Do you feel lucky?26 September 2013

As CS Forrester's Lord Hornblower said: "The lucky man is he who knows how much to leave to chance." That's true of making maintenance sustainable, too.

There are very few genuinely new ideas in life, and engineering maintenance is no exception to that rule. Fact is, the vast majority of methodologies and technologies have been thought of before, and what novelty there is tends to lie in their application. So while you're wrestling with RCM (reliability-centred maintenance), TPM (total productive maintenance), etc, it makes sense to spare a thought for what others are doing. And where better to turn than to those facing the greatest challenges?

Without doubt, right up there in that cadre are the high-hazard plants – those bound by COMAH (Control of Major Accident Hazards) onshore and DSEAR (Dangerous Substances and Explosive Atmospheres Regulations), particularly offshore. Examining the raft of ACoPs (approved codes of practice) associated with both those sets of regulations is a good starting point.

Another is seeking guidance from those whose task is to maintain ageing assets, where the primary focus tends to be on preventing – or perhaps more realistically mitigating – stuff that could cause incidents. We're not just talking about explosions here, but also serious outages, due to plant failures. Inspectors in these environments tend to draw on guidance from the PAS 55 (specification for the optimised management of physical assets) standard – so there's another useful source.

What's striking is that both of these sets of guidelines map well to improving plant reliability. As Brian Hudson, who currently leads the ABB Consulting team embedded in BP and is deputy chair of the IMechE's Offshore Engineering Committee, says: "Invariably, on high-hazard and ageing plants, reliability, safety and hazard prevention go hand in hand."

Why? Quite simply, because safe plants are reliable and reliable plants are safe. For Hudson, that means putting some serious effort into understanding not only the risks, but also the site and asset vulnerabilities – and putting plans in place to manage them in the short-, mid- and long-term. "Likelihood multiplied by consequences equals risk," he asserts. So there's your route to assessing plant priorities. These should translate to maintenance and operations strategies that are sustainable and proportionate. They should also shed light on the required resources.

"With ageing plant, it's not so much how old the equipment is that matters; it's what you know about its condition and how that's changing over time," explains Hudson. "If you understand the future risks and their likelihood, then you can do things proportionately and proactively to manage them. For example, equipment might start showing signs of deterioration associated with current operational procedures. So, as well as appropriate maintenance, it may make sense to manage those operations slightly differently in order to halt, or at least slow, that process so that plant lasts longer."

He gives the classic example of cavitation on pumps, which may only occur during plant start-ups or under unstable conditions. "It may only happen for a short time, but make a major contribution to plant deterioration. So maintenance and operations should focus on doing something about that to extend the life of the pump and associated plant and pipework."

Just as important as understanding your plant and operations, however, is having a plan to manage identified contingencies, should they arise. "If you identify that a problem could occur, then you need to look at putting appropriate plans in place so that, if it does, the impact is mitigated," says Hudson.

Obvious? Maybe, but how many operations and maintenance teams (where they even exist), have the authority, the resource and budget to do so? It's an aside, but as Richard Jones, managing director of lean maintenance specialist MCP Management Consultants, puts it: "Asset management is still seen as the maintenance manager's responsibility and nothing to do with production. So planned and preventive maintenance may be there but engineers aren't enabled do it, because the operations director wants products out the door and won't stop for maintenance."

Even if management is more enlightened, how many factories would contemplate carrying spares of very large electric motors, say in the 3.3-11kV range, with MW outputs, unless there was an irrefutable business or high-hazard case? The point: if we're to learn the lessons from those doing this right, we need to consider what we would do if ours failed. Find ways, for instance, to reduce the lead time to getting a replacement on site, installed, commissioned and operational.

"A few years ago, we had a client with a 35 year-old 3.3kV 4MW motor that, according to its MBTF data, was on borrowed time. So, as well as doing the simple things, they talked to their local repairer and agreed what could be done to reduce any rebuild time from, say, six months to three or four weeks. But they also spoke to the motor manufacturer and asked for a list of companies that had bought similar motors. In the meantime, inspection revealed that the rotor bars were starting to crack and, when off-duty, shed material. So they contacted the sites with similar motors to ask if they had a spare, and found one with the very next production line item that was now redundant. They bought the motor for a fraction of the new price and, at the next opportunity, dropped it into place without even needing to repaint the base plate."

The point: anything you can do in advance – and it needn't be sophisticated – reduces the consequences of potential failures, and hence your vulnerability. And the same applies to people and incident planning. Ask yourself, do you have the right skills in place to deal with potential problems? If not, do you need to consider where to get them from or who to train? And what about removing damaged equipment? Can you work out a lifting plan in advance, or alter some of the surrounding structures so that you're prepared?

"Engineering competence becomes more of a challenge as plant grows older, because fewer people have the knowledge to fix it, you probably can't buy straightforward replacement parts and you can't easily justify investing in new equipment," observes Hudson. "So you become increasingly dependent on people who can solve these kinds of problems, and that generally takes some organisational rethinking."

He also makes the point that, because these are 'soft' issues, they tend to be cheaper and easier to deal with – as long as they're not overlooked. Sometimes, he says, all that's required is to make someone responsible for understanding the plant deemed to be vulnerable, providing them with proper OEM training so that, over time, you build in appropriate cover. Rocket science, it isn't.

Note that Hudson is not just talking about big plant, such as catalytic reformers. Those already get plenty of attention, he reasons, so they don't tend to go wrong. The issue is often something as innocuous as an ID (induced draft) fan, a pump set, a compressor or a motor, without which the whole plant cascades into an off state. "People are generally quite good at understanding the big risks, but they're not so good at getting vulnerability," he asserts.

His recommendation: as part of your maintenance strategy, check that operating instructions are up to date and fit for purpose. Do the same with maintenance instructions and spares stocks, in line with your contingency planning. And check that the required skill sets are either in place or can be sourced in acceptable timeframes. "Take your standard risk matrices, but add columns for likelihood, consequences and vulnerability. Then act on what you find."

Slicing downtime
Sometimes the simple things are, well, simple. British baking firm Warburtons says it has reduced maintenance costs, minimised risk of product contamination and cut unscheduled downtime since installing SKF extreme-temperature Y-bearings. Engineering manager Paul Moodey says that MTBF has been extended from six months to three years with the bearings, which use a dry lubricant option that removes the need for high-temperature greases.
He explains that Warburtons wanted to increase efficiency on the ovens at its Enfield site, where oven unloaders transport trays of product on rollers throughout the day. Despite frequent re-lubrication, its bearings had been failing and automatic lubricators were not an option – because of the temperatures.
Hence SKF's Y-bearings (VA228):?savings in lubrication and maintenance alone are £7,000 per year, and Moodey expects return on investment of 200%.

Brian Tinham

Related Companies
ABB Ltd
MCP Consulting & Training
SKF (UK) Ltd

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