Have you ever read a RAGAGEP and wished you had been a fly on the wall in the room where a particular requirement was presented and debated amongst the committee members? I have set on my fair share of RAGAGEP committees over the past 20 years and in almost all of muy experiences, when someone would bring an idea to the floor that was well outside any fundamental risks acceptance or engineering, they were usually asked to sit down in a polite manner. Today, sometimes I wonder what goes on behind the closed doors.
As I have said, the “dumbing down” of some of the most prestigious RAGAGEPs that have been around for decades (well before OSHA promulgated its PSM standard) continues to increase. This is done simply to limit OSHA and EPA’s enforcement – NOT because of new technology or better science/engineering. Here is one that left me scratching my bald head until it bled…
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5.8.2 Hydrostatic relief valves 5.8.2.1 A facility operating in the United States under 29 CFR 1910.119 Process Safety Management or in Canada, under the Canadian equivalent, may modify the requirement for a hydrostatic relief valve based on possible trapped line volume by technical analysis using methods and analysis in accordance with a recognized and generally accepted engineering approach [10]. In no case shall the possible trapped volume of a line without hydrostatic relief valve protection exceed 26.4 gallons (100 liters). |
Footnote 10 directs us to NIOSH Pocket Guide to Chemical Hazards, National Institute for Occupational Safety and Health, Center
for Disease Control and Prevention. www.cdc.gov/niosh
So basically, the most fundamental safety device to protect piping can be omitted from the piping design where the trapped volume of NH3 liquid does not exceed 26.4 gallons. Then to reference the NIOSH pocket guide is more puzzling; this must have been a grammatical error as it makes no sense.
I would like to point out that even OSHA’s basic NH3 standard (1910.111) requires Hydrostatic RVs on piping where liquid can get trapped…
| 1910.111(b)(9)(ix) A hydrostatic relief valve shall be installed between each pair of valves in the liquid ammonia piping or hose where liquid may be trapped so as to relieve into the atmosphere at a safe location. |
So a piping run of Liquid NH3 does not even have to be a PSM/RMP covered process and OSHA would still require hydrostatic protection!
I am not sure, as I had never heard of this before, where the 26.4 gallons (100 Liters) exception came from or what risk model it follows. I can say this for sure: the 26-gallon release of NH3 is a significant release. This equates to being a REPORTABLE release > 100 pounds (e.g., 113 pounds), so they were not using the RQ of NH3 to declare the amount to be an “incidental” release.
I am also unaware of any recognized and accepted “technical analysis using methods and analysis in accordance with a recognized and generally accepted engineering approach” to exempt piping containing gas in a liquid state under pressure from being protected from a “blocked in” scenario.
Anyone who can help me understand this “crap engineering,” I would be forever grateful.