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Accumulation of dust and dirt on all rotor blades leads to a 1x vibration peak in the velocity spectrum. The sine waveform and phase analysis confirmed the results. A static unbalance was the reason for the increased vibration.
The balancing procedure was successfully performed on-site during the next shutdown phase of the plant. VIBXPERT II and OMNITREND® software were used for the balancing runs. The static unbalance requires only a one-plane balancing procedure which was ideal for those fans. The accelerometers were attached to the non-drive end (NDE) bearing in the horizontal direction. VIBXPERT offers a “second plane control feature” where the second accelerometer controls any negative influence on the NDE bearing during trim runs. This ensures that the vibration on both bearings will be equally reduced and balanced. The target quality grade of 6.3 according to DIN ISO 1940 was easily reached.
The plant went back online a few days later and the customer was extremely satisfied with the result of this service, he later stated:

“In the last 6 years, I have never seen those fans run so smooth.”

Special thanks to PRUEFTECHNIK Canada for sharing this success story with us.

At Fleming Enterprises we service the needs of the printing industry: printing press line installations, repairs and revisions. A typical sixteen-color line (eight perfecting units) and associated equipment can run over 150′ long and require section to section alignment not to exceed .003″ in any plane. About 15 years ago, we rented a ROTALIGN® system for testing purposes to compare our conventional installation techniques side by side with the laser alignment system. Immediately and with minimal familiarization, our installation labor was reduced by 50% (substantial savings, as the crew rate can exceed $300.00/hr plus material handling equipment) from 14 days using the “conventional method” down to 7 days using the ROTALIGN while at the same time dramatically increasing alignment accuracy. In addition to this benefit, we discovered that various anomalies and lineshaft wear could be detected, that we could do uncoupled sectional alignments with great accuracy up to 10 meters point separation and correct for thermal growth. If it’s shafted, ROTALIGN can align it faster, more accurately and with relative ease. Since then, we have successfully align many presses with our own ROTALIGN alignment tool.
As a maintenance services vendor, I recommend LUDECA highly. The knowledge, skills, integrity and customer support LUDECA continually provides us is of the first rank.” —Jeff Fleming, Fleming Enterprises

PUMPS & SYSTEMS • May 2012

“If you can find a path with no obstacles, it probably doesn’t lead anywhere.” ?— Frank A. Clark

“So easy that even a caveman can do it, ” as stated in a popular TV commercial, could easily be used to describe today’s predictive maintenance tools because they work so well. However, to be truly competitive, a company’s goals should go further than being satisfied with marginal improvements in machine reliability.
Achieving equipment reliability that is required for maximum profits is both realistic and obtainable for any company. Proper use of predictive maintenance (PdM) tools is a key factor in realizing such goals. This article provides solutions to overcoming obstacles and issues associated with monitoring machinery and using predictive maintenance tools—such as precision shaft alignment and vibration instruments.

Read my entire article Overcome the Obstacles to Successful Predictive Maintenance

Background
The practice of dowel pinning machinery was originally conceived within the U.S. Navy, well over a century ago.

This innovation was triggered by the need for a solution to the extreme conditions faced onboard naval surface vessels and submarines by directly-coupled rotating machinery with respect to hull and foundation deflection related to changing temperatures and storms at sea, as well as the forces generated by firing munitions (shells and depth charges.) The original concern that resulted in the use of dowel pins was positional security.

Given the fact that on Navy and commercial vessels excess mass is a major concern, the sound engineering practice of designing a base structure to weigh three to five times the mass of the machinery mounted upon it is impractical, resulting in flimsier, more flexible foundations. This is the principal justification for dowel pinning machines in the Navy, and this practice became almost universally adopted.

After World War II, the vast majority of the industrial maintenance workforce in the United States that dealt with rotating machinery was comprised of men who had served in the Navy, as this was the branch of the armed services with the bulk of such machinery and maintenance need. As a result of deeply ingrained Navy tradition and training, the practice of indiscriminately dowel-pinning all rotating machinery filtered out onto dry land installations, even though in most cases there was no longer any technical justification for this practice.

