Isolation, Lockout, and Use of Hold Tags

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Chapter : Lockout Tagout (LOTO)

Isolation, Lockout, and Use of Hold Tags

The purpose of the isolation, lockout, and use of hold tag process is to prevent injury or loss from the uncontrolled release of stored energy.

Electrical isolation, lockout, and use of hold tag procedures shall be used before and during any activity requiring personnel to work on or near de-energized circuit parts or where there is danger of injury due to an unexpected startup of equipment (e.g., a motor-driven pump).

Other energy sources such as pressurized gas, process fluids, and hydraulic, pneumatic, thermal, chemical, and mechanical systems shall be isolated by valves, blinding, double block and bleed, or disconnecting.

Follow the local isolation, lockout, and hold tag procedures and requirements for the proper isolation procedures for energized equipment and systems.

Electrical Energy Isolation Methods

1. Accomplish electrical isolation using a device that physically prevents the transmission or release of energy like a manually operated circuit breaker or a disconnect switch.
2. Control circuit type devices such as push buttons and selector switches are not energy isolating devices.
3. Isolation may be accomplished by removal of fuses, disconnection of electrical cables, or physical removal of a component of the system supplying energy to the equipment.
4. Isolation is completed only when no associated control device has the capability of energizing the equipment.
5. Identify physical isolation points accordingly with a hold tag.

Lock, Tag, Clear, and Try

1. Identify isolation locations and types of isolation devices required prior to beginning work.
2. Shut down/de-energize equipment and remove any residual energy (e.g., contents of process piping) by draining, venting, or purging after isolation. The proponent organization shall always be the first to install an approved Lock(s) on all isolation points, and the last to remove them.
3. Tag the lock(s) with a “DANGER, DO NOT OPERATE” tag.
4. Clear the equipment/area of all affected personnel and tools prior to trying to start the equipment.
5. Before starting work, Try to start or energize the equipment locally to verify proper isolation and de-energization.
6. Install lock(s) at each corresponding isolation point (maintenance/contractor personnel). If performing maintenance or servicing of equipment, verify that isolation and de-energization of the equipment has been accomplished.
7. Only the person(s) originally attaching the lock and tag is authorized to remove the lock and tag. When a shift change occurs, the oncoming supervisor must review isolation locations and placement of locks and tags. Proponent’s locks and tags may be left installed and keys to locks may be transferred.
8. Remove lock(s) and tag(s) when the work is completed or you leave the job permanently (craftsman).
9. Remove lock(s) and tag(s) when the equipment is safe to energize (proponent organization employee).
10. When work is complete and all lockout devices removed, affected personnel shall be notified and the equipment placed back in service.

Process, Hydraulic, and Pneumatic Energy Isolation Methods

There are four primary methods for isolating process lines and equipment to prevent the release of energy or materials. The isolation methods are arranged below in general order of protection provided from lowest to highest, but the specific isolation method is determined by the tasks to be performed and the associated material/ stored energy.

Single block valve

Use of a single block valve is the minimum isolation procedure for certain routine maintenance operations where no open flame work or toxic material is involved. This isolation method shall not be used when piping or equipment containing hazardous materials is to be opened for confined space entry or hot work activities.

Double block and bleed

Double block and bleed (DB&B) is a method of isolating process piping where two block valves in series are closed, locked (chained), and tagged with a bleed or vent valve in the line between the two closed valves that is locked and tagged open. Details on applying DB&B as an isolation method. This isolation method shall not be used when piping or equipment containing hazardous materials is to be opened for confined space entry or hot work activities.

Blinding

Blinding is the installation of a solid metal plate between two pipe flanges or at the end of a disconnected pipe to prevent any materials from being released. It involves inserting a slip blind or blind flange at a flanged joint or swinging (rolling) a spectacle blind if provided by design. The blind point(s) must have a completed hold tag.

Disconnection of piping

Disconnection of piping is the physical disconnection of the piping where allowed by flanges. Steps must be taken to ensure no hazardous materials can leak or be discharged from the open ends of piping (e.g., blinding). The disconnection point(s) must have a completed hold tag.