LOTO is not a game of chance
A properly executed Lock Out Tag Out (LOTO) prevents injury or death from the unexpected release of hazardous energy. The following is a concise description of hazardous energy from OSHA.
“What is hazardous energy? Energy sources including electrical, mechanical, hydraulic, pneumatic, chemical, thermal, or other sources in machines and equipment can be hazardous to workers. During the servicing and maintenance of machines and equipment, the unexpected startup or release of stored energy can result in serious injury or death to workers.
Workers servicing or maintaining machines or equipment may be seriously injured or killed if hazardous energy is not properly controlled. Injuries resulting from the failure to control hazardous energy during maintenance activities can be serious or fatal! Injuries may include electrocution, burns, crushing, cutting, lacerating, amputating, or fracturing body parts, and others.
Craft workers, electricians, machine operators, and laborers are among the millions of workers who service equipment routinely and face the greatest risk of injury.”
LOTO’s range from simple to complex and may deal with one or multiple hazardous energy sources. A simple LOTO may require locking out one manual valve and circuit breaker. But typically, LOTO’s are far more complex, requiring the customer to map out all the paths the energy source might take to get to the work area. Then every valve and electrical circuit must be identified and locked out. Each automated valve must have its power source locked out, and its manual declutch mechanism locked. Gas systems require double block and bleed to assure that no gas enters the work area.
Once this process is complete the customer and contractor(s) must walk down the entire LOTO and visually identify each valve for locks and tags. The customer’s keys are then placed into a lock box. Each crew member locks the box, and the customer seal is attached to the box. This completes the LOTO, and work may begin.
Work can continue from day to day if the seal remains in place. But if the seal is cut by, let’s say, the night shift. Then the system as been activated and the LOTO may have been compromised. If this happens the entire system must be walked down to assure that every valve, switch, de-clutch mechanism and breaker is locked and tagged. Only then can the Seal be replaced and the box locked for work to begin.
Attention to the details of a LOTO is very important to maintaining a safe work area. Things can go wrong. For example, Midwestern Contractors was working on a piping system under a LOTO when it was revealed that a universal key could open any lock on the LOTO and several individuals had keys. This precipitated a stop work action. The locks had to be changed with strict control over all keys and all keys placed in the lockbox.
Other vulnerabilities arise when a LOTO is incomplete. A valve might not show up on a system map, or it could be overlooked. Walk downs should catch these omissions. The de-clutch mechanism on automated valves is another vulnerability. These mechanisms allow an operator to throw the valve into manual mode. If the automated valve is locked but the de-clutch mechanism is not locked, then the valve can be operated manually leaving a potential pathway for hazardous energy.
The bottom line for LOTO’s is attention to detail, clear communications with the customer, rigorous inspection by walkdown, comparing the map with the actual layout on the ground. These efforts pay off, but even with a LOTO in place no worker should ever be in the line of fire.