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2446

6:00 am
November 1, 2007
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Success in a High-Pressure Refinery Heat Exchanger Diaphragm Removal/Retrofit

Some creative thinking and willingness to take the initiative helped resolve a significant recurring reliability issue, all during a quick turnaround window.

This article describes the successful removal of a tube side cover plate diaphragm (gasket) from a high-pressure heat exchanger. The diaphragm was replaced with a metal pressure-energized seal ring. While the technology has been utilized in piping and offshore applications for several years, this retrofit was its first known application on a refinery heat exchanger of this magnitude. Modification of the cover plate to accept the pressure-energized seal ring eliminated the need to reinstall the metal diaphragm gasket, thereby saving 75% of the reassembly cost of the exchanger.

Utilized in conjunction with mechanical multi-jack bolt tensioners, this innovative retrofit has eliminated a recurring, costly problem (in both maintenance cost and loss of opportunity). This additional reliability coupled with the significant future cost savings from less downtime justified the retrofit—not including the cost savings foreseen by preventing unplanned outages from the exchanger.

It is anticipated that this modification eventually could change the way that refiners will specify how high-pressure heat exchangers in hydrocracking services are designed and constructed.

1107_refinery_fig1The problem
It is not uncommon for diaphragm plates in high-pressure heat exchangers to develop cracks in their seal welds. The diaphragm, which is generally a thin plate of alloy steel, serves as the gasket and corrosion resistant liner for the channel cover (Fig. 1). This arrangement is common for heat exchangers in hydrogen services at operating pressures above 1600 psig in our refinery’s Gas Oil Hydrotreater (GOHT) unit. We have had multiple diaphragm leaks over the past several years.

Until recently, the repair process had been the same. It entailed removing the diaphragm, machining the channel face, welding and re-machining a nickel “butter-coat” layer on to the channel face and finally welding on a new diaphragm under controlled heat. This repair would suffice for a time, until some process upset or other anomaly would create another cracking “event.”

This procedure had become the standard operation of repair and, in turn, our “insanity clause,” as we continued to perform the same repair steps repeatedly, and yet, after returning the exchanger to service, would expect a different result.

Criticality of process [1]
Hydrotreaters process feedstock for fluid catalytic cracking units (FCCU) and hydrocrackers. The economic impact of these conversion units are crucial to a refinery’s profit and loss statement as well, maybe even more so than hydrotreaters. Downtime in a hydrotreater forces refinery logistical issues such as throughput curtailments in the FCCU and hydrocracking units. Their close integration to each other (and the bottom line) emphasizes the need for unit availability. Equipment reliability is critical to success.

From a business perspective, hydrotreater units are required to meet the low sulfur fuel specifications that are now in effect. Hydrotreater units are critical to a refinery’s balance sheet. The cost associated with taking one out of service can be dwarfed when compared to the potential lost income. Hydrotreaters are often large volume units. The 3-2-1 and 2-1-1 crack spreads have been favorable for refiners in the recent years; even further elevated the last few years following both hurricanes Katrina and Rita.

Hydrotreater units are expensive to build. Their high pressure and elevated temperatures necessitate heavy wall vessels, piping and ancillary equipment. Their severe service often requires exotic metallurgy. The preferred method of fabrication is butt-welding due to material and equipment costs and to prevent possible leak locations. These constraints often minimize block valve installations between equipment and any possibility of isolating or “bypassing” equipment, without taking the complete unit down.

Hydrotreater units also are expensive to start up and shutdown. They are labor- and maintenance-equipment intensive. Large volumes of inert gas are required to cool and protect the multimillion-dollar catalyst beds and equipment. There is always some associated risk involved in starting up or shutting down a hydrotreater unit. Rapid thermal gradients can damage equipment and the repair or replacement time could be several weeks or months.

Why diaphragms crack [2, 3, 4]
Diaphragms are generally fabricated from thin stainless steel (SS) sheets (0.100”-0.125”) such as 304 or 304L. Diaphragms are GTAW fillet welded to exchanger channels in a lap-joint configuration along the edge of the diaphragm plate. This joint configuration has limited transverse strength due to the limited size of the effective fillet leg or cross sectional area of the fillet weld reinforcement. Because of the thin diaphragm, there is high welding residual stress adjacent to the weld.

There are several reasons why cracks can develop. They include:

  • Tensile overload caused by differences in the thermal expansion of the low alloy steel channel (carbon or Cr- Mo) and the SS diaphragm. Some exchanger channels contain effluent streams up to 730 F and diaphragms can be over 80” in diameter.
  • Chloride Stress Corrosion Cracking (SCC) – A salt which drops out in hydrotreater effluent exchangers is ammonium chloride. The diaphragm is susceptible to this failure mode due to its high residual stress. The crevice between the diaphragm and channel contain concentrated chlorides and aggravate the cracking mechanism.
  • Polythionic Acid Stress Corrosion Cracking – Hydrotreater effluent systems use austenitic SS for sulfidation resistance. Polythionic acids are formed in the process during shutdown periods when the prevalent metal sulfide scale reacts with oxygen and water condensed during the steam out cleaning process. These acids cause SCC in SS, which is sensitized from welding or from operating temperatures in excess of 750 F.

1107_refinery_fig2

SCC is the result of combined mechanical stresses with corrosion reactions. The combination of a susceptible alloy, sustained tensile stress and a particular environment lead to the eventual cracking of the alloy. It is difficult to alleviate the environmental conditions that lead to SCC. Chloride levels required to produce stress corrosion are very small, generally below the macroscopic yield stress. The stresses are often externally applied but are quite often residual stresses associated with fabrication, welding or even thermal cycling. Unfortunately, stress relieving heat treatments cannot completely eliminate all the residual stress.

Knowing, and ultimately reducing (or eliminating) the important variables of SCC propagation is the best avenue for success. These variables again are:

  • The level of stress,
  • The presence of oxygen,
  • The concentration of the chloride,
  • The elevated temperature and
  • The conditions of the heat transfer (often the design).

This failure mode is not uncommon for exchangers of a certain age, design and service. Diaphragm fillet welds encounter high stresses from the combination of high hoop stress and large compressive stresses generated from the cover plate bolting. This cracking is common in the diaphragm welds of high-pressure heat exchangers in hydrotreating units found throughout our nation’s refineries and abroad.

Seeking a solution
Faced with repeated failures of the diaphragm welds in hydrotreater exchangers—14 exchangers, seven in two separate trains (see Fig. 2)—and the economic impact of these exchangers to the refinery, developing a solution to this phenomenon became a priority.

1107_refinery_fig3The Reliability and Maintenance groups designed or investigated a handful of possible solutions, but none of them received total buy-in. Then, following several months of study, an innovative, alternate solution was identified. It involved eliminating the diaphragm plate entirely and replacing it with the pressureenergized seal ring (Fig. 3). The solution from Taper-Lok® was simple, effective and quite field compatible within the timeframe of a shutdown.

Seal concept…
The Taper-Lok metal pressure-energized seal ring was designed to use on piping applications for topsides of offshore platforms, flow lines, production risers, manifolds, chemical plants, refineries, power generation, supercritical wet oxidation and numerous other practical applications. Most assemblies consist of a male flange, female flange, seal ring, and a set of studs and nuts. The pressure-energized seal ring seats into a pocket in the female flange and is wedged and seated by a male nose located on the male flange.

Utilizing this concept, the exchangers channel cylinder would contain the female pocket, while the channel cover would have the male nose geometry.

In the pre-bolted condition, the Taper-Lok seal ring lip stands off of the face of the channel. The converging seal surfaces are brought together like a wedge during bolt up. This wedging motion forces the seal ring onto the male nose and into the female pocket forcing a compressive hoop stress. Minimal bolt load is required to achieve the required contact stress on the seal surfaces.

