Archive | October, 2008

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October 1, 2008
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What Do Successful Reliability Engineers/Managers Do?

So you’re the reliability engineer? Now what?

Corporations large and small have finally realized that if everyone is responsible for reliability, no one is responsible for reliability. The move to put someone “in charge”— with his/her primary responsibility being to assure reliable physical assets and operating systems—has spawned a position in industry that may remind one of the vegetable juice commercial and have management slapping themselves on the forehead and saying, “I should have had a reliability engineer.”

1008_roles2We will use the title “reliability engineer” (RE), and there are, indeed, certifications that bear this title. Petroleum plants, airlines and nuclear power facilities usually have degreed and/ or certified REs, but many small- to mid-size companies are realizing great benefit from “reliability managers,” “reliability supervisors,” “condition monitoring engineers,” “preventive maintenance specialists,” etc. Just having someone who feels that reliability is his/her first responsibility brings immediate dividends in many cases. This article is meant to help those who have been thrown into the fray and may need a little direction and camaraderie.

Today’s reliability engineer (RE) position can be one of the most exciting and most rewarding jobs in industrial America. It can be likened to a revolution in management with the RE being the “field general.” Unfortunately, some organizations may struggle when it comes to clearly identifying and communicating the actual job responsibilities for such a position. While you, as an RE, may find yourself in this situation, remember that it presents you with a tremendous opportunity—you can “define” the role of a reliability engineer for your company. Once you see the possibilities, you’ll probably become one of the busiest people in your operations, and you’ll love every minute of it!

Continuing with the “field general” analogy, one of the RE’s most important tasks is to assess the enemy’s strengths and his own forces’ weaknesses, then convey that information to headquarters so the resources necessary to attain victory don’t dry up. Anytime we use the word “assess,” the word “measure” won’t be far behind. How can you:

  1. Measure your need for reliability (assess your facilities’ weaknesses)?
  2. Measure your capabilities to meet the need for reliability (assess your department’s strengths and weaknesses)?
  3. Quantify your successes, so that the resources necessary to sustain the “revolution” are forthcoming?

Job #1
Job #1 is measuring reliability (or, if the glass is half empty, “unreliability”). That’s because the level of support you receive is directly related to how imperative your work is perceived to be.

There must be a measure that is understandable at the top levels and directly related to the bottom line. Operating Equipment Effectiveness (OEE) is an excellent measurement that can be related to everyday occurrences and makes sense in the boardroom. You must make sure the measurement is done with total integrity. If people know it is a fudged number, it (and perhaps you) will become, at least to a degree, meaningless. OEE is the product of available operating time, operating time efficiency and product quality, and it is a cornerstone of Total Productive Maintenance (TPM).

An equally important measurement of reliability is MTBF (mean time between failures). While OEE is a great “overall” number and a starting place to begin understanding what should be worked on, MTBF can be more easily targeted at groups of poorly performing machine populations. Once quantified, certain causes will be obvious. Ricky Smith of Ivara notes that MTBF “is the number one measurement of reliability worldwide.” If you are not measuring MTBF of processes or production trains, and individual equipment populations, you are neglecting some of the most powerful information an RE needs to have at his/her fingertips.

Many times, with these two measurements (OEE and MTBF) quantified and publicized, conscientious employees spontaneously will begin to seek out improvements.

There are many other measurements that are a “must” for the RE. Are you measuring the “leading indicators” of reliability? There are behaviors that lead to improved reliability that should be measured; condition monitoring (CM) route compliance, predictive maintenance (PM) route compliance, training, planning, scheduling, stores, tool time, etc. Put these measurements in place and improve them, then watch your OEE and MTBF begin to improve.

While we refer to “measuring” as Job #1, there are several others that also could share that title—jobs that must be done simultaneously with measuring, and to a high level of proficiency.

Lubrication
Every moving part in your facility is subject to friction and wear. Moving metal parts are separated by mere microns of lubrication (or should be). Join the Society of Tribologists and Lubrication Engineers (STLE) or the International Council of Machinery Lubrication (ICML). Become an expert on lubrication. More importantly, make sure you have highly trained and qualified lubrication technicians on staff. They should be well paid and understand that the organization is keenly aware of their contribution.

When your lube techs are out in the field, going through the tedious and dirty task of making sure their jobs are done correctly, your company is depending on their personal integrity even more than their technical expertise. A tiny amount of contamination in the wrong place can alter that top level of OEE.

If you don’t lubricate well, not much else will matter. Your maintenance department will be tied up responding to failures, and no one will feel like he/she can afford to invest in resources other than those needed for repair. Lubrication, performed at the necessary level of competency, can help stop the vicious cycle of break and repair quicker than anything else in many facilities.

  • Predictive technologies and technicians
    Do you have a training plan for your condition monitoring technicians? Since the success of any leader is greatly impacted by the competency of those he or she is directing, don’t leave this to chance. Develop goals for each individual and drive excellence in your department. Become at least competent in knowing what technology will give you the most cost effective condition evaluation and see that the individuals performing the tasks are well trained and take personal pride in their abilities.
  • Vibration analysis
    Of all technologies, vibration analysis still yields the most complete picture of rotating equipment health. The well-trained and equipped vibration analyst doesn’t have a crystal ball, but he or she will be capable of tracking the health of rotating equipment. In addition, vibration measurement can detect many conditions, such as misalignment, that can be alleviated or improved, which will lead to much healthier and more reliable equipment.
  • Infrared thermography (IR) and oil analysis
    Thermal imaging detects many problems that vibration analysis cannot, and oil analysis is a must in optimizing hydraulic system and gear reducer life expectancy and yielding excellent equipment condition and failure analysis information. There are other valuable condition monitoring technologies, but these are the most widely used.
  • RCFA (Root Cause Failure Analysis)
    Are you driving root cause analysis of past failures? Some level of RCFA training is a must. Failure analysis is a kind of proactive reactiveness, if that makes any sense. You are reacting to past failures in order to prevent future ones.
  • RCM (Reliability Centered Maintenance)
    Some level of Reliability Centered Maintenance training is absolutely necessary. (Can you define “failure?”) RCM actually is a type of failure analysis— before the failure happens. Moreover, it is completely proactive. The marriage of RCM and RCFA is unbelievably robust.
  • PMO (Preventive Maintenance Optimization)
    You should be facilitating some form of preventive maintenance (PM) improvement or optimization. The RCM training will impact this, and is necessary before seriously installing a PMO vehicle. The most effective PMO incorporates RCM principles. PMs are the backbone of reliability. (Lubrication is really a subset of preventive maintenance.) PM improvement should be ongoing, with established triggers to re-evaluate any PM task that proves to be insufficient.
  • Precision Maintenance Practices
    Although the repair technicians may not report directly to you, you must understand that the quality of their work will profoundly impact your success. Use simple charts to illustrate the hidden cost of poor repair practices such as shaft misalignment, improper bearing mounting, etc. It should be demonstrated how these affect the OEE and MTBF measurements.

A relatively small investment in the proper tools and training can easily result in equipment lifetime extensions of 100 to 500%! Many times we congratulate ourselves on a four- or five-year equipment lifetime, yet a properly aligned machine train wouldn’t wear out seals or bearings for many more years.