Download our article “Thoughts On Dowel Pins In Machine Feet” including Positional Security: Technical Considerations, Alternative Solutions, and Positional Repeatability.

iPURCHASE, A supplement from IMPO MAGAZINE • March 2012

Companies are attempting to operate leaner and more efficiently every day, with predictive maintenance still serving as a driving force. With a variety of tools on the market, there is something for every operation, large or small.

There is so much technology available to manufacturers and distributors, it’s hard to know where to start looking, especially when it comes to industrial maintenance equipment.

Getting Started
If you’ve thought about starting up a predictive maintenance program in the past, but have shied away because of the details involved, or if you currently have a program in place and just aren’t seeing the results that you would like to see, you are not alone – this is a complex topic with constantly evolving technological solutions. And from a distributor standpoint, possessing a purchasing and sales team that truly understands the functionality and value these tools can bring to the customer is a great way to stand out from the pack. Two individuals in the predictive maintenance industry who deal specifically with vibration analysis were willing to share their scoop on the issues that they found most critical to understanding the significance of this technology.

“Predictive maintenance technologies can be applied to almost any equipment or system that has rotating, electrical or lubricated components,” notes Trent Phillips, the Condition Monitoring Manager for Florida-based LUDECA, Inc. “This includes motors, pumps, fans, gearboxes, turbines, generators, compressors, milling machines and many more. Some of the common equipment faults detected with vibration analysis are bearing defects, lubrication issues, misalignment, unbalance, gear defects, electrical problems, belt issues, resonance, looseness, foundation problems, and many more.” It looks like everybody needs predictive maintenance equipment.

Read the entire article Predictive Maintenance Technologies

Smith Pump modeled the discharge head in Solidworks. Since the measured natural frequency was 1500 CPM, and the pump operating range was 1500 to 1800 RPM, we wanted to lower the natural frequency below 1500 CPM. We knew by removing stiffeners from the discharge head we would lower the unit’s natural frequency. We removed stiffeners and ran a finite element analysis to determine how much we would lower the natural frequency. Our model study showed that by removing all the external stiffeners and half of all the internal stiffeners we would lower the natural frequency by 30%. Pump #2 was removed and its discharge head was modified by removing stiffeners.

Pump #2 was put back into service with its modified discharge head and vibration testing was performed. The new bump test data gave a measurement of 86 CPM in line with discharge. The vibration measured at 50 HZ at the top of the motor was 0.05 in/sec RMS. The vibration dropped from 0.47 to 0.05 in/sec RMS.
In conclusion, determining a unit’s natural frequency is very important when designing a vertical turbine pump. Every fabricated steel discharge head that Smith Pump makes is modeled in Solidworks and goes through a finite element analysis to make sure the unit’s natural frequency (mainly discharge head and vertical motor) is 25% away from any running speeds.  In this example, the discharge head (built by others) was too stiff and had a natural frequency at the pump operating speed causing high vibration.  Since Pump #2 was so successful, we are currently modifying Pumps #1 and #3 the same way. Common sense tells us that the stiffer and stronger the discharge head the better, but this case study clearly shows us that is not the case!

Special thanks to our customer Josh Jurgensen, service engineer at Smith Pump Company for sharing this case study with us!

PLANT ENGINEERING • March 2012

Don’t contribute to unnecessary maintenance costs

A condition monitoring analyst encounters many challenges. One of the primary ones is to determine when to report a defect finding. Should it be reported now or should reporting wait until the severity of the defect increases? How near is the problem that has been found to actual failure? Each of these questions is difficult to answer.
A good analyst can use the condition monitoring data that has been collected to determine the severity of the problem found. However, it is impossible to determine the time of day the identified component will actually fail.
What happens if the replacement component (bearing, etc.) requires a very long lead time to obtain? What happens if a crane has to be scheduled to remove the equipment for repair? What happens if contractors have to be scheduled to support the repair effort? What if an outage is scheduled soon and the analyst waits until afterward to report the problem?

