9/2020 UPDATE: I have contacted the Minnesota Department of Agriculture, Pesticide & Fertilizer Management Division regarding a statement on this 2-page “Cheat Sheet” regarding their apparent requirement that Hydrosrtatic RVs be put on NH3 vapor piping and vapor hoses. This is how it is presented:
Hydrostats must be installed in each section of liquid and vapor system piping and hosing in which ammonia could be isolated between shut-off valves.
As soon as I hear back or get an updated document I will update this posting.
For some clients, Anhydrous Ammonia (NH3) is used as a fertilizer and/or an environmental scrubbing agent and for these facilities, ANSI K61.1 (now CGA 2.1) Safety Requirements for the Storage and Handling of Anhydrous Ammonia is our “baseline” RAGAGEP. Both versions of the RAGAGEP reference ASME B31.3 as the Piping RAGAGEP for non-refrigerated ammonia systems piping. This is different for facilities where Anhydrous Ammonia is used as a “refrigerant” (i.e. R-717); these facilities use ASME B31.5 as their piping RAGAGEP. Recently I was helping a power plant with their PSM/RMP questions and came across what may be the best summary of ASME B31.3 for facilities that handle NH3 in non-refrigerated ammonia systems. This “cheat sheet” (my term) does an excellent job in just two (2) pages of covering the many requirements for safe non-refrigerated ammonia systems piping.