Think, walk & talk “reliability”
One cannot hope to succeed in a campaign of defect elimination until repair technicians are properly trained and equipped. When an improving MTBF is viewed with pride and coveted by the staff of repair technicians and involved operators, as well as the “reliability group,” you are on your way to world-class performance and reliability.

Networking can be valuable for those in a reliability role. Join an association of reliability professionals! Think, walk and talk reliability. Learn and promote the TPM concept of “basic” equipment condition or “clean, tight and lubed.” You cannot expect extended equipment lifetime if these three conditions are not met—and you must sell this to everyone, from upper management to every shop floor employee.

This recap of roles and responsibilities for individuals who find themselves in the RE position is by no means comprehensive—but it is enough to keep one busy for a while. And why not? After all, your job should be the busiest. If you do it well, the repair department isn’t jumping through hoops and the production department is just going through a routine. The upset conditions will become a thing of the past.

A final thought
Here is a little advice about communicating a CM mindset. When others are convinced of the bedrock logic of condition monitoring, your job will be much easier. What I mean is, those at the top level of leadership in your company are looking at quantities that begin with $$$. They can easily connect uptime (the root of the availability # in OEE) to $$$. This being the case, they expect uptime! Everyone must understand that for this expectation to be rational, the condition of the equipment they expect uptime from must be known. You wouldn’t walk into the doctor’s office and expect a diagnosis without the necessary tests to determine your condition. By the same token, only when the condition of the equipment is measured and known can anyone rationally predict uptime. MT

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October 1, 2008
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Pump Statistics Should Shape Strategies

1008-refinery1

How are your operations doing on pump MTBF? How do you compare with the best of the best?

Examining pump repair records and MTBF (mean time between failures) is of great importance to responsible and conscientious pump users. In view of that fact, the preface to the 2006 Pump User’s Handbook (Ref. 1) alludes to “pump failure” statistics. For the sake of convenience, these failure statistics often are translated into MTBF (in this case, installed life before failure).

In an effort to avoid arguments on statistics, during the early 2000s, many best-practices plants simply took all their installed pumps and divided that number by the number of repair incidents per year. For a well-managed and reasonably reliability-focused U.S. refinery with 1200 installed pumps and 156 repair incidents in one year, the MTBF would be (1200/156)=7.7 years. The refinery would count as a repair incident the replacement of parts—any parts—regardless of cost. In this case, a drain plug worth $1.70 or an impeller costing $5000 would show up the same way on the MTBF statistics. Only the replacement of lube oil would not be counted as a repair.

A best-practices plant’s total repair cost for pumps would include all direct labor, materials, indirect labor and over-head, administration cost, the cost of labor to procure parts, even the prorated cost of pump-related re incidents. There exist many references to the stated average cost of pump repairs: $10,287 in 1984 and $12,000 in 2008. We believe this indicates, in relative terms, a repair cost reduction, because a 2008 dollar bought considerably less than the 1984 dollar. It also can be reasoned that predictive maintenance and similar monitoring have led to a trend toward reduced failure severity.

Using the same bare-bones measurement strategy—and from published data and observations made in the course of performing maintenance effectiveness studies and reliability audits in the late 1990s and early 2000s—the mean time between failures (installed life before failure) of Table I have been estimated.

1008-reliability2

Other studies of pump statistics In early 2005, Gordon Buck, John Crane’s chief engineer for Field Operations in Baton Rouge, LA, examined the repair records for a number of renery and chemical plants to obtain meaningful reliability data for centrifugal pumps. A total of 15 operating plants having nearly 15,000 pumps were included in the survey reflected in Table II. The smallest of these plants had about 100 pumps; several plants had over 2000. All facilities were located in the United States. In addition, all plants had some type of pump reliability program in progress. Some of these programs could be considered as “new,” others as “renewed” and still others as “established.” Many of these plants—but not all—had an alliance arrangement with John Crane. In some cases, the alliance contract included having a John Crane technician or engineer on-site to coordinate various aspects of the program.

Not all plants are refineries, however, and different results can be expected elsewhere. In chemical plants, pumps have traditionally been “throw-away” items as chemical attack can result in limited life. Things have improved in recent years, but the somewhat restricted space available in “old” DIN and ASME-standardized stuffing boxes places limits on the type of seal that can be fitted. Unless the pump user upgrades the seal chamber, only the more compact and simple versions can be accommodated. Without this upgrading, lifetimes in chemical installations are generally believed to be around 50 to 60% of the refinery values.

Target pump and component lifetimes Based on the lifetime levels being achieved in practice in 2000 and combined with the known “best practice” as outlined in available reference texts, the target component lives of Table III are recommended and should be considered readily achievable.

1008-pump3

It should again be emphasized that many plants are achieving these levels of installed lives. The actual operating life of a seal would be approximately one-half of its installed life. Nevertheless, to reach these pump lives, the pump components themselves must be operating at the highest levels. An unsuitable seal with a lifetime of one month or less will have a catastrophic effect on pump MTBF, as would an under-performing coupling or bearing.

Upgrades can reduce maintenance costs Many “standard” ANSI and ISO-compliant pumps were designed decades ago—when frequent repairs were accepted and plant maintenance departments were loaded with personnel. Unless selectively upgraded, a “standard” pump population will not allow 21st century facilities to reach their true reliability and profitability potentials.

We are intending primarily to provide pump failure statistics on relatively inexpensive ANSI and ISO pumps, as well as API-compliant (“traditional”) refinery centrifugal pumps. But, this article also should remind the reader of important issues that cannot be overlooked in attempting to extend pump life. Pump sealing, advanced bearing housing protection and bearing lubrication topics are of primary importance (and the author would be pleased to alert you to specifics at either his or another relevant Website).

It goes without saying that unscheduled maintenance often is one of the most significant costs of ownership, and failures of mechanical seals and bearings are among the major causes. Therefore, in recent years, improved pump designs and the management of mechanical reliability issues have led to significant increases in the pump MTBF rates for many process plants. Back in the 1970s and early 1980s, it was not unusual to find plant MTBF rates of six months to 12 months. Today, most reliability-focused plants have pump MTBF rates that track the tabulations found in Tables I through III. Important improvements have been achieved by paying proper attention to pump components with the highest failure rates.

Buried in Table I is information from a plant with more than 2000 installed pumps—in average sizes around 30 hp—that presently enjoys an MTBF in excess of nine years. This, as one might suspect, is a facility that looks at mechanical and process interactions. The reliability professionals at this plant fully understand that pumps are part of a system and that the system must be correctly designed, installed and operated if consistently high reliability is to be achieved. It should be pointed out that plants of this type are conducting periodic pump reliability reviews.

1008-pump4

Reliability reviews start before purchase The best time for the first reliability review is before the time of purchase. This subject is given thorough treatment in Ref. 2. It is rather obvious that individuals with reliability engineering backgrounds and acute awareness of how and why pumps fail are best equipped to conduct such reviews. This implies that these contributors should have an involvement in the initial pump selection process. Individually—or as a team—those involved should consider the possible impact of a number of issues, including the ones mentioned above. They merit close attention and are again summarized for emphasis:

  • Keep in mind the potential value of selecting pumps that cost more initially, but last much longer between repairs. The MTBF of a better pump may be one to four years longer than that of its non-upgraded counterpart.
  • Consider that published average values of avoided pump failures range from $2600 to $12,000. This does not include lost opportunity costs.
  • One pump fire occurs per 1000 failures. Having fewer pump failures means having fewer destructive pump fires.