The converging angles of the seal ring create a wedge or “doorstop” effect. As the equipment internal pressures increases, the seal seats tighter into this sealing wedge.

Taper-Lok seals are made from the same material as the process equipment (exchanger channel and cover) to ensure that thermal expansions are consistent across all components. The effects of bi-metallic (galvanic) corrosion are eliminated. A baked-on moly coating is applied to the seal to prevent galling.

This promising sealing technology required minor modifications to the heat exchangers. It was simple, reusable, provided a metal-to-metal seal and took very little time to make the modification. This application, however, was unique in that there was no published history utilizing the seal on a refining exchanger of this pressure and severity.

Reliability assessment and risk mitigation
Since this could have been the first use of this type of seal on a fixed equipment cover, a reliability assessment had to be conducted and the risks needed to be identified and subsequently mitigated. All known applications for Taper-Lok pressure- energized seals were researched. These seals, it was discovered, had been used in many different types of connections, including:

  • weld neck flanges
  • blind flanges
  • closures
  • clamps
  • swivel flanges
  • misalignment flanges
  • tube sheets

These seals also have performed well in temperatures from cryogenic to 1600 F and at pressures to 40,000 psig. Applications of note included:

  • heat exchanger internals
  • hydrogen processing
  • high temperature measurement equipment
  • offshore (both sub-sea and topside)
  • high pressure compressor connections

A study conducted by JP Kenny proved to be helpful. It compared the Taper-Lok to standard ANSI bolted connections. While the study did not focus on welded diaphragm connections, it did point out some of the beneficial characteristics of the seal. The results of the study showed that the pressure seal was preferable to ANSI standard gaskets connections.[6]

A design of the seal for one of our heat exchangers was created and calculations according to ASME Section VIII, Division 1 Unfired Pressure Vessels [7] were conducted to ensure code compliance. Because the seal is self-energizing, the gasket factor “m” and the minimum design seating stress “y” are both zero, the required bolt load is reduced and equals the hydrostatic end load of the closure only.

A finite element analysis (FEA) was conducted by an independent third-party engineering firm.[8] Analysis consisted of both 2D and 3D nonlinear models with contact elements. Both models showed a wide contact area with pressures at the sealing surfaces to be in excess of 20ksi. The analysis verified that the seal would be kept in an elastic state and that the stresses in the components would be below code the allowable limits.

Even though all data suggested that the Taper-Lok seal would work in our application, we were still concerned with the possibility of a leak or failure of some sort. Without published history, we needed a fallback plan. It was determined that when we implemented the Taper-Lok sealing system in one of our exchangers, we would build a new channel cover with the male nose geometry as opposed to retrofitting our existing closure. This would then require only the cutting of the female pocket into the exchanger channel. In the event of something unexpected showing up during the retrofit, we could reuse the old closure and weld back a diaphragm plate and seal the opening as we had always done.

Implementation
Description of modification…
The modification centered on the elimination of the welded diaphragm gasket and implementation of the double angled pressure seal.

Simple modification procedure…

1. Remove/replace channel cover plate
A new channel cover plate was fabricated to reduce downtime. Originally, the existing channel cover plate was to be modified via a rapid turnaround machining effort to allow the cover to accept the tapered pressure seal; a minor effort that was not difficult. The original channel cover plate was salvaged for modification and installation on the sister exchanger in the second train. It was also available to reinstall if any unforeseen problem existed with the retrofit.

2. Remove metal diaphragm gasket/seal
The diaphragm seal was removed in a multi-step process that began with drilling a hole through the diaphragm and performing a safety check for any residual hydrocarbon. Once complete, the center of the diaphragm was removed by arc gouging, being careful not to cut close to the inside diameter of the channel. The remaining diaphragm, including the fillet weld that attaches the diaphragm to the channel, were machine cut from the channel. The channel was also faced to insure a true, flat surface.

1107_refinery_fig4563. Field machine female pocket into exchanger channel (Fig. 4)
The Taper-Lok pressure-energized seal geometry requires two sealing surfaces. One a female pocket, the other a male nose. The female pocket was machine cut into the exchanger channel while the new, fabricated channel cover plate featured the male nose. During assembly, an additional benefit to the design was observed. This male nose on the channel cover plate configuration acted as a guide.

4. Insert pressure seal ring into pocket (Fig. 5)
Since the Taper-Lok geometry of the female seal pocket is angled, the seal ring was installed into the female pocket and held in place by fricton, providing a hands free, safe installation of the channel cover plate.

5. Insert channel cover plate on studs and pressure seal

6. Pre-tension studs (Fig. 6)
To ensure that the channel cover plate was assembled square and free from misalignment and to reduce bolt interactions, hydraulic tensioning equipment was utilized. Four tensioners were used at 90 degrees and the tensioners were kept under load while all nuts were installed and hand tightened.

A second deviation from the exchanger’s original design was applied at this time. In lieu of the traditional heavy hex nuts, mechanical multi-jack bolt tensioners were utilized. This also proved quite fruitful as torque wrenches were then used to apply the proper torque required to seat the pressure- energized seal ring. The traditional impact (and accompanying crane used to hold it in place) was rendered obsolete.

Hot torquing was not necessary after the installation, even after the unit had gone through a few cycles. This is attributed to the spring effect that the seal and component geometry create during and after seal seating. This spring effect refrains the bolts from relaxing.

Conclusion
Several benefits were realized from this retrofit using the Taper-Lok® sealing technology. One of the most important benefits was the elimination of the diaphragm cracking, which, in turn, increased equipment reliability and unit availability. Since the Taper-Lok seal is fabricated from the same material as the pressure parts (channel and cover), bi-metallic or galvanic corrosion cannot occur. All thermal expansion observed during operation is constant. The new seal or “gasket” remains in compression and in an elastic state. The seal is self-energized, creating a tighter seal with any increase in pressure. Elements that promote the cracking are eliminated.

Following the first retrofit, a second exchanger was retrofit in March 2006. The remaining 12 exchangers are scheduled to be retrofit during the next two scheduled GOHT outages.

Additional benefits—some initially unforeseen—were the reduced costs or downtime from several items, including:

  • the reduction in the exchanger turnaround time from six shifts to three shifts
  • the utilization of one crane in lieu of two (one for cover plate and one for impact)
  • the elimination of any hydrogen bake out from weld contamination and weld dilution on alloy exchangers with a stainless steel corrosion overlay
  • the elimination of machining of weld buildup (Nickel butter coat)
  • the elimination of seal weld and metal diaphragm seal
  • the elimination of NDE to search for cracking throughout the entire process

Downtime has decreased since the root cause of the process leaks (cracking of diaphragm welds) at the cover have been eliminated. The retrofit was deemed a success. No downside opportunities have been observed or foreseen. MT


Doug Hughes is turn around superintendent at Valero Refining – Texas City, TX. E-mail: doug.hughes@valero.com

James Cesarini is president of Petro Spect, based in Texas City, TX. E-mail: chezo@petrospect.com

Erick Howard is vice president Engineering of Taper-Lok, in Houston, TX. E-mail: ehoward@taper-lok.com

References
  1. Woodard, Wayne, Manager of Process Engineering, Central Engineering Department, Valero Refining Company– Texas, personal interview and review
  2. ASM Handbook Volume 13, Corrosion (Formerly 9th edition, Metals Handbook), pgs. 146, 554, 564 and 934
  3. ASM International “Corrosion and Corrosion Prevention” Course 0135, Lesson 12, January, 2001 pg. 29
  4. Hegger, Al, Director of Metallurgy, Central Engineering Department, Valero Refining Company–Texas, personal interview and review
  5. Taper-Lok® Corp., “Eliminate Clamps and Welded Diaphragm Plates,” March 2002, October 2005
  6. OTC 15276 “Large Diameter Flanged Connection Make-Up With Zero Reworks,” John W. Aaron III and Waverly L. Johnson, Taper-Lok® Corp.
  7. 2004 ASME Boiler and Pressure Vessel Code Section IIII, Division I, Unfired Pressure Vessels, Mandatory Appendix 2, Table 2-5.1, Gasket Material and Contact Facings
  8. Hannah Xu, Ph.D. and Cliff Knight, PE. “Valero Heat Exchanger Taper- Lok® Channel Flange,” Knight Hawk Engineering Report #: TLC0050927-01

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236

6:00 am
November 1, 2007
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The Conquest of Breakdowns

How you rally and arm your troops is crucial to the outcome of this ongoing battle.

