building so far as reasonably practicable.

Deterioration and blockage

A part's stated service life is a safety limit. The part may show no damage before it becomes dangerous, so replace a limited-life fitting before that period ends, unless it has been shown to be safe for longer. Ask the manufacturer whether the life can be extended, what examination or testing that needs, and for how long at most. A warranty date, a tidy appearance or an old tightness test result does not answer that.

Think about what could get into the equipment. Where dirt or debris could block a gas inlet or an airway, fit a suitable filter or other protection on each path at risk. The protection must suit the fitting, and a filter on the gas side does nothing for a separate air passage.

Think about the surroundings too. Damp, chemicals and coastal salt cause corrosion, so use a material that resists it or protect the fitting. A coating must not stop the fitting working safely: keep clear any openings or moving parts it relies on.

While the work is going on

• Never leave a fitting unattended with an open gasway. Seal every open end with the right fitting, such as a cap or plug made for the pipe, unless the fitting is otherwise safe. Whoever disconnects a fitting must seal every outlet of every pipe it was connected to (6(2) and 6(3)).
• No smoking or other ignition source where gasways are exposed, and no ignition source at all when searching for an escape.
• Before using a blowtorch on pipe that has contained gas, isolate it and purge the gas out.
• If the work could have affected tightness, test for gas tightness straight away. The test must at least cover the section between the closest valve on each side of the work, and it can cover more of the installation (regulation 6(6)).
• Where needed to prevent danger, a suitable bond keeps electrical continuity across a break in metal pipework until permanent continuity is restored.

Where gas equipment may not go, and alterations

• No gas storage vessel, and no LPG appliance with automatic ignition or a pilot light, may be installed in a cellar or basement.
• No one may alter a building so that an existing gas fitting would break the regulations if it were installed after the alteration (8(1)). The duty falls on whoever makes the alteration, builders included. For example, a conservatory built over a room-sealed flue terminal would send products of combustion into an occupied space. Either the plan changes, or a registered engineer re-routes the flue first.
• Before a chimney is capped or lowered, find out whether a gas appliance still uses it. If one does, a registered engineer must disconnect the appliances first and test them after the work.
• Regulation 8(2) binds everyone, not just engineers: a decorator or householder must not block a vent or flue that a gas appliance relies on.

Emergency controls

Gas may not be supplied to premises for the first time unless there is a suitably sited, accessible emergency control. Its lever lies parallel to the pipe when open, and its open and shut positions are marked. Unless it is beside a primary meter, a permanent notice near it must say what to do if gas escapes.

Common mistakes

• Leaving an open end taped, behind a closed valve, or with a note to the occupier: each leaves an open gasway that can be opened or leak.
• Testing only the new joints or the new section: disturbed joints that were not remade can fail just as easily. Testing the whole installation meets the minimum and is often the practical choice.