Read my entire article For A Condition Monitoring Analyst, It’s Just The Facts 

MAINTENANCE TECHNOLOGY • February 2012

So many machines. So little time. What’s the best approach?
Vibration analysts are often faced with scores—perhaps hundreds—of machines, many of which exhibit vibration frequencies that are very hard (if not impossible) to identify. Some machines can absorb countless hours of an analyst’s time before he/she can confidently identify all the discernible peaks in their FFT signatures. The danger is that an analyst could waste precious analyzing time trying to identify the source of a vibration that will never cause a problem, and possibly miss the rise of another, more lethal vibration. What does an efficient analyst do?

Read my entire article “The Efficient Vibration Analyst”.

Dial indicators are ubiquitous in shaft alignment; they have been used (and misused) extensively for alignment throughout the industry for many years. In the right hands, a very accurate alignment can be performed with dial indicators. However, even under the best of circumstances, it will be a time-consuming task with many traps and pitfalls for the unwary or the untrained.

Using dial indicators properly for shaft alignment is almost an art form. One key consideration is the measurement setup. What method should be used? The Rim & Face Method? Rim & Reverse Face Method? Reverse Indicator Method? Rim & Two-Face? The Face-Face Distance? Each setup may be appropriate for one situation but not for another. Extensive training is required to make this decision correctly. In addition, some proficiency with algebra and geometry will inevitably be required to make sense of the readings taken and calculate corrective moves for the machines.

Once the proper method has been chosen, initial setup preparations require the millwright to check for sag. Sag (also called bar sag) is the result of gravity acting on the overhung hardware spanning across the coupling that holds the indicator(s). It is always present, and its magnitude and repeatability must be accurately measured and known for the millwright to have any hope of measuring the misalignment accurately.
The effect of bar sag is doubled: When initially zeroed at the top, this radial (rim) indicator is already sagging; when it is rotated 180 degrees, it now sags in the opposite direction, doubling the travel of the indicator.

Over longer spans (such as with spool piece couplings or jackshafts), sag can quickly become unmanageable, forcing the use of alternative compound setup methods. Sag will also affect a face (axial) indicator but to a lesser extent. When bar sag is ignored, the impact on the readings can be very significant, rendering the data obtained misleading, or at worst useless.

Besides sag, field conditions may conspire to bedevil the results. Consider the following:

Vibration and Dial Indicator:

Surrounding running machines may cause vibration to enter the machines you are aligning, making the indicators vibrate as well. Because of the overhung installation of the indicator and its supporting hardware, this vibration tends to be greatly amplified at the indicator itself, to the point where it becomes difficult to read accurately, or even impossible to read at all.

Tilted Dial Indicator:

Space constraints may force you to install the indicator at an angle to the reference surface being measured. This tilting will lead to a significant error in the readings as the movement being measured results in a significantly reduced travel of the indicator stem. The only way in which the travel of the indicator stem can accurately reflect the movement being observed is for it to be mounted perpendicular to the direction of the movement being measured.

Parallax Effect and Reading Error:

If space constraints do not allow you to view the face of your dial indicator squarely, you may misread the indicator by several thousandths of an inch. Also, if the travel of the indicator stem is not observed all the way around, a huge reading error may occur if the needle reversed direction during rotation and the millwright did not notice this. The consequences of such a mistake might be recording a reading as +40 mils when in fact it should be –60 mils! A similar error can occur when reading an indicator with a mirror in order to be able to see it at locations that are inaccessible to the naked eye, or from not noticing that the indicator stem is no longer contacting the reference surface.

Dial Indicator Resolution:

Another concern is the measurement resolution of the dial indicator. If a delicate measurement task is undertaken, such as measuring the effect of machine frame distortion by observing the angular changes at the coupling, it must be remembered that these effects dwindle through mechanical looseness and the fact that the shaft is midway between the feet laterally; thus, when one machine foot is loosened, the effect on the shaft is halved. This, coupled with an insufficient measurement resolution of the indicator may render the reading inadequate to perform a meaningful diagnosis of the distortion condition.

