ccjersey - 6/27/2025 16:03

My understanding is that pop-off valves are required to be steel or other suitable material when used for anhydrous, and cannot be brass as is commonly used for LPG.

The use of valves suitable for anhydrous ammonia on that tank did not result in any recommendations during the CSB investigation. The only remark was that the pressure setting was 250 psi and that the guts were blown out during the explosion, so no testing was performed.

Link to the CSB final report

https://www.csb.gov/file.aspx?DocumentId=5609

The first failure here was the lack of physical protection for the above ground piping leading away from the tank allowed a vehicle to damage it. The second failure was having the excess flow preventer valve on the lines connected to the tank incorrectly sized for the piping connected to them. A 3” excess flow preventer will not close even when a 3/4” line breaks cleanly away!

Then, once the fire had started and the fire department arrived, the major failure was not evacuating the area or attempting to cool the surface of the tank EVEN THOUGH the imminent danger of a BLEVE was recognized by the on-scene commander and other personnel.

This is not to say that they could or should have attempted to cool the tank without a source of water beyond the trucks tanks, but that was the only conceivable reason not to evacuate the area. Staying to attempt to save the turkey barns from fire was the wrong decision.

There’s shades of the West, Texas ammonium nitrate explosion here, but those guys can be excused for maybe not knowing what they were dealing with. Not so with the Albert City fire.