Natural Gas is a hazardous material commonly found in nearly every structure in the USA. It is so abundant that many have lost respect for this highly flammable gas. I deal with NG nearly every month, either as a utility to appliances within a facility or as a “critical utility” to a PSM/RMP-covered process. Recently, a facility experienced a severe leak, which triggered an “emergency shutdown” of several processes and the evacuation of a portion of the facility. This leak was caused by “failure to meet code” during a major NG project in one of the units. The International Fuel Gas Code and NFPA 54 – National Fuel Gas Code require that:
7.7.2 Each outlet, including a valve, shall be closed gastight with a threaded plug or cap immediately after installation and shall be left closed until the appliance or equipment is connected thereto. When an appliance or equipment is disconnected from an outlet and the outlet is not to be used again immediately, it shall be capped or plugged gastight.
The importance of this requirement cannot be stressed enough. Fires can be caused by gas leakage from open pipes in buildings. They can also occur during construction, where a pipe end is not plugged or capped prior to turning on the gas. This often happens because there is an intent to plug the opening the next day, but it does not happen. If the gas system is not pressure tested, the open end may not be found. Fires can also occur where an appliance has been removed, and the gas valve is turned off but not plugged or capped. The valve, usually a quarter-turn valve, is accidentally opened by coming into contact with moving furniture or by some other unintentional contact.
All these accidents can be prevented by capping or plugging pipe ends and valves when the appliance is not connected and immediately after removal or disconnection.
Exception No. 1 of 7.7.2.1. Laboratory equipment, such as a Bunsen burner, is connected and disconnected from hose-end valves as a normal, everyday operation. Laboratory equipment is exempted from the requirement for a plug or cap because of the frequency of use and the requirement in 7.8.3.3 for a single shutoff valve serving the entire laboratory.
Exception No. 2 of 7.7.2.1. Listed quick-disconnect devices, as shown in Exhibit 7.22, and gas convenience outlets are not required to be capped or plugged.
Quick-disconnect devices are specially designed fittings used to provide a fast and automatic shutoff upon disconnection. Hand-operated (without the use of tools), they replace threaded and flanged connections. The device works by having an internal valve that opens and closes as needed. Quick-disconnect devices are very useful when used on equipment or appliances that are altered or moved frequently.
Each outlet, including a valve, shall be closed gastight with a threaded plug or cap immediately after installation and shall be left closed until the appliance or equipment is connected thereto. When an appliance or equipment is disconnected from an outlet and the outlet is not to be used again immediately, it shall be capped or plugged gastight.