Remember that there are several critically important applications where buying on price alone is almost certain to ultimately cause costly failures. Included are the following:

  • Applications with insufficient NPSH or low NPSH margin ratios [Ref. 3];
  • High- or very-high-suction energy services;
  • High specific-speed pumps [Ref. 4];
  • Feed and product pumps without which the plant will not run;
  • High-pressure and high-discharge energy pumps;
  • Vertical turbine deep-well pumps.

At a minimum, then, these are the six services where spending time and effort for pre-purchase reliability reviews makes much economic sense. Such diligent reviews concentrate on typical problems encountered with centrifugal pumps; an attempt is made to eliminate these problems before the pump ever reaches the field. Among the most important problems that the reviews seek to avoid are:

  • Pumps not meeting stated efficiency;
  • Lack of dimensional interchangeability;
  • Vendor’s sales and/or coordination personnel being reassigned;
  • Seal problems and compromises in materials, flush plans, flush supplies, etc.;
  • Casting voids (repair procedures, maximum allowable pressures, metallurgy, etc.);
  • Lube application or bearing problems [Ref. 5];
  • Alignment, lack of registration fit (rabbetting), base plate weakness, grout holes too small, base plates without mounting pads, ignorance of the merits of pre-grouted base plates;
  • Documentation: manuals and drawings shipped too late;
  • Pumps that will not perform well when operating away from best efficiency point, i.e. prone to encounter internal recirculation [Ref. 6].

Perform your own projected MTBF calculations Although not perfect from a mathematician’s perspective, simplified calculations will give an indication of the extent to which improving one or two key pump components can improve overall pump MTBF [Ref. 7]. Say, for example, there’s agreement that the mechanical seal is the pump component with the shortest life, followed by the bearings, coupling, shaft and sometimes impeller, in that order. The anticipated mean time between failures (operating MTBF) of a complete pump assembly can be approximated by summing the individual MTBF rates of the individual components, using the following formula:

1/MTBF = [(1/L1)2 + (1/L2)2 + (1/L3)2 + (1/L4)2]0.5Eq. (1)

In a 1980s study, the problem of mechanical seal life was investigated. An assessment was made of probable failure avoidance that would result if shaft defections could be reduced. It was decided that limiting shaft defection at the seal face to a maximum of 0.001″ (0.025 mm) probably would increase seal life by 10%. It was similarly judged that a sizable increase in seal housing dimensions to allow the installation of the newest seal configurations would more than double the MTBF of seals. By means of such analyses, all of the components under consideration for upgrading were examined, the life estimates collected and the latter used in MTBF calculations.

1008-pump5

In Equation (1), LLL and L represent the life, in years, 1,2,34 of the component subject to failure. Using applicable data collected by a large petrochemical company in the 1980s, mean times between failures and estimated values for a reliability-upgraded pump were calculated. The results are presented in Table IV. As an example, a standard construction ANSI B73.1 pump with a mechanical seal MTBF of 1.2, bearing MTBF of 3.0, coupling MTBF of 4.0 and shaft MTBR value of 15.0, resulted in a total pump MTBF of 1.07 years (actual operating hours). By upgrading the seal and bearings, the estimated achievable pump MTBF (actual operating hours) can be improved by 80%, to 1.93 years.

Table IV thus shows the influence of selectively upgrading either bearings or seals or both on the overall pump MTBF. Clearly, choosing a 2.4 year MTBF seal and a six-year MTBF bearing (easily achieved by preventing lube oil contamination via superior bearing housing seals), had a major impact on increasing the pump MTBF and—assuming the upgrade cost is reasonable—may well be the best choice.

As has been noted, a typical pump failure, based on actual year 2002 reports, costs $5000 on average. This includes costs for material, parts, labor and overhead. Let us now assume that the MTBF for a particular pump is 12 months and that it could be extended to 18 months. This would result in a cost avoidance of $2500/yr—which is greater than the premium one would pay for the reliability-upgraded centrifugal pump.

In addition, the probability of reduced power cost would, in many cases, further improve the payback. Recall also that the proper hydraulic selection of a pump can have a further marked positive impact on the life and operating efficiency of a pump. Audits of two large U.S. plants identified seemingly small pump and pumping system efficiency gains that added up to power-cost savings of many hundreds of thousands of dollars per year. Thus, the primary advantages of reliability-upgraded process pumps are extended operating life, higher operating efficiency and lower operating and maintenance costs.

Table IV provides a quick means of approximating the annual pump repair frequency based on the total (installed life) MTBF. Equation (1) and Table IV also can be used to determine potential savings from upgrades and should shape the pump user’s strategies. MT


Contributing editor Heinz Bloch is the author of 17 comprehensive textbooks and over 340 other publications on machinery reliability and lubrication. He can be contacted at: hpbloch@mchsi.com

References

  1. Bloch, Heinz P., and Allan R. Budris, Pump User’s Handbook, Fairmont Press, Lilburn, GA 30047, ISBN 0-88173-517-5, 2nd Edition, 2006.
  2. Bloch, Heinz P., Improving Machinery Reliability, Gulf Publishing Company, Houston, TX, 3rd Edition, 1998.
  3. Karassik, Igor J., “So, You Are Short On NPSH?” presented at Pacific Energy Association Pump Workshop, Ventura, CA, March 1979.
  4. Ingram, J.H.,”Pump Reliability— Where Do You Start,” presented at ASME Petroleum Mechanical Engineering Workshop and Conference, Dallas, TX, September 13-15, 1981.
  5. Bloch, H.P., “Optimized Lubrication of Antifriction Bearing for Centrifugal Pumps,” ASLE, Paper No. 78-AM-1D-1, presented in Dearborn, MI, April 17, 1978.
  6. McQueen, R., “Minimum Flow Requirements for Centrifugal Pumps,” Pump World, 1980, Volume 6, Number 2, pp. 10-15.
  7. Bloch, Heinz P., and Don Johnson, “Downtime Prompts Upgrading of Centrifugal Pumps,” Chemical Engineering, November 25, 1985.

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October 1, 2008
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Corrosive Chemical Plant Environment

Proven technology is helping to assure greater production capacity and also making life easier than in the past for the maintenance team at an Arkansas Albermarle facility.

If you are a utilities manager at a major chemical plant, the notion that cooling towers corrode should come as no surprise—it’s a fact of life. How you choose to overcome the problem is another matter, as there are many products to choose from. Countless corporations, however, are turning to towers engineered with rugged plastics such as high-density polyethylene (HDPE) that remain impervious to harsh chemicals, bitter environments and pH deviations.

That was the decision Albemarle Corporation made for its fire retardant plant in Magnolia, AR, where a galvanized metal tower had been badly compromised by the chemical environment. The plant specializes in products that help plastic molders, compounders and foamers meet or exceed stringent legal and regulatory requirements to protect property. Each flame retardant also helps save lives. Now the company wanted to save a new cooling tower from the same fate as the one that was being replaced.

