Archive | 1999

283

2:02 am
November 2, 1999
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Maintenance–How Do We Gain Respect?

Insights into critical issues of plant equipment maintenance and reliability management

Judging from comments received via e-mail, expressed on maintenance-oriented web sites, and repeated in Bob Baldwin’s Uptime editorials in the July/August and September issues of MAINTENANCE TECHNOLOGY, there seems to be general agreement in at least one area within the maintenance and reliability community. Maintenance professionals are concerned about the stature, respect, consideration, and response received from both their own and supplier organizations. Although there appears to be a lot of complaining, there does not appear to be much real corrective activity.

The primary issue The general question is how do we as a community change what most agree are discouraging conditions. The real question is what are you doing personally to drive change?
Before the answer, some observations: For a soon to be released book on asset management, I personally reviewed over 100 papers presented over the past two years. Out of more than 70 pages of notes, I had a little more than two pages on results and benefits. Many authors seem to be talking about what to do and how to do it, but they seem to be ignoring the benefits that have been achieved. Is that because process is more important than results to maintenance professionals? If so, priorities are reversed.

If my experience is typical, comments to Viewpoint opinions are always well thought out–but are few in number. This observation parallels that of others. A good friend who writes monthly editorials for another magazine seldom receives any comment–even to controversial subjects. On one occasion he offered more detailed information on a subject of great interest. Only a few replied. One of the replies was so far removed from his offer that he had to go back to the editorial to make certain he had been clear. Do these observations mean that many members of the maintenance community like to complain but few are willing to take the next step and become personally involved driving a solution?

We seem to be a vast army, largely unorganized and content to complain among ourselves and on web sites. We complain to the choir in ways that will never attract the attention or interest of a manager or anyone positioned to do anything about the complaints.

Is there a solution? There are at least three organizations capable of driving a process to gain greater respect and stature for the profession: the Society for Maintenance & Reliability Professionals (SMRP), Association for Facilities Engineering (AFE), and the American Society of Mechanical Engineers (ASME), Plant Engineering and Maintenance Division. These three organizations probably have a total membership of 16,000 to 20,000 maintenance professionals.

That leads to more questions: why isn’t membership larger and are you an active, participating member? If you are a member, are you weighing in with your successes and results and your requirements for the changes that must be made to gain recognition and respect for your contribution? If not, please don’t complain about how managers and suppliers don’t listen. While they may not listen to you individually, they will have to listen to 15,000 yous, especially if the message is conveyed through an influential organization known to represent a consensus of active, energized members. If you are complaining but don’t belong to any of the professional societies, don’t help set their agenda and drive their efforts, don’t participate in any conferences, and don’t publicize your requirements and successes. I suggest you need look no further than the nearest mirror to find the person who could make real change occur. Some are probably saying I don’t have the time to participate, can’t afford to join, my boss won’t allow me to attend conferences, and my company won’t allow me to publicize success. Again I’ll say you must do something more than complaining individually for change to occur. Some are finding the time–more must do so.

Your participation is mandatory not just needed. With your active participation and leadership, changes are not only possible, they will occur. MT


For more information on the professional societies mentioned, visit their Internet sites:
Society for Maintenance & Reliability Professionals, www.smrp.org
Association for Facilities Engineering, www.afe.org
American Society of Mechanical Engineers, www.asme.org

 

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421

1:18 am
November 2, 1999
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Strategies for Leak Detection, Repair, and Prevention

ultrasound

Ultrasound equipment can identify compressed air leaks so they can be repaired before they result in unscheduled downtime, affect product quality, pollute the environment, or endanger people’s lives. Photograph courtesy UE Systems, Inc.

Leaks cost industry millions of dollars each year. A few small 1/2-in. leaks in a facility using air at 100 psi with an electric production cost of about 6 cents/kilowatt hour (kWh) wastes more than $22,000 per year. A recent compressed air leak survey at a New Jersey manufacturing plant resulted in a savings of more than $40,000 a year and an annual reduction in electrical energy consumption of 496,893 kWh.

Delaying the replacement of a leaking $100 steam trap could waste $50 a week or $2,600 a year. Since an average facility has hundreds of steam traps, leaking ones may be squandering hundreds of thousands of dollars annually. In addition to wasted dollars, unattended leaks also may result in unscheduled downtime, affect product quality, pollute the environment, and endanger people’s lives.

This article deals with leaks from three different perspectives: detecting and pinpointing leaks before they mushroom into major trouble, using mechanical adhesives to repair leaks, and installing hardware to prevent leakage and improve equipment reliability.

Early leak detection Ultrasonics has been industry’s technology of choice to detect and pinpoint leaks for more than 25 years. Inspectors using a hand-held, battery-operated ultrasound instrument, such as the Ultraprobe 2000, from UE Systems, Inc., Elmsford, NY, can hear leaks in vacuum or pressurized systems as well as faults in operating machinery and electric transmission and distribution systems. State-of-the art accessories such as close-focus modules and stethoscope extensions enhance the capabilities of ultrasonic instruments.

An ultrasonic detector senses subtle changes in the ultrasonic signature of a component and pinpoints potential sources of failure before they can cause damage. Longer wavelengths of lower-pitched sounds are gross waves that can be difficult to locate. But higher frequency sounds are short wave signals localized to the source of emission. For this reason, it is possible to use ultrasonic sensors in relatively noisy environments.

Continuous monitoring. While most applications for ultrasonic inspection are focused on hand-held portable instruments, there has been increasing interest in continuous equipment monitoring.

Continuous monitors include two basic components: a processing unit and a sensor, which often is in the contact mode. A wave guide is affixed to a set test point by either bonding it to a surface or by drilling a threaded hole and screw-mounting the wave guide on the object to be monitored. The processing unit may feature adjustments for sensitivity/dB level, a threshold setpoint for alarm, and outputs such as 0-10 V dc, 4-20 mA. Some units provide a heterodyned signal which allows remote listening or downloading to recording devices such as vibration analyzers, tape recorders, or computers.

An example of this type of monitoring device is a valve leak onset alarm. When a valve is shut, there is no sound. A baseline is set when the instrument is installed. If the valve leaks, the onset or increase of sound intensity over the set threshold will set off an alarm. The generated sound is usually localized to the test area where the sensor is affixed. This reduces false alarms produced by irrelevant sound generation.

fluidleak

More than a billion gallons of industrial fluids are wasted through leakage every year. This hydraulic pump leak can be repaired using anaerobic thread sealants. Photograph courtesy Loctite.

Long range and close-up detection. While many ultrasonic translators offer a sensitivity range capable of locating gross leaks at a distance, there is a need to locate more subtle distant leaks and to scan electrical apparatus accurately at a safe distance. Also, close scans of low level sounds, usually associated with low level leaks such as vacuum leaks, are a challenge to standard ultrasound microphones. Long range detection devices can detect and enhance the signal of remotely generated ultrasounds. Some applications include locating leaks in overhead pipes and cables, and detecting arcing tracking or corona emitted from high voltage equipment including transformers, insulators, or switchgear.

Since the ultrasound event produced by these emissions can be detected at a distance, these detection devices provide safe scanning around potentially hazardous high voltage equipment. Low level emitting leaks are a different problem. The signal amplitude is extremely low and needs some form of amplification beyond the normal range of most standard microphones. Receptors to enhance low level leak emissions have been developed and offer a reliable method for locating these leaks.

