OSHA 1910.147(d)(5)(ii) is one of the most critical, yet frequently overlooked, requirements of the Lockout/Tagout (LOTO) standard. It moves LOTO from a static, one-time task (“lock it and check it”) to a dynamic process that accounts for the physical reality of residual and regenerative energy. Think about isolating “compressed air” to a machine/equipment and the isolation valve “bleeds by” allowing the air pressure to reaccumulate and present a hazard to the workers doing the maintenance/servicing.
1910.147(d)(5)(ii) If there is a possibility of reaccumulation of stored energy to a hazardous level, verification of isolation shall be continued until the servicing or maintenance is completed, or until the possibility of such accumulation no longer exists.
In short, Verification is not a single moment in time if the system has a memory.