William Wright, a unit leader for Albemarle’s utilities department, explains that company officials took a sensible approach to the decision, starting with looking for reasons the tower in question failed. “Among other things,” he notes, “the tower was sitting right next to components that had the potential to give off corrosive vapors. We needed something that could withstand that and a whole lot more.”

Wright calls HDPE the “ideal material” for replacing Albemarle’s traditional metal-clad cooling tower. Just as plastics have overtaken metal for applications ranging from plumbing to aerospace, they now are eliminating the need for metal in cooling towers for a broad range of applications. In fact, the fire retardant plant already was using piping made from plastics when officials decided to buy a unit developed by Delta Cooling Towers.

1008-maint1According to Wright, the new tower has functioned without a hitch—and has helped his company save money. Since the interior surface of the tower is dark and protected from the sun, water temperatures remain cool with less biological growth. As a result, treatment chemical usage is down. “I’d like to replace about 10 more,” Wright says.

Over the next five years, Wright may get the chance to do just that, as Albemarle fulfills its plan to upgrade the Magnolia plant’s other 26 towers and equipment of various kinds. The overhaul comes at a time when the global corporation headquartered in Baton Rouge, LA, is expanding. It now develops, manufactures and markets specialty chemicals for consumer electronics, petroleum and petrochemical processing, transportation and industrial products, pharmaceuticals, agricultural products and construction and packaging materials.

As Wright puts it: “You try to get all the value you can out of something you’ve paid for. That’s where we are now. We’ve got a five year plan. We’ll take a look when the time comes. We keep a good eye on maintenance.”

Low maintenance, easy installation
Using advanced resins and molding techniques, engineered plastic cooling towers are available today in sizes and modular configurations that make them ideal for even those types of high-capacity applications (1500-2000 cooling tons) that traditionally depended on expensive field-constructed installations. Plastic towers are easier to install because they weigh 40% less than their metal counterparts, yet they are five to 10 times thicker.

Engineered plastic equipment often means less maintenance—and, therefore, lower ownership costs. Over time, traditional metal towers require process downtime for patching and welding areas that have corroded. Traditional designs also will have more complicated fan systems incorporating gearboxes or belts and pulleys that wear. Delta uses direct-drive fan systems that eliminate these maintenance items. Less moving parts translate into less maintenance, less downtime and less aggravation.

Answering the skeptics
Despite advances in plastics technology, suggesting a plastic cooling tower can still draw some skepticism. Some people hear the word “plastic” and assume “new” and “unproven”. These technologies, though, actually have been at work for decades—and HDPE products have an excellent track record. Individuals accustomed to a seven- to 12-year life cycle for galvanized metal may be very surprised to learn that an installed plastic tower may outlast their facility.

Wright, like other successful managers, is eager to embrace new technologies that help reduce the daily trouble-shooting so common around a large plant. “Most of our towers are quite old,” he points out. “They’re getting close to the end of their useful life. But a chemicals plant is a very corrosive environment. What do you expect?” Even so, it appears as though the new plastic tower has lived up to Albemarle’s expectations, in terms of heat transfer, etc. “It now runs at 70% loaded,” Wright continues, “and we’re comfortable running it up to 100 percent soon.”

The need for more capacity
Although age and failing efficiency are the main reasons for upgrading equipment, Wright reminds us that some old cooling towers were built with materials that included asbestos. “We’re replacing those. Age makes them more difficult to maintain, and we’re to a point where we need more capacity.”

Corrosion problems at facilities in coastal locations also can be caused by pH levels. High or low (alkaline or acidic), a pH imbalance can trigger a destructive trend that causes metalclad cooling towers to fail early or require extensive service. For example, a pH level lower than four can destroy the metal protective lining of a tower within months. pH levels are affected by various harsh environmental conditions, such as sunlight and pollution—and even routine chemical treatments. HDPE towers are engineered to withstand these problematic pH deviations.

Going forward
When replacing other towers, Albemarle will consider many issues, including flow rate and heat transfer capacity, and will carefully analyze the conditions of the plant that the new tower will service. The company may even consider ceramic and stainless steel towers—although the cost of those types generally exceed HDPE products.

While many questions will need to be answered, Wright already has made up his mind on one issue: “We won’t buy galvanized metal. The Delta tower is working just fine. I’m anticipating it’ll last a lot longer than what it replaced.” MT

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October 1, 2008
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Uptime: Training Rule #1: Adults Are Not Children

bob_williamson

Bob Williamson, Contributing Editor

Whenever the idea of “training” comes up in most workplaces, some employees tend to think back to some horrible experience they had in school: A nasty teacher, crowded classroom, required and boring subjects, reading and studying and, most of all, TESTS and GRADES!

So, when the company announces that they are going to set up a “maintenance training program” to improve equipment effectiveness and plant performance, some employees will embrace the idea— others will run the other way!

Training and learning, however, is an absolute MUST in today’s mechanized, automated, technology-dependent, equipment-driven businesses. Unfortunately, experience and anecdotal information from thousands of contacts in the U.S. have shown that nearly 80% of maintenance personnel in mid- to small-plants and facilities have not formally been trained to perform the work they are asked to do each day. Both maintenance and operations employees must possess the skills and knowledge to perform meaningful tasks right the first time— every time. Without that level of job performance, accidents happen, equipment frequently is down for extended periods and operating costs increase, all while throughput and revenues decline. Makes sense, doesn’t it?

Overcoming the roadblocks to workplace training for all levels of employees is essential for effective workplace learning. Such roadblocks all but disappear when we understand and apply “Training Rule #1: Adults Are Not Children.”

Early memories
Most of us have childhood and young-adult education memories that form our reaction to training in today’s workplace. I disliked math in high school—a dislike that followed me to college. In my college freshman trigonometry class, I remember wondering what possible use I would ever have out in the real world for this subject (and I was not alone)! In fact, I darn near failed the course because that question was never answered. In order for me to graduate, though, my course of study required a passing grade in freshman trig.

As I discovered later, formal education is “SUBJECT CENTERED.” From an educator’s perspective, “trig is a required subject in the tooling and machine design curriculum, so hit the books!” Conversely, while the practical use of trigonometry really was not important to the math department, the passing grade was. Thus, I focused on passing the tests. Somehow, somewhere, the tooling and machine design program developers knew the importance of trigonometry (only to be figured out by the students years later).

Fast forward to my first year of teaching, when— wouldn’t you know it—I was asked to instruct a college class in descriptive geometry that was based heavily on the principles of trigonometry. Aaarrgghh!

You know what they say about teaching: You stay one step ahead of the students and you will learn more about the subject than you ever thought possible. That’s exactly what happened. I learned a lot. I survived. The students had fun learning, and many went on to do well in their academic programs. Whew! Saved by the principles of adult education and my “Training Rule #1: Adults Are Not Children.” I discovered that adults—young adults included—learn differently than children in school.

