Fix It Before It Breaks
Condition-based maintenance (CBM) detects equipment failures before they happen. Can you afford to be without it?
By Barry Parker
Condition-based maintenance (CBM) was perhaps best described by maritime writer Ryan Skinner, who observed a shift from the prevailing industry maxim of “If it ain’t broke, don’t fix it” to an emerging philosophy of “Fix it before it breaks.” More formally, the International Standards Organization, in a 2004 publication, defined CBM as “maintenance performed as governed by condition monitoring programmes.” Danny Shorten, Product Manager for Maintenance Management at Lloyds Register (LR), defined CBM in a recent presentation as “An equipment maintenance strategy based on measuring the condition of equipment to assess whether it will fail during some future period, and then taking appropriate action to avoid the consequences of that failure.”
CBM has seen applicability to rotating devices with close tolerances, like shafts, which are difficult to inspect. More recently, with advances in technology, it’s been applied to up-and-down movements – within engine cylinders, for example. Shorten and others emphasize that switching to CBM from a different maintenance approach requires ongoing input from the individuals involved as the processes and policies surrounding maintenance are changed. It’s a people business, ultimately, and maintenance culture is impacted as much by people as it is by new technology. Just because it’s possible to monitor a process (a spinning shaft, say) using a new indicator (likely tied to the home office via a VSAT or maritime broadband hookup) doesn’t mean that everyone involved, both shoreside and on the vessels, need not be comfortable with their new and evolving roles.
The business case and return on investment (ROI) for CBM, at the highest level, is based on the trade-off between costs and benefits, the most obvious of which is the increased “up” time for components. Not surprisingly, the early inroads have occurred in the less price-sensitive parts of the maritime world with a high “shadow price” on downtime. These include naval vessels, oil company supply chains, gas transportation and the cruise sector. An important crossover sector has been offshore oil platforms where, by definition, the working assets did not come into port, allowing maritime applications aboard commercial vessels to benefit from the ingrained learning curves developed around the offshore sector. A secondary set of economic benefits may come from outsourcing, whereby a component manufacturer assumes responsibility for the maintenance function, or for one or more items.
Choose Your Weapon
A great deal of practical engineering theory, melded with experience with hard-to-get-at onboard equipment, lies behind CBM. Lt. Commander Harry Lijzenga of the Royal Netherlands Navy has written and consulted extensively on CBM and now oversees a LinkedIn group on the subject. In a presentation provided to MarEx, he contrasted the traditional concepts of corrective maintenance (running until the part fails) and preventive maintenance (changing out parts based on time or usage intervals) with CBM.
Lijzenga explained that shorter maintenance intervals will offer a better chance of capturing the slippage of a component from potential failure (when a reading enters a critical zone) to functional failure (when the part fails). Traditionally, increased cost accompanies increased frequency of inspections. But with CBM the continuous remote monitoring of a system effectively provides the equivalent of high-frequency inspections at a much lower cost compared to stopping a vessel and opening up a cylinder head.
From a business perspective, decisions must still be made on which maintenance battles to fight. LR’s Shorten points out that: “If we limit our CBM activities to only those highly critical assets, we can achieve a greater impact in terms of optimization for a much less significant investment.” Lijzenga sees maintenance management similarly. When looking at vibration monitoring, the Dutch Navy uses a four-part taxonomy. At one extreme are “critical” installations such as gas turbines that are monitored online. In the mid-range are “essential and complex” systems (including diesel engines, gearboxes and shafts) and “important” installations (including compressors, fire pumps and motors) that are monitored offline through an onboard inspection. In the lower range are “operationally less important” components that may be subject to a more traditional scheduled approach.
As experimentation evolves into common practice, the use of CBM is now on the cusp of a growth phase, supported by type approvals where equipment conforming to specific design criteria will gain the blessing of class societies. In early 2011 Germanischer Lloyd (GL) granted its first approval according to its “Guidelines for Machinery Condition Monitoring” after testing on MAN engines and Hapag Lloyd ships. The inaugural recipient was AMOT Controls, a system that monitors the crank trains of low-speed diesel engines with an eye toward detection of wear on the bearings. In October Kongsberg Maritime gained a similar approval for its Bearing Wear Condition Monitoring system. Kongsberg explains that its offering, where a pair of sensors in each cylinder monitors wear, can sound an alarm before steel meets steel. The new system can be integrated into existing Kongsberg onboard alarm and monitoring installations.
In a paper presented at a recent conference on Condition-Based Monitoring, Lt. Commander Lijzenga identified three major business benefits: greater equipment availability, whole life cost savings, and reduced manning. As he explained, the savings also include fewer expensive ship visits from specialists. LR’s Shorten’s list of positives included insurance benefits – fewer sub-deductible losses and increased leverage versus deductibles.
