What Is a Lockout/Tagout Valve?

Lockout/Tagout (LOTO) is a safety procedure that locks a valve in a fixed position (open or closed) and attaches a tag identifying who locked it and why. LOTO prevents accidental or unauthorized operation of isolation valves during maintenance, repair, or inspection. It is a legal requirement under OSHA 29 CFR 1910.147 (Control of Hazardous Energy) in the United States and similar regulations worldwide.

When LOTO Is Required

LOTO is mandatory any time personnel could be exposed to the unexpected release of hazardous energy. For piping systems, this means locking isolation valves before:

• Equipment entry (confined space)
• Hot work (welding, grinding near live systems)
• Pipe breaking (opening flanged joints)
• Instrument maintenance on live systems
• Equipment maintenance (pumps, compressors, heat exchangers)
• Blinding and spading operations

LOTO Devices by Valve Type

Valve Type	LOTO Device	How It Works
Gate valve	Handwheel cover or chain lock	Encases handwheel or chains stem to prevent turning
Ball valve (manual)	Lever lock	Clamps over quarter-turn lever, prevents rotation
Butterfly valve	Handle lock	Bracket or clamp locks lever in closed position
Plug valve	Wrench lock	Locks wrench fitting to prevent quarter-turn operation
Actuated valve	Solenoid lockout + handwheel lock	De-energize solenoid + lock manual override
Chain-operated valve	Chain lock	Locks chain wheel to prevent remote operation

OSHA LOTO Requirements (29 CFR 1910.147)

Requirement	Details
Written procedure	Specific LOTO procedure for each equipment/valve group
Authorized personnel	Only trained, authorized employees may apply/remove locks
Individual locks	Each worker applies their own personal padlock
Multi-lock hasp	Allows multiple workers to lock the same valve
Tags	Identify the worker, date, purpose, and expected duration
Verification	After lockout, verify zero energy (bleed, test, confirm)
Annual review	LOTO procedures must be reviewed at least annually
Training	All affected and authorized employees must be trained

LOTO Procedure Steps

1. Notify: inform all affected personnel of the planned isolation
2. Identify: locate all energy sources and isolation points for the equipment
3. Shut down: bring equipment to safe shutdown per operating procedures
4. Isolate: close isolation valves, disconnect electrical, depressurize
5. Lock and tag: apply personal padlock and danger tag to each isolation point
6. Verify: confirm zero energy (bleed valves, try-to-start, pressure gauges)
7. Perform work: maintenance proceeds with verified safe isolation
8. Restore: remove locks/tags in reverse order, only by the person who applied them

LOTO vs DBB

Feature	LOTO	DBB (Double Block and Bleed)
Purpose	Prevent accidental valve operation	Verify positive isolation integrity
Scope	Administrative (padlock + tag)	Physical (two barriers + bleed verification)
Required for	Any maintenance with hazardous energy	Hot work, confined space entry, high-risk isolation
Complementary?	Yes (used together	Yes) DBB provides isolation; LOTO prevents tampering

In practice, critical maintenance combines both: DBB isolation verifies the seal integrity, and LOTO prevents anyone from inadvertently operating the block or bleed valves during work.

Common Mistake

Using tags without locks (“tagout only”). OSHA permits tagout alone only when lockout devices cannot be physically applied. Wherever possible, apply a physical lock. Tags can be ignored; locks cannot be removed without the key.

Read the full guide to valve types