Picking the lock
December 1st 2004

Tim Hughes of Castell Iso-Lok considers why your choice of padlock supplier could be a life or death decision.

Most equipment used today is complex, using electrical power, stored energy such as in springs, stored air and oil pressure, and stored electrical energy in capacitors. Working on this sort of equipment can lead to serious injury, and even death, if steps are not taken to put them out of action correctly. Using padlocks and Multi-Clasps in this manner, for locking electric isolators and valves in the off position, is a procedure now referred to as "Locking-Off" (Locking-Out in the U.S.A.).

Locking-off contributes to the elimination of accidents when people work on plant and machinery. Locking-off systems make an important contribution to the health and safety of operatives, in accordance with the Health and Safety at Work Act 1974 and the Electricity at Work Regulations 1989. These make it obligatory that locking-off precautions be taken against risk of death or personal injury in work activities. Both the Electricity at Work Regulations 1989 and the Provision and Use of Work Equipment Regulations 1998 state that provision to prevent inadvertent reconnection must be made.

The devices are mechanically very simple. A Multi-Clasp is attached to a machine's isolation point and each operative inserts their own padlock, locking machine controls or stopping valves being operated while work is carried out. The Multi-Clasp cannot be undone, and the machine cannot be restarted, until all the padlocks are removed, ensuring the safety of workers involved in activities such as maintenance and cleaning. The same principle works for valves or any other prime mover, using relatively new devices that cover the valve handwheel or lever.

Isolation padlocks, and the keys that fit them, are therefore at the very heart of safety locking-off procedures. Despite this fact, sourcing padlocks for use in such procedures often fails to give due consideration to the possibility of unauthorised removal. It is very easy for a purchaser to pull an industrial equipment catalogue off the shelf, identify the shape and size needed, and place an order.

However, making a choice about sourcing padlocks can directly affect the welfare of operators and maintenance personnel. Making the wrong decision can significantly endanger them. During a lock-off procedure, if a padlock is removed from the machine isolator or other prime-mover, the machine can be re-energised and the person working on the machine may suffer injury or death.

An important feature of locking-off, therefore, is that it should involve personalised safety padlocks, to prevent one person from opening another person's padlock. Unless this feature can be assured, the integrity of the system is negated. If duplicate keys are in circulation in a workplace, the possibility arises that one will be used to remove a padlock protecting a worker during maintenance or cleaning procedures.

Everything should therefore be done to make sure that no duplicate keys are in circulation. The more often someone procures padlocks from a supplier who does not maintain records of the keys and padlocks sold to each purchaser, the risk increases. In order to avoid the problem of duplicate keys, to keep staff safe, padlocks should be purchased from a manufacturer who keeps what are called 'key differ' registers.

A key differ register is a record of every key number ever produced by a manufacturer, and every customer has their own register of keys and corresponding padlocks purchased. When padlocks and keys are purchased, the manufacturer can check previous orders and ensure that no duplicates are being supplied. They will, instead, supply key differs that are sequentially next from the register. In the case of lost keys, the manufacturer should verify the authority to supply a new key. They should also ensure that the replacement is allocated to the customers record. By keeping accurate logs, the manufacturer is able to protect the purchaser and their companys best safety interests.

Next time you reach for that equipment catalogue, remember Murphys Law: Anything that can go wrong will go wrong. Consider the possible consequences of purchasing padlocks for locking-off procedures that are unrecorded, and then think again. If someone suffers loss or damage, employer or employee could find themselves in a court of law. More importantly, lives are at stake and it just might be yours.

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