Archive | June, 2001

238

9:07 pm
June 1, 2001
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Infrared Thermography – How to Get Started

Determine what features are desirable, according to the results you want.

If you are not familiar with infrared thermography and thermal imaging, you may wonder what a thermal image looks like. A thermal image is a black-and-white picture. On a relative scale, it will show hot objects as white and cold objects as black. Temperatures in between are depicted as shades of gray. Some thermal imaging cameras display the images in color that is artificially generated by the cameraís video enhancement electronics, based on the thermal patterns seen by the camera.

Several types of infrared sensors are used in thermal imaging cameras today, known as BST and microbolometer focal plane arrays.

BST (barium strontium titanate) is a type of sensor developed by Raytheon Corp. Ceramic-like thermal-energy-sensing material is used to manufacture BST focal plane arrays, which measure heat by storing it as a fixed value (similar to a capacitor) at each pixel. When the grid of pixels, or focal plane array, is monitored simultaneously, a thermal image is generated. Because of their fixed-image properties, BST pixels must be refreshed regularly to maintain the perception of real-time imaging.

A microbolometer is the newest type of thermal imaging focal plane array. Its materials measure heat by changing resistance at each pixel. The most common microbolometer material is vanadium oxide (VOx). Amorphous silicon is a relatively new microbolometer material. There are several manufacturers of this type of infrared sensor.

Match camera to needs
In today’s maintenance environment, you will find a need for various levels of thermal imaging capabilities. Several thermal imaging camera manufacturers have taken this into consideration and have developed cameras that fit the bill. Prices for cameras and basic accessories start around $13,000 and expand as various features are added, to more than $75,000.

A practical type of thermal imager should match the needs of the user. The more sophisticated imagers have features which may include temperature and analytical analysis. These features may be necessary in some applications because of the level of analysis that is needed.

To determine the type of thermal imager you need, list the jobs you want your camera to handle, then find the features that meet your needs. You may be surprised to learn that the best thermal imager for your applications comes at a comparably modest cost.

Documenting your findings is an important part of your facility health care records. This can be done in many ways depending on what kind of thermal imaging camera you choose. Thermal images can be saved on a PCMCIA card, 3 in. floppy disk, videotape, and, in some cases, a memory stick. You also may find that recording is not necessary if you are using the thermal imager as a verification tool after a new installation has occurred or after repairs have been made.

Reporting software can enhance the results of thermal imaging. This software offers many features, including colorization of a black-and-white image, temperature measurement, filtering, averaging, isotherm highlighting, and custom report generation.

Many lower-priced thermal imaging cameras that do not have some of the attributes the higher-priced imagers offer can provide the majority of the features through software. Every year management looks at more ways to keep spending to a minimum. It all comes down to the level of sophistication your facility maintenance program requires, what your needs are, and how you choose to accomplish your maintenance goals.

Training is vital
When structuring your facility maintenance program, donít forget training. More and more companies require continuing education and mandate a specific number of hours of training time per year. As budgets are cut for travel and expenses, it becomes harder to fulfill the training time. With many nondestructive testing techniques, training on the equipment and technology is critical so results are accurate and useful.

It is important that users of thermal imaging cameras have training in thermal imaging. Costly mistakes can occur if users are not trained to interpret their findings properly. Is there wet insulation? Is it reflection? Is it the wrong time of day for the inspection? Not enough load? Good trainers in infrared will provide training on imager use, interpretation of images, and include a section on safety while conducting infrared inspections. There are many hazardous environments as well as unknowns in the facility you are inspecting. Remember to make safety a factor as well.

Training is important, regardless of the difficulty of the application. You can choose from several experienced infrared trainers. They usually conduct a one-week training course in several locations throughout the United States. If you require an in-house training class for a group of individuals, they can tailor a class specific to your needs.

If you are about to purchase one or more thermal imaging cameras, you will need to make a number of decisions about equipment and training. Remember, as with any other tool or instrument, you first need to determine what features are desirable, according to the results you want from the tool. Then you can evaluate the offered features in a more objective way and eliminate those that would bring little or no benefit to your program.

Thermal imaging cameras will continue to play an increasing role in businesses and communities. They save money and time, and contribute greatly to safer and healthier working environments, even saving lives. MT


Rebecca Whitworth is product specialist, industrial thermal imaging cameras, at Mine Safety Appliances Co. (MSA), P. O. Box 426, Pittsburgh, PA 15230; (412) 967-3103

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221

3:27 pm
June 1, 2001
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No Pain, No Gain

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Robert C. Baldwin, CMRP, Editor

Yesterday, I paid more than $2 a gallon for regular gasoline in Chicago. Each time I fill up, I see motorists muttering under their breaths. If you listen closely, you hear words such as “oil company greed,” “environmentalists,” “President Bush,” and “energy crisis” sprinkled among the expletives.