As the well-known civil engineer and author Henry Petroski put it, “Success is foreseeing failure.” It’s only four words, but it defines what every preventive maintenance (PM) program should strive for. Whether you have been working for many years or are a newcomer, your most effective weapon against breakdown is a well-organized and on-schedule PM program.

1107_breakdowns1It also doesn’t matter what field you are in or how large or small your organization is. The fact remains, if you do preventive maintenance correctly and consistently, it works. Proper staffing levels are required to stay on schedule and staying on schedule is the cornerstone of all successfully run programs. You still can run your program behind schedule, but breakdowns will increase and your program will become less and less efficient. Your troops will be doing more breakdown maintenance than preventive maintenance, a sorry situation for everyone concerned (including your company, your department and your customers).

We are all familiar with the various predictive (PdM) technologies that have emerged to supplement PM programs (i.e. infrared scanning, oil analysis, vibration analysis, etc.). But, while such technologies are very effective and can add much more refinement to a program, they still are supplemental in nature. They do not take the place of a PM program, but enhance it. There is no substitute for the day-in-day-out battles that must be waged to keep breakdowns at bay.

The dictionary defines “breakdown” in terms of “failing to function.” A breakdown can be a complete failure, i.e. a motor burns out. It can be a partial failure, i.e. a motor overheats but still runs. It can be an intermittent failure, i.e. a motor stops and starts for no apparent reason. Or, it can be a calibration failure, i.e. a thermostat won’t control temperature properly. Whatever the form, though, be it major or minor, a breakdown is always a problem that needs to be corrected.

Let’s look over the accompanying chart. As you can see, the planning, strategy and tactics to conquer breakdowns start at the headquarters.

1107_breakdowns2

Planning
Planning is the first and most important step. According to John Wooden, former UCLA basketball coach, “Failing to plan is planning to fail.” It’s the same in maintenance as it is in basketball.

Take the time needed—months if necessary—to develop your plan and always involve your troops in the planning phase. Furthermore, “know your enemy.”

  • Do you have 1000 motors that you have to keep running 16 hours a day, 300 days a year?
  • Do you have computer room air conditioners that never can be shut down? How can you schedule the maintenance these air conditioners need?

You get the idea. You have to know your plant, your systems and their needs—and you need to develop your strategy around this information.

To give you an example, our program has 225 pumps that must have preventive maintenance done twice a year, on schedule. This is part of our overall planning strategy— to do the PMs needed to keep these pumps operating at their designed efficiency. We have a planned strategy for all of the equipment in our program. 

Tactics
Let’s assume that you have enough troops to move against the enemy. If you were setting up your program in a new plant that had yet to start up, adequate staffing should have been part of your overall planning. There is information available to help you plan tasks and how long they should take to complete.

If you are coming into an existing plant, your troop levels may or may not be sufficient. If you have enough troops, good! If you don’t, you’ll have to do your best to control and defeat breakdowns working under a disadvantage.

Refer to our chart again—you will notice we have the enemy surrounded. He cannot break out as long as we keep pressure on him and keep him under control. Keeping him besieged is your tactical objective.

I’ve set the stage for our attack to begin. We have a sound plan, we have developed tactics and we have enough troops to control the growth of our enemy. Now what?

Gather your troops and explain your overall strategy (they should have been in the planning phase). Discuss the benefits of the program if it is done correctly and on schedule as much as humanly possible.

What are the benefits?

  1. Increased reliability and life of equipment
  2. Fewer major repairs and downtime
  3. Shift from breakdown maintenance to preventive maintenance
  4. Fewer emergencies
  5. Better customer relations
  6. Less work stress = POM (Peace of Mind!)
  7. Increased profits
  8. Glory for you and your troops (A Bonus!)

Attack with vigor
Look at the chart, again. The following items are your prongs of attack. 

Persistence (refusing to give up)…
Next to your overall strategy, “persistence” may be one of the most critical elements in your program. You must—at all costs—keep your program active and vigorous. In our own organization, I try to ensure that preventive maintenance is done every workday. If you are understaffed, you will have to prioritize and be willing to adapt to changing conditions. As a maintenance manager, it is YOUR responsibility to make sure the work gets done.

Training …
Train your troops both on the job and in formal settings. New technology is a blessing and a bane. It gives YOU an edge—but, it also gives breakdown an edge. Your troops must be properly prepared to meet these new threats.

Standards (the level of requirement)…
What brand of line starters do you prefer? Will you accept sloppy and shoddy workmanship? Will you tolerate late shipments from vendors? These are questions of standards or levels of requirements. Your preventive maintenance will live or die based on what kind of standards you set for it. Set high standards and have your troops, contractors and others who report to you rise to meet them. Don’t lower your standards to meet theirs.

Routine…
The next prong of attack is the routine (course of action or schedule). Your schedule is your guide. Routine for your organization could be quarterly, bi-annual, yearly, whatever. Only you and your troops can determine that. Don’t, however, underestimate the role of “routine.” Without it, you are like a ship at sea without a rudder.

Documentation…
The documentation that you do and the level of quality and importance that you place on it will be another major factor in your success or failure. Your office staff must be involved, hopefully from the very beginning. Moreover, they must be properly trained and committed to the program and its success.

Auxiliaries (contractors and vendors)…
Your auxiliaries also play key roles in your conquest of breakdowns. If you can’t get the logistical support to the front when you need it, breakdowns will begin to defeat you and instead of being on the attack, you will be in retreat, Sit down with your key contractors and vendors and discuss their roles in the program. Let them know what is expected of them—and that they are essential to your success. If they won’t or can’t conform to your high standards, muster them out and recruit new auxiliaries to fill the gaps in your lines.

Observation (paying attention)…
Sounds simple enough. How hard can paying attention really be? Talk with your troops about taking ownership of their equipment, their areas and their customers. Your troops are your eyes and ears out on the front lines; they are the ones that hold back the “hordes of breakdown.” Their input is essential to the conduct of the war. Always be on guard. As the great Neil Young album noted, “Rust never sleeps.” It’s true.

Ingenuity (inventive skills)…
This last assault is what separates the winners from the losers. Everyone in your program will contribute to this effort by presenting new ideas (i.e. “Let’s switch to this new grease for motor bearings, it protects better and will last longer without drying out”).

Try to foster in your troops a climate where their ideas and ingenuity are valued and used. If they can improve the program, they will take ownership of it—it will become “their” program. As a result, they will nurture it and believe in it and its value. This is another way to make constant improvements. Remember, if you are not moving forward, you are falling behind.

Taking up the flag
There’s no industry where preventive maintenance won’t pay off. Now that you know what it will take to make you, your troops and your PM program a success or failure, roll up your sleeves, put on your battle gear and get out there and conquer breakdowns.

As The Battle Rages On

So what is breakdown doing while you are doing your best to defeat it? It’s getting older and next to neglect that’s what is going to give you the most problems. Certainly, the other factors are important—but they are easier to control. The older the equipment, the more it has worn out. If you have a 35-year-old air handler, it will take more of your resources than a 10-year old air handler in good condition. (Age really can be your enemy, too.)

