Features Research & Innovation
Domtar Windsor a leader in reliability

Domtar’s huge paper mill in Windsor, Que., has gone through many changes in the past decade, resulting in higher productivity, reduced maintenance costs, reduced overtime (from 12% to just 7%), fewer emergencies and improved safety. The benefits include higher employee qualifications, improved communications between maintenance and operators, and a complete overhaul of the maintenance program.

These improvements result from the mill having completely re-engineered its maintenance strategy following the implementation of reliability-centred maintenance (RCM) in 1998-99, along with many other improvement programs. The genesis of these improvements, however, can be traced to the years after Domtar started up the new mill in 1987, which eventually replaced its Windsor-based Watopka and St. Francis mills, closed in 1992.

Engineers drew up preventive maintenance (PM) programs for the new mill, but, recalls Alain Richard, maintenance superintendent, finishing and converting, “We had so many emergencies during those first years that there were many reasons to skip PM tasks. Workers did the routes that they believed were good, but gradually dropped the PM program.”

Those were the days of ‘every man for himself’ maintenance: each worker did his own planning; e.g., inspections, work preparation, repairs, and parts ordering and pick-up. They would go back to the machines that required work and ask the operators to shut them down.

There were no minimum educational requirements for many trades and operating positions. One quarter of the mechanics had no high school trades diplomas (they came from apprenticeship programs), half had high school trades degrees and one quarter had specialized, college-level trades degrees. This made implementing new maintenance practices challenging. “Maintenance people with high school diplomas mostly are action people and do not like taking measurements,” Richard says.

The decision to implement RCM started a profound shift in the plant’s maintenance culture and training requirements. Of several versions of RCM, the Windsor mill uses the original documented by John Moubray.

Richard explains the basics: “RCM is a process used to determine what must be done to ensure that any physical asset continues to do what its users want it to in its present operating context. First, you find failure modes, that is, causes of equipment failure; a piece of equipment might have a few, or hundreds of failure modes, depending on its complexity.

“The next step is to define the actions or tasks that will prevent or reduce the consequences of each failure mode. Consequences can impact safety, the environment, customers and costs, such as those due to production and maintenance losses. Most actions are basic maintenance tasks, such as lubrication and cleaning, and condition-based maintenance; e.g., monitoring the condition of equipment and doing repairs when required.”

A failure mode on a gearbox might be described as “Seal on shaft damaged by normal wear.” The defined action would be “Check for oil leak from seal every two weeks.” Doing this prevents the consequence: “Broken equipment caused by oil missing.”

Another gearbox failure mode might be “Bearing seized by normal wear,” with the defined action described as “Take a vibration measurement every three weeks.” If abnormal vibration is measured, mechanics, having been forewarned that a failure could occur anytime, can do a planned repair, rather than an emergency repair that could be three to 10 times more expensive.

RCM also covers protective — or hidden — functions. For these, actions can be defined that stimulate the protective device to see if it is functioning properly; e.g., start a by-pass pump or test a relief valve.

RCM is time well spent

Doing an RCM analysis on a piece of equipment is a team effort that brings together personnel from different departments; e.g., maintenance workers, operators and supervisors. A team of five or six normally takes 10 days to do an analysis, but a complex piece of equipment might require weeks to analyze. For this reason, the mill has targeted complex equipment that is subject to frequent failures and high consequences.

The time invested doing RCM analyses is well spent, Richard says. “RCM is good training for your people. The day you finish your analysis, your employees know your equipment much better.”

Richard has deliberately used RCM, with the detailed familiarization with equipment that it demands, as a substitute for formal equipment training. Immediately after an RCM exercise, with the extensive analysis of failure modes and the equipment functions it requires, the operation of the equipment will be improved and maintenance costs will decrease.

Other programs in the mill’s maintenance revolution have allowed equipment operators to become much more involved and lend their expertise to the development of maintenance strategies. The Operations/Maintenance Services program is a good example: It brought operations and maintenance personnel together to rethink all of the processes involved in preparing for maintenance activities: ordering parts, preparing shutdowns, identifying problems, determining the availability of equipment slated for maintenance, estimating downtime required, parts and heavy equipment needed, execution of work and by whom, and follow-up and evaluation of the work.

For many pieces of equipment where RCM analyses would be overkill, the mill has chosen preventative maintenance optimization (PMO), which is a simpler methodology requiring less personnel time, Richard explains.

“We use PMO when the criticality of the equipment is moderate to low. You can review a lot of equipment in a very little time, [doing] a PMO of a small department in a couple of weeks, with the operators, maintenance workers and [the mining of our] history of failures.

“We feel that we can solve 80% of our problems with 20% of our failure modes. When you have thousands of pieces of equipment, you need shortcuts. RCM, PMO, and root cause analysis each has its place. You have to choose the right one.”

The mill also makes extensive use of condition-based maintenance to detect the signs that failures could be imminent. It installed Ivara EXP in 2004-2005, a software package that manages and monitors the condition of mill assets.

These asset conditions are termed ‘indicators’, of which there are many different types. The most used is descriptive, e.g., visual belt condition. Others are numerical, calculated, counter, and logical. Each indicator, of which the mill monitors about 38,000, has its own criteria for when an alarm will be generated. Once the alarm is verified, maintenance will generally prepare a work order to fix the abnormal condition.

Some indicators are collected automatically from a process data archiver software called The PI System, from OSI Software. Employees collect other indicators on their routes, using everything from their own senses to tools such as strobes, infrared, vibration and ultrasonic probes. The data is entered on handheld computers.

This ability to predict failures has made just-in-time ordering of parts possible, with less money tied up in fewer spares.

This revolution has entered its second decade. The many benefits include more motivated employees, better communication between better-trained maintenance staff and more self-reliant operators, fewer bottlenecks and better understanding of the equipment, making this mill a leader in equipment reliability among all of Domtar’s mills.

PPC

Montreal-based Carroll McCormick is the senior contributing editor for Machinery & Equipment MRO. This article first appeared in Machinery & Equipment MRO, June 2009.

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Domtar Windsor mill

• Annual paper production capacity of 670,000 tons. Annual pulp production capacity of 454,000 tonnes (includes 33,000 tonnes of mill trade pulp) 1 pulp line and 2 paper machines

• Uncoated
freesheet papers.

• Bleached hardwood wet-lap market pulp.