If you are a regular visitor to this site, you know I love to use the International Fire Code, which many states adopt in full or in some “revised” langauge as their “state fire/hazmat code”. One particular item that garners a lot of questions and comments is the IFC’s requirement that ALL hazardous materials (those with toxic or physical hazards) be in piping constructed per ASME B31.3 and labeled per ASME A13.1. This also includes a requirement that “Backflow prevention or check valves shall be provided where the backflow of hazardous materials could create a hazardous condition”. This OSHA case file is a good example of how this requirement would apply to a chemical process.
First, here are the IFC requirements for the piping, tubing, valves, and fittings…
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5003.2.2 Piping, tubing, valves and fittings. Piping, tubing, valves, and fittings conveying hazardous materials shall be designed and installed in accordance with ASME B31.1 or other approved standards, and shall be in accordance with Sections 5003.2.2.1 and 5003.2.2.2. 5003.2.2.1 Design and construction. Piping, tubing, valves, fittings and related components used for hazardous materials shall be in accordance with the 1. Piping, tubing, valves, fittings and related components shall be designed and fabricated from materials that are compatible with the material to be contained and shall be of adequate strength and durability to withstand the pressure, structural and seismic stress and exposure to which they are subject. 2. Piping and tubing shall be identified in accordance with ASME A13.1 to indicate the material conveyed. 3. Manual valves or automatic remotely activated fail-safe emergency shutoff valves shall be installed on supply piping and tubing and provided with ready 3.1. The point of use. 4. Manual emergency shutoff valves and controls for remotely activated emergency shutoff valves shall be identified and the location shall have accessclearly 5. Backflow prevention or check valves shall be provided where the backflow of hazardous materials could create a hazardous condition or cause the Exceptions: 1. Piping for inlet connections designed to prevent backflow. 2. Piping for pressure relief devices. |
On April 2, 2003, Employee #1 and a coworker, the technicians, were watching a polymerization process involving styrene and acrylonitrile monomers. Employee #1 and the coworker’s jobs involved monitoring a reactor vessel throughout the process. At the end of the batch process, non-polymerized monomer and vapors were stripped from the reactor through a condenser system to a distillate collection tank and were ultimately charged to subsequent batches. Toward the end of the stripping process, Employee #1 left the control room to determine if enough distillate had been removed to allow the remaining water and mixture to be dumped to the “dirty” sewer and a collection system. While Employee #1 was in the vicinity of the reactor, an explosion occurred in a small auxiliary charge tank. A piece of metal struck Employee #1’s abdomen and killed him. Although the charge tank was not in use at the time of the accident, a small amount of the batch had back-flowed through a valve between the reactor and the auxiliary tank during the reactive process. The batch continued to react in the auxiliary tank, overheating and overpressurizing the tank.