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How Permit To Work Systems Can Fail?

how permit to work systems can fail

A permit to work or PTW system. if properly implemented, should go a long to preventing accidents.  However, HSE research into accidents involving maintenance related tasks shows that the single largest contributory factor was lack of, or deficiencies in, Permit To Work systems.

Unfortunately, permit to work systems often deteriorate into bureaucratic box ticking systems that do little to manage risk effectively.

In this article will take a look four common failures in permit to work systems and some of the lessons that come from these.

1. Failure to Use PTW System?

There are many accidents that have been caused because a permit to work system was not used – either because a system was not in place, or an available system was not instigated.

There are many possible reasons why many workers involved in a task may not use a permit to work system that is in place – including a lack of training in the system on site; as well as a failure by the main duty holder to properly control and manage the work on site.

The golden rule is always check if you are in any doubt whether a permit to work applies – and never start until you have checked.

2. Permit to Work is Not Linked Risk Assessment

Another category of accidents involve those where a permit to work system was instigated, but where the safety controls or precautions required by the system where inadequate.   In other words, all of the workers involved implemented the controls required by the permit, but an accident still occurred because they were inadequate.

 What this research highlights is that a permit to work can become a dangerous illusion unless it is linked to a thorough risk assessment.  Just because there is a permit to work system doesn’t mean that the risk will be adequately controlled.

Risk assessments need to cover all aspects of the task and put in place suitable controls.   However, even when this occurs, jobs and environments can change, and so all concerned must be on the look for shortfalls in the permit requirements, particularly in the precautions.

The golden rule is – never assume that a permit to work system makes a job safe to perform – if anything, it highlights the heightened risk and the need for extra vigilance and suitable risk assessments.

3. Inadequate Communication

Perhaps the most common factors in accidents linked to shortfalls in permit to work systems include failures in communication between the various parties, along with a failure to follow the permit system.  These shortfalls were clearly demonstrated in one of the most famous industrial accidents – the explosion and total destruction of the Piper Alpha oil rig.

 The effectiveness of any permit to work system relies heavily on the quality of communication it facilitates between the various parties.  In the case of Piper Alpha, this lack of communication included a failure to display the relevant permit at the point of the work as well as in the control room.

Permits were routinely filed in the safety office, not in the control room.  In addition, the accident investigation found that it was common practice for permits to be stored in the pocket of the issuer!

What this meant is that a lead production operator could go to the control room, and as occurred, be completely unaware of what permits-to-work were in operation.   If the system does not communicate clearly and consistently to all concerned then, as Piper Alpha shows, it becomes a meaningless exercise that protects no one.

Piper Alpha also demonstrates the common problem of a gradually deteriorating work system.  Overtime workers slowly stopped following prescribed systems of work.   A permit to work is a formal work system  and unless it is followed precisely, every time, then again it becomes a meaningless exercise.

The reasons why a permit to work system degenerates are many and varied.   In the case of Piper Alpha the accident investigation was critical of the level of training for all levels of staff, and, management in particular.   Managers had minimal safety qualifications which led directly to poor management practices and ineffective audits of the permit to work system.

And, this leads us to our final category of failure – a lack of competence.

4. Inadequate Training/Incompetence

Systems of work alone do not achieve safe workplaces – competent people are also required.   These two ingredients together are essential.

Take as a case in point a fatal accident that occurred on Glomar Arctic IV – a semi-submersible drilling exploration rig that was at the time moored for repairs in Dundee Harbor, Scotland.

Two men employed by a contractor died as a result of an explosion and fire whilst repair work was being undertaken in one of the rigs legs.

The rig operator’s permit to work system was being used at the time of the incident.

The explosion was caused by a leak from a propane hose which the contractors were using for cutting and welding.

The Leaking Gas had built up in the rigs leg.

The subsequent accident investigation found that a lack of training and competence had played a major role.

In particular, there was inadequate training for the contractor tradesmen regarding their role and responsibilities within the permit to work system.

Indeed, it was found that everyone involved, including the rig operator, the contractor’s management and workforce did not properly understand the permit to work system.

As a result, all necessary precautions had not been established, workers had not been adequately trained to implement those that had been identified, and, the work-site had not been inspected –and to the extent that management were not fully aware of the nature of the work being carried out.

If workers do not know what they are doing then the permit to work system will fail.   As we have seen, ignorance in this subject is often fatal.


In this article we have reviewed a range of common failures in permit to work systems. Tasks that require a permit to work are by their very nature higher risk and so it’s essential that this last line of defence is carefully implemented and managed on an on going basis.

Unfortunately, there is often a tendency for work processes like a permit to work system to drift slowly towards failure over time. Only constant vigilance and monitoring can ensure that a permit to work system is operating effectively.

This article provides some common factors to look out for during such monitoring that provide early warning signals of potential problems that need to be corrected.

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