Liquid leak amplification. When low level leaks do not produce turbulent flow, it is not possible to detect them with conventional scanning probes because ultrasonic leak detection of either pressure or vacuum leaks depends on the generation of a turbulent flow as the gas moves from high pressure to low pressure. When it is not possible to locate this type of low level leak (typically below 1×10-3 ml/sec), using a liquid with a low surface tension will help. Only a small amount of liquid must be applied to the leak test area. As the gas migrates through the leak hole and passes into the film of the fluid, bubbles will form and burst. The bursting produces a detectable ultrasound. Leaks with rates as low as 1X10-6 ml/sec have been detected with this method.

Remotely positioned transducers. In some cases, it has been difficult to maneuver and hold a probe at a test position while recording or listening to the generated ultrasounds. Some manufacturers provide multi-directional sensors with a cable that can be positioned in confined spaces. This technique is used to determine the presence of remote leakage without performing the time- consuming procedures required for entering confined space areas.

Valve leak monitoring/trending. An increase in amplitude over a baseline is often a warning signal of impending failure or worsening condition. Valves should be inspected routinely since the information collected can be extremely useful. Aside from go/no-go leak inspection, the worsening condition from acceptable to unacceptable can be determined. For valve monitoring, there should be a consistent test point and conditions within the test object (such as flow rate) should be constant. A baseline should be set and compared to future readings under the same conditions and recording modes

When used in tandem with other technologies such as vibration analysis and infrared thermography, ultrasound has myriad uses. The technology enables knowledgeable inspectors to go beyond the basic applications of leak detection and valve and steam trap inspections, and opens opportunities for improved equipment uptime, energy savings, and safety.

Sealants block leak paths Though leaks of gas or air at a facility are often overlooked, they can become a significant operating cost especially when the situation is chronic. Once a comprehensive survey to detect and pinpoint leaks in a system is completed, the next step is to stop the leaks. State-of-the-art machinery adhesives can reduce costs by eliminating leak paths.

In the average threaded fitting, metal-to-metal contact is approximately 20 percent. Eighty percent is air space surrounding spiral threads, a potential fluid or gas leak path. Loctite, Rocky Hill, CT, supplies engineering adhesives, sealants, and dispensing equipment.

Many situations can cause loosening and/or cracking of fittings, valves, and other connections which result in leaks. Vibration, shock, thermal, and environmental changes all take their toll. Practically all conventional methods of sealing–cork gasketing, pipe dope, or Teflon tape–have their shortcomings.

Conventional gasketing products like cork, paper, and rubber have a tendency to set even when they are properly torqued. When the bolts relax there may be a minute separation leak path. Having an inventory of all size gaskets is virtually impossible, and gaskets can shrink, tear, or deteriorate before use. Also, cutting gaskets is time consuming.

Pipe dope also is no guarantee against leakage. Pipe dope relies on solvents to carry them and form solid seals. When the solvent evaporates, the product dries to form a tough seal. The rigid, brittle nature of pipe dope causes cracking which creates leak paths. And with pipe dope, disassembly can be difficult.

Teflon tape, originally designed as a thread lubricant and not a sealant, can cold-flow out of the pipe and leak. It also can permit overtightening, a situation that may result in threads that lathe up on each other thus increasing the leak path. Another disadvantage of Teflon tape is that it has a tendency to contaminate systems. If a Teflon shred enters a system, it can foul a check valve or other critical component.

The best sealants are based on anaerobic technology. They are a liquid or paste plastic monomer that changes from a liquid to a solid when it comes in contact with metal and when air is excluded.

Because these anaerobic sealants do not dry out but cure without shrinkage, they are excellent when applied to threaded fittings. These sealants provide correct sealing without cold-flow and offer ongoing lubricity that acts as a mild threadlocker. They are also noncontaminating.

The company’s anaerobic gasket product for use on rigid flanges allows the flanges to be taken down virtually metal to metal. The plastic gasket material uses similar chemistry to fill in all the voids. Seen under a microscope, these voids appear as mountain peaks and valleys. The sealant fills in the voids between the mountain peaks with a liquid or paste that changes to a solid. And the piece of equipment still can easily be disassembled and removed.

One application of these super sealants is sealing and casting of porosities. A liquid anaerobic sealer can be painted on a clean surface. It will penetrate into every porosity and seal it. For extremely large vats of up to 100 gallons, porous metal parts can be submerged to both seal them and to increase their machinability.

The application of anaerobic sealers is a relatively simple process. And for anyone who needs guidance, some manufacturers conduct in-plant training sessions on the proper selection and application of its sealants.

swaglock

Once leaks are identified, using gaugeable tube fittings reduces problems, improves equipment reliability, and conserves energy. Drawing courtesy Swagelok.

The proactive use of these machinery adhesives provides reliability at the base component level. Manufacturers are discovering that using high-end sealants and adhesives in their equipment can improve equipment reliability, reduce costs, and stem wasted energy.

Gaugeable tube fittings improve reliability The installation of high-end tube fittings and valves often has dramatic results. An energy survey conducted for a pulp and paper company revealed 23 percent leakage in its fluid system. Once gaugeable fittings were put in, the leaks dropped to zero.

Swagelok, Solon, OH, provides connectors for fluid systems ranging from 1/16 in. to 2 in. o.d. Its tube connectors and valves are used in air systems, condensate return systems, hydraulics, pneumatics, analytical instrumentation, acid systems, caustic systems, and small bore process applications.

The company works with maintenance engineers to conduct energy surveys of their facilities. All fittings in a given area of a plant where gas (not liquid) service is common are tested for leaks. Once leaks are identified, the use of gaugeable, two-ferrule tube fittings to reduce problems, improve equipment reliability, and conserve energy is demonstrated.

In a typical scenario, a company representative together with plant personnel checks for air leaks in a compressed air system. Working from as many as 1000 check points, about 24-30 percent leakage is usually identified. This statistic is applied to the company’s cost per kilowatt hour and losses are determined. A performance contract to correct the problems is generated. Studies show that properly installed fittings correct leakage to less than 3 percent.

To ensure reliable performance, a tube fitting composed of four components–nut, back ferrule, front ferrule and body–is recommended. The consistency and quality of matched components permit their use in many difficult services. These fittings become a 5-piece connection when affixed to the tubing

The 2-ferrule design and sequential action of the fitting overcome variations in tube material, wall thickness, and material hardness to ensure safe, reliable, and leak-free connections.

Unlike a bite-type fitting which can cut into the tubing and result in a weak point that occasionally may vibrate and break off, a four-piece tube fitting is gaugeable, i.e., every quarter turn is about a 0.0125-in. movement. Consequently there is a go/no-go gauge that enables the person assembling the fittings to put them together and then gauge each one individually during the first makeup to ensure that every fitting will measure up to its properly installed performance factor (1¼ turns).

Leaks may also result from faulty valves, or more commonly from valves whose sealing and packing mechanisms are subject to wear or unsuitable applications. The challenge is to determine the specific application of each valve and choose the right valve for the job.

There are many different types of valves including shut-off valves, regulating valves, uni-directional valves, and pop-off relief valves available for a variety of applications.

Some valves can be pneumatically operated; some may be electrically operated, and some work manually. How frequently should valves be monitored? It is a good idea to check the valve packing and make adjustments periodically according to the cycle requirements of the valve. MT

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685

12:45 am
October 2, 1999
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Keeping Threaded Fasteners in Their Place

It’s been said that man’s invention of nails, rivets, screws, and other basic fasteners helped pave the road from the Stone Age to the Space Age. If that is true, then fastener loosening has provided quite a few of the speed bumps and pot holes on that road.

