International safety procedures: LTT (Lock-out, Tag-out, Try-out)
A terminal by its very nature is full of equipment that contains hazardous energy in one form or another. Many safety barriers and shielding devices are in place to keep the employees safe during normal operations. But safety is also essential during non-operational activities, e.g. during maintenance or repair, as an unexpected energization, start-up or release of stored energy can cause injury. Serious accidents can happen when someone starts working on a machine with its power safely switched off, and someone else comes along and unwittingly restarts the power. The main method recommended and used in industry to ensure that hazardous energy sources are adequately isolated, with verified zero energy flow, and unable to start up again prior to completion of maintenance work is known as LTT (lock-out, tag-out, try-out). Besides electrical sources, where the LOTO (lock-out, tag-out) procedure was mainly applied, mechanical isolations are equally important, and for the same reasons.
How does the LTT (lockout, tag-out, try-out) procedure work?
In practice, lock-out is the isolation of energy from the system (e.g. a pump) which physically locks it in a safe mode, e.g. the circuit breaker. In most cases these devices will have an attachable or built-in locking mechanism or integral part to which or through which a lock can be affixed. The locking device can be any device that has the ability to secure the energy isolating device in a safe position, e.g. a singularly identified padlock. When the system's energy sources are to be locked out, there are specific guidelines that must be followed to ensure that the lock cannot be removed, and the system cannot be inadvertently operated. Each lock has only one key, a master key is not allowed. When there are multiple groups/ disciplines working on a job, a lock-box is used to manage the keys, and the employees are afforded a level of protection equivalent to that provided by the implementation of of a personal lock-out and tag-out device.
When an energy source is isolated but cannot be locked, it is acceptable to apply a tag-out device only. In practice, a prominent warning tag-out device (usually a standardized, durable label) is securely attached to the energy-isolating device to indicate that the energy-isolating device and the equipment being controlled may not be operated until the tag-out device is removed. Tags do not provide the same level of physical restraint as a lock, so additional safety measures need to be in place. A verification tag, usually similar to a tag-out device in terms of the information it provides, is typically used in conjunction with a lock. Only the authorized person who placed the lock and/or tag onto the system is permitted to remove them. This procedure helps ensure that the system cannot be started up without the authorized individual’s knowledge.
In practice, during the tryout the colleague has to verify that the system is properly and adequately locked out with no residual energy before beginning any work. The LTT processes involve more than putting a lock on a switch and a tag next to it. They are comprehensive steps that involve the preparation of an Energy Control Plan that facilitates the coordination, verification and communication for both authorized and affected employees.
What is the purpose of the LTT (lockout, tag-out, try-out) processes?
Tryout puts an emphasis on an additional safety step to ensure that zero energy verification is not missed out in the LOTO process. LTT is a visible, real-time system. In conjunction with training and communication on the safety concept and rationale, it will increase safety awareness and help to enhance the health, safety and welfare of everyone at the workplace. Think, plan, check and communicate are investments in each and everyone’s own safety – whether one is authorized or not.
LTT (Lock-out, Tag-out, Try-out) at a glance
|Lock-out||Isolate the energy source and physically lock the isolating device in the “off” or “safe” position|
|Tag-out||Isolate the energy source and/or communicate a condition or situation|
|Try-out||Test the energy state and administrative controls to ensure zero energy state|
Status: December 2016
All information subject to change. Errors and omissions excepted.