Lockout-tagout (LOTO) or lock and tag is a safety procedure which is used in industry and research settings to ensure that dangerous machines are properly shut off and not started up again prior to the completion of maintenance or servicing work. It requires that hazardous power sources be “isolated and rendered inoperative” before any repair procedure is started. “Lock and tag” works in conjunction with a lockusually locking the device or the power source with the hasp, and placing it in such a position that no hazardous power sources can be turned on. The procedure requires that a tag be affixed to the locked device indicating that it should not be turned on.
A good Lockout/Tagout Procedure, at a minimum, should contain the following elements:
1. All maintenance personnel shall be provided with a good lock. The lock shall have the individual workers’ name and other identification on it. Each worker shall have the only key to the lock.
2. The worker shall check to be sure that no one is operating the machinery BEFORE turning -off the power. The machine operator shall be informed before the power is turned off. Sudden loss of power could cause an accident
3. Steam, air and hydraulic lines shall be bled, drained, and cleaned out. There shall be no pressure in these lines or in reservoir tanks.
4. Any mechanism under tension or pressure, such as springs, shall be released and blocked.
5. Each person who will be working on the machinery shall put a lock on the machine’s lockout device(s). Each lock shall remain on the machine until that worker’s work is complete.
6. All energy sources that could activate the machine shall be locked out (blocked/tagged).
7. The main valve or main electrical disconnect shall be tested to be sure that the power to the machine is off.
8. Electrical circuits shall be checked with proper and calibrated electrical testing equipment. An electrical failure could energize the equipment even if the switch is in the off position. Stored energy in electrical capacitors shall be safely discharged.
9. When working on machinery such as power presses and welding presses that have a ram that could fall, the ram shall be supported with safety blocks or pins. Fully interlocked safety blocks are the safest.