Keeping fasteners tight, particularly threaded fasteners, seems like a simple task, but the moving nature of the machinery they are used on is what makes them so troublesome. How nails and rivets work is fairly well known. But because the physics of the threaded fastener is not as well understood, it tends to cause the most problems.

Causes of loosening
Threaded fasteners are employed primarily to clamp objects together using tension. Rotary force or torque imposed on the fastener provides that tension. Problems occur when this clamping load deteriorates.

About 85 percent of the torque and effort of tightening a bolt is absorbed by the friction in the threads and under the head. Only 15 percent produces clamping load. Therefore, high torque may be absorbed by high friction and not produce tension. Torque is not the most precise method of controlling clamping load, although it is the most common. When bolt and nut manufacturing is closely controlled, the tension produced in a bolt for a given torque varies up or down by 15 percent.

Although it is always the first suspect in any case of lost clamp, vibration, as commonly perceived and observed, is not capable of bolt loosening by itself. If vibration is violent enough to cause shifting of the threads, then it will cause loosening, and in only 50 to 100 cycles. However, vibration that violent is usually perceived as shock, shudder, or impact. Toward the end of the loosening cycle, common vibration can and will rattle the fastener loose. This is why it often takes full blame for loosening.

The actual cause of loosening is side-sliding or shifting of the threads. The empty space between the threads of a nut and bolt leaves room for movement that leads to self-loosening and loss of clamping force. The friction in the threads and under the head of the bolt is reduced to zero when the clamped parts and threads slide sideways to the bolt axis.

Each time this happens, the bolt can unwind by itself. The loosening process of a non-locking fastener starts with the first motion. It normally takes less than 100 side motions to completely loosen a bolt.

This shifting can occur any time the side force exceeds the friction between surfaces, as produced by the clamping load. There are three common causes of shifting:

  • Bending. Bending of parts causes stress on the friction surface. If slip occurs, the threads and head also will slip. Each slip causes a partial downhill or unwinding slip in the threads. After 50 to 100 of these, the bolt is completely loose.
  • Thermal expansion. Differences in temperature or in clamped materials can cause the same effect as bending. If the effect is strong enough to cause side-slip, then downhill slip also will occur and loosening will result.
  • Applied loads. The impact of loads applied directly to the fastening point can cause side-slip as well.

Any one or combination of these conditions can occur from shipping trauma, extreme heat or cold, or just plain abuse. The effects are cumulative and self-accelerating. As these affect clamping load, there is increased probability that side-sliding will occur.

Threadlocking
Various methods and devices have been employed over the years to reduce or prevent loss of clamping load in threaded fasteners.

The earliest attempts involved the use of lock wires and split pins in conjunction with nuts and bolts with holes drilled in them. Although effective, these measures had some serious drawbacks. Each fastener had to be the correct length, and the holes had to be aligned on each individual bolt. Consider the difficulty and time required using this method to assemble numerous parts requiring many threaded fasteners.

As fastener manufacturing skills improved, more complex methods of threadlocking were developed. Two of the most common mechanical methods of threadlocking are thread distortion and the use of washers. Although these methods can be effective for short-term threadlocking, anaerobic threadlockers can provide short-term, long-term, and even permanent tightening when necessary.

Liquid threadlockers
The first chemical threadlockers, developed by Loctite, eliminated many of the design faults and shortcomings of threaded fasteners. Chemical threadlockers are anaerobic liquids that cure to a tough, solid state when activated by a combination of contact with metal, and a lack of air. The resulting cured material is a thermoset plastic that cannot be liquefied by heating, and resists most solvents.

The purpose of threadlockers is to lock and sometimes seal threaded components without changing fastener characteristics or altering torque-tension relationships. In addition, chemical fasteners offer a number of other advantages over mechanical tightening methods:

  • Breakloose and prevailing torque. Liquid threadlockers find their way into tiny imperfections of threads. As they cure, these imperfections serve as molds for thousands of tiny keys that resist fastener movement in any dimension.
  • Anti-corrosion. Because threadlockers fill the voids between threads, they block the entry of moisture, preventing corrosion and subsequent seizure.
  • Strength control. Most threadlockers are graded by their various strengths and characteristics into distinct classifications. The different formulations of Loctite threadlockers, for instance, are distinguished by the color of the threadlocking material: low-strength is purple, removable is blue, permanent is red, and the penetrating formula is green.
  • One size fits all. Because they are liquids, threadlockers do not come in different sizes. The same bottle that locks in a tiny screw also can be used on a large bolt. Stocks of various size mechanical threadlockers are no longer necessary.

Selecting the right threadlocker There are several key factors to consider when choosing a threadlocking compound:

  1. Shear strength. If all threaded fasteners were designed never to be removed, then only one type of threadlocking compound would be necessary, the strongest available. Most assemblies that are held together with threaded fasteners will, with varying frequency, need to be dismantled for repairs, maintenance, or adjustments. Consequently, threadlockers of various shear strengths are available.
  2. Cure speed. The cure speed of threadlockers can vary, depending on several factors, including temperature, base metal, surface treatments, clearance between parts, and surface cleanliness. The use of chemical primers can speed cure and result in higher ultimate strength.
  3. Gap filling requirements. Most threaded fasteners are designed with some clearance between their mating surfaces. Larger clearances between mating surfaces require more product to fill them. Thixotropic liquid threadlockers will easily fill clearances in threaded fasteners, without migrating to other areas of the assembly. Where a higher shear strength product is required, and product migration is considered a potential problem, a higher viscosity compound is recommended.
  4. Operating environment. Both chemical resistance and operating temperature should be considered when selecting a liquid threadlocker.

The chemical resistance properties of threadlocking compounds vary between different grades. The most popular anaerobic products will generally resist water, natural or synthetic lubricating oils, fuels, organic solvents, and refrigerants.

Like most organic materials, threadlockers lose strength at elevated temperatures. Most show significant strength retention at temperatures up to 300 F (150 C). Hot-strength formulations can increase this working temperature to 450 F (230 C) for those applications where it is considered necessary.

Removability
The most common myth about liquid threadlockers is that once they are cured, they cannot be removed. In fact, all threadlocked fasteners can be removed. Different grades of threadlocker can be used depending on the task. Fasteners secured with low- and medium-strength grades can be removed with common hand tools. Those secured with high-strength grades can be removed by applying heat for a specified time.

Threadlockers are not just for specialized uses, either. They perform effectively on fasteners and threaded assemblies of any type and size, in any kind of equipment. MT


Information supplied by Robert A. Valitsky, a manager of technical communications at Loctite Corp.’s North American Engineering Center, 1001 Trout Brook Crossing, Rocky Hill, CT 06067; (860) 571-5416; Internet www.loctite.com

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239

10:33 pm
October 1, 1999
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RPM Can Work!

Reliable Predictable Manufacturing process eliminates defects in can line at Coors, improving performance and cutting costs.

There is universal agreement that improved machine performance can control and reduce manufacturing costs. That was the goal of Coors Brewing Co., Golden, CO, when it commissioned a maintenance benchmarking study of its can and bottle packaging lines and the warehouse operation.

The study results compared the maintenance operations at Coors to a world class model and other companies in similar industries. The benchmarking process, developed and administered by Charles Brooks Associates, Inc., uses a grading system to determine a company’s level of maintenance effectiveness.

Although the brewery’s maintenance operations performed better than most of the comparison companies, two major opportunity areas were identified: planned maintenance and mechanic training.