John Camillo is an engineering supervisor at the Princeton Healthcare System in Princeton, NJ. He also is the Engineering Department’s training coordinator. Camillo studied at the Philadelphia Wireless Technical Institute, majoring in HVAC-R. Over the past 40 years, he has worked in various industries, including hospitality, aviation, missile reentry, mill/canning and healthcare, where he has specialized in developing and implementing PM programs. E-mail: jcamillo@princetonhcs.org

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229

6:00 am
November 1, 2007
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Going Where Others Can't

As a number of Louisiana refineries are finding, flexible sensor technology can deliver an especially cost-effective way to measure temperatures almost anywhere in a system.

As a systems integrator that services refineries and chemical plants in Louisiana, we have found our customers’ biggest maintenance headaches come in the area of temperature sensor replacement. Rigid temperature sensor technology, used inside thermowells for 20-50 years, is the nightmare of every maintenance department. Problems using rigid sensors include stocking difficulties, finding suitable replacements, ordering the correct length and size, and being unable to install a replacement sensor in an existing thermowell.

Flexible temperature sensors, on the other hand, offer a universal solution for all maintenance dilemmas. A flexible sensor fits nearly everywhere, can be cut to the correct length and reduces the number of spare parts a plant has to keep on hand.

1107_flexsensor1Rigid sensor challenges
A standard rigid temperature sensor, made by virtually every sensor manufacturer in the world, consists of a sensor element—thermocouple (T/C) or Resistance Temperature Device (RTD)—protected inside a rigid stainless steel shaft in a 2” sensitive area, forming what most users know as a “fixed length sensor” (Fig. 1). These fixed length sensors are either spring loaded (for use with thermowells), welded to a hex nipple for a fixed immersion length into a process or sealed with epoxy, exposing the sensor leads for external measurement connections.

Typically, the T/C or RTD element is embedded inside the bottom two inches of a stainless steel tube, which is then filled with mineral insulated powder (MGO) and sealed with epoxy to prevent moisture penetration. The rigid sensor assembly fits into the thermowell beneath the connection head. The wires from the sensor are then terminated in the enclosed head and connected to extension wires using a terminal block, or attached directly to a transmitter. Wiring is then run back to the control room, usually encased inside conduit for long wire runs.

The first problem posed by rigid sensors is the difficulty involved in replacing a faulty sensor. Typically, a maintenance technician has to remove the enclosure cap, disconnect the wires from the transmitter or terminal block, disassemble the union, conduit and fittings attached to the transmitter and thermowell, and then move them out of the way before he or she can pull the rigid sensor out of the thermowell. Depending on the age of the installation, the corroded conditions of the conduit or junction, and the amount of room available, this can be an arduous task, particularly on the top of towers or columns, or in close confinement areas.

The next problem involves determining the correct length of the replacement sensor. In many cases, a maintenance technician may know that the sensor needs to be replaced, but doesn’t know the exact length of the rigid sensor. If the loop is critical, the plant may not want to pull out the old sensor yet. Instead, they will make all the necessary measurements first, order a new sensor and wait for it to arrive. In that case, the technician will have to make multiple visits to the sensor—first to determine as much information about the installation as possible, including sensor type, connection style (nipple union nipple, direct thread, lagging length, approximate insertion length, etc.)—and then go back to stores to try to find a best fit, probably returning with a number of different sizes to avoid a third trip. Of course, the unused sensors then have to be returned to stores (another trip)!

In some cases, the technician leaves the old system intact, gets on the phone to a sensor representative, and the two of them make an educated guess based on a thermowell’s length, size of the union, length of nipples, etc. At least one sensor manufacturer we deal with admits that they only get it right about 85% of the time when they have to guess. Another solution is for a maintenance tech to carry 8-10 spare sensors out into the plant, in hopes that one of them will be the right size. All this could be avoided, of course, with proper documentation—that is, the size and type of each temperature sensor should be recorded for future reference when replacements are needed. This, however, can be a daunting task, considering that some plants have hundreds, if not thousands, of temperature sensors. Plus, engineering drawings do not always represent the “as built” installation.

1107_flexsensor2Once a replacement sensor is found, ideally it will slide back into the thermowell. Unfortunately, thermowells can cause other problems. Some thermowells will “sag” (bend) when exposed to high temperatures over prolonged periods, as is the case with flare stacks (Fig. 2). It may be possible to extract the existing sensor from a sagging thermowell, but it is usually impossible to install a new rigid sensor into a sagging thermowell. Instead, the thermowell itself must be replaced.

Thermowells also can accumulate debris, which makes it difficult to install a new replacement sensor. In areas with high humidity, such as Louisiana and other southern states, thermowells can fill up with assorted contaminants that condense out of the air. When the rigid sensor is removed, this debris can then prevent a new sensor from being fully inserted back into the well.

Finally, the length of a rigid sensor can affect accuracy of the measurement: A rigid sensor inside a short, 2”-3” thermowell may not be measuring the correct process temperature. This is because a sensor with a rigid metal sheath is not measuring just the process inside a short thermowell; some of the sensor’s sheath protrudes up into the nipple, union or enclosure, which is outside the process. Such a sensor actually measures part of the process temperature and part of the ambient temperature outside the process. This situation typically will result in erroneous temperature readings with possibly adverse effects on process control. In one case at a tire plant, the lower inaccurate reading resulted in higher process temperatures that, in turn, caused the thermowells to overheat and sag. Sagging thermowells resulted because the actual temperature was much higher than the sensor could record.

1107_flexsensor3Flexible solutions
Even if an application spec calls for a rigid sensor, a flexible sensor can fill the requirement. A flexible sensor typically consists of a 1” stainless steel sensor element and lead wires that are protected either with Teflon or fiberglass insulation. Flexible sensor wires can be trimmed to the correct length depending on assembly (Fig. 3).

The sensor element is held in place with a spring at the top of the thermowell (Fig. 4). The spring keeps the sensor in constant contact with the bottom of the thermowell, allowing the best heat transfer to the sensor. If there are large open areas within the union/nipple junction, spacers can be used to facilitate insertion through these areas.

Replacing a flexible sensor in the field is much simpler, compared to rigid sensors. To insert a new flexible sensor in place of an existing one, a technician only has to remove the cap, disconnect the sensor wires, remove the transmitter or terminal block and pull out the old sensor. It is not necessary to disassemble the union, conduit or any other fittings.

 

1107_flexsensor4Because a flexible sensor can be trimmed to the correct length, a technician only has to carry a single sensor to the field. Flexible sensors typically are available in various lengths to accommodate nearly every size of thermowell or application a plant may have.

In the case of a sagging thermowell, if the rigid sensor can be removed, a flexible sensor can be installed without replacing the old thermowell. We usually purchase flexible sensors that are slightly smaller in diameter than rigid sensors. The most popular rigid temperature sensors built in the U.S. have a ¼” (0.25”) O.D. metal shaft. Most thermowells installed today have a 0.260” internal bore (in Europe a 7mm bore is used). We order flexible sensors with a 6mm O.D. (slightly smaller than 0.25”), making it easier to slide into a sagging well or into dirty thermowells that have built-up or caked-on debris inside them.

Because a flexible sensor has a 1” sensor with flexible fiberglass or Teflon insulated lead wires and a spring, it can be trimmed to fit even the smallest of thermowells. Furthermore, since the spring and lead wires cannot conduct ambient temperatures to the sensor, outside measurement errors cannot exist. Like the previously mentioned tire plant, we’ve had several applications on other flare stacks where we installed flexible sensors and the process engineers were surprised to see that their stacks were operating at much higher temperatures than the previous rigid sensors had indicated. The energy and fuel cost savings obtained from operating these stacks at the proper temperatures paid for the replacement sensors many times over.