Dial Indicator Hysteresis:

Hysteresis of the indicator may also conspire to reduce the accuracy of your readings. Hysteresis is the friction of the internal moving parts of the indicator mechanism. The best dial indicators use precious jewels in their movements (like fine watches) to keep them from “sticking”. This makes them delicate instruments that must be handled with great care. Dropping a dial indicator or subjecting it to extremes of heat, cold or humidity may exacerbate hysteresis conditions to the point that the indicator becomes inaccurate or inoperative.

End Float (Axial Play):

End float, or shaft end play, can bedevil a face indicator. This is particularly true on machines with journal bearings or sleeve bearings that permit a certain amount of axial play to occur in the shaft as it is rotated. This will play havoc with the accuracy of a face (or axially mounted) indicator. It can only be overcome by rotating the shafts while applying significant thrust load (which is often impracticable) or by means of the Rim & Two-Face Method, whereby two face indicators are mounted on the same setup 180 degrees opposed from one another. When the shafts are turned, end float will affect both face indicators equally and therefore only the difference in their readings is observed, arriving thereby at the true gap difference between them. However, a great disadvantage of this method lies in the fact that an extra indicator is now required to be mounted, which in turn requires full rotational clearance all the way around; in addition, the extra indicator significantly increases the bar sag of the entire setup.

Obstructions to Rotation, Measurement Range, Algebra, and Geometry:

The millwright using dial indicators must be proficient in geometry to understand the meaning of the readings he is obtaining; then, he must also be proficient in algebra to perform the necessary rise over run calculations needed to obtain the corrective moves for the alignment. One alternative is a full rotation of the shafts when obstructions to rotation exist is to rotate the shafts only 180 degrees and extrapolate the fourth (or missing) reading through the mathematical circular validity rule. This requires some mathematical skills of the technician in the field. Moreover, the nature of misalignment is such that an elliptical math model is more accurate than a circular one; however, neither the resolution of the dial indicators nor the math skills of the technicians in the field are equal to the task of applying these models in the calculation of results.

When radial obstructions to rotation exist that do not allow for even a half rotation of the shafts, very few millwrights have the necessary mathematics skills to compute the misalignment conditions and corrections from shaft rotations of less than 180 degrees. Moreover, if misalignment causes the indicator stem to run out of range, it must be repositioned for a fresh range, adding complexity to the calculations, since segments of readings must be “spliced” together. If an indicator bottoms out the entire reading process must be begun again since the initial starting reference position of the indicator has been compromised.

All of this tells us that performing competent shaft alignment with dial indicators is a painstaking and time-consuming task. As we have seen, there are numerous potential pitfalls and conditions that make extensive training and experience a necessity in achieving good results with dial indicators, and an unavoidable expense in downtime in getting the job “done right the first time.”

Is there a better (and faster!) alternative to using dial indicators?
Of course, there is! Laser Shaft Alignment

The best alternative to using dial indicators for shaft alignment is to use a good laser alignment system such as the ROTALIGN® ULTRA or OPTALIGN® SMART. All the inherent problems and disadvantages of dial indicators are immediately eliminated. Here’s why:

