Q53. What activities require permit-to-work controls?

In any place of work where there are tasks that meet the permit-to-work (PTW) definition, these should be covered under a PTW system. In general, PTW systems are considered most appropriate for:

• Non-production work (risk-assessed tasks, such as maintenance and repair, inspection, testing, alteration, construction, dismantling, adaptation, modification, cleaning, etc).

• Routine work requiring a higher degree of control than normally would be expected of other routine tasks (risk of fire, explosion, uncontrolled release of chemicals, etc).

• Non-routine operations presenting infrequent, unusual or unexpected hazards.

There are a number of specific work tasks widespread across a range of industry sectors that have been recognised for some time as hazardous and which generally require the controls of a PTW system. These include:

• Hot work: Any work where sparks, heat or flames are generated or used (such as welding or cutting equipment, grinding with portable power tools, etc).

• Confined space entry: Any work activity that requires access to a space classed as a confined space (such as a tank, void space, deep excavation, etc).

• Working-at-height: Any work activity that requires access to work locations generally higher than two metres off the ground.[1]

• Isolation of energised equipment: Any work activity that requires the safe isolation of work equipment, which can include hydraulic, electrical, pneumatic and mechanical systems.

• Lifting operations: Any work involving the lifting of loads by crane or other lifting equipment.

Of course, a PTW system depends upon the industry sector - for example, for the offshore seismic industry, additional permitted work activities may include small boat operations and oilfield close approach procedures and, for the maritime industry, may include work-over-the-side procedures.

Q54. What is the lock-out / tag-out system and how is it used in permit-to-work activities?

Lock-out / tag-out (LOTO) is the common name for a procedure that provides for the safe isolation of energised equipment and systems. It can be defined as: "a process of blocking the flow of energy (electrical, pneumatic, hydraulic, air, liquid, solids, etc.) to a piece of machinery, equipment or system and keeping it blocked out".

LOTO procedures can be developed for work on electric, pneumatic, hydraulic, gas or solid flow systems and equipment. The process ensures that the equipment being worked on does not become accidentally energised resulting in potential injury to personnel, property damage or both. Typical work tasks that may require LOTO are maintenance and repair, installation, commissioning, cleaning and decommissioning activities.

LOTO comprises two components: lock-out points / devices and tags. Isolation or LOTO points come in many forms; they can be electrical switches, mechanical valves or hydraulic valve levers. They should have the ability to be locked effectively, normally in the closed position by use of a bracket or other purpose-made device that can have a locking device attached to it. For complex work locations, these locations should numbered and be recorded in a register so that isolation points can be easily identified for specific work tasks and the appropriate lock-out or isolation device specified.

Lock-out devices used to lock-out plant and equipment can be a combination of (but not limited to):

• Fixed securing covers or guards placed over valves or other isolation points that accommodate a lockable padlock.

• Lockable scissor hasps around the isolation point.

• Cable with lockable hasps at the end.

• Trapped key systems.

In all instances and whatever device is applied, ensure that the isolation point cannot be accidentally, inadvertently or intentionally over-ridden.

The second LOTO component are tags: labels that can be written on and securely attached to isolation points to provide information. Tags come in various shapes, sizes and colours and often indicate safety or hazard messages, such as 'Out of order', 'Do not operate', 'Do not open valve', etc. Tags are NOT an effective means of isolation on their own and must never be used as such. Tags must always be applied jointly with a lock-out device.

In all instances, the following information should be entered on the tag:

• ID of the plant or equipment that is isolated.

• Reasons and remarks in relation to the isolation.

• Time and date of isolation.

• Name of designated person who applied the LOTO devices.

• Reference number to track back to a LOTO register, isolation certificate or permit.

LOTO is a very useful component that can be used in conjunction with a PTW system, where the PTW task requires equipment or systems to be isolated before the permitted work can take place. For example, if a section of pipe that would normally have a flammable product flowing through it is to be cut out of a pipe-rack using welding gear, then it would be necessary to ensure that the pipe is effectively isolated (valves locked out) at both ends to ensure that no product is accidentally released into the pipe section being removed (for example, by a valve being opened at a remote location) during the hot work operation.

  • [1] The height above ground for which a PTW system may be required depends on local legal requirements in the jurisdiction where the activity takes place.
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