The adult learner
In between the two personal experiences cited here, I learned much about adult education while pursuing my teaching degree and developing hundreds of workplace training programs. Dr. Malcolm Knowles also helped set the stage in his book The Adult Learner: A Neglected Species, as did other authors. Furthermore, I learned much about the numerous practical applications of many of the academic “subjects” that I was subjected to in school. I share some of these insights here in an attempt to help you make your own workplace training more meaningful and effective. It all begins with the following principles of adult learning and “Training Rule #1.”

  1. Adults want to know why they should learn what is being offered in the workplace training sessions. In other words, WIIFM? (“What’s in it for me?”). Adults want to know the benefits of learning something new and/or different versus the risks of not learning it.
  2. Adult learners in the workplace want to take responsibility for learning much in the same way they take responsibility for everything else in their lives. Since they are “self-directed” in most aspects of their lives, they must be empowered to learn and to take responsibility for their own learning. Unfortunately, in many workplace training situations, early public education memories often are triggered within an adult learner, setting expectations for how the training will take place and how successful (or unsuccessful) he/she will be.
  3. Adult learners have formed a dominant learning style over the years and they know how they learn best. Three major learning styles include visual (seeing), auditory (hearing) and kinesthetic (doing). Early studies showed that learning retention rate increases with trainee participation and hands-on application. For example, lecture alone results in 5% retention; reading and audio-visuals 10-20%; demonstration 30%; group discussion 50%; and practice by doing, immediate use on the job and teaching others results in 75-80% or higher retention. The more we use what we learn, the more we retain it.
  4. Adults bring life experience to the learning environment. This can be both a positive and a negative: Some experiences are just old habits, while others are rich and meaningful. Adults also tend to define themselves by their experiences. Effective workplace training must respect and account for these experiences, as well as build on them.
  5. Adults are ready to learn when the need arises. The need for workplace training tends to include skills and knowledge for a new procedure, a new machine or piece of equipment, a new tool or technology, a job promotion, etc. Sorry to say, when those needs are not apparent, employer-provided training is perceived (and structured as) as “employer-required training” and it, too, shall pass.
  6. While adults may be “ready to learn,” they may NOT have the “ability to learn” certain higher-level skills and knowledge. Basics like reading, writing, math, mechanical aptitude and having the ability required to learn most maintenance tasks are one thing; acquiring the working knowledge of electricity, electronic circuits, microprocessors and ladder logic diagrams required to learn maintenance of programmable logic controllers (PLCs) is quite another. These are examples of “prerequisite” skills and knowledge.
  7. Adults are task-oriented. Effective workplace training must be organized around actual tasks in the workplace for the specific job role rather than the “subject.” The more relevant the training is to immediate needs in his/her job role, the more the adult learner will participate and learn. Mastering the task at hand and getting immediate and regular feedback during the learning process through peer coaching and support are essential.

12,000 maintenance tasks and counting
On what should maintenance training in the workplace focus? What classes, programs and materials should we buy? These are typical questions encountered in the early stages of considering maintenance training. However, they should NOT be the first questions asked. Start by identifying the job-performance requirements for a very narrow scope of work or the broader job classification. These tasks define what maintenance employees need to know to perform on the job. Remember that adults are “task oriented” in their learning processes.

In the 1980s, I was responsible for developing training programs and materials for literally thousands of employees in many different manufacturing plants and industrial construction projects. In 1985, I began accumulating a unique data base of maintenance-job-performance requirements in the form of action-oriented and measurable “duties and tasks.” This database grew every time I performed or led a job-task analysis to develop maintenance training programs and materials in dozens of industries—and more so when the training programs turned into on-job performance qualification, employee assessments and pay-for-applied-skills program design. More recently, with a 36-plant maintenance training needs analysis and work with a precision equipment component manufacturer thrown into the mix, my database has become much larger—significantly.

What continues to amaze me about maintenance job-task analysis is the huge breadth and depth of skills and knowledge the typical maintenance employees must have to properly maintain, repair, operate, plan and lead others for numerous facilities, processes and equipment. In excess of 12,000 individual tasks that describe the skills and knowledge requirements in nearly 40 maintenance-related job roles have been identified and documented. These job-performance tasks identify the skills and knowledge for the basics, the core craft and specialized craft requirements. Beyond that are the thousands of equipment-specific tasks reflecting what these maintenance employees must know and be able to do in every plant—and in facility-specific applications.

The bottom line to workplace learning is TASK MASTERY ON THE JOB. It’s not about seat time in a class or passing tests. It’s not about studying materials online, in the break room or on the job. Task mastery means that an employee can satisfactorily perform the task, with the proper skills and knowledge, on the job—whenever needed. How he/she gets to that point is the “training process.”

The bottom line
A “training needs analysis” is where the workplace training process truly starts. That means identifying the specific areas of the business where training will likely eliminate problems and/or improve human performance (focused improvement). Then, determine what the employees must know and be able to do on the job to address these improvement needs (specific duties and tasks).

Given the training needs and the specific job duties and tasks that address these foregoing needs, 1) the employees’ skills and knowledge can be assessed; 2) training programs can be designed, developed, purchased and/or scheduled; 3) training and learning can take place; and 4) the maintenance employees can successfully demonstrate the duties and tasks on the job. Later, in the spirit of continuous improvement, 5) an evaluation can be conducted to identify the efficiency and effectiveness of the whole training process.

The bottom line here is that maintenance training and qualification is a HUGE overlooked opportunity for improving business performance (see “The Perfect Storm Intensifies,” Uptime column installment, pgs. 6-8, Maintenance Technology, August 2008). Because proven principles of adult learning typically have focused on specific and measurable job duties and tasks, they often have been overlooked or thought of as roadblocks. As a result, many traditional maintenance training efforts have been based on classes, workshops, vendor presentations and studying materials. While there are benefits associated with this type of maintenance training, the most beneficial—and most successful—training tends to be of a FORMAL, on-the-job, task-specific nature with peer coaching. Sure, there always will be someone in management who asks,”What if we train them and they leave?”A more important question to ponder is “What if we don’t train them and they stay!?!” Your operations, like countless others, probably can’t afford to gamble on such a scenario—at least not for very long. Now is the time to put your workplace training processes in place; to recognize the needs of the adult learner and to focus training on very task-specific skills and knowledge linked to improvements. The payback will be substantial. MT

Critical Success Factors In Developing & Implementing Workplace Training

  • Answer “WIIFM” from the learner’s perspective. What are the benefits and risks associated with the training?
  • Avoid classroom-style, lecture and graded classes as much as possible.
  • Put adults personally in charge of their own learning for the job and on-the job.
  • Appeal to a variety of dominant adult learning styles (i.e., seeing, hearing, doing).
  • Build on the experiences that adults bring into the training sessions.
  • Make the training immediately useful in job performance.
  • Train for task mastery through performance demonstration on-the-job rather than via scored tests and quizzes.
  • Use peer coaching and training as much as possible.

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Forever Growing!

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Henry Peck, President, Geiger Pump & Equipment Company

My children, one in high school and one in college, lead extremely busy lives. They take fabulous academic courses and participate in a range of great extracurricular pursuits. Although they probably won’t use all the details of what they learn through their various courses and activities after they get through school, that’s not the point. Just like it was when we were young, these things are part of the pleasure of growing up—an irreplaceable learning experience and preparation for our lives ahead.

