tagout

Tagout is a safety procedure used to prevent the unexpected energization, startup, or release of stored energy in machinery during maintenance or servicing. It involves applying a warning tag to energy-isolating devices to indicate that the equipment must not be operated until the tagout is removed by an authorized person. Tagout is often part of the broader Lockout/Tagout (LOTO) program, which may also use physical locks to secure energy-isolating devices.

Tagout devices are associated with energy sources such as electrical circuits, mechanical drives, hydraulic and pneumatic systems, thermal sources, and chemical processes. A tag includes information such as the reason for isolation, the identity of the person applying the tag, the date, and any precautions. Tags are designed to be durable, legible, and tamper-evident, but unlike locks, they do not themselves physically prevent energization.

Key roles include authorized personnel who apply and remove tagout devices and affected employees who must not operate equipment that bears a tag. Written procedures specify the steps for isolating energy sources, applying tags, verifying zero energy, performing the work, and restoring equipment to service. Common steps include identifying energy sources, shutting down equipment, isolating and securing energy sources, applying tagout devices, verifying isolation, and removing tags only after work completion.

Limitations of tagout include reliance on human compliance and the fact that a tag does not provide a physical barrier to energization. Regular training, periodic inspections, and proper documentation are essential to maintain program effectiveness. Regulations in many jurisdictions, such as OSHA in the United States (29 CFR 1910.147), govern the use of LOTO/tagout procedures in industrial settings.