• Training: Far less training and expertise is required of the millwright to use a laser system proficiently than to use indicators. No algebra or geometry skills are required for the technician to perform excellent alignments since the system performs all necessary calculations automatically. The entire setup, measurement, and correction process can be accomplished in less than half the time required with indicators. This saves downtime and saves money!
• No-Sag: The bracketing and components of the ROTALIGN and OPTALIGN laser systems are carefully designed to have their center of gravity directly between the support posts that hold them. The laser beam itself is weightless and thus no-sag exists with these laser systems. This saves setup time since sag does not have to be measured nor accounted for.
• No effect from End Float: The optical measurement principles used by the ROTALIGN systems render them entirely impervious to the effects of shaft end float, since the axial distance between sensor planes in the receiver is fixed. In the OPTALIGN system end float has no effect on angularity whatsoever due to the optical principles of a roof prism; the effect on the offset is negligible because even at the worst angles typically existent between misaligned machines the impact on the projected offset from the axial play is less than the measurement tolerance, whereas a face indicator is impacted directly by end float by the full magnitude of the axial displacement.
• Vibration mitigation: Even the most severe vibration from surrounding machines presents no problem for three reasons: First, the components are not overhung and therefore do not amplify the vibration. Thus the vibration of the components cannot exceed the amplitude of the vibration itself at the points on the machines where they are mounted. Secondly, the averaging of the readings can be adjusted so that the effect of any vibration on the laser beam is totally negated. Thirdly, the artificial intelligence that is programmed into the firmware of the system fires the laser beam at random intervals so that its pulse rate can never be in phase with any vibration. Thus all of the conditions that can render a dial indicator useless in these circumstances are eliminated.
• No Reading Errors or Parallax Effects: None of these potentially great human errors is possible with the ROTALIGN or OPTALIGN laser systems because all data collection is fully automated.
• No Tilting Error: As long as the laser system components can be securely mounted on the shafts or solid coupling hubs, no error can occur since the only movement registered is that of the beam across the sensor caused by misalignment of the shafts as they are turned. This is true even if the laser, prism, or receiver components are mounted cocked, or tilted with respect to each other!
• No Hysteresis Problem: No hysteresis errors can occur because there are no moving parts in the laser system components that can be affected by environmental conditions or rough handling. In fact, ROTALIGN and OPTALIGN systems are waterproof, shockproof, and dustproof. They can therefore withstand the rigors of use in an industrial environment far better than a delicate dial indicator.
• Measurement Resolution and Obstructions to Rotation: ROTALIGN and OPTALIGN have a measurement resolution of just 1 micron (0.00004″). This together with sophisticated artificial intelligence-based elliptical math models programmed in the firmware means highly accurate shaft alignment results can be obtained with only 70 degrees of shaft rotation, starting anywhere and stopping anywhere. ROTALIGN and OPTALIGN are totally independent of the clock positions that must be arrived at when measuring with indicators. Thus, obstructions to rotation are no longer a problem. The systems’ high resolution also means they are ideally suited to the task of measuring machine frame distortion at the coupling, sparing the millwright the problems and inaccuracies associated with mounting indicators at the machine feet for soft foot measurement. This too saves time and money.

Yes, pipe strain is soft foot!

Soft foot means machine frame distortion. If you are missing shims under a foot and tighten the hold-down bolt until you have forced the foot down to the base, you will have distorted the machine frame. If you have severe pipe stress on a pump, and the anchor bolts are tight, chances are great you are also distorting the pump casing.

Consider that if the pump’s anchor bolts were completely loosened or removed, the pump might be hanging in the air from the piping. So if you were now to tighten the anchor bolts, you would be forcing the pump down to the base and distorting it, just as happens when you are missing shims under a foot.

Shimming the feet will rarely solve the problem completely; rather, the correct solution is to eliminate the undesirable pipe stress. “Stress” is the force acting on something, while “strain” is the deflection or distortion resulting from the stress. A soft foot condition means you have machine frame strain, and pipe stress is just one of several examples of this. When the machine casing is distorted, the internal alignment between the bearings is changed and the shaft is deflected. This produces enormous stress on the bearings and increased vibration in your machines, resulting in premature wear and tear as well as loss of efficiency. Your seals and bearings will fail much faster. If a significant soft foot condition exists, a good alignment of the centerlines of the shaft rotation is almost pointless. The machines will still fail more quickly and lose efficiency. How do we diagnose and fix this?

The trick lies in knowing how to recognize that a pipe strain problem exists. The behavior of a machine with pipe strain differs significantly from one whose soft foot condition is caused by one of the more traditional shimming problems or unevenness of the base or feet. Fortunately, there is an easy measurement solution: The Pipe Strain Wizard in the OPTALIGN® SMART. The Pipe Strain Wizard will guide you through all of the necessary steps to quickly and easily ascertain whether a pipe strain problem exists and measure its precise impact on the shaft alignment.

Essentially the process involves taking an initial reference reading of the shaft alignment condition. Thereafter the piping is completely loosened and a second reference reading is taken. The wizard then calculates the difference and yields the results.

These results can be documented in a full-color Pipe Strain report printed directly from the OPTALIGN SMART to a USB memory stick as a PDF file.