Intriguing applications
Flexible sensors offer several interesting ways to approach temperature measurement applications and their problems. For example, the intense humidity in Louisiana causes “Green Rot” at the wire termination points with thermocouples, so engineers and technicians try to avoid as many termination points as possible. Because a flexible sensor can be made with any length of wire, we now have several plants in the area that do not use terminal blocks anymore; instead, the wires are run directly to temperature transmitters located in a separate cabinet. The sensor wires are run inside rigid or flexible conduit, all the way from the thermowell to the remote mounted transmitter, without using any intervening termination blocks. This eliminates one major source of failure.

Another plant noted that since the sensor wire did not carry any dangerous voltage or current, it was not necessary to encase it inside conduit. Therefore, all their sensor cables run directly from the thermowell to a remote transmitter without conduit (Fig. 5). The flexible insulation covering the sensor wires is sufficient to protect it from most environments, but stainless steel braid or flex armor can be added at very little cost.

In one application, a plant had a burner with dozens of temperature sensors, but none could be replaced without shutting down the entire burner. It was simply too hot for a tech to walk into the burner while it was operating. By using flexible sensors inside long protection tubes attached to the points of measurement, it was possible to slide a flexible sensor in and out of the tube from a safe location without shutting down the burner.

In a similar situation, a refinery had a problem with calibrating and replacing sensors with transmitters on top of columns or towers. It was physically dangerous for a tech to climb to such heights while the hot process was running, and try to safely work with rigid conduit, fittings and transmitters. This refinery replaced all its rigid sensors with flexible units and installed the transmitters at the bottom of the towers for easy access. Again, because a flexible sensor can be made to any wire length, the transmitter could be calibrated or replaced from the bottom of the tower, and the flexible sensors were easier to change out if they failed.

Adding up the savings
Over the last year, several refineries in Louisiana have begun systematically replacing all their rigid temperature sensors with flexible sensors because of the cost savings they expect to gain.

  • Maintenance will be easier, take less time and cause fewer shutdowns or process interruptions.
  • Fewer thermowells will have to be replaced because of sagging or foreign debris that clogs the wells.
  • Only two or three standard sensor lengths will be needed for an entire plant, reducing the spare parts inventory.
  • The refineries will get better measurements in shorter thermowell applications, leading to increased accuracy and energy savings.

Although conventional rigid temperature sensors have proven to be a workhorse for the past 50 years, modern flexible sensors are now starting to replace them across Louisiana.

Robert Poole is an engineer with Process Measurements & Monitors, in Baton Rouge, LA.

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The Maintenance/Sales Partnership

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Ken Bannister, Contributing Editor

“ABC Corporation of Smalltown, USA, today announced a manufacturing sales order worth over $100 million…”

Such announcements are commonplace in today’s business press, leaving little doubt that the sales and marketing department are still revered as corporate heroes when a large sales order is closed. Getting that order to the customer, however, as ordered, on time and with first-time quality requires the effort of many unsung heroes within the plant.

From the post-war 1950s to the 1980s, North American corporate philosophy surrounding the sales process often was “close the sale and we’ll worry about design, quality and delivery later.” Since many sales were closed in a wine-anddine forum, and in a somewhat indiscriminate consumer culture of the time that tended to be accepting of poor design, quality and delivery, countless corporations were successful in spite of themselves.

That all changed when the Japanese singlehandedly raised the bar, having been attributed largely with the responsibility for raising consumer awareness and expectations surrounding quality and service throughout the 1970s and 1980s. This state of affairs finally forced the North American industrial giants into compete mode by the 1990s. New heightened consumer awareness resulted in an intelligent customer who was unafraid to demand quality products at reasonable prices, delivered on time. Competing in this new world order forced many corporations to rethink their sales strategies.

A renewed sales approach
To be considered a viable contender in today’s marketplace, a corporation must attain quality assurance certification. Many customers demand ISO 9000 or TS 16949 certification (quality assurance through audited documentation and procedural control to a defined international standard) as a contract bidding prerequisite.

With ISO/QS 9000 certification, the customer is assured that a qualified maintenance program is in effect and also that manufacturing equipment is being maintained to a specified level of reliability. Through this link, the maintenance department is now established integrally with the sales department.

Building on this newly established integration, the modern-day sales approach utilizes a corporate team effort to put together a winning sales proposal. This sales process calls for the salesperson to listen and document the customer’s requirements exactly, so that these requirements can then be reviewed by a multi-faceted manufacturing and sales team comprising members of the finance, engineering, production, purchasing and maintenance departments. Because many sales contracts contain penalty clauses for poor quality and poor delivery, the sales team must ensure corporate capability to attain and maintain a sustained level of production throughput for the duration of the sales contract. This only can be assured by the maintenance department.

Further links between maintenance and the sales force recently have been established through the implementation of Lean Manufacturing initiatives, in which the sales department is no longer called upon to fire-sell surplus “made for inventory” product. Instead, sales is made intimately aware of current long-term/short-term surplus manufacturing equipment capability that can be tapped into and sold competitively with high profit margins and low manufacturing cost in a pull manufacturing environment.

Maintenance facilitating the sales process
Although maintenance rarely involves itself in the sales process, it can assist in the sales effort through the provision of reliable equipment performance information, such as:

Throughput capability report—Covering the manufacturing equipment or line intended to produce the new parts, this is essential information in determining the ability to deliver the requested product volumes. Through the process of analyzing the specified equipment maintenance history, a detailed downtime record is used to compare against the machine’s design throughput figure, so that a true throughput measure can be predicted. If throughput requirement is more than capability for the plant in question, alternate manufacturing requirements will be needed to provide quality and delivery.

Maintenance cost report—Once again, knowing what equipment will be used to manufacture the product helps the maintenance department establish past maintenance costs for the equipment in question. These cost figures are then averaged out and a projected maintenance cost can be established for the proposed production contract term. Such projections allow the sales department to accurately calculate operation and manufacturing costs. In turn, controlled costs allow corporations to lower profit margins and be more competitive.

Maintenance health reports—Standard maintenance health reports, such as Availability, Reliability, PM completion, Overall Equipment Effectiveness, etc., are all excellent reports for the sales department to have in its possession. Providing these reports are favorable; they can be used within a sales presentation to bolster confidence in the corporation’s ability to deliver the required goods and services being bid on to potential and actual customers.

In the course of the sales process, maintenance also may be called upon to directly interface with potential customers and provide them with a tour of the maintenance facilities, as well as present an overview of the maintenance process.

The benefits
Establishing a partnership with the sales department allows the maintenance department to once again be recognized as an entity within the corporation. Being aware of pending contracts lets maintenance better plan any equipment maintenance and overhaul requirement so as to be ready for the production contract in the event the sales department is successful. Involvement in the front end of the sales process also allows maintenance to keep in check the possibility of ‘overselling’ the plant design capacity. Inattention to this element can accelerate maintenance demands quickly, increasing equipment downtime and, ultimately, leading to corporate losses.

Ken Bannister is lead partner and principal consultant for Engtech Industries, Inc. Telephone: (519) 469-9173; e-mail: kbannister@engtechindustries.com

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Making Room For Sustainability

Over the past few months we have read with interest how Maintenance Technology has adopted and re-energized the concept of “capacity assurance” as it applies to industry. This underscores the time-proven influences exerted by proactive maintenance approaches, strategic reliability initiatives and improved energy efficiencies in contributing to an operation’s full potential, productivity and profitability.

The enabling toolbox to attain the highest levels of capacity assurance has been filling up with a variety of solutions. From our perspective “sustainability” tops the list.

The International Trade Association (ITA) defines sustainability as “the creation of manufactured products using processes that are nonpolluting, conserve energy and safe for employees, communities and consumers.” Specialized technologies and expertise offers various avenues to turn the process into progress.