As a result, Gene Rowe, senior consultant, and Coby Frampton, partner and president of Charles Brooks Associates; and Paul Altimier, director of can packaging at Coors, designed a program for the company that later became known as Reliable Predictable Manufacturing (RPM). The goal of RPM is to improve equipment performance and control or reduce manufacturing costs.

The RPM process includes many of the elements of other improvement processes such as critical component analysis, equipment upgrading, planned maintenance, and performance evaluation. It differentiates itself through the use of Defined Equipment Standards (DES) as the basis for maintaining and operating equipment, as well as being the vehicle for achieving employee participation, skills enhancement, and production/maintenance cooperation.

The 20 steps required to implement RPM are shown in the table “Steps for RPM Implementation.” The first eight have to do with proper planning and setting the stage for change. The last 12 steps outline the implementation of the DES, modification of preventive maintenance routines and audits, and mechanic training. While quite specific in application, DES is essential in implementing Total Productive Maintenance (TPM) and Reliability Centered Maintenance (RCM).

To insure that the project goals were being met, a baseline was established measuring unscheduled downtime, quality, and production.

Monika Seiler, the plant’s RPM process manager, and Rowe involved the hourly mechanics and electricians from the onset to gain support for the RPM process. They developed the DES, prepared updated preventive maintenance (PM) routines, and conducted extensive, formal peer-level training. They also made presentations to upper management explaining their work and the benefits that were accruing. Hourly maintenance personnel took ownership of the analysis of line performance data and developed specific action plans to correct recurring problems.

Understanding how the program works and how it will affect them was essential in gaining their confidence and cooperation. The mechanics and electricians were empowered by the knowledge that they had an opportunity to participate in and assist with the development of a key business strategic program that would affect the company’s bottom line. In order to request program funding, the supervisors, mechanics, and their appointed peer leaders met with L. Don Brown, senior vice president, operations and technology, to voice their support of and commitment to the program.

In order to determine the pilot production line, the team analyzed downtime data and identified the line with the greatest problems.

The variables analyzed were quality, production data, unscheduled downtime, and maintenance spending. Can Line No. 10, it turned out, produced the most can defects and received the most maintenance dollars.

Can Line No. 10 was broken down into major equipment systems or subassemblies. An analysis of subassembly downtime and maintenance cost determined which subassemblies were causing the can defects.

Next, current machine settings were identified, documented, and evaluated with input from mechanics from all shifts. Not unusual with many companies, each mechanic used a different setting. After gaining consensus from the mechanics, machine settings were adjusted to a set standard and were documented. This standard setting became part of the DES.

Once the can line’s collator was upgraded and set to the new machine standard, can defects were reduced by 87 percent. After further evaluation, a variable speed drive was added to reduce pressure from the accumulator table, thereby eliminating all defects that prevented shipments.

Machine performance was monitored at the set standard and adjustments were made as necessary to optimize machine and line performance. When optimal machine and line performance were achieved, the machine settings were documented in the DES. Maintenance personnel took digital pictures of each machine and documented how the settings were achieved.

The use of digital pictures proved to be an important training tool as well as a creative way to document the DES for all the line equipment.

As a result, PM procedures were modified to reflect changes in the machine settings and new PM procedures were developed. Machine audits also were developed and implemented to assess the level of maintenance received and the current machine condition to ensure optimal machine performance.

Detailed PM procedures were developed once the optimal level of PM was achieved, and entered into the computerized maintenance management system.

At this point, the training process was begun to train mechanics on the new machine settings and PM procedures. A technical job skill training process called the Analytical Method of Training (AMT), used by Charles Brooks Associates since 1971, was implemented.

It begins with a thorough analysis of training needs, followed by standardization on the best trainable method. Once the method is known, skill development begins with peer-level instructors providing training until the trainee can perform at the expected level. When single-cycle skill has been achieved, the stamina buildup phase begins. The entire process is measured and monitored through extensive testing and performance demonstration.

Through an improved planned maintenance process starting with Defined Equipment Standards and mechanic training, reduced maintenance costs and improved efficiency can be achieved. The involvement and assumed ownership of the program by hourly employees, supervisors, and managers assures long-term results can be realized. MT


Katherine Berntzen and Gene Rowe are consultants with Charles Brooks Associates, Inc., P. O. Box 11758, Charlotte, NC 28220-1758; (800) 868-3553; e-mail rtt@charlesbrooks.com

Steps For RPM Implementation

Stage Step

Description

Planning
and setting
the stage
for change

1 Educate unit management on benefits of RPM
2 Procure necessary equipment (cameras, printers)
and identify work area
3 Identify a unit RPM champion
4 Appoint a RPM coordinator
5

Conduct RPM orientation for unit management, team leaders, and support personnel

6

Conduct shift meetings to describe the process to all hourly personnel and recruit volunteers to work with the team

7 Conduct RPM workshop
8 Implement RPM
Implementation 9 Review existing documentation
10 Establish benchmark measurements
11 Break equipment down into subassemblies
12 Develop timeline to track progress
13 Develop Defined Equipment Standards (DES)
14 Upgrade equipment to new standards
15 Monitor equipment performance
16 Modify preventive maintenance procedures
17

Develop machine audits

18 Develop and install revised CMMS PM checklists
19 Train mechanics
20 Implement new PM procedures

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367

9:48 pm
September 1, 1999
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Strengthening Asset Management at Amoco Chemical

Networking, benchmarking, and TPM comprise three-tier approach for cutting maintenance costs in half and boosting overall asset effectiveness by 25 percent.

Maintain Assets Network (MAN) has served as a vehicle to substantially strengthen the culture of maintenance and reliability in Amoco’s chemical businesses over the past two years. It is one of five “networks of excellence” established by the Amoco Chemicals Manufacturing Council in 1996 to drive improvement in 20 manufacturing metrics established to measure performance of the company’s chemical sector and chemical plants.

MAN met for the first time in late 1996 and consisted of representatives from nine U.S. chemical plants, three non-U.S. chemical plants, and one representative for eight fabrics and fibers plants. The group met bimonthly and began to set priorities, with initial activities centered on improving three metrics:

  1. Maintenance costs, as a percent of estimated replacement value (ERV)
  2. Availability ratio (reliability)
  3. Sustaining capital

Baseline costs were established and a goal set for 1999 to reduce maintenance costs by 50 percent. The group struggled with the magnitude of the goal, differing maintenance accounting practices, and the calculated replacement value of the plants. One network member was assigned the task of developing standard guidelines for maintenance cost accounting and replacement value calculations. MAN members also devoted time to understand each other’s organizations, work processes, current improvement activities, and opportunities.

Strategy development
Early in 1997, it became apparent that the group had to move beyond discussing the merits of the metrics and start to impact them. The network established five subcommittees to cover:

  1. Long-term MAN strategy
  2. Reliability improvement
  3. Pumps
  4. Centrifuge
  5. Product change

The first subcommittee mission was to develop long-term MAN strategies to give the group needed direction. The other four subcommittees were to research and recommend best practices in their assigned areas that could be implemented at the plants to quickly improve equipment reliability and to reduce maintenance costs. They covered equipment reliability, pump maintenance and reliability, centrifuge maintenance and reliability, and reducing lost capacity from product changes.

It was believed that all of these efforts, if embraced by the plants, would deliver the overall asset effectiveness (OAE) goal of a 25 percent increase and the maintenance cost goal of a 50 percent reduction. The MAN strategy is summarized in the section “Three-Tiered Strategy.”