Any impact on the alignment of more than about 2 mils indicates a pipe strain problem that should be dealt with. Correcting pipe strain is a task for an experienced pipefitter who must see to it that connecting and torquing the piping should not move the machine from its rough aligned condition, nor distort its casing in any way. Proper pipe hanging techniques and a good knowledge of calculating and designing “Dutchman” spacers are essential.

Being bolt-bound means you have to move the machine sideways to get it aligned and you can’t: you’ve run out of room. The anchor bolt is up against the side of the hole in the foot.
Being base-bound means you need to bring the machine down to get it aligned, but you can’t: the machine feet are down against the base and there are no more shims left to remove from under them.

Are you in a quandary with either of these situations? No problem! You have five possible solutions:

• Open up the holes in the feet.
• Turn down the anchor bolts.
• Redrill and tap new holes in the base.
• Make an “Optimal Move”.
• Make a “Rolling Move”.

Let’s take the last one first. Making a rolling move of a bolt-bound machine simply means shimming up one side of the machine but not the other (or lowering one side but not the other.) This displaces the horizontal centerline of rotation of the shaft. But this is a big no-no! Do not do this! It will create angled soft feet and distort the machine frame when you tighten them because the feet are no longer evenly supported. Moreover, with gearboxes, you may change the gear mesh pattern and destroy the machine. Many machines must be carefully leveled in addition to being aligned, so rolling moves are out!

Download entire article including making an “Optimal Move” with ROTALIGN ULTRA.

RELIABLE PLANT • February 2012

Orbits have historically been used to measure relative shaft movement within a journal-type bearing. The shape of the orbit told the analyst how the shaft was behaving within the bearing as well as the probable cause of the movement. This was accomplished using proximity probes usually mounted through the bearings with a 90-degree separation and a tip clearance set to around 0.050 inches. With today’s modern analyzers, it is possible to also collect an orbit using case-mounted velocity probes or accelerometers to see how the machine housing is moving. Another way of putting it would be the orbit represents the absolute path in space that the machine housing moves through (see Figure 1).

Read my entire article “Using Orbits for Condition Monitoring”.

PLANT SERVICES • January 2012

Vibration analysis and condition monitoring are part of a bigger picture.

Reducing maintenance cost, reducing production cost, improving uptime, reducing risk, improving safety, and improving product quality are some of the essential drivers for deploying vibration analysis and other predictive maintenance tools. They should be the goals of any plant or corporation.

Vibration analysis and condition monitoring (CM) are important ingredients in all of these goals. Vibration analysis, if applied correctly, can provide identification of specific problems that routinely prevent these goals from being achieved. Furthermore, vibration analysis can be used as part of root cause analysis efforts within a facility. It is very important to identify what is causing specific problems to routinely occur and eliminate those causes.

Many considerations should be taken before and during the implementation of a vibration analysis program or any other CM technology. Some of them are commonly overlooked, but the best way to avoid obstacles that limit the success of vibration analysis and predictive maintenance programs is to take these 11 steps. Read my entire article “11 steps to ensure PdM success”.

ENERGY-TECH • January 2012
At a power generating station in Florida, a severe electrical fault caused such extensive damage to a 40 MW gas turbine-driven generator that a complete replacement of the generator stator was required. An on-site spare generator core was available but needed the faulted generator’s bearing support brackets to be installed to make it complete. As this combination of bearing support brackets and generator frame would be considered a “mismatch”, it was decided that the position of the bearing supports should be verified to ensure proper centralization of the generator’s field (rotor) relative to the generator core.

The primary objective was to accurately determine the centerline position of the generator core and position the bearing support brackets so that an equal radial air gap between the rotor body and core laminations would be obtained during generator operation.

The exact positioning of the support brackets was accomplished using specialized tooling such as the CENTRALIGN® ULTRA laser bore measurement kit and the ROTALIGN® ULTRA laser tool from LUDECA.

Read the entire article Internal component alignment of 40 MW A.C. generator by our customer Chuck Hildebrand, Dynamic Balancing Company.

