Third Quarter, 2006
Recently, we were involved in the investigation of an explosion that occurred in a residential structure. The fact that an explosion has occurred is not, by itself, unusual. The use of propane gas, the piping used to supply gas to the appliances, and the operation of appliances were also found to have been items in common use. However, although copper tubing is in common use with both natural and propane gas systems, its use is actually prohibited by the National Fuel Gas Code. The chemistry is such that additives like the compounds used to odorize the fuel will cause corrosion of copper. Specifically, hydrogen sulfide will attack the copper tubing and over a period of years will result in gas leakage. It should be noted that ethyl mercaptan, the odorizing ingredient in propane and natural gas contains both sulphur and hydrogen and for this reason is corrosive to copper.
Throughout the state of Tennessee, copper tubing can be found in natural gas and propane fuel systems. Why is the use of copper tubing permitted? The truth of the matter is that copper tubing has been used for so long that no one questions it use, although aluminum tubing is an acceptable substitute and is easily obtained. In addition, in many areas of the state, no permits are required and no licensed contractor is required to do the work. The only requirement imposed on the installer may be to contact the local gas utility for a final inspection. This was the case in the explosion previously mentioned. The codes and the people who should be enforcing the codes aren't necessarily in place. As a result, a gas leak developed where the copper tubing had corroded. Propane gas then filled the space between the floor and ground. Some of the gas found its way into the living space where it was subsequently ignited by a standing pilot in a space heater.
So, who's at fault? It is a well known fact that a property owner is responsible for the care and maintenance of his property. But, how many homeowners are aware of the corrosive effect that ethyl mercaptan has on copper tubing? Instead, property owners rely on the expertise of those who are actively engaged in the business of servicing gas fired equipment. In this case, the gas utility. The utility was contacted and reports of a gas smell reported two times in the same year. Both times the utility tested its tank but did not test the copper piping or examine the gas appliances. The utility company's position is that its responsibility is to get the gas to the consumer and ends at the tank or gas meter. However, when the question of a gas leak arises, the utility has a responsibility to its customers and the public in general to make sure that gas leaks are found and stopped, regardless of who performs the repairs. But the utility personnel failed to test the piping and the consequences were disastrous. Luckily no one was killed.
The explosion could have been avoided if the leak had been located and repaired or more importantly, if copper tubing had never been used. But it was used and as long as copper tubing remains in use with natural gas or propane fuel systems, the potential for gas leaks and subsequent explosions will remain a constant threat.
|