This guiding principle is intended to highlight the necessary procedures to disable machinery or equipment, in order to prevent the release of energy during service, maintenance and commissioning activities.

Commissioning and testing activities, where the equipment on board of the vessel is tested in service to confirm the integrity of the system, should be considered as de-isolation. Therefore, the same controls should apply.


This guidance will cover:

  • Hazards involved during servicing/maintenance
  • Lock-Out and Tag-Out Devices
  • LOTO Procedures


Injuries resulting from the failure to control hazardous energy can be serious or fatal. Workers that are tasked with the servicing/maintenance of machines or equipment may be exposed to burns, crushing or fracturing of body parts, lacerations, amputations and/or electrocution.
The types of hazardous energy that needs to be isolated include:

  • Potential Energy (mechanical springs in tension or compression, compressed gas cylinders, counter weights, etc.)
  • Kinetic Energy (rotating flywheel, moving parts, rolling components, etc.)
  • Utility Energy (electricity, compressed air, steam, domestic water, etc.) that may be part of a particular machine or utility system.

Even if a machine has been shut off, accidents may occur if there is an inadvertent activation of the machine. This happens when someone accidentally turns on machine/equipment because they were unaware that maintenance was taking place. The generally accepted way to minimize the risks of injury due to unintentional start up is to ensure that the machine is isolated, locked and marked at the points of control, using a method that cannot be easily or accidentally overridden.


  • LOTO may only be performed by authorized persons.
  • Notify all others in area of LOTO activities and the hazards involved.
  • Ensure that LOTO devices are properly fixed and durable.
  • Verify the isolation and de-energization of the machine/equipment before starting work.
  • LOTO devices may only be removed by the authorized person(s) who applied them.

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Guding principle LOTO introduction

Lock-Out / Tag-Out