“Does misalignment waste energy?” is a question often asked. The answer, emphatically, is yes! General Motors Corporation and Ludeca performed and published a study on this issue in 1993 which showed conclusively that energy savings (Real Power savings) of 2.3 percent could be obtained on loaded machines. On unloaded machines, the savings ranged as high as 9 percent! At ICI Chemicals, a UK chemical plant in the north of England, a carefully controlled doctoral research project revealed even higher savings. Other studies suggest averaged savings of 4 to 5 percent.

In late 1993, Infraspection Institute in New Jersey demonstrated in a carefully controlled study conducted at Miller Brewing Company that misalignment generates heat and wastes energy. This was clearly demonstrated in the comparative infrared signatures obtained on the same machines when running in an aligned and misaligned condition with different types of couplings (see Figures 1 and 2.) Precise magnitudes of misalignment were very carefully set with an OPTALIGN® laser system and the results were meticulously examined with calibrated thermograms recorded for each case.

Clearly, the energy required to accommodate the increased sliding velocities from misalignment within flexible couplings must come from somewhere, and this wasted energy comes at the direct expense of the efficiency of the rotating machines. While the percentage of savings may not seem very significant, a plant that reduces energy consumption by 4 percent on an energy bill of $50,000 per month would save $24,000 in just the first year, more than enough to justify the purchase of a higher-end laser shaft alignment system.

Read the entire Shaft Alignment, Soft Foot and Energy Savings 

PLANT ENGINEERING • November 2011

Friction can cause damage, but it also can be an energy hog.
Keeping your rotating shafts in alignment is a fundamental—and often overlooked—maintenance project. Alan Luedeking, the manager of technical support for LUDECA Inc., Doral, FL, talked with Plant Engineering (PE) about some of the critical issues in shaft alignment, and how they affect safety, energy, and productivity.

Read entire interview

“If you think the cost of training is high, try calculating the cost of ignorance.”
“What if we train them and they leave?”
“What if we don’t train them and they stay?”
“Training ain’t learning.”

When we see a magician pull off his head and stick it under his arm we are amazed; but when we know how the trick is performed, it becomes unimpressive. Technologies sometimes have the same effect on us. To see someone measure vibration on a machine and then be able to state that the inner race of a bearing has a flaw can be almost as amazing as a magician’s trick. It shouldn’t be, because all the stakeholders in machine reliability should be sufficiently trained to know how these “tricks” are performed. If stakeholders understand the basics of the technologies involved in maintaining machinery, the proper maintenance strategies are more likely to be developed. Many years spent in maintenance training reveals a most important concept: Frequently trainees have expressed a desire to have their supervisors present for the training.  Unfortunately, they return to the job with high expectations of improving machine reliability only to discover that their bosses aren’t as thrilled about making the needed changes learned in the recent training. The saying, “We don’t know what we don’t know” comes to mind. Without training all the stakeholders, the full importance of what was learned by some is not understood by all. Consequently, the full value of the training goes unrealized.  It is imperative that all stakeholders know the basics of the technologies used if the strategy is to be implemented successfully.

On-the-job training is a wonderful way to learn most jobs and should be part of the training in all jobs. Today’s predictive maintenance technologies are more complex and require more precision in order to be competitive in a world where machine reliability is a must for plant success. This new precision requires more than OJT because there may be some basic knowledge that OJT doesn’t address. Sometimes OJT teaches us to take shortcuts that may, in the long run, be harmful to machine reliability. OJT alone is not usually adequate in teaching the philosophy required for successfully maintaining machinery.  Formal classroom training is the best way to learn the principles and standards required in order to keep machines running at peak performance. Proven, researched-based training provides adequate hands-on learning, as well as basic principles that apply across all technologies. These basic principles and standards embody the philosophy of successful machine management.

The author remembers teaching an electrical class where one of the participants declared, “Microfarads, picofarads… we don’t need all that theory stuff, we just need to know how to fix it.” What the student failed to realize was that “fixing it” is simply the application of theory.  The application of any technology is putting theory to use, and theory is best learned in the formal classroom.  A person with OJT can eventually learn to be an electrician on a specific job; but when that person is moved to a new location, he/she must learn the new job. Whereas, a person well-trained in theory can be a good electrician regardless of where he/she is placed, once the individual learns the locations of the equipment.

