Industrial Safety & HSE Blog by Mohd Shams Tabrez Khan sharing practical knowledge about LOTO, Permit to Work, Construction Safety, PPE, Risk Assessment, and Workplace Safety.

 

LOCKOUT & TAG OUT (LOTO) PROCEDURE 

🔒 What is LOTO?

LOTO is a safety procedure used to make sure that equipment is completely shut down and cannot be started again while maintenance or repair work is being done.

⚙️ Meaning:

* Lockout 🔐 → Physically locking the energy source (valve, switch, breaker) using a lock
* Tagout 🏷️ → Placing a warning tag to show that the equipment must NOT be operated

General Requirements for Lockout / Tagout

• The Person in-charge or Shift in-charge shall be the only authority responsible for controlling and ensuring necessary provisions for providing field hasps, including hasps for electrical lockout.
• Each plant control room shall maintain a comprehensive procedure for monitoring and controlling field activities through proper documentation and shift-to-shift communication, ensuring that no device remains unnoticed.
• All hardware used for hazardous energy control must be durable enough to withstand the workplace environment and must be used solely for the purpose of controlling hazardous energy.
• In case of a lost key, the concerned person shall inform the Person in-charge or Shift in-charge through formal written communication. The Division Chief shall be the only approving authority for breaking any locks of the energy-isolating device.
• For ease of identification of the department associated with the executing person or team leader, locks shall be color-coded as follows:
  • Electrical Department – Red
  • Mechanical Department – Yellow
  • Process/Operation Department – Black
  • Instrumentation Department – Blue
  • Others – Green
• If an energy-isolating device cannot be locked out, a Tag Out procedure (Tagging System) shall be followed.
• When the Tag Out procedure is used for hazardous energy control, the person must be fully aware of the limitations of tags.
• Tags are essentially warning devices affixed to energy-isolating devices and do not provide the physical restraint that locks do. Tags may evoke a false sense of security, and their meaning must be clearly understood.
• When a tag is attached to an energy-isolating means, it shall not be removed without authorization from the responsible authorized person. It must never be bypassed, ignored, or defeated.
• Tags must be securely attached to energy-isolating devices so they cannot be inadvertently or accidentally detached during use. They must be legible and understandable by all persons whose work operations are or may be in the area.
• Tags and their means of attachment must be made of materials that can withstand the environmental conditions encountered in the workplace.

Restoring Equipment back to Service/Operation

• After servicing or maintenance is completed, the Maintenance Engineer or Team Leader shall check that the equipment and the area around it are cleared. Equipment guards, safety devices, etc. must be reinstalled, temporary grounds removed, and the equipment made ready for intended operation.
• The Maintenance Engineer or Team Leader shall ensure that all persons have safely moved out of the hazardous zone.
• The Maintenance Engineer or Team Leader shall verify that control devices are in the “OFF” position. All blinds, blocks, etc. shall be removed prior to removal of locks.
• The Maintenance Engineer or Team Leader shall remove all locks provided on lockout devices (hasps) at the energy-isolating points, including electrical energy sources, and clear his/her danger tags.
• The Field Operator or Operation Engineer shall check and inspect the integrity of the equipment and remove his/her danger tags.
• The equipment is then normalized for restoration into operation as per the Safe Operating Procedure (SOP).

Guidelines for Positive Process Isolation:  

• The most positive method of isolation is the complete physical disconnection of the line with blind flange or blank put on the live end. Where there is work on pressurized hydrocarbon system or entry into a vessel, physical disconnection is the mainly recommended method of isolation. If this method is not reasonably practical, then, as a next best method, the insertion of a slip plate with the correct size, specific MOC and appropriate pressure rated blind is preferred for the purpose of authorizing a confined space entry. 

•  Isolations shall be checked by one of the following methods:

•  By releasing pressure or draining liquid via a suitable vent or drain point. Do not rely on pressure gauges - pressure should be seen to be released. Check that drain points or vents are clear and free from chokes. If the isolating valves are holding, flow of material should stop after pressure is vented.

Caution

• It is not possible to provide specific instructions covering the various ways in which the equipment can be freed from hazardous process materials before maintenance work can take place. In some cases this may be achieved by pumping out and draining to a safe place; in other cases by blowing; or in the case of gases by purging or steaming. In some instances decontamination is carried out after the section of item can be fully isolated, in other cases it will be necessary to purge or pump out before valves can be closed and slip plates fitted. Each case must be carefully considered by the Person In-Charge/Shift In-Charge, taking into account the hazardous properties of the materials involved and the details of plant design. 
• In many situations, remotely operated valves and motor operated valves (MOV) are the only isolations. Basically for these on-off type valves the correct procedure is to positively disable it, by either disconnecting the instrument air supply or remove the actuating signal wires or in the case of MOVs electrical lockout / tag out is to be ensured. 
• Having achieved line/equipment isolation by the closure of single or double isolation valves, this valve isolation must remain effective until the purpose of the isolation has been achieved and the Work Permit signed off. To ensure this, the valve or valves must be locked/tagged in the closed position or open position in the case of vent/drain valves. 