On a macro scale, the great American economy is built on a continuous cycle of people like you and me—and, now, our children—most of us moving directly from being full-time students into roles of full-time workers. Unfortunately, when someone enters the workforce, he/she don’t always find an environment that supports learning at the same pace found in school. In a relatively short time, we grow up—we have to!

A business may be passionate about its new workers’ short-term vocational goals, but those workers may not readily embrace new experiences and continuous improvement—at least not like they demanded of themselves before entering the workplace, or the way we do for our children. Admittedly, our hectic work lives are full of deadlines and tasks, with little time or wiggle room for addressing ambitions to continuously learn. It can, however, be done. Here are some practical suggestions that have worked for our organization.

Put every employee on his/her own computer and workstation, with access to all of your company’s basic business and PC tools. Reach far and wide in your organization and encourage professional communication with internal and external customers. Help every person with the basics— like 10-finger typing and the use of proper grammar. This acknowledges the dignity of managing time wisely for everyone in the organization.

If your company does not already do so, offer a tuition benefit for every employee—design it for everyone, not just for management. Pay for these courses up front and include the cost of books. Be liberal with the course selection, which may include non-accredited classes. Be flexible and accommodating with work hours for those who take classes.Additionally, keep in mind that paying for other business-related books an employee is willing to share with others around the company is a way to build a library—and dialogue—within an organization.

Employ high school work-study students or college/university coop students. These programs are good for our community and have a positive influence on our company’s collective esteem.

Commit your organization to a learning event that rallies all of your associates and reaches out to your business community. For us, it’s our Mid-Atlantic Pump and Process Equipment Symposium, a full day of sharing what we know through hands-on training classes directed to our contemporaries in the fluid-handling community. Designed as an inclusive event, it involves everyone in our company—and is appreciated and attended by all of our business friends, well beyond the decision-makers in our trade.

Most importantly, don’t forget—and don’t let your organization forget—to enjoy the pleasure of learning and the satisfaction that comes from making a positive impact in the lives of others. In short, keep growing…forever! MT


Henry Peck is president of Geiger Pump & Equipment, a leading, regional process equipment distributor and service provider, headquartered in Baltimore, MD. E-mail: hpeck@geigerinc.com

The opinions expressed in this Viewpoint section are those of the author, and don’t necessarily reflect those of the staff and management of MAINTENANCE TECHNOLOGY magazine.

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MT News

News of people and events important to the maintenance and reliability community

EMERSON MAKES NEW EXECUTIVE APPOINTMENTS

John M. Berra, president of Emerson Process Management, has announced a number of leadership changes in the corporation. Effective Oct. 1, 2008, Steven A. Sonnenberg will become executive vice president of Emerson and business leader of Emerson Process Management, serving as president. Berra, who has been business leader since 2000, is taking a new role as chairman of Emerson Process Management to focus on strategic planning, technology, key customer relationships and organizational planning. Michael H. Train, president of Emerson Process Management Asia Pacific, will return to the United States from Singapore and become president of Rosemount. Train’s former position will be assumed by Sabee Mitra, who currently serves as president of Emerson Process Management Middle East. In turn, David A. Tredinnick, vice president Southeast Asia for Emerson Process Management Asia Pacific, will move to Dubai and replace Mitra as president of Emerson Process Management Middle East.

Gene Shanahan, group vice president for the Emerson Process Management Flow Group will retire Oct. 1, 2008 after 21 years of service to Emerson. He joined Emerson with the Dieterich Standard acquisition in 1996, and has led the Flow Group over the last three years. Larry W. Flatt, who will replace Shanahan, began his career at Emerson in 1979 as an employee relations supervisor for the special products division. Since 2001, Flatt had been serving as president of Emerson Process Management Regulators.

INTEGRATED POWER SERVICES ACQUIRES TRICO TCWIND SERVICES

Integrated Power Services, a leader in the service and repair of electric motors, generators and mechanical power transmission components, has acquired Trico TCWind, a family-owned power-services company, based in Litchfield, MN. Trico TCWind specializes in the North American service and repair of wind generators and turbines, as well as the repair of electric motors and other rotating equipment for the Minnesota regional market. The deal marks the third acquisition for IPS in 2008, following the company’s prior purchase of Electro-Mec and The Monarch Group. Terms were not disclosed. Headquartered in Greenville, SC, IPS now has 16 regional service centers across the country, offering coast-to-coast 24/7 coverage to more than 2000 customers across a wide range of capital-intensive industries. Trico TCWind will operate as an IPS company, enhancing the company’s full-service capabilities, particularly in North American wind energy service and repair markets and providing a presence in the upper Midwest.

ISA RAISES FUNDS FOR HURRICANE RELIEF

In response to the devastation left in the wake of Hurricane Ike, which hit the Gulf Coast states as a Category 2 storm on September 13, ISA recently announced a hurricane relief fundraising program to be held in conjunction with ISA EXPO, October 14-16, in Houston, TX. The association also pledged to match funds collected during the event, up to $10,000, and dedicate the EXPO’s Tuesday evening industry reception to the relief effort with a silent auction to raise money for the American Red Cross Hurricane Ike disaster relief fund. Since the catastrophe, the Red Cross has provided shelter, food and emotional support to tens of thousands of residents. With more than 200 shelters across several states, the Red Cross and its partners have, among other things, provided more than 100,000 overnight stays to people affected by Hurricane Ike.

In discussing this relief effort, ISA executive director and CEO Patrick Gouhin said: “The Red Cross can’t do their important work without the support of the community—our community. After all, these are our colleagues, our friends, our customers and our suppliers, and we’ll support them and help them rebuild.” (EDITOR’S NOTE: A list of the largest corporate contributors to the ISA hurricane relief fundraising program will be published in the November 2008 issue of this magazine.)

21ST OPERATIONS CHALLENGE AT WEFTEC.08

More than 200 of the world’s best and brightest wastewater treatment professionals are scheduled to compete in this year’s Operations Challenge, a unique, fast-paced skills competition presented in conjunction with WEFTEC®.08 – the Water Environment Federation’s 81st annual technical exhibition and conference. The first event kicks off on Tuesday, October 21, at 9:15 a.m. in Hall C2 of McCormick Place, in Chicago, IL.

Now celebrating its 21st year, Operations Challenge has grown from a 22-team event into today’s 43-team, two-division format, with each four-member team judged on the best combination of precision, speed and safety. Winners are determined by a weighted point system for five events, including collection systems, laboratory, process control, maintenance and safety. Events are designed to test the diverse skills required for the operation and maintenance of wastewater treatment facilities, their collection systems and laboratories—all vital to the protection of public health and the environment.

WEFTEC.08 is expected to host more than 18,000 of the world’s leading water quality experts and 1000 companies featuring the latest in water-quality technology. For more information, visit www.weftec.org

ASHRAE OFFERS NEW FACILITIES CERTIFICATION

Energy use in buildings can be reduced by 10 to 40 percent by improving operational strategies in buildings, according to a study by the Energy Systems Lab at Texas A & M University. A new certification program from ASHRAE helps building owners know they are hiring and retaining employees and consultants who know how to take advantage of such strategies.

