Total productive maintenance (TPM), a term coined by Japanese car components company Nippon Denso, is a system for improving the integrity of production and quality systems through a company’s machinery, equipment, processes and employees (see panel text below). Inevitably, plant owners do not want to be faced with unexpected events that occupy their time and resources to put right. Fortunately, high-hazard events are rare. However, this is something of a double-edged sword.
“Because such events occur only infrequently, it’s important not to become complacent and assume that because last year was okay, the next year will be the same,” says Adam Potter, director of Axiom Engineering Associates.
Potter quotes former US defence secretary Donald Rumsfeld, who said: “As we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say, we know there are some things we do not know. But there are also unknown unknowns – the ones we don’t know we don’t know. And if one looks throughout the history of our country and other free countries, it is the latter category that tends to be the difficult one.”
But Potter adds a caveat of his own: “Whether it was deliberate or not, Rumsfeld missed a final category: unknown knowns. “This could be one of two things: Information that was known, but turned a blind eye to: eg, bad practice, corner cutting, etc. Also, on a corporate knowledge management level, information existed within the company, but it was not available to the right person at the right time. Prosecution lawyers have a field day with both of these scenarios, as any employee at Volkswagen may well tell you.”
Best practices for TPM
Axiom are based in Stockton, close to Europe’s largest petro-chemical complex on Teesside, while Potter comes from a high-hazard process background and has worked with a range of industries over the years. During this time, they have come up with a list of best practices for total productive maintenance.
1 Senior management’s commitment to risk reduction
“Most incidents involve human error,” he points out. Thus, it’s important that all personnel understand that the senior management team are truly committed to reducing risk. Statements and policies that show commitment to Health, Safety and Environment (HSE), quality, legislative and/or industry best practice are vital. “The key aspect of this is to engender these values in all parts of the organisation, so personnel exhibit behaviours that align with senior management commitments,” he adds. “We’ve also seen that the best companies strive to reinforce these values and behaviours regularly through both soft and formal communication channels.”
2 Structuring an effective organisation
Dips in the business cycle, mergers and takeovers may result in an organisation being hollowed out to realise cost savings. Understanding the impact of such changes on the long-term risk profile of the facility is essential to ensuring that key roles remain filled.
“When looking at business processes, having skilled and experienced personnel in key risk management roles is crucial,” Potter says. “We’ve seen reorganisations where the engineer responsible for equipment integrity is redeployed to cover three plants, rather than just one, or where such a role remains unfilled, due to retirement. The question to be asked is then who has ownership for integrity and risk management?”
3 Only employ competent people
The performance of an organisation rests on individuals’ ability to perform. As people retire or leave, ensuring that competency and knowledge transfer is carried out is essential. It’s as important for personnel to know what is required of them, especially when things go wrong. “One key feature that we’ve seen in excellent organisations is that competence isn’t just measured by skill and experience, but also by what’s called ‘personal attributes’,” Potter continues. “If it’s critical that a role requires almost pathological levels of diligence, then
this should form part of the competency profile and the role only filled by those that meet these criteria. Our experience is that this is the hardest to benchmark against.”
4 Keep accurate records
A process plant is complex and seemingly small components can cause accidents. Thus, having an up-to-date list of equipment is actually very important. “We’ve gone on to plant and found relief valves missing where the drawing says there should be one,” he reveals. “We’ve also seen protective devices fitted, but were not on the maintenance management system, so were never overhauled. Insulation can hide bellows and other components. During an incident, decisions will be based upon the information available to the response team at the time. If this isn’t accurate, then the decision may make things worse, not better. Information usually resides in several different locations, whether that’s on the P&IDs or other drawings, in the maintenance management system or project equipment files. Stopping such lists diverging can be hard work.”
5 Understand and list which equipment is critical to you
If there is an accurate equipment list, then those that are important should be plainly identifiable. There can be several criticality categories and one item of equipment may be critical for different reasons. For example, relief valves may be safety critical, scrubbers may be environmentally critical, and instrumentation may be both safety and business critical. This helps decision-making when identifying what routine maintenance to do, and what priority should be given to maintenance and capital budget expenditure.
6 Understand how your critical equipment can fail
If a piece of equipment is critical, then the best organisations will also know how it can fail – and plan for such an eventuality. Failure can be many things: a leak or a failure to function on demand, for example. “Knowing which deterioration mechanisms that cause failure and how often they could occur will help the best organisations design effective intervention strategies,” Potter explains. “This could be routine maintenance, inspection, condition monitoring or performance testing. The advantage of this is that such intervention strategies will be optimised.”
7 Knowing what you don’t know and test your assumptions
Returning to Donald Rumsfeld’s quote again, he says: “We’ve seen really good organisations review what they know about the equipment and try to understand what they don’t know. Without going too Rumsfeld, evaluating what you don’t know (but should) and what you don’t know (but isn’t even reasonably foreseeable) can help you manage your equipment. We’ve seen organisations analyse deterioration mechanisms, but also, because they’ve identified weaknesses in the assumptions they made in the first place, go looking for mechanisms that they think won’t be there. This validates that, in fact, nothing is occurring and then increases the body of knowledge to help them manage the risk. If you found something, then you’ve possibly stopped an accident before you even knew it would become a problem to you.”
8Developing work processes that reduce risk
The only true means of risk reduction is through intervention. This may be periodic, such as maintenance, servicing or routine repairs. It may also be one-off activities, such as replacement with new equipment that’s designed so that identified failure mechanisms do not occur.
It could also include reducing inventories, pressures or temperatures, or even replacing the substances processed with less hazardous ones. That’s where specialists like Axiom Engineering come in. “Businesses only have limited budgets,” acknowledges Potter, “so knowing which items present you with the most risk can help manage this process.”
In today’s hectic – and complex – work environment, hoping for the best is no longer good enough. Companies need to take a proactive attitude to risk management.