It does NOT take a PSM/RMP threshold to make “line breaking” a hazardous tasks

I have written numerous times about how the PSM/RMP thresholds are inconsequential regarding line/vessel opening hazards.  A 1/2″ line in a water treatment process, NOT covered by PSM/RMP as it ran on 150# cylinders, poses the same risks as if the 1/2″ line was part of a covered process.  Granted, the LOPC event could release more in the covered process thus causing a wider area of impact.  But for the worker(s) doing the hazardous work, Chlorine will behave the same and have the same impact in either process.  Case in point…

Employees #1 and #2 went to the City water purification station to check or repair the scales on which the chlorine cylinders for water purification rested. The chlorination system used 150-pound cylinders of chlorine with flow metering regulators. The flow metering regulators had a critical orifice to provide a constant flow of chlorine. These regulators did not have any visible flow or pressure gauges. There was also no visible flow or pressure gauge downstream of the regulators. The only way to determine if the flow of chlorine had ceased was to feel the endpoint of the main cylinder valve. Employee #1 entered the chlorination station and attempted to close the valve on one cylinder. He then removed the regulator. The main valve failed, or there was human error, and he was struck by a jet of chlorine. Employee #1 then ran out of the shed. Neither he nor Employee #2, who was standing by, had a respirator. Employees #1 and #2 then drove to an emergency room, where they were treated for inhalation injuries.

Source: https://www.osha.gov/ords/imis/establishment.inspection_detail?id=301239505