The Operations and Performance Management Professional Certification (OPMP) program helps earners demonstrate their knowledge of the management of facility operations and maintenance and their impact on HVAC&R systems’ performance. The program will launch at the ASHRAE Winter Meeting in Chicago in January and will be available via electronic testing centers worldwide starting in March 2009. For more information, visit www.ashrae.org MT

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Solution Spotlight: Environmentally Considerate Lubricants

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Increased awareness of the environment and tighter legislation have led to increased use of environmentally considerate lubricants. When operating in environmentally sensitive areas such as mines, forests, lakes, rivers, harbors and ski-slopes, equipment may require lubricants that help reduce environmental risks. Environmentally considerate lubricants should combine a number of important properties, including high biodegradability, which means it is rapidly removed from the environment by natural processes in the event of a leak or spill (fate) and low ecotoxicity (effects). Furthermore, such lubricants should provide effective lubrication with performance meeting the needs of operators (function).

Biodegradability: Lubricants and other organic materials are broken down in the environment by micro-organisms in a process called ‘biodegradation’—biodegradability is the ease with which this can occur. There are a number of ways in which biodegradability can be measured. To meet the internationally recognized requirement for ‘ready biodegradability,’ lubricants must be at least 60% CO2 evolved after 28 days when tested according to OECD guideline 301B. Ecotoxicity: The effect that a material may have on the environment usually is assessed by measuring its toxicity toward plants and animals that represent different levels of the food-chain (‘ecotoxicity’). For example, in the aquatic food chain there is determination for toxicity towards algae, water fleas (Daphnia) and rainbow trout. Lubricants must meet the limits for ‘not harmful’ when tested by independent laboratories using OECD 201, 202 & 203 Test Guidelines for ecotoxicity.

A considerate solution Shell Lubricants has been working to develop environmentally considerate lubricants that are formulated and tested to the highest standards to help keep equipment running efficiently while protecting against premature wear and breakdowns. Shell Naturelle is a range of lubricants specially developed for applications operating in environmentally sensitive areas. Their biodegradable qualities mean that any accidental spillages or leaks are readily broken down by natural processes in soil or water; their low eco-toxicity means that their impact on the environment is reduced should a spillage or leak occur. Shell Naturelle lubricants offer a more environmentally acceptable alternative to conventional industrial lubricants without compromising performance. In the U.S., Shell currently offers Shell Naturelle HF-E and HF-M hydraulic fluids, which are well suited for use in environmentally sensitive areas. Both formulations are readily biodegradable (1) with low ecotoxicity (2).

  • Shell Naturelle HF-E uses a special blend of synthetic esters and a tailored additive system. It offers multi-grade perfor•mance, good shear stability and good oxidation resistance.
  • Shell Naturelle HF-M is blended with a mixture of synthetic ester and vegetable oil. Shell Naturelle HF-M has low deposit-forming tendency and stable low-temperature viscosity, providing benefits over products formulated from natural based esters only.

In the future, Shell Lubricants is planning to introduce additional products to its portfolio in the United States. Currently, Shell Lubricants is considering adding a gear oil, expanding the viscosity grades for the hydraulic fluids, and possibly adding a grease. Dates are not yet set for distribution. MT

(1) as measured by OECD 301B test (2) as measured by OECD 201-203 test

Shell Lubricants
Houston, TX

For more info, enter 30 at www.MT-freeinfo.com

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Enhanced Cooling Tower Maintenance Saves Water

1008-enhanced1Any amount of wasted water is too much. Perhaps it’s time to compare your maintenance procedures to current best practices. Do they measure up?

Water is an undervalued utility. Since many consumers essentially view it as a “free” resource, many plants make little effort to conserve water the same way they try to conserve fuels and electricity. While countless opportunities to conserve Btus and kilowatts have been explored over the past 30 years, less attention has been paid to reducing water consumption. But things are changing…

Severe droughts, like those seen in the Southeast and Southwest, combined with rapid population and industrial growth in those and other water-stressed regions, have created a water crisis in many parts of the United States. The available supply of fresh water is decreasing as residential customers compete with industry for available water supplies. (Witness the lawn sprinkling and car washing bans in many communities. Agriculture, the largest consumer of water, increasingly relies on irrigation to offset drought conditions that limit yields. Residential customers accuse farmers of drawing down the water table and causing local shortages. Meanwhile, government regulatory agencies are hesitant to wade in to restrict water withdrawal rates or raise usage fees force conservation, since most consumers view the plentiful supply of safe, clean water as an inalienable right.

The conflict is intensifying. What’s worse, scientific and government forecasters predict no relief is in sight over the next decade. Blame it on global warming or not, the need to conserve water is here to stay.

On the bright side, most plants already have a water conservation program under way. It’s called a cooling tower. As shown in Fig. 1, cooling towers conserve water by recycling it through equipment such as mechanical chillers, turbine condensers, air compressors, oil coolers and process heat exchangers. In the process, unwanted heat is removed and then rejected to the atmosphere by evaporative and convective cooling.

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It is estimated that over 1,000,000 cooling towers—that’s one million—are in service. They are used in every conceivable application where water conservation is a concern, including electric utilities, oil refineries, steel mills, manufacturing facilities, pharmaceutical plants, food processing operations, hospitals, universities, commercial buildings and many more.

Interestingly, plant maintenance teams play a critical role in keeping their cooling towers operating at peak efficiency. They focus on keeping plant equipment clean by preventing mineral scale deposits, mitigating corrosion, limiting bacteria growth, and controlling fouling. Because of the growing importance of water conservation, however, best maintenance practices have been updated to cover the operation of cooling towers in a way that reduces fresh water withdrawal rates and produces less wastewater. That means if you are still maintaining your cooling tower the same way you did five years ago, it’s time to upgrade to the newer water conservation format.

Cooling tower basics Cooling towers work by evaporative and convective heat transfer. As water flows over the tower, some of it (about 0.1% of the flow) is evaporated to the atmosphere. About 1000 Btus of heat is removed for every one pound of water evaporated. Removing this heat from the bulk of the cooling water decreases the temperature by 10 to 15 degrees. On average, 75% of the heat rejected at the tower is by the evaporative cooling process; 25% of the cooling occurs due to the direct contact of cooler air with the warmer water. This varies, of course, based on weather conditions. If the air temperature is warmer than the water temperature, for example, all of the cooling takes place by the evaporative process. When the air is colder, such as during the winter, more heat is removed by convective heat transfer.

The water that is evaporated from the tower is pure—that is, it doesn’t contain any of the dissolved minerals present in the raw water supply. As the evaporation process continues, these minerals concentrate in the cooling water. If this is allowed to continue without limit, the dissolved minerals soon concentrate to a point where they can no longer remain in solution. Here the less-soluble minerals such as calcium and magnesium precipitate to form an insoluble sludge, or an adherent, dense scale in the tower basin or within plant equipment. For these reasons, cooling towers must be operated to keep the dissolved minerals soluble. This is accomplished by bleeding a small amount of tower water to drain while replacing the water lost by evaporation and bleed with fresh makeup. The ratio between the dissolved solids in the cooling water and the dissolved solids in the makeup is called the “concentration ratio,” “cycles of concentration” or, more simply, “cycles.” This is an indication of how efficiently the cooling tower is recycling water. A simple way to measure cycles is by calculating the ratio of the specific conductance of the cooling water to the specifi c conductance of the makeup. Alternatively, if the cooling tower has a water meter on the makeup and bleed lines, you can estimate cycles by computing the ratio between the gallons makeup to the gallons bleed. The cycles determined by either method should be in fairly good agreement assuming there are no uncontrolled water losses due to leaks or an overflow condition.