Sustainability programs among manufacturers have accrued significant gains with successes large and small. For those most engaged, organizations have been able to engineer annual reductions in CO2 emissions and water consumption; made recycling of scrap metal routine and profitable; equipped pumps with frequency controls to promote energy efficiency; and have moved from harmful chemicals and lubricants to environmentally friendly and lubrication-free solutions.

Countless other examples abound to affirm the viability, achievability and rationale of sustainability programs, regardless of a manufacturer’s size or industry. For those seeking to make their own inroads with sustainability, these keys for success can help unlock programs and keep them moving forward:

  • Evaluate your operations top-to-bottom. Energy and environmental analyses can be conducted to pinpoint areas where high energy consumption is the norm and check chemical treatments, lubrication use and other operating processes to determine environmental risk. Improvements linked to opportunities then can be introduced, based on remedial action recommendations.
  • Establish goals and targets. Analyses additionally provide benchmarking data for arriving at realistic objectives and measuring subsequent results that contribute to the business goals.
  • Apply new technologies. Targets of opportunity for sustainability improvements can be found in virtually every piece of equipment and among all applications and processes within industry. Great strides have been made in the evolution of relevant technologies and these can be enlisted as appropriate to meet particular sustainability goals.
  • Promote equipment reliability. Practices aimed at improving and enhancing the reliability and efficiency of assets can pay big dividends. Regularly monitored and well-maintained equipment can save energy, increase uptime, drive profitability and advance sustainability objectives.
  • Manage information effectively. Data is “king” for documenting and quantifying sustainability efforts and satisfying mandated obligations for environmental, health and safety compliance reporting. Customized Web-based EHS (environmental, health and safety) information management systems offer solutions to electronically automate key EHS functions, including audits, chemicals management, regulatory reporting and sustainability metrics. This can drastically reduce the time and money usually spent in collecting, analyzing, re-formatting and preparing data. Capabilities expand with live CO2 footprint tracking and performance tracking and measurement.

Immediately and over time, sustainability programs can allow operations to reap the inherent rewards in reduced operating costs, increased productivity, generated energy savings and enhanced asset reliability. In today’s competitive business arena, making room for sustainability programs simply makes perfect sense.

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Determining Levels of Maintenance Staffing

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Bob Williamson, Contributing Editor

“What is the formula for determining the optimum maintenance staffing level for our plant?” someone recently asked. I have asked the very same question about optimum maintenance staffing levels for over 20 years. It’s a tough one to answer.

Unfortunately, there seems to be no logical or easy answer to this seemingly straightforward question. I’m sure there may be some readers out there who have mastered this mythical formula, or have come up with an effective method for their respective situations. Still, I feel obligated to share my own thoughts as to the difficulties associated with maintenance staffing levels as we wrestle with maintenance costs, reliability improvement and an era of skills shortages.

Plant staffing levels can be determined by a number of different methods. For example, determining the number of operators for machinery, material handling or control stations is a relatively simple task due to the number of operating positions, job tasks, narrowly focused scope of work and specific but limited skills and knowledge requirements. On the other hand, determining the number of maintenance mechanics or technicians is not so simple—in fact, in some plants it is extremely complex. I’ve heard of formulas based on headcount per installed horsepower, mechanics per replacement cost or technicians per square foot. Why don’t these work across the board? Here are the BIG variables that affect maintenance staffing level decisions:

Variable #1 – scope of work
The breadth and depth of job-performance requirements varies widely in today’s industries from extremely-narrow, single-task, repetitive job tasks to broad, multi-skill job roles. Maintenance is rarely a narrowly focused job role, either geographically in the plant or intellectually in the skills and knowledge requirements.

In general, maintenance includes very broad core job skills and knowledge such as in-depth principles of mechanical, machine repair, electrical, instrumentation/controls, machining, etc. We also must include equipment-specific, facilityspecific task skills and knowledge. Then there are advanced trouble-shooting and problem-solving skills and knowledge. Furthermore, we cannot ignore the specialized skills and knowledge requirements for condition monitoring and predictive maintenance. In many plants I’ve often heard this scope of work scenario described as “an inch wide and a mile deep for equipment operators” and “a mile wide and a mile deep for maintenance technicians.”

Variable #2 – individual competency
The second big variable for maintenance headcount is the skill set of each person—individual competency. If all maintenance people had the same level of skills and knowledge, there could be an easy answer to the question of “optimum maintenance staffing levels.” BUT, there is a lack of comprehensive skills standards as applied to industrial maintenance job roles especially in the areas of equipment-specific tasks.

Today, many plants do not FORMALLY train and qualify all of the maintenance staff to address the maintenance and reliability needs of the plant’s equipment and facilities. Why is it that equipment and plant operators typically receive job- and task-specific training and qualification, but the maintenance staff rarely does? There seems to be an “assumed” higher level of maintenance competency than what actually exists, or an over-simplification of the job roles that gets some plants into deep trouble.

Variable #3 – equipment reliability
Highly reliable plants and equipment can be managed with relatively fewer maintenance technicians than comparable highly reactive plants. If you have a very RELIABLE plant and equipment, the maintenance workloads are usually very well defined in terms of scope, skills and duration due to planned, scheduled and preventive/predictive maintenance. And, when jobs are assigned only to qualified maintenance technicians, accurate staffing level decisions are much easier.

Reactive or repair-based maintenance is highly unpredictable in terms of scope, skills and duration due to high levels of unplanned, unscheduled, reactive work loads. A wide variety of individual competencies also adds to the sporadic nature of equipment problems. It is almost impossible to plan anything day-to-day, let alone the proper staffing levels.

Variable #4 – historical information
Work orders capture a whole host of information about maintenance and repair work, including problems, causes, corrective action and laborhours worked by named technicians. Sadly, there is a huge void of decision-making information if the plant or facility does not use work orders or does not reinforce the need for accurate equipment and work history information. Staffing levels are arbitrary, repetitive problems are not identified, common causes are overlooked, improper actions and rework go unnoticed.

An analysis of comprehensive maintenance work order information often reveals that most of the root causes of the perceived “maintenance problems” with the plant and equipment are outside the direct control of the maintenance staff. Other departments and/or personnel that must be involved in improving “maintenance” include maintenance and repair parts procurement, inventory control, operations management and staff, process technicians, engineering, production scheduling, etc. The maintenance department alone cannot make equipment reliable.

Variable #5 – maintenance & reliability trends
Many business decision-makers do not have enough information to truly understand maintenance and the BIG maintenance staffing variables outlined here. Regrettably, for decades “maintenance” has been treated as an overhead expense line item and a “non-value-adding” activity in many business operations. Some business decision-makers also perceive maintenance technicians as “fixers” rather than “preventers” of equipment problems.

Current information about maintenance workforce demographics, hiring trends, retirement forecasting and knowledge retention often is overlooked, not fully understood and/or not factored into the staffing level decisions. More and more plants will experience higher maintenance costs and higher turnover of top skilled people as the “maintenance skills shortages” grips our nation’s business and industries, furthering the inability to determine proper maintenance staffing levels.

Real-world example
I spent time recently with a business that modifies and tunes high-performing street motorcycles using a custom-designed chassis dynamometer. One of the shop’s modifications includes changing from chain-driven to gear-driven cams and new push rods. This design eliminates high amounts of friction and improves engine torque and horsepower measured at the rear wheel. In one case, when the new cams and push rods were installed in a customer’s motorcycle, the dynamometer test revealed a sizeable LOSS in torque and horsepower!

The highly experienced mechanic who installed the new gear cams and push rods did not notice anything unusual during the assembly and adjustment. I noticed that he was impressively meticulous about his work. There was, however, a real problem somewhere.

A second highly experienced mechanic disassembled and inspected the new cams and push rods and immediately spotted a problem: The wrong push rods were installed!

