Has OSHA taken a position with regard to the elimination of safety devices based on “trained operators”?
Response 10: Your scenario addresses a requirement in ANSI/IIAR 2 related to the control of an over-pressure hazard created when equipment containing liquid ammonia (NH3) is isolated. Isolated equipment has potential to be over-pressured due to thermal expansion effects of the liquid which can result in rupture and loss of containment from the equipment (liquid expansion hazard). As you mentioned, ANSI/IIAR 2 contains requirements to address this hazard. Given the serious nature of the liquid expansion hazard, you question whether the administrative control alternative listed in ANSI/IIAR 2 1999, Section 7.3.4 is adequate to control this hazard. You also question whether OSHA accepts administrative controls exclusively when engineering controls, i.e., safety devices, are also identified as a control measure for the same hazard/condition. It is important to understand that the ammonia refrigeration industry, through ASHRAE 15, ASME 31.5 and ANSI/IIAR-2, has identified this liquid expans
