Isolation and Lock Off
21 July 2017 - 09:53
It is with great sadness that I have heard about a number of recent incidents in our industry that have resulted in fatalities.
We work in a hazardous industry but with the correct controls we can be safe. I am devoting the next couple of months’ topics to plant isolation and lock off, and traffic management.
It always sounds so simple: isolate the plant you are working on, isolate the equipment feeding on to it and isolate the equipment away.
However, we get it wrong. People don’t always know exactly where the isolator is, and/or they are not sure exactly what plant needs isolation. The isolator can be remote from where the work is being undertaken. All these elements can impact on a successfully isolated plant.
I once inspected a site and found that a pull wire was damaged on the first conveyor I came to. I wrote down ‘Pull wire on conveyor 1 is damaged and needs repair’. The site manager said that it wasn’t conveyor 1, it was conveyor 3. Conveyors 1 and 2 had been removed a few years back.
When we visited the switch room I found that isolators for conveyors 1 and 2 were still in place but not connected. If I didn’t know better, I could have isolated No. 1, tested it to see if it started and then started work on a live conveyor, conveyor 3.
So, challenge your site. How easily identifiable are the items of plant? Maybe fit ‘number plates’ with the description of the plant: ‘Conveyor 2b’, ‘Nordberg 4ft’, ‘Scalping sceen’ etc.
In your risk assessments, do not just state ‘Isolate and lock off’, but state where, eg ‘Isolate the screen on isolator 2 in the main switch house’.
Post on each isolator exactly which item of plant it isolates and ensure that people check the items of plant they are working on are listed.
And train people in your isolation and lock-off procedure. I attach below a simple procedure that can be modified for your site. Ensure everyone applies their own lock.
If you require any templates for isolator listing or the procedure below, please drop me a line.
Before work begins on any part of plant or machinery it must be ISOLATED AND LOCKED OFF.
- ENSURE that all stored energy is safely released prior to working on equipment (moving parts or equipment is chocked or safely secured).
- ALWAYS use an isolator for protection. Do not rely on stop buttons or trip-wire switches which are control circuits and do not isolate the main power supply. Remember that equipment may start immediately a local isolator is closed.
- NEVER isolate a drive if it is running: use a stop button first.
- ALWAYS check that the lock off is effective by attempting to start all equipment which has been locked off before starting any work on it.
- ALWAYS use a multi-padlock calliper to lock off where there is any possibility that more than one person may work on the equipment. You must add your own personal lock to the calliper and ensure it is locked in the OFF position.
- KEEP the key in your possession until you have completed working on the equipment.
- ALWAYS isolate every relevant drive with a separate padlock, as some situations require more than one drive to be isolated, eg working in chutes requires the feed and discharge conveyors to be isolated.
- REMOVE your lock as soon as you have completed the work.
- REMEMBER that you are responsible for ensuring that the equipment is safe to run if your padlock is the last to be removed from the isolator.
- CHECK, before removing your lock, that:
Moving parts are free and clear to run
Guards have been properly fixed
Stop buttons and trip wires are reset
All persons are clear of the danger area.
- ADVISE the plant operator before a machine is isolated and after the lock has been removed.
- NEVER give your padlock to someone else to lock off for you.
- REPORT direct to your manager if someone has forgotten to remove his padlock at the end of maintenance work. It is an offence to attempt to remove or tamper with an isolator padlock without the direct authority of the manager.
- CHECK that you know where the callipers are stored.