Today’s training must provide a thorough understanding of the theories of technology if we are to be successful tomorrow.  Technology has provided improved learning opportunities surpassing what was available in the past. Computers allow us to simulate scenarios that may be too expensive or time-consuming to develop with physical components. This provides us with a greater learning advantage than was available in the past. Computers also allow us to easily individualize training for our particular needs and situations.

The knowledge base in all predictive maintenance technologies grows daily along with the data we collect on our machines. We will continue to find new parameters to measure as we improve our ability to keep our machines running. We can expect this trend to continue in the future because we can foresee a day when small devices will let us collect and share data with huge, smart data banks, making use of the collective knowledge in all maintenance fields. The new tools and technologies will always require a solid basic knowledge, well-grounded in theory, learned in the classroom. Data becomes meaningless if we don’t have the knowledge to sort and interpret what is needed in order to keep our machines reliable. The knowledge base will continue to grow, so we must continue to learn.

“The only true competitive advantage is the ability to learn faster than the competition.”

UPSTREAM PUMPING SOLUTIONS • Spring 2011

Mud Pump Vibration Analysis
Online condition monitoring for hard-to-reach or hazardous places
A mud pump is a reciprocating piston/plunger device designed to circulate drilling fluid under high pressure down the drill string and back up the annulus.
Mud pumps come in a variety of sizes and configurations, but for the typical petroleum drilling rig, the triplex (three piston/plunger) mud pump is the pump of choice. Duplex mud pumps (two piston/plungers) have generally been replaced by the triplex pump, but are still common in developing countries. A later development is the hex pump with six pistons/plungers.
The normal mud pump consists of two main sub-assemblies—the fluid end and the power end. The fluid end produces the pumping process with valves, pistons, and liners. Because these components are high-wear items, modern pumps are designed to allow for quick replacement.

Vibration Reduction on a Six-Pump Rig
To reduce severe vibration caused by the pumping process, mud pumps incorporate both suction and discharge pulsation dampeners. These are connected to the inlet and outlet of the fluid end.
The number of mud pumps varies per drilling rig depending on the size of the drilling rig. The larger the rig the more mud pumps that will be needed. The mud pumps are considered vital to the operation of the drilling rig. If the mud pumps fail it affects production and can be very costly to repair due to the downtime in production.
Six mud pumps were running on a drilling ocean rig.

The Monitoring System
To avoid any failures of the pumps, an online monitoring system was selected to collect and transmit vibration data back to a software system for analysis. This online monitoring and diagnostic system can also be expanded by a series of program modules (MUXs) that are specific to the application:

• Band analysis module for the automatic evaluation of complex vibration processes in rolling element bearings, gears, or special   machines
• Cepstrum analysis
• Orbit analysis
• Data server for the automatic or event-controlled readout of data and for transferring this data to higher systems

Continue reading “Mud Pump Vibration Analysis”

PLANT SERVICES • JULY 2011

Misaligned pumps can affect energy efficiency
Align pumps with laser accuracy.
By Heinz P. Bloch, P.E., Process Machinery Consulting

In brief:

• Intern approaches pump laser alignment with laser accuracy.
• Tips to compare the energy wasted by a hot coupling to the energy loss.
• Misalignment affects bearing load and excessive bearing load causes exponential decreases in bearing life.

In the summer of 1994, Jack Lambley, an intern at Imperial Chemical Industries’ (ICI) Rocksavage site in the United Kingdom, was quantifying the effect of misaligned process pumps on power consumption. He arranged to have a surplus pump overhauled and fitted with new bearings. He then had the pump installed in a suitably instrumented closed-loop arrangement operating on the water. Prüftechnik loaned Lambley a laser-optic alignment instrument.

As an undergraduate student, Lambley had learned that misalignment affects bearing load and that excessive bearing load causes exponential decreases in bearing life. His supervisor, Steve Moore, had asked Lambley to read the engineering sections of SKF’s general catalog, which stated that a 25% increase in bearing load cut its rated life in half.

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