When the two mechanics met and discussed the findings, they discovered that the new push rods were in the WRONG package from the manufacturer! Even though the shrink-wrapped labeled package indicated otherwise, they were not the correct parts for this engine and were about 5/8” too short. Because of their design, the first mechanic was able to easily adjust the push rod length and set the proper valve clearance. But, adjusted to their maximum limit, they flexed while running under load, limiting the valve travel and causing a reduction in torque and horsepower.

In this real-world example, both mechanics were trained, experienced and more than adequately skilled to work on the motorcycle in question. The second mechanic, though, had been factory trained and certified during the past 10 years. Both had made this particular modification hundreds of times, yet what was clear to the certified mechanic was overlooked by the uncertified experienced mechanic. While the root cause of the problem was obvious, neither mechanic had ever experienced mislabeled parts from this specific high-performance parts manufacturer.

Such subtle differences in today’s mechanics’ skill sets—or competencies—can create or eliminate maintenance-induced failures and the need to rework a recently completed job. Think how much difference there is among all the maintenance technicians’ skill sets and competencies in your plant or facility.

Plants and equipment would be highly reliable with a relatively smaller maintenance workforce if everyone were highly skilled and knowledgeable and only assigned to jobs that they were qualified to perform—right the first time. Gee, aircraft mechanics and top NASCAR race team mechanics do that all the time.

Bottom line
An analysis of plant equipment, chronic and sporadic problems and overall equipment effectiveness losses can lead to the determination of the required “skill sets” to achieve optimum levels of equipment performance and reliability. Until these “skill sets” become core competencies for maintenance staffing, I believe it is IMPOSSIBLE to use a formula to determine the optimum maintenance staffing levels.

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Maintenance information systems…Going Beyond EAM: Asset Performance Management

Advances in open technologies, fieldbus integration and information technology are extending the reach of enterprise asset management

To many plant-level professionals, the term “asset management” is synonymous with equipment maintenance or field device management. But, to business managers responsible for process manufacturing operations, asset management implies the effective deployment of all assets within their operational domain to meet business objectives. These assets include: plant equipment, energy, raw material, products, people, facilities, instrumentation, automation, information and even time.

Maintenance is certainly one important element of an overall asset management solution set, but maintenance improvements by themselves will not maximize the business performance of the manufacturing asset base. In fact, attempting to optimize plant operations while improving maintenance, without regard to the operational consequences, or vice versa, actually can degrade performance. True business optimization requires a holistic balance of tradeoffs between maintenance and operations—as dictated by the corporate profitability strategy, not by the isolated improvement objectives of either maintenance or operations.

Five years ago or so, balancing requirements of maintenance and operations across the enterprise, affordably, was more of a vision than a reality. Today, serviceoriented architectures, systems integration standards, high-speed networking and numerous other technologies have advanced to a new level of performance and economy, making platforms that unify maintenance, plant floor, business and customer systems a reality.

Balancing availability and utilization
Maintenance functions typically strive to maximize asset availability while the operations functions strive for maximum asset utilization. Although there are no industry-standard definitions, asset availability often is represented by the percentage of time the plant asset base is available for operating over any given period of time, and as the percentage of total output from an asset base divided by the theoretical maximum output over a period of time. Because it is impossible for a refinery to be 100% available and 100% utilized simultaneously, the only way to manage assets from a business perspective is to manage both holistically, according to the business measures such as plant profitability. Asset performance management (APM) is the holistic approach that has emerged to describe the practice of balancing availability and utilization around business performance.

APM includes what traditionally has been known as enterprise asset management (EAM), but that is only part of it. Although the initial EAM vision did indeed seek to bring together business and operations enterprise functions, in practice, it has focused primarily on optimizing availability. Traditional EAM tactics for optimizing availability have included maintenance repair and operating (MRO) inventory management, condition based maintenance and preventive maintenance. Although these are indeed critical to refinery health and success, most of the maintenance strategies are still at the isolated unit and equipment level—and of these, many are focused even further on instruments and valves.

Similarly, tactics to optimize utilization have been traditionally isolated at the advanced process control level, including such technologies as model-based production management, multivariable control, recipe management and online process optimization.

Moving to APM
Moving from traditional EAM to APM requires extending the scope of traditional EAM systems in at least two directions. One direction involves seamless integration with business and customer systems; the other involves seamless integration with production and production optimization systems. This extension includes the following elements:

  • Comprehensive enterprise asset management system with reliability centered maintenance (RCM) and extended condition based maintenance
  • Integrated and open field device management
  • Condition management, not just condition monitoring
  • Knowledge management
  • Decision support
  • Effective measurement systems
  • Improved communication and collaboration

EAM is still pivotal
EAM remains very much at the core of APM. It automates management of the complete lifecycle of plant assets from the device level up to the overall plan. The core capabilities of the Enterprise Asset Manager are as follows:

  • Work requests/work order management
  • Work crew planning and scheduling
  • Workflow and approvals management
  • Maintenance cost tracking and analysis
  • MRO inventory management, shipping/receiving and supply chain management
  • Contract and warranty management

The EAM function also provides a central collection point and access point for asset information, such as cost, performance and history. The EAM component adds value in a number of key operational areas. A study by A.T. Kearney found that the following benefits are achievable from EAM:

  • Improved throughput—uptime increases within 10-25%
  • Reduced operating expense—labor productivity increased between 20 and 30%; overtime costs reduced between 20 and 35%
  • Reduced inventory—MRO Inventories reduced 15-25%; with MRO Supply Chain Savings between 15 and 25%
  • General improvements—improvement in health, safety and environmental compliance, reductions in costs of outages and emergency repairs

Benefits such as these are heightened when EAM also includes integrated field device management.

Multi-protocol field device management
Field device management improves flow of operating data from field devices to the EAM system. One of the main benefits of fieldbus technology is the capability to utilize advanced device management applications in host systems that can interact with asset performance diagnostics resident in their intelligent field devices. But EAM systems have had little access to such information when host and field devices come from different vendors.

Although each device had Device Description technology that supported its configuration, this alone was inadequate and, until recently, there were no other standards. However, a consortium of process manufacturers and vendors has collaborated on an open field device toolkit (FDT) that, when combined with recent enhanced data description language (EDDL) developments, has changed the picture significantly.

FDT technology is ideal for making advanced “plug-in” applications, including highly capable valve testing plugins that attach to the host’s device management software in a standard manner. And, through the efforts of the multi-vendor EDDL cooperation teams, the recent EDDL enhancements address one of the key limitations of earlier device description technology by allowing the device vendor to organize the data shown on simple live data screens on the host system and provide the menus to organize the user selection of displays. Invensys, for example, has recently introduced a field device management toolset that lets users take advantage of any EDDL, Enhanced EDDL and/or FDT host deliverables supplied by the device vendor.

In cases where the device vendor supplies only traditional device descriptions (EDDL), the Invensys field device manager lets the users add functions, such as organizing their own live data maintenance screens and watch windows for each model of field device. The field device manager also lets users set up templates for the commissioning behavior and attach supporting manuals, repair procedures, and any other Windows files they find useful in device maintenance.

If the device vendor supplies enhanced device descriptions (Enhanced EDDL), this reduces template setup work because the device vendor has already organized many of the configuration and maintenance displays. Those displays may contain gauge style indicators, trend waveforms and graphic images.

And, if the device vendor supplies both enhanced device descriptions and an FDT device type manager plug-in, users can realize maximum device management capabilities. FDT technology enables the device vendors to go beyond the capabilities of even enhanced device descriptions. With FDT, the device vendor can program a rich graphical user interface (GUI) application as a plug-in to any other FDTcompliant host system engineering application. The plant maintenance staff would call up this application when they want to analyze the health and performance of a specific model of field device or run comprehensive diagnostic tests and archive the test results.

