Yes, I am still on this horse! As I discussed last month, there are a number of chemicals that specifically REQUIRE HRVs on liquid piping. Those are chemicals like NH3, Cl2, and LPG, to name the top three (3). But I have recently read a root cause analysis in which a flammable-liquid piping flange leaked, and it was attributed to “thermal expansion.” I called BS, and this is why…