Posted By Ken Taylor This sort of question is always difficult to answer without seeing the site in question (and sometimes even then!). It is essentially a matter of risk assessment but I would be unhappy about a situation where hot work could impinge upon gas-carrying pipework or in such proximity to gas valves that it would be within fire or explosion air concentrations in the event of gas escape or letting-by. I would suggest that the Fire Authority would be better judges of the situation than the HSE - particularly as they enforce the legislation for fire risk assessments. Have you asked a local Fire Prevention Officer to visit?.

Posted By John Webster I agree that it would be difficult to answer this one without seeing the premises, and a visit from your local fire prevention officer is recommended. However, when you are looking at risk, then consider what parts of your gas system pose the greatest risk of escape. I would suggest that your distribution system/pipework is low risk - certainly no greater than in any other industrial, commercial or even domestic premises. It is likely to be at low pressure. If the pipework is safe from mechanical damage, the main potential leakage points are at the valves to the heaters, flexible connections and associated glands. A regular inspection programme should control this risk. In the event of escape whilst the premises are occupied, the smell of gas SHOULD be detected long before an explosive atmosphere is reached (not that we can always rely on smell - the nose is one of the most sensitive gas detectors on the market, it's just not the most reliable). So we come to your "nest" of pipes and valves. I assume this is where the mains comes in, and is regulated and metered. Regular inspection is again the key to safety, as well as protecting the equipment from mechanical damage. Incoming gas is at higher pressure, and the risk of escape, though still small, is higher than elsewhere in the system. Regulator diaphragms can, though rarely, rupture. More likely are small weepages from valve stems etc. For added peace of mind, would it be possible to enclose the "nest", and ventilate the space externally? (I don't expect anybody to follow this control measure, but perversely, it can in practice be safer to have lots of sources of ignition in close proximity to a potential escape - that way the leak will ignite before an explosive atmosphere fills a large area!!! However, if driving at 80 mph it is safer to drive 6inches behind the car in front than 20feet behind - and I have come across quite a few people who actually use this, some of them on motorbikes :-).) John

Posted By Phil Roberts Dave , have you thought about the installation of a gas monitoring system that would indicate a leak long befor an explosive atmospher was reached. There are several on the market both battery and mains powered. They can be calibrated to measure very low concentrations down to 2 or 3 ppm. Regards Phil