Networking activities
The Reliability Subcommittee explored reliability best practices inside and outside the chemical sector and the company and reported to the network in December 1997. It recommended the use of 12 reliability practices and six reliability tools:
Reliability practices

  • Elements of preventive maintenance
  • Equipment repair history
  • Corrosion monitoring
  • Portable vibration monitoring
  • On-line vibration monitoring
  • Infrared thermography
  • Positive material identification
  • Rotating equipment alignment
  • Steam trap monitoring
  • Lube oil analysis
  • Rotating equipment balancing
  • Critical equipment monitoring

Reliability tools

  • Reliability in engineering
  • Reliability modeling
  • Equipment maintenance plans
  • Root cause failure analysis
  • Reliability centered maintenance
  • Data recording and analysis

All documents were placed on the Amoco Web page and updated as needed. The Reliability Subcommittee developed a self-assessment process for the plants that serves as the basis for “scorecards” developed by a new Measurements Steering Committee. The subcommittee’s official task is complete, but the company continues to benefit from the relationships and networks that exist between the plant representatives, and the group plans to meet at least twice a year to share successes and problems they are experiencing in the reliability arena.

The Pumps Subcommittee also met extensively in 1997 and 1998 to explore and recommend best practices relating to pump maintenance and reliability in the same fashion as the Reliability Subcommittee. It completed its work in 1998 and issued seven best practice documents: pump repair procedures, pump repair documentation, pump repair training, condition monitoring, preventive maintenance, mechanical seals, and root cause failure analysis.

These documents are on the Amoco Web page, and the group also made recommendations to the Measurements Steering Committee to follow progress of the implementation of these practices. Amoco continues to benefit from the relationships and informal networks that remained in place.

The two other subcommittees produced best practice documents that were distributed throughout the chemical sector.

Benchmarking
The benchmarking process used by Edwin K. Jones, P.E., Inc. is conducted in three steps and focuses on a model of seven best practices:

  • Leadership
  • Planning & scheduling
  • Preventive & predictive maintenance
  • Reliability improvement
  • Spare parts management
  • Contract maintenance management
  • Human resource development and training

The first stage of the assessment process was a kickoff meeting at each plant. It was designed to form the plant’s benchmark team, define the roles of team members, review the benchmarking process, and provide an initial tour of the plant. A data questionnaire was left for the benchmark team to complete.

The second stage was a two-day meeting referred to as the validation visit. During this stage, key data are validated to be consistent with the comparison database. There are also interviews with maintenance craftsmen, maintenance supervision, operators, operator supervision, stores employees, reliability/maintenance engineers, contractor supervision, training coordinators, and maintenance planners and schedulers. A preliminary, verbal report of the findings is made to the Plant Leadership Team at the conclusion of the validation visit.

At this point, interpreting the comparison data, the interview issues, and the plant condition is initiated with discussion among team members. These issues are included in the final report, along with the observations of the “unbiased, external, calibrated resources,” highlighting the opportunities for improvement. The final report has a balanced mix of team observations of maintenance practices and validated comparison data displayed in graphic plots along with data from “World-Class” plants.

The final stage, another two-day meeting, takes place approximately one month after the validation visit. The plant usually receives a benchmark report about a week before the third visit. The report includes plant data compared with other Amoco plants and with a selected set of “World-Class” plant data. Also provided is an initial estimate of the potential savings that might be obtained if the plant could close the gaps with the World-Class plants.

This third visit concludes the assessment process with a plant-wide review of the benchmark report. A great deal of emphasis is placed on shifting from the “assessment mode” to a “strategy development mode.” The basic concept is: “OK, now that we have a better idea of where we are, where do we go from here?” The second day of this visit is then devoted to jump-starting the beginning of a Maintenance and Reliability Strategic Plan. The team selects areas to be improved, then lists specific tasks to deliver the desired results. Champions, resources, and dates are assigned to each task. The benchmark team then completes the strategic plan development over the ensuing two to three months.

Benchmarking results are summarized in the section “16 Plants Benchmarked.” Each site’s plan usually includes an overview of the maintenance strategy and how it fits with the plant’s overall manufacturing strategy. It also includes some analysis of the savings potential that results from executing the plan. Savings are viewed in two categories: maintenance cost savings and business benefits of improved equipment reliability and availability. The plan lists the areas of improvement, the key issues, specific actions to be taken, metrics to be tracked, and a Gantt chart showing a timeline for all of the tasks to be completed. Seven plants have presented their plans to the network, with the remaining plants scheduled to do so in 1999.

Total Productive Maintenance (TPM)
After a TPM presentation to the Manufacturing Council in July 1998, the TPM Steering Committee (TPMSC) started to develop details around the essential TPM elements Amoco planned to pursue. These elements included:

  • Equipment improvement teams (EIT)
  • Asset ownership (autonomous maintenance)
  • Asset reliability
  • Maintenance effectiveness
  • Early equipment management
  • Training

The TPMSC included in its TPM model all known best practices from the subcommittees, the pockets-of-excellence from the benchmarking initiative, and other best practices gleaned from networking with other TPM companies and consultants. Because much of what was included already existed somewhere in Amoco, the TPMSC developed a site assessment tool to enable the plants to assess the quantity of work required in each of the TPM elements. This enabled plants to develop short-term strategies for the elements that were in use, and longer-term strategies for the elements requiring more time and effort.

The TPMSC then selected four areas of TPM as good places to start. They were autonomous maintenance/clean to inspect; process recording and data entry (PRIDE), an operator-based data gathering process using a combination bar code reader and data entry tool; equipment improvement teams; and work order prioritization.

These “places to start” provided a means to quickly immerse the plant in a TPM culture using best practices that had proven successful within Amoco. Plants could quickly link up with other plants that had implemented a given process, learn from their experience, and generate early success while developing their longer-range plans.

“Clean to Inspect,” a process taught by Productivity, Inc., a TPM consulting firm, works on the principal that as you clean equipment, you inspect it thoroughly in the process. The detailed inspection identifies small abnormalities that could lead to poor performance or a breakdown. In other words, if you take care of all the little things, the big things will take care of themselves. It also has several ancillary benefits in that the employees who return equipment to like-new condition will work to keep it in like-new condition. During the process, cross-functional teams look for opportunities to improve the performance and maintainability of the equipment. It has been very successful at two sites in transforming operators from merely operators of the equipment into equipment caretakers.

PRIDE is an Amoco data-gathering tool that also can transform the operator into an equipment reliability resource. Using the Equipment Specific Maintenance Plans (ESMP), employees can select the equipment reliability data to monitor the equipment condition, predict impending failures, and help troubleshoot the root cause of breakdowns. This information can then be trended and used by the equipment improvement teams.

Equipment Improvement Teams (EIT) exist in some form at most of the plants. They are cross-functional teams that are given the time, training, and resources to address the root cause of poor equipment performance or breakdowns. Several plants have well-established EIT programs that serve as the cornerstone of their TPM effort. Other plants use them sporadically to solve major problems. The intent of TPMSC is to upgrade plants’ use of EIT.

As cited in the benchmarking report, work order prioritization, misuse, and abuse were barriers to plants being able to plan and schedule their work. The Texas City plant recognized this in 1996 and learned a process called the Ranking Index of Maintenance Expenditures (RIME) at a planning and scheduling workshop at the Marshall Institute. It is a process where criticality of the equipment and the importance of the different types of work determine priority with minimum interference from people. Its use dramatically reduced the number of urgent work orders and it was cited as a pocket-of-excellence during benchmarking. It was thought that by using RIME, all plants could do more and better planning and scheduling to reduce costs and take a first step away from reactive unplanned maintenance.

