I talk a lot about “safe locations” when we discuss Pressure Relief Device (PRD) discharge. The phrase “safe location” is used in just about every PRD RAGAGEP; however, none of them DEFINE or QUANTIFY the phrase, leaving it open to some poor designs. Here is a case where two workers were doing work 30′ under a Rupture Disc discharge.
On January 15, 2022, Employee #1 and Employee #2 (Millwrights) were assigned to replace a pump in a Methylene Diphenyl Diisocyanate (MDI) Unit at the Di-Chlorination Column at approximately 2:00 a.m. The discharge line for this column discharges about a foot off the ground right next to the pump where the employees were working. The employees were working at ground level, had removed the old pump, and were starting to replace it with a PP4800 pump.
As they started to install the new pump, a process rupture disc operating above 30 psi three (3) stories up blew.