Establishing the proper operating limit for cycles is one of the supercritical decisions one faces in cooling tower maintenance. Towers that operate at high cycles use less water and produce less waste than towers that operate at lower cycles. The maximum permissible cycles of concentration are limited by the makeup water quality, bleed rate and uncontrolled water losses. Set the cycles too high and you risk running the tower under scale-forming conditions. Set it too low and you waste water, chemicals and energy.

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Makeup water quality is key The quality of the cooling tower makeup determines the maximum cycles of concentration. Since calcium and magnesium are the primary scale-forming impurities, tower operation is confined to keeping the cycles below the solubility limit of calcium carbonate. This requires a proper balance to be maintained between the calcium hardness, total alkalinity, total dissolved solids and pH in the recirculated cooling water. Since these variables differ from one water supply to another, the limitation on cycles also varies. As a general rule of thumb, the calcium hardness is limited to 350 to 450 ppm in most cooling towers. Other limiting factors—such as silica, phosphate and process contaminates—need to be considered as well.

Generally, cooling towers use potable water as their makeup supply. This is a good choice when a plentiful supply of fresh water is available. But, as competition for clean, fresh water heats up, plants are increasingly forced to use alternative sources. Reclaimed water from municipal or industrial wastewater treatment plants is often an alternative source for cooling tower makeup. Although this reduces fresh water withdrawal rates, some pre-treatment of the wastewater may be required to make it suitable for use in the cooling tower. In many cases, regeneration by simple filtration may be all that is necessary to reuse wastewater as cooling tower makeup. Reverse osmosis (RO) continues to gain favor as a method for pre-treating makeup for steam boilers. The RO process produces a continuous supply of softened and dealkalized water for this application. The downside of RO is that it produces a continuous waste stream that is sent to drain—25% of the feedwater to the RO is lost to drain, while 75% is recovered for use as boiler makeup. In many cases, the RO reject is perfectly acceptable for use as cooling tower makeup. Although dissolved solids in the RO reject are about four times that of the RO feedwater, if the water is softened ahead of the RO to remove calcium and magnesium, it is of acceptable quality for reuse in this manner.

If the plant does not produce enough recycled wastewater to meet the cooling tower demand, the wastewater may be combined with fresh water to produce a suitable blend. Using an alternative water supply in this way reduces fresh water consumption and wastewater generation.

Maximize cycles to reduce water consumption Obtaining maximum performance from a cooling tower requires it to be operated at the maximum permissible cycles of concentration. Since the concentration ratio is determined by the ratio between makeup and bleed (C=MU/B), reducing the bleed increases the cycles, and conversely, increasing the bleed decreases the cycles. As shown in the Fig. 2 of bleed versus cycles, a point of diminishing returns is soon reached at about 10 cycles of concentration. From a practical view, it is difficult to operate a tower at more than 10 cycles because of leaks, windage and other uncontrolled water losses that contribute to the “bleed” and thereby limit cycles. If 10 cycles of concentration is taken as our target, then cooling towers that operate at less than 10 cycles can be considered as less than 100% efficient as determined by freshwater consumption and wastewater generation.

Table I reflects measures of tower efficiency as determined by the cycles of concentration, if we assume 10 cycles represents a practical 100% water efficiency rating. This table suggests that cooling towers that use freshwater makeup and operate at less than four cycles are not achieving their full potential. This condition wastes water, consumes excess chemicals and produces more wastewater. Towers that operate at five to eight cycles are acceptable for most applications, although large systems can save significant volumes of freshwater by reaching eight cycles. Towers that are maintained at nine to 10 cycles are operating at peak efficiency in terms of water consumption, chemical usage and energy demand.

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Strategies to achieve cycles goal If the cooling tower is on the low end of the efficiency scale, several maintenance strategies are available to increase cycles, including pH adjustment and softening the makeup.

The standard method for increasing cycles on high hardness, high-alkalinity makeup is to use a strong mineral acid—such as sulfuric or hydrochloric—to reduce alkalinity and control pH. Calcium carbonate scale forms as a result of the chemical reaction between calcium hardness and carbonate alkalinity. By neutralizing the alkalinity with acid, the chemical reaction leading to calcium carbonate is stopped. Enough acid is injected into the tower makeup to reduce the total alkalinity to 50 to 100 ppm and maintain the pH of the cooling water within the range of 6.8 to 7.5.

Acid also has the reputation for being “forgiving” in that if scale deposits should form, a slight drop in pH will help remove them.

On the negative side, sulfuric acid is a hazardous, aggressive chemical. An accidental overfeed will cause a very corrosive condition that will result in irreversible system damage. Low pH conditions will also cause deterioration of concrete basins, steel pipe and galvanized steel cooling towers. For these reasons, the use of acid is generally restricted to very high hardness and alkalinity conditions.

As mentioned previously, calcium in the makeup restricts cycles of concentration to a practical limit of 350 to 450 ppm. A makeup supply that has 100 ppm calcium hardness, for example, limits the cooling tower cycles to 3.5 to 4.5. A practical way to remove this restriction is to soften the makeup to remove the calcium and magnesium hardness. An industrial or commercial water softener removes essentially all of the hardness and iron from the makeup. This water can be used “as is” or blended with a percentage of raw water to produce a final makeup of any desired hardness. Reducing the hardness to 50 ppm by softening and blending would permit the tower in our example to operate at seven to nine cycles instead of 3.5 to 4.5.

Softening offers another advantage in that it does not remove the alkalinity nor depress the pH. The high alkalinity and pH of the cooling water tends to passivate (make less prone to corrosion) steel, copper and galvanized steel. The higher pH also serves to inhibit bacteria growth in that many organisms do not thrive at pH values above nine.

Benefits of improved maintenance Maintaining cooling towers at maximum cycles of concentration is a practical way to conserve on freshwater withdrawal rates and produce less wastewater. This has a secondary benefit in that operating a cooling tower more efficiently reduces chemical treatment requirements and saves energy.

The maintenance team plays a vital role in helping to increase profit, gain competitive advantage and protect the natural environment. Water and energy conservation are at the core of this effort. These simple upgrades in cooling tower maintenance practices will help achieve these goals now and into the future. MT


William F. Harfst, president of Harfst and Associates, Inc., has 35 years of water management experience. An independent consultant, he works with industrial, institutional, government, utility and commercial clients on projects that conserve water, minimize waste, reduce chemical consumption and save energy. His strategies focus on increasing profit and gaining competitive advantage for his clients by implementing water management programs that protect and enhance the natural environment. Telephone: (815) 477-4559; e-mail: wfh@mc.net

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