The class societies, LR, GL and their peers, have more than a passing interest in CBM. A less apparent, but central, tenet of the ROI is derived from a not always obvious, but still important, time-saver. In the words of GL’s Dr. Jörg Rebel, “Condition monitoring reduces the overall cost of inspection services and optimizes maintenance schedules, reducing the risk of equipment failures or damages.” Scheduled inspections of propulsion components (for example, a crankshaft) require careful planning; they also lead to vessel downtime. As an alternative, continuous monitoring of operations – and actions, as needed, tied to diagnostics – can provide the basis for the class survey. The Type Approval paves the way for more control and monitoring systems that can eliminate the requirement for “open-up” inspections.
Leading the Charge
Well-known shipping companies are leading the CBM charge. According to GL, its Noble Denton division has been working with Chevron Shipping where CBM has replaced its previous time-based system in maintaining critical pumps, purifiers and steering gear, functions characterized by frequent operation and high repair cost if there is a failure. GL has also worked closely with Hapag Lloyd and Peter D?hle Schiffahrts. GL explained that engine maker MAN Diesel has mandated CBM on certain engines with a key objective of avoiding damage from maintenance done the old way – by opening up the crank train.
Like MAN Diesel, the major engine manufacturers and key propulsion system vendors have taken a leadership role in CBM. In July Wärtsilä announced that it had signed a five-year contract covering dynamic maintenance planning for engines on six vessels operated by Ceres LNG. According to Wärtsilä, “The engine’s operational data and parameters are continuously fed into a database and then evaluated at our CBM center. The maintenance needs are thus predicated on the actual condition of the equipment, allowing maintenance intervals to be amended according to actual need. Service work and spare parts availability can be arranged accordingly.”
Earlier in the year, Wärtsilä had inked a five-year maintenance support deal covering engines on 29 cruise ships among brands in the Royal Caribbean family. A Wärtsilä executive explained, “The main idea is that Wärtsilä will organize the work that needs to be done on the ship engines, leaving RCL to concentrate on its core business – looking after cruise guests.” He stressed the benefits, which included better budgeting, planning and logistics for actual parts deliveries and installs, and noting that fuel consumption is optimized while emissions are reduced.
An independent provider of predictive maintenance software, UK-based RCM Marine, offers real-time reporting. Its Voyager product, used to remotely monitor main engine and diesel generator turbochargers, has been taken by Qatar Gas Transport (Nakilat) on a group of vessels managed by Shell Trading & Shipping. P&O Cruises has also utilized Voyager for monitoring turbochargers aboard vessels in its fleet. Another RCM offering, Mariner, has been installed on vessels managed by Northern Marine Management, a division of Stena.
SKF, well known for the precision bearings found in rotating shafts (and also for associated couplings and seals), has also integrated CBM into its marine business. It described possible multipronged programs to support CBM of turbochargers (where an outright failure could occur very rapidly after the initial fault is detected), main engine lubrication oil systems, engine room fans/blowers and cargo pumps. These hypothetical programs, described by SKF but applicable across the industry, could include (1) assessment and mapping, (2) data collection, (3) on-line surveillance, (4) analysis, (5) correction, and (6) verification and continuous improvement.
The Future Is Now
Where is CBM heading? It began in the aircraft industry and also became commonplace in offshore oil production, two businesses full of rotating devices. Lijzenga of the Royal Netherlands Navy traced a maritime time-line that began in the 1990s as the naval sector, a very early adopter, sought to closely monitor vibrations using infrared measurements. Peering into his crystal ball, he sees a future with far more remote monitoring, tied to a wider and cheaper communications pipe, at a time when navies (like commercial shipping) must do more work with fewer crew.
To date, CBM has been closely intertwined with the continuing declines in maritime communications costs and the ongoing advances in software, both of which have made remote monitoring of shipboard components and machinery a more affordable proposition. Reduced communications costs provide the backdrop for supporting a broader shift in maintenance philosophies to CBM. No longer in an early adopter phase, the ability of CBM to gain traction will no longer be driven purely by engineering wizardry and cheaper communications.
The Silicon Valley venture capitalist and writer Geoffrey Moore looked at the spread of innovations in the software business and contrasted those which don’t get across the great divide between niche users and the rest of the marketplace with those that do. Analogies to maritime CBM are very appropriate. As vendors try to push CBM across the chasm to a broader maritime market, the very powerful forces of ROI, the logistics of stopping ships and sending parts, and the all-important human factor will all come into play. My money’s on CBM. – MarEx
Barry Parker is a maritime consultant and writer.