Netherlocks' Key Transfer Stops Human Error
16 February 2007
Industrial plants are designed with the highest accuracy in mind, with several separate safety loops often checking the integrity of process systems. However, these apparatus cannot check for human intervention.
A small human error could cause an enormous catastrophe. Bear in mind that 70% of reported incidents in the oil and gas industry worldwide are attributable to human error and account for in excess of 90% of the financial loss to the industry.
Improving your plant process is normally very complicated and expensive. However, using Netherlocks' add-on devices improve safety and operability in a simple way without taking process equipment out of production.
WHY AN ADD-ON PHILOSOPHY?
As mentioned above, most errors are caused by humans, not machines. Therefore, in order to control safety, we need to control people.
How do we do this? In cases where process equipment is not actuated and controlled by a PLC or DCS, it can be operated by anyone and at any time. Of course you could guide operators with written procedures or by the use of lock out systems, but this will not eliminate error. The only way to eliminate error is practice. Operators need step-by-step guidance and the answer to this problem is key interlock systems.
KEY INTERLOCK SYSTEMS
Humans are subject to failure, so in every operation involving human intervention there is a chance of an error.
Key interlocking is a 'best practice.' Using key interlocks completely eliminates human error. This idea is not new: it began in the 1980s. Its strength is its simplicity: just mount a key transfer device onto your switch, valve, closure or actuator to guide the operator through every step of the process. This concept is used worldwide and accepted by all major end users, while most institutes also add them to their regulations:
HOW DO KEY INTERLOCK SYSTEMS WORK?
Once mounted on the host equipment, a key interlock is fully integrated and not removable. The lock contains two keys. If one of the keys is not inserted, the system is locked and therefore cannot be operated. Furthermore, a key can only be released in the fully open or closed positions.
This is totally different from chain-padlock type protection. As is well known, a padlock can only block a device; it doesn't guarantee position and it cannot guide operators through a step-by-step procedure. Therefore, chain-padlock solutions are always subject to failure irrespective of the operator's knowledge or experience.
The position-controlled key release guides the operator through the critical steps that they need to take. In other words, it doesn't make his daily work more intensive or complex. On the contrary, it helps him avoid mistakes even when he is distracted or ill.
The fast-speed world leads to an increased risk of accidents through human error. Well designed interlocking systems can mitigate these risks – either by eliminating error or by greatly inhibiting the potential for violations. Well-designed key interlock systems are always operator friendly – they require no additional work effort from the operator beyond that required by normal procedures and, most importantly, should never permit more than one key to be free at any one time. The message is: Keep it simple and let's make it safe.
