What is Lock Out & Tag Out?
Lock Out & Tag Out is a common practice applied worldwide to isolate sources of energy in machines and proces equipment. Possible energy sources for example are:
Mechanical energy (rotating parts, hydraulics, etc.)
These sources of energy are being isolated by a sequence of actions which are written down in a so called LOTO procedure. This LOTO procedure is the foundation for every lockout, because it is focussed on the planned work only. The LOTO procedure is primarily conducted by the operational department in accordance with the related P&ID’s, site work instructions and the related work permit(s).
The LOTO procedure contains for example all necessary actions to depressurize, empty or purge piping and equipment, switch off electrical equipment (with support of E&I) and carry out necessary preparations for placing blinds or spectacle blinds. Alongside these isolation actions a physical lock is being placed on valves and electrical switches to prevent accidental operation. All matching keys are being kept safe with all the documentation of the lockout, mainly in a central control room or In Plant House where so called Lockboxes are used which hold these keys.
On the locks a danger tag is being placed with all relevant information from the corresponding LOTO procedure for identification purposes. Some danger tags have a tear off part, which could be used as a double-check and kept safe with the keys in the Lockbox. Common practise is to apply these tear off parts during a line break where piping is disconnected and opened for blinds. Each tear off part stands for the progression of the work, opening and checking, placing of blinds and in the end removal of blinds
Maintaining the isolation
The Lockbox keeps all keys safe (and tear off parts if applied) and is locked with a Master lock to prevent opening before all related work permits have been returned. Often multiple locks are placed onto the Lockbox by owners of all related work permits.
If all related work permits have been returned then all locks can be removed from the Lockbox. The operational department then can commence with removing the lockout and take all necessary preparations to restart the equipment or installation.