The TPMSC also researched job postings for TPM coordinators, external TPM consultants, and Amoco technical experts for specific elements and tools, as well as suggested training and training material. All of this was assembled into a TPM Manual to assist the plants with developing their implementation plans.

TPM workshops
TPMSC realized there was a need for a wider base of TPM knowledge throughout the sector. As plants discussed TPM with their employees, inaccurate statements were causing resistance to the initiative. A three-day workshop was designed to teach the attendees the fundamentals of TPM, let them meet people who were already doing TPM, see TPM in action at a plant, learn about site implementations, and learn about “good places to start.” It was hoped that the attendees could then return to their plants and accurately describe TPM and start to develop implementation plans.

By September 1998, five more workshops were held. In all a total of 325 people were trained, giving the sector the knowledge base it needed to move forward.

TPM implementation plans
Most plants now have TPM implementation plans. Several sites have appointed full time TPM coordinators, most have EIT, half are committed to installing PRIDE, and six have contracted with external resources and have done “Clean to Inspect” training. More than half has instituted RIME.

The TPMSC continues to meet every two to three weeks, usually via teleconference, to discuss progress. It advertises successes and assigned action items to investigate areas where progress is slow or lacking. A TPM activity scorecard is used to track progress and TPM metrics are being incorporated into computerized maintenance management system (CMMS) software. In 1999, the TPMSC plans to initiate a TPM Users Forum so people from across the sector can come together to share successes, work on common issues, and look for help in problem areas. The committee will make detailed assessments of the issues at each of these sites to develop the topics for the forum.

The TPMSC has asked MAN to further develop a vision and training for Asset Reliability/Reliability Engineering and for Maintenance Effectiveness/Planning and Scheduling. MAN commissioned these steering committees in August 1998. These visions are described in the section “Planning and Scheduling” and the section “Reliability Engineering.”

Best practices implementation
MAN established the Best Practices Steering Committee (BPSC) to facilitate implementation of the best practices recommended by the Reliability and Pumps Subcommittees and to investigate new best practices for new issues. The BPSC charter ncludes:

  • Place best practices in the “top drawer” of people who use them everyday. Make available expert maintenance resources to all levels of personnel. Provide a Web page search engine to obtain easy access to these practices and resources.
  • Best practices and resources will be investigated and recommended to the plants by the BPSC. Each plant will be urged to evaluate the strategic fit of these practices and tools to their business. If applicable, they will perform a cost/benefit analysis to determine the priority of implementation.

Metrics and measurements
Because the plants used different computer systems and accounting practices, getting consistent unmanipulated data for measurements has been a major problem for MAN. With the impending start up a new company-wide system, MAN commissioned the Measurements Steering Committee (MSC) to develop standard measures. Its objectives are:

  • Establish standard CMMS cost reports for all U.S. chemical plants.
  • Consolidate MAN best practice scorecards for the purpose of measuring progress.
  • Select and define key CMMS metrics to be used and recommend targets.
  • Investigate reporting for non-CMMS and non-U.S. plants.

Effects of strategy
The most dramatic effect of MAN has been the downward trend in maintenance costs. Cost performance has closely followed the goals set forth in the three-tiered strategy and was reduced by 30 percent in two years. However, the improvements in reliability measures did not materialize as quickly as expected but their goals are still expected to be met.

Several of the activities sponsored by MAN should deliver additional benefits in 1999 and 2000. The Maintenance and Reliability Strategic Plans at each of the plants were completed in 1998 and should have a substantial impact as they are fully implemented. Most of the pump and reliability best practices have been migrated to the plants and are beginning to have an impact on performance. Plants will be implementing their TPM plans, and Reliability Engineering will be significantly upgraded in 1999.

Together these two initiatives will fundamentally change maintenance in Amoco’s chemical sector from reactive to proactive and should dramatically impact the availability ratio and OAE for Amoco Chemical’s manufacturing assets. MT


Edwin K. Jones is principal of Edwin K. Jones, P.E., Inc., 28 Quartz Mill Rd., Newark, DE 19711; (302) 234-3438; e-mail JJones1432@aol.com. Mark E. Lawrence is an internal maintenance and reliability consultant and is the coordinator for the Maintenance and Reliability Network (MRNet) at BPAmoco, WL4 Room 1794B, 200 Westlake Blvd., Houston, TX 77079-2682; (281) 560-4411; e-mail lawrenme@bp.com.

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236

1:25 am
June 2, 1999
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They Just Don't Get It… And Neither Do I

bob_baldwin

Bob Baldwin, Editor

Although conference and trade show attendance has been off recently, a couple of user group conferences in which I’ve been able to participate have bucked the trend. Perhaps it is because the condition assessment technology vendors sponsoring these particular events do such a good job facilitating the exchange of information.

I heard a number of great presentations on how organizations are leveraging various maintenance technologies. Here are two examples:

A government laboratory where operating funds are being reduced 10 percent a year over a 4-year period is using condition-based maintenance to help compensate for the loss of funding. It is an appropriate strategy for attacking maintenance costs while supporting availability of research equipment.

A processing company increased its competitive position by a proactive maintenance process that includes a precision alignment policy that specifies alignment targets and tolerances for critical machinery. After a jump in the first year when the policy was initiated, maintenance costs have declined steadily because there are fewer failures and the length of time between scheduled maintenance has increased. Meanwhile, product unit costs have declined steadily because of increased equipment capacity and availability.

However, amongst the many success stories, there was considerable conversation about the difficulty in obtaining resources for condition assessment operations, about the precipitous decline in reliability and maintenance capability in many organizations, and even about plants that are sliding back into the morass of reactive maintenance.

What is going on? While conference attendees are pushing forward with condition assessment technologies and reaping the benefits of proactive maintenance, they often receive increasing pushback from upper management. Proactive maintenance is not an extravagance. It is a value-adding function that produces plant capacity. What’s the matter with these managers? Evidently, they just don’t get it.

I always thought a responsible manager of a business should endeavor to protect the value of the company’s equipment and insure that it is available to meet market demand. It has been said that rational people consider the consequences of their actions. If so, there must be a reason why so many managers are destroying their company’s reliability and maintenance capability. What is it? Now, I don’t get it. Can anyone explain it to me? MT

rcb

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515

1:04 am
May 2, 1999
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Infrared Thermography for PPM

With increasing demand to cut costs and remain competitive, many companies are expanding their maintenance programs to include predictive and proactive technologies such as infrared thermography

Recent years have seen an increase in the acceptance and use of infrared thermography for preventive and predictive maintenance. While early applications were confined primarily to electrical and structural situations, today’s industrial environment has found new and diverse applications for thermal imaging and noncontact temperature measurement.

The introduction of focal plane array (FPA) imagers during the early 1990s revolutionized infrared imaging by providing high-resolution imaging systems while greatly reducing size and weight. Thermal imaging systems have evolved from cumbersome systems often weighing more than 20 kg (44 lbs.) to systems resembling a video camera that fit in the palm of the user’s hand.

These high-resolution infrared imaging systems allow thermography to be applied to more applications than ever before, such as with mechanical systems, intricate process equipment, and printed circuit boards. Infrared thermography can detect unseen problems such as loose or deteriorated electrical connections. Timely repair of these incipient failures can provide tremendous cost savings by avoiding unscheduled downtime.

