Lockout tagout is a system whereby hazardous energy in a machine, process, or device is isolated and contained or neutralized while the machine, process, or device is being serviced, inspected, repaired, installed, or replaced. The lockout tagout system, as prescribed under OSHA CFR 1910.147 and 1910.147 App A, is comprised of two parts: an engineered method of hazardous energy control, and an administrative method whereby direct and indirect employees are trained to apply the engineered methods or are trained not to touch or remove any applied engineered methods.
What constitutes hazardous energy? A machine, process, or device may contain a variety of hazardous energy forms including:
- Electrical energy
- Pneumatic or hydraulic pressure, typically stored in pressure vessels
- Mechanical energy (i.e. springs, gravity)
- Thermal energy
- Chemical energy
Does this hazardous energy mean that the machine, process, or device is dangerous? No. During the typical use of the machine, the operator or indirectly exposed employees are protected by the normal machine guards, machine location (remoteness, locked room, or height), or other engineering or administrative controls. Lockout tagout comes into play when the machine must be turned off and the normal protection devices removed or bypassed in order to service, inspect, repair, install, or replace parts on the machine.
Lockout tagout typically goes above and beyond the normal emergency stops, machine control stops, or keys on a machine. Engineered elements of lockout tagout may include some or all of the following:
- A switch that has a bracket and holes in order to lock the switch in the off position.
- Padlocks individually identified and provided to the trained persons authorized to lockout a machine.
- Multi-holed hasps which allow more than one padlock to be applied to a single lockout. This allows multiple users to lockout a machine for a complex or multi-part service or repair. For example, a machine may be locked out simultaneously by an electrician, a plumber, and a HVAC/burner technician.
- Lock labels – helps to identify the person locking out a machine, and provide contact information for the person locking out the machine.
- A method to de-energized stored energy. For a pressurized tank, there will be an engineered way to release the pressure. For a car lifted by a jack, there will be jack stands to ground the potential energy of gravity.
- A method to contain energy or hazards. A pinch point may be blocked or wedged. An overhead object may be moved out of the way during service. An oven may have a temperature controlled lock so that the door can’t be opened until the oven has cooled. Chemicals may be pumped back to storage tanks out of process piping before pipes are repaired.
ARCCA’s engineering, biomechanical, and human factors experts have the multi-discipline background to assist you in understanding the complexities of lockout tagout.