Conversation at a neighborhood social can easily move from the price of gas, to rolling blackouts, to energy crisis, to energy conservation, with all the “depth” of understanding that goes with such discussion. I’ve also noticed an increase in the number of press releases with energy conservation themes in our mail.

With all the talk, the articles, and the news stories, the conservation idea has likely reached the executive suite where it may ricochet back down the chain of command as an order to do our part by conserving energy.

Energy shortages and high prices are emotional issues, prone to emotional rather than rational responses. First of all, the current energy situation is not a crisis when compared with the shortages of the 1970s. Where are the lines at the gas pump? Prices are indeed high, but not so high as in other countries. We gripe, but we continue to buy our SUVs and light trucks.

Yes, heating bills were very high this winter, and cooling bills may be even higher this summer. It is the economic principle of supply and demand at work. We gripe, but we continue to leave the thermostats set at the comfort levels to which we have become accustomed. (Speaking of comfort levels, I have never been so chilled as in a meeting room in the South during summer, nor as uncomfortably hot as in a meeting room in the North during winter.)

At the plant, we grip about the stupid “turn out the lights” conservation promotion, but we continue to run leaky unregulated compressed air systems, steam systems with faulty insulation and traps, and electrical systems powering old motors driving throttled systems.

Conservation is patriotic, but waste and poor management of productive resources is just plain dumb.

Why don’t we start managing our energy systems like rational managers, engineers, technicians, and operators? Perhaps it is because of another basic principle of free markets–rational people think at the margin, that is, they take action when they believe the marginal benefit of the action will exceed the marginal cost. Perhaps the price is not high enough to make us change our behavior.

Although “no pain, no gain” may be the operative phrase, the rational asset manager will start managing energy now so that economic discomfort never reaches the threshold of corporate pain. MT

rcb

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372

3:19 pm
June 1, 2001
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Why PM Programs Do Not Significantly Reduce Reactive Maintenance

Your company probably has an extensive preventive maintenance (PM) program in place. In spite of all the PMs, you are still finding that well over 50 percent of your maintenance work is reactive maintenance. Sound familiar?

This is a very common problem. There are many companies that have extensive PM programs but are finding that they are not making significant headway in reducing the number of breakdowns. I have personally worked in a company that did a lot of PMs, but 75 percent of its work was reactive. In my latest roleÝ in consulting I have seen that most companies today are experiencing this same problem. On average between 50-60 percent of total maintenance work is reactive.

Before proceeding let me first define what I mean by PM programs. PMs are time-based overhauls on assets. They are jobs that are scheduled at regular intervals either based on calendars–replace filters every 6 months, or based on readings–change filters every 5,000 operating hours.

Companies have invested millions of dollars over the years to develop, implement, and sustain their PM programs. Why then, do so many companies that have comprehensive PM programs still find that 50 to 60 percent of their maintenance work is corrective or reactive maintenance? Isn’t the purpose of the PM program to keep the equipment in proper working order to ensure that failures don’t happen?

Before answering these questions, I would like to review the history of maintenance to see what led companies to utilize PMs in the first place.

The first generation of maintenance viewed equipment failures as fitting one pattern. As equipment got older it deteriorated and eventually failed. At this time most companies just ran equipment to failure. However, some companies started to recognize that ancillary damage caused by running equipment to failure was expensive. Since it was thought that all equipment deteriorated at a fixed rate over time, they tried to determine when it was likely to fail and schedule an overhaul to restore the equipment andÝ avoid the failure and ancillary damage. This was the birth of PM.

During the second generation of maintenance, most companies started embracing PM

We are now in the third generation of maintenance. We know that there are actually six different equipment failure patterns. Three are age related, but the other three follow random failure patterns, with no relationship to age. Research has shown that less than 20 percent of equipment follows age-related failure patterns; the other 80 percent are random.

Now let’s get back to the original question. Why don’t PMs significantly reduce the amount of reactive maintenance being performed in your plant? The answer is simple. PMs were designed around the theory that equipment failures are directly related to the age of the equipment. Since only 20 percent of equipment failures fit this pattern that means that 80 percent of equipment failures are not being effectively managed by doing time-based PMs.

What’s the answer? The key to significantly reducing equipment failures is to monitor the condition of your equipment. Random failures do not adhere to any specific pattern and therefore the only way to effectively manage these types of failures is to closely monitor the key indicators-vibration, hot spots, leaks, cracks, etc. New technologies such as predictive maintenance devices combined with advanced methodologies such as reliability-centered maintenance (RCM) are now making it possible to easily determine what indicators need to be monitored and how to monitor them.

Remember the company I said I worked for that was doing 75 percent reactive maintenance work? Well we implemented a comprehensive condition based maintenance program combined with RCM and that company is now experiencing only 20 percent reactive maintenance with a goal to get to 10 percent. So now that you know why your PM program isn’t working the way you hoped it would, it is time to do something about it. The tools and technologies are there. I strongly urge you to take the plunge. The payoff will be tremendous. MT
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