Infrared thermography also can provide substantial savings by helping to detect problems in products or processes. Permanent improvements in such systems often offer the greatest cost benefit because the repairs are permanent and savings are realized every day that the process operates. Even greater savings are realized when the process or product output is increased.

infrared-2

Infrared thermography can be used in a wide range of applications. Thermograms show (1) a deteriorated connection within an air switch jaw, (2) wet insulation within a flat roofing system, (3) a hot spot on a steel ladle caused by deteriorated refractory, and (4) the heat pattern caused by an improperly aligned motor.

Theory
The theory of thermal imaging is simple. All objects above absolute zero (0 Kelvin) emit infrared radiation. While infrared energy is invisible to the human eye, infrared imagers detect and convert these invisible wavelengths into visible light images that are displayed on a screen. Images can be either monochrome or multicolored where the shades of gray or color represent temperature patterns across the surface of the object. These thermal images can be viewed in real time or stored on videotape, computer disk, or PC card. Thermal images then can be recorded onto photographic film or paper; the images are called thermographs or thermograms.

Thermal imaging is both noncontact and nondestructive. Since it is noncontact, it is useful for inspecting energized electrical systems as well as mechanical systems and rotating equipment. Since the infrared energy emitted from a surface is proportional to its temperature, imaging radiometers are capable of providing surface temperatures as well as images.

Equipment technology
Early sensor technology typically used a mechanical scanning system to focus infrared energy onto a single element detector. As a result, displayed thermal images often had poor resolution. Visible light photographs were often required in order to help identify the object of interest in a thermogram.

Early infrared sensors also required liquid nitrogen or compressed gas in order to cool the sensor. The introduction of Stirling cycle and thermoelectric coolers in the 1980s eliminated the need for user-installed cryogenic fluids and gases.

Many infrared imagers now use FPA detectors. These multi-element, solid-state detectors are arrayed together to provide a high-resolution image and eliminate the need for a mechanical scanning system within the optical path.

Detector size is often expressed in terms of the number of horizontal and vertical elements. Typically, FPA detectors have more than 70,000 elements or pixels. As a result of the large number of pixels, thermograms taken with an FPA imager often do not require a corresponding visible light control photograph to help identify the object.

There are currently two types of FPA imagers being offered: cooled and uncooled. Cooled FPAs have been commercially available since the early 1990s. These systems operate in the 3-5 micron range and generally provide excellent sensitivity.

The newest FPA imaging systems use uncooled detectors. Unlike previous infrared systems that sensed photons, these systems operate by sensing changes in electrical resistance across the detector. The microbolometers produce high-resolution images but do not require cryogenic cooling systems. Currently all microbolometers operate in the 8-12 micron range. The increased resolution found on FPA and microbolometer systems enables users to discern minute temperature variations and provides highly accurate temperature readings.

Originally designed for military and aerospace applications, early microbolometers did not provide temperature measurement. Since 1998, many manufacturers have begun to offer microbolometers that can measure temperature. Although they represent the newest detector technology, it is expected that microbolometers will gain in popularity within the next few years.

General Recommended Spectral Responses For Preventive Maintenance Applications

Application
Indoor electrical systems
Outdoor electrical systems
High-temperature targets
Highly reflective targets
Boiler/heater tubes – gas fired
Boiler/heater tubes – coal fired
Long-distance imaging
Smooth-surfaced roofs
Gravel-surfaced roofs
Glass
Plastics
2×5 microns
X

X
X
X

X
X
X

8×14 microns
X
X

 

X
X

X

Traditional, new applications
Infrared thermography can be applied anywhere the knowledge of heat patterns and associated temperatures will provide meaningful data about a process, system, or structure. Infrared thermography is useful for condition assessment, forensic investigations, and quality assurance inspections.

Using infrared thermography to detect incipient failures within electrical systems is well documented. Over the past 20 years, the inspection and subsequent repairs of electrical distribution systems have saved companies millions of dollars in avoided downtime.

Infrared thermography continues to be used successfully to inspect building envelopes and flat roofs, boilers and steam systems, underground piping systems, refractory systems, and rotating and process equipment. Results and opinions regarding thermography’s effectiveness for rotating equipment inspections have been mixed. However, recent research has found that infrared thermography can be used to accurately detect problems in belted and mechanically coupled rotating equipment.

In 1997, a cross-technologies study was conducted at Eli Lilly in Indianapolis, IN. The study results found that infrared thermography detected misalignment, over/under lubrication of bearings, and improper tension in belted systems more readily than vibration analysis. The study also found that temperature readings taken on the drive-end bell housing within 1 in. of the drive shaft closely approximate the internal winding and bearing temperatures.

For optimum results, a baseline inspection must be made upon installation or retrofit of mechanical equipment. Equipment then must be inspected periodically and results trended. Further investigation or corrective action can be undertaken when an alarm limit is reached.

From the results of the cross-technologies study, predictive maintenance procedures at Eli Lilly were modified to increase infrared thermographic inspections of rotating equipment. This change has allowed more equipment to be inspected while reducing the unit cost for each item inspected and increasing the overall effectiveness of the maintenance program.

Equipment selection
Thermal imaging systems vary greatly in their performance and capabilities. The spectral response of a system is dependent upon the type of detector and lens materials used in the construction of the system. While it is possible to buy filters and accessories, some imagers may not be suited for certain applications due to their spectral response.

Spectral response for commercial imagers generally falls into two categories: 2-5 microns (near infrared) and 8-14 microns (far infrared). Commercial infrared imagers and radiometers are not manufactured in the 5-8 micron range due to atmospheric absorption of infrared energy at these wavelengths. The accompanying table shows recommended spectral responses for general PM applications.

It is important to note that there is currently no single imager that will perform every type of infrared inspection. The selection of the imaging system is dependent upon the object being inspected. For some applications such as plastics, it may be necessary to consult with the manufacturer to determine if a particular system can achieve the desired results.

Training
Infrared imaging systems have become more sophisticated; however, they are often easier to use than older systems. Because of this, many people mistakenly believe that infrared thermography can be performed with little or no training. While infrared thermography is a science, it is also an art.

Since the greatest limiting factor in an infrared inspection is often the thermographer, proper training is critical to success. This includes knowledge of infrared theory, heat transfer principles, weather influences, and radiometer operation and limitations as well as a thorough understanding of the system being inspected.

Because of the many variables involved in procuring an accurate radiometric reading, the thermographer will have to address all variables that affect the object being inspected. Some of these variables include target emissivity, background radiation, target size, weather and atmospheric influences, spectral response of the imaging system, and specialty filters. While advances in technology continue to improve the performance and capabilities of thermal imaging systems, proper use of infrared imaging equipment requires formal training.

In-house or contract service
Whether starting or expanding an infrared predictive maintenance program, a company must decide whether to use in-house personnel or outside consultants. If frequent infrared inspections are planned and corporate management is committed to investing in proper equipment and training of personnel, using on-site employees may be appropriate.