Special Precautions

• For equipment like pumps or blowers where shafts or blades may rotate even after handing over, ensure they are locked suitably against rotation using a locking device before starting maintenance work.
• Existing slip plates should not be relied upon for positive isolation since they may be corroded. They should be removed, inspected, and replaced where necessary with new ones.
• Process and service lines, or equipment (e.g., pump casing) relying on valve isolations must not be left with open ends. Blanks must be fitted to the open ends immediately after the section of the line or part of the equipment is removed.
• Always ensure that slip plates compatible with the process materials conform to the piping design standards to which the plant was designed, and these should be fitted as close as possible to the equipment to be isolated. Always ensure that blind detail is entered in the blind register.
• Where cutting or welding is to take place, the line or equipment must be purged, and either slip plates must be fitted after the section or item has been isolated, or the item of equipment must be removed and open ends leading to other process equipment blanked off.
• Equipment containing corrosive chemicals must be washed or steamed out, where possible, after depressurizing and draining. Where residual contamination is unavoidable, full protective clothing should be worn.
• In case isolation is required again due to some problem (like change in DOR), then this procedure is to be followed afresh.
• For work on an electrical distribution system, all Lockout/Tagout activities will be the same. However, to avoid back-feeding of power, isolations shall be ensured from all possible paths (upstream and downstream).
• While working on electrical installations, after Lockout/Tagout is done, equipment shall be discharged safely of all its residual energy. If required, special care may be taken to keep the terminals earthed till the completion of the job.
• Diesel engine-driven or battery-operated equipment shall be made inoperable by disconnecting and removing battery cables safely.
• For isolation of electrical sources where lockout provision is absent, physical disconnection of outgoing power conductors shall be ensured.

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Key Safety and Regulatory Standards for Hazardous Energy Control

• OSHA 29 CFR 1910.147 (U.S.)
  Occupational Safety and Health Administration standard governing the control of hazardous energy.

• NFPA 70E
  Addresses electrical safety in the workplace, including energy control procedures.

• ANSI/ASSE Z244.1
  American National Standard for the control of hazardous energy.

• ISO 45001
  Global standard for occupational health and safety, integrating Lockout/Tagout (LOTO) principles into broader risk management frameworks.

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Step By Step LOTO Procedure

1. Preparation for Shutdown
   Identify all energy sources connected to the equipment. Review the procedure and gather necessary tools and personal protective equipment (PPE).

2. Equipment Shutdown
   Perform a normal shutdown using standard controls to cease equipment operation.

3. Isolation of Energy Sources
   Physically isolate each energy source using switches, valves, breakers, and plugs.

4. Application of Lockout/Tagout Devices
   Apply appropriate lockout devices and attach warning tags. Each authorized employee working on the equipment should use a personal lock.

5. Release of Stored Energy
   Drain hydraulic lines, bleed pneumatic systems, discharge capacitors, and secure any movable parts against gravity.

6. Verification of Isolation
   Attempt to start the equipment using normal controls to ensure that it will not operate. Then return controls to the OFF position.

7. Performing the Maintenance & Service
   Once isolation is verified, employees can begin working on the equipment safely.

8. Removal of Lockout/Tagout Devices
   After the task is complete, ensure the area is clear, remove tools, notify employees, and remove each lock and tag in reverse order of application.

Common Lockout Devices

Device Type	Application & Description
Padlocks	Personal locks for electrical or mechanical controls
Valve Lockouts	Prevent rotation of gate, ball, or butterfly valves
Plug Lockouts	Secure electrical plugs in the disconnected position
Circuit Breaker Lockouts	Clamp onto circuit breakers to prevent activation
Cable Lockouts	Multi-purpose device used to lock several components at once
Hasp Lockouts	Allow multiple workers to place locks on a single energy source

Source Note:

This document is based on information gathered from multiple reputable websites and technical resources related to safety net standards and practices. 

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MD Shams Tabrez Khan

HSE (Health Safety & Environment) Professional

Usia, Dildarnagar, Ghazipur, Uttar Pradesh, India

Safety is not just a rule, it is a responsibility for everyone.

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