Field device management that supports both EDDL and FDT helps boost engineering and maintenance productivity over the entire lifecycle of an intelligent field device. Reusable engineering is facilitated through customizable templates for each FOUNDATION fieldbus device model, making it easier, for example, for technicians at all skill levels to correctly replace a failed device.

The value delivered by effective field device management can be considerable. In most complex process environments, up to 20% of the ongoing maintenance cost is associated with intelligent devices, sensors and other devices that act as the eyes and ears of the plant. By using a common toolset that works on the wide diversity of intelligent devices from multiple vendors, this cost can be reduced by up to 40%. For a shop with maintenance spend of $50,000,000, these savings can amount to several hundred thousand dollars per year. Customers are able to greatly increase the number of loops managed per individual, where on average, clients are doubling the loops managed per person.

Field device management enables advancement from condition monitoring, which is characteristic of conventional EAM systems, to condition management, which is essential for the new era of asset performance management.

Condition management
Where many technologies provide basic condition monitoring, describing what is happening with the system, field device management enables condition management, which guides in improving asset performance to achieve specific business objectives. Condition management helps move from the reactive or preventive mode of operations to a proactive and predictive environment. Ultimately, it is this linkage between the real-time and operational environment that moves an organization from asset management to asset performance management.

Condition management has three phases: collecting information (which is comparable to traditional condition monitoring); analyzing information to spot trends and areas requiring action; and acting on the results. Also, where traditional condition monitoring tends to be equipment or area focused, condition management takes a complete contextual view in bringing together operations, maintenance and engineering to resolve critical business issues. Where the previous era of condition monitoring focused on gathering plant level data and making it available as information, condition management goes the next step, advancing information to knowledge and action.

The difference is much more than semantic. Where condition monitoring will help you estimate when a valve might need to be replaced from a wear perspective, condition management might add the business context, assisting you in balancing the risks and gains of replacing that valve this month or next and also ensures that all the key stakeholders are engaged in the decision.

Condition management also extends to fully integrate with DCS/PLC, safety and equipment diagnostic systems, ideally presenting information from these systems through business intelligence frameworks.

1107_beyondeam1The value of condition management is clear. A recent industry survey shows that on average, more than 5% of production is lost every year to unplanned or unexpected outages. For a plant with a total production value of $50,000,000 per year, this amounts to $2,500,000 annually in lost production. The role of condition management is to monitor the key assets that have the largest impact on production, providing early warning of any impending failure, allowing the plant personnel to proactively deal with the issue before it causes a costly shutdown and/or extended outage. In our example, using a conservative estimate of a 30% reduction in outages yields an annual return of more than $750,000.

This predictive capability is further extended by condition management’s ability to collect key performance data to support RCM (Reliability Centered Maintenance) analysis. Based on an independent industry survey conducted by Invensys, more than 50% of preventive maintenance, while valuable in terms of preventing outages, is unnecessary and can often introduce problems. By analyzing the RCM data collected via condition management, organizations can greatly reduce the level of unnecessary maintenance, delivering a further 10-20% reduction in maintenance spending.

Decision support
Condition management also fuels decision support systems that further integrate and present data from additional sources, including all other components of the EAM system: real-time, historical and analytic plant operations data and other plant and business information, including (especially) financials and customer order management systems.

Such data can be presented through role-specific “digital dashboards” (similar to Fig. 2) tailored to show only the information that users require to make informed decisions within their roles and in the context of the key performance indicators and dynamic performance measures for their department, plant or overall operation. These dashboards can combine multiple formats—meters, graphs/charts, tables, raw statistics and spatial data, with full drill-down and drill-around capabilities.

Knowledge management
The real-time integration is much more than a simple process of catching an alarm/alert and generating work requests. It requires full workflow capability that enables engagement of key individuals in the resolution, including operations, engineering and maintenance with full visibility at the management level. It also requires direct connection to devices, system and process alarms/alerts through control system historians and equipment condition monitoring solutions to provide the complete set of information required to understand the context of the potential issue.

In addition, this integration must extend to an HMI in the control/operations environment to allow the operations personnel to spot potential issues immediately, drill down into the details and history and fully interact with the maintenance team and maintenance application(s).

The information solution must further include the ability to capture all the key readings and trends for the critical assets that are necessary to support reliability and availability analysis, which is fundamental in supporting the move to a proactive and predictive approach to operations and maintenance.

Today’s technologies allow us to more effectively capture this wealth of data. Knowledge management is the process of capturing the context and interrelationships of the data points to deliver usable and actionable information. With the “greying” of the workforce, a systematic and automated approach to knowledge capture is fundamental —and a critical element in the move to APM.

The measure of success
Although general descriptors of asset availability and utilization provide a sense of the operation of an asset base, they are lacking in specificity and in any real-time context. Both are required to provide operations and maintenance with an effective performance measurement system. A more specific approach would be to measure the following dimensions:

  • Effective Asset Availability—the maximum output possible from an asset set in the current state divided by the theoretical maximum output.
  • Effective Asset Utilization—the current output from an asset set divided by the maximum output possible in the current state.

These definitions preserve the integrity of the initial descriptors, and provide real-time context, as well as more accurate assessment of the performance of the operators and maintenance teams. Regardless of which definition is used, it is clear that there is a strong relationship between availability and utilization. It turns out that the relationship tends toward the inverse (Fig. 1) as availability and utilization approach their maximums. This inverse relationship presents a challenge to the maintenance and operations teams in industrial plants because the better they do their individual jobs, the more they will tend to negatively impact each other.

Balancing these factors requires an effective business measurement system that can provide business value insight into the desired operational balance between effective availability and effective utilization. Invensys has a patented approach to real-time business measurement that does exactly this: dynamic performance measures (DPM). DPMs measure the business value of base assets, asset sets or groups of asset sets as a real-time vector that represents the true value that they generate. Instead of optimizing availability or utilization, manufacturers are now able to optimize the business value.

1107_beyondeam2

The real-time business performance data (DPMs) enables a much more effective approach to true asset management. Rather than merely managing the availability of some instrumentation, plant personnel can drive business performance from asset sets, up to and including the entire plant. To bridge the gap between the traditional approach to asset management and asset performance management, a threelevel model has been developed (Fig. 2).

In this model, the Base Asset Management level represents the narrow approach traditionally deployed in industrial plants in which base assets, such as instruments and valves, were independently managed from an asset availability perspective. As a matter of fact, even this level is an expansion on the traditional approach to asset management since it includes effective utilization as well as effective availability improvements.

The second level, Asset Set Optimization, goes beyond traditional asset management by combining assets into logical production sets through the use of advanced technologies, such as first principle models so an entire logical set of assets can be effectively managed.

The third level, Business Performance Management, is an all-encompassing level in which advanced technologies and business measures, such as predictive maintenance and multivariable predictive control, can be used in balance with each other to maximize the business value generated of groups of asset sets.

Almost all organizations have the core elements in place that are required for utilizing asset performance management data to drive business value. When implementing this approach, however, it is important to evaluate the current state of the plant. In particular, there are five key elements that must be assessed:

  • What is the culture of the company? Are the company and employees ready and willing to change and do they recognize the issues involved with changing?
  • Do the employees have the skill base that is required for implementation?
  • What are the current business processes in place? Business processes must be evaluated to see if they are current, optimized and built on best practices and benchmarks.
  • What is the current technology level? The technology must be assessed to see if the company is based on current and open standards, and what level of enterprise integration is employed.
  • Is corporate knowledge readily available and accessible?

While being up-to-date on all these elements is not necessary, all must be evaluated to determine the current status of the plant and how and where to move forward. This will aid implementation, help to identify risks and establish a phased plan for full implementation.

Neil Cooper is vice president