If infrequent inspections are planned or the company cannot afford the initial investments in equipment and training, an outside consultant may be a better choice. While arguments can be made for either arrangement, properly trained and equipped personnel can help to increase the effectiveness of a PM program and a company’s bottom line. MT


Craig K. Kelch and R. James Seffrin are president and staff engineer, respectively, with the Infraspection Institute, 3240 Shelburne Rd., Suite C, Shelburne, VT 05482; (802) 985-2500; Internet www.infraspection.com Continue Reading →

265

12:56 am
May 2, 1999
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Portable Infrared Imaging

An overview of cameras, the industry, technological improvements, where to use them, and suppliers.

infraredThe use of infrared thermography to evaluate the operating condition of electrical, mechanical, and process equipment for early warning signs of impending failure has increased dramatically over the past few years. The industry is forecast to continue growing at unprecedented rates, driven by:

  • Market awareness and acceptance. More information and articles are being published on this technology than every before.
  • Application diversity. Infrared thermography is used to inspect electrical and mechanical equipment, detect leaks in underground pipes, and check for subsurface metal corrosion, insulation deficiencies, building energy loss, and roof moisture intrusion. It also is used for monitoring and control of a wide range of processes. New applications are being developed continually.
  • Equipment. The equipment is compact, easy to use, provides high-quality imagery and fast analysis, and uses software that allows reports to be written easily. Prices continue to drop.
  • Standards. Standards for thermography are beginning to be developed (ASNT, ASTM, ISO), which means that it is gaining recognition and credibility. For example, in Canada, the United States, and Norway, most companies are requesting that thermographers have a Level I status to perform infrared thermography inspections.
  • Training. Training, educational programs, and seminars are now available at locations throughout the world.

The industry
Market evaluation companies such as Frost & Sullivan, Maxtech International, and Thomas Marketing Information Centre have prepared market studies and surveys that look at infrared thermography. The results are similar and show that infrared thermography is an emerging technology that is coming into its own. According to strategic research conducted by Frost & Sullivan, the total market is projected to experience a compound annual growth rate of 31 percent from 1996 to 2003.

Infrared equipment manufacturers are very aware of this growth potential and are positioning themselves to achieve greater market share. Raytheon purchased Texas Instrument IR Technology Divisions, Amber Infrared, and Santa Barbara Research Center. Last year FLIR Systems Inc. acquired Agema Infrared Systems. Most recently, FSI announced the purchase of Inframetrics, Inc., a privately owned infrared imaging company based in Billerica, MA.

Technology advances
Infrared camera technology has advanced significantly since the early 1960s when the Swedish company AGA introduced the first commercially available infrared imaging instrument. Early instruments were heavy and bulky, required liquid nitrogen to operate, provided black and white fuzzy images, and offered only relative temperature measurement that required the use of long and complex formulae. Infrared imagers fall into three categories. Electromechanically Scanned instruments collect and direct the incoming infrared radiation onto a single detector element, or linear array, by means of rotating or oscillating prisms or mirrors. The Pyroelectric Videcon imager uses a pyroelectric surface detector, which after being aimed at the target, develops a charge distribution that is proportional to the target’s radiant energy. The infrared focal plane array (FPA) camera makes use of a high-density mosaic of small detector elements, which are aimed at the target. Each element sees a single infrared pixel of the target, and no mechanically scanned optics are required. The size of the array ranges from a matrix of 128 horizontal elements x 128 vertical elements to one that contains 512 x 512 elements. These instruments are classified as staring systems in contrast to opto-mechanical scanning infrared devices.

The greatest single benefit of an FPA is its ability to generate high-quality images. In mechanically scanned single-element detectors, 14,000 to 26,000 picture elements make up the field of view. An FPA covering the same field of view will comprise 65,000 to 262,000 pixels. This means the FPA will have 3-10 times more image detail. An image with higher resolution allows problems to be identified without the camera operator having to change lenses, enhances analysis procedures, and provides an image that is easier to read and understand.

The FPA detector may be a significant breakthrough in technology but without advancements in the optics, electronics, and microprocessor technologies it would not have been possible to develop these cameras. The interaction between these components determines the diversity and quality of the instruments available today.

Clearly, uncooled infrared FPAs represent a revolution in infrared instrumentation. It is expected that the technology will continue to develop, particularly in the area of improved detector performance and reduced noise equivalent temperature difference and electronics.

As costs continue to decrease and production volumes rise, the price of solid state uncooled, lightweight systems should drop significantly. Expect to see larger arrays (640 x 480) and smaller, lightweight instruments using less power.

There is a movement now into a new semiconductor-based FPA detector technology, Quantum Well Infrared Photodetector. The interest in this technology is that it promises major advances for infrared focal plane arrays. It:

  • Provides excellent pixel uniformity, imaging, and sensitivity performance.
  • Offers large pixel format capability, up to 640 x 480.
  • Is tunable and can be made responsive from about 3 to 25 microns, for broad band and dual band applications.
  • Can be produced at relatively low cost and in large quantities.

The simplicity, flexibility, high performance, and low cost will guarantee the development of this technology.

Camera EvaluationOnce the plant’s requirements are understood, a plan established, applications identified, and a training course completed, then consider purchasing equipment. Do not purchase a camera and then try to work out what to do with it. That approach has caused many programs to fail. These points should be considered when choosing an instrument:

  • Portability
  • Rugged, compact design
  • Weight
  • Temperature range (both measurement and operating range)
  • Image resolution
  • Accurate, repeatable temperature measurements, under your specific conditions
  • Lenses (Will you require additional lenses for close-up or long-distance inspections?)
  • Viewer (Is the eyepiece adequate or is a viewer required for certain applications?)
  • Image storage and retrieval capabilities
  • Camera and peripheral accessories
  • Image analysis and report software (simple to use, exportable to other programs, etc.)
  • Warranty
  • Service, service, service (Get references, find out how long it takes to have equipment repairs, will a loaner instrument be provided?)
  • Technical support (Phone their technical support line with some questions and see how efficient, knowledgeable, and friendly they are.)
  • Training
  • Price (This is the last thing to consider. Do not buy on price; you will regret it. Purchase the instrument that works for your program.)

Establishing a program
In order to profit from the benefits of infrared thermography, regardless of the technology chosen, a company must give much consideration to establishing an infrared inspection program. One that is properly initiated is guaranteed to provide users with a quick return on investment. Typically this will occur within 3 months of purchasing and using the equipment, but many companies claim receiving a payback the very first day on which they performed an infrared inspection.

The first step in setting up a successful thermography program is education. Find out about the products and technology that are available and how they can be used:

  • Go to introductory seminars and conferences.
  • Request product data sheets and application literature from equipment vendors (see the accompanying chart).
  • Browse the Internet. This is a little time consuming, but there is a wealth of information on the Web.
  • Contact specialist groups and associations. They publish newsletters regularly and sponsor conferences and meetings each year.
  • Contract an independent consultant to assist in the assessment and education process.
  • Hire an experienced infrared service company and learn from their employees while they are performing an inspection in the field.
  • Take a training course before you purchase your instrument. This will provide you with an understanding of the infrared industry and technology, equipment, and application knowledge, and allow you to gain valuable experience from the instructors and other students. You will then be prepared to deal with and negotiate efficiently with the instrument sales representatives.

Selecting a camera
Although the methodology used to implement and purchase equipment, and the program requirements, vary from plant to plant or from person to person, the following observations should be helpful.

  • Select an instrument that will make inspections successful now and in the future. An infrared camera is a diverse tool. When deciding on a particular type, also take into account your future requirements.
  • Plan the implementation phase carefully. Decisions on how to collect and manage data should be made at the outset, and should focus on the desired output of the program. This planning will both simplify implementation and maximize the value of the program.
  • Provide good training for the personnel involved. Set aside sufficient time for the equipment operators to become proficient at their jobs. Strive for continual improvement and remember that each challenge that is successfully completed is followed by additional new and exciting opportunities. MT

Ron Newport is president of the Academy of Infrared Thermography, 177 Telegraph Rd., Suite 720, Bellingham, WA 98226; (360) 676-1915; e-mail airt@infraredtraining.net; Internet www.infraredtraining.net

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