I am presently designing a cooling water flow for oil tanks. The local codes call for the design to take account of two different cooling water flowrates onto the tanks ('tan on fire' and 'neighbouring tank'). Without designing two different sizes (ID's) of cooling rings, I cant figure out how...
Not sure about NFPA, but IP 15 would detail a hazardous area, depending on the pressure within the pipe. Hazardous areas only tend to runs from a leak source, not the whole pipe.
