GIUSP: defect classification and safety actions

Two unsafe categories

The Gas Industry Unsafe Situations Procedure (GIUSP) classes an unsafe gas appliance or installation as one of two things:

• Immediately Dangerous (ID): an immediate danger to life or property if it stays connected to the gas supply. Typical causes are gas escapes, combustion products entering the room, and serious flueing, ventilation or combustion faults. It does not have to be running: a gas escape is dangerous with every burner off.
• At Risk (AR): one or more faults that could become a danger to life or property in future. Inadequate ventilation is the classic example.

Check the installation against the manufacturer's instructions first; where there are none, assess it against the current standards. The examples below are common cases, not a complete list. Your assessment on site decides, including the combined effect of several small defects, and if you are unsure you seek further guidance.

Typical ID situations

• A correctly performed tightness test still fails the applicable criterion after set-up and stabilisation are checked, or a gas smell remains despite a pass. A valid failure is ID while the engineer investigates its section and cause; one falling gauge reading does not locate a leak.
• There is evidence that combustion products have escaped from a flued appliance or its flue, with no evidence that the problem has been corrected.
• An appliance that should be flued is not flued.
• A room-sealed flue terminates inside the building, for example into a conservatory.
• Pipework has an open end, or is made of an unsuitable material such as hose or plastic water pipe.
• A safety device such as a flame supervision device is disabled, inoperative or failing to danger.
• A flueless or open-flued appliance is installed in a room containing a bath or shower.
• The appliance is not suitable for the gas supplied.
• A joint or fitting is made from unsuitable materials, such as tape wrapped round the outside of a joint to seal it or an improvised connector. It is ID even if it is not leaking when you arrive, because the chance of it causing a serious incident is very high.

Typical AR situations

• Purpose-provided ventilation is less than required. For an existing installation, at least 90% of each ventilator requirement is accepted when the appliance otherwise works safely and correctly.
• A ventilator can be closed, or has a gauze or fly screen fitted.
• An open flue is incomplete or damaged but products are not entering the building, such as a missing terminal or a missing gas fire closure plate.
• A flued appliance gives unsatisfactory combustion readings, or shows signs of incomplete combustion, without spillage. Spillage makes it ID.
• An appliance on a sealed heating system has no effective pressure relief.
• A gas fire, space heater, water heater or boiler that is not room-sealed is in a room used for sleeping, such as a bedroom or bedsit, and is either over 14 kW gross heat input or 14 kW or less without a built-in atmosphere-sensing device (which shuts the burner off before combustion products build up to a dangerous level). Compare a room containing a bath or shower, which is ID.
• An appliance is insecure or unstable enough to be potentially unsafe, such as a freestanding cooker that could tip forward. If a cooker remains stable under foreseeable use, a missing bracket or chain by itself does not make it AR. Record the omission and recommend a suitable restraint.

What happens next

First try to put the fault right, with the gas user's agreement. If you cannot:

• ID: with permission, disconnect and seal the supply, attach a DANGER DO NOT USE label and complete a warning notice. If the user refuses, turn the appliance off where you can and call the Gas Emergency Contact Centre, or the gas supplier for LPG.
• AR: with permission, turn the gas off, attach a DANGER DO NOT USE label and complete a warning notice.
• AR where turning off will not reduce the risk, for example a building constructed over a polyethylene gas service pipe or an incorrectly sited LPG bulk tank: explain why, give a warning notice saying who to contact, and do not attach a label.

An appliance that cannot be fully commissioned must not be left connected: disconnect it, seal the supply and label it not to be used until it has been commissioned.

After repairing a gas escape, prove the affected section tight before returning it to use. Where the work may have admitted air, follow the applicable purge procedure before relighting. Tightening a joint alone does not establish soundness.

What about NCS?

"Not to Current Standards" (NCS) is no longer a GIUSP category. If something falls short of a current standard but you have judged it safe, record it as advice, separately from the unsafe procedure. Being old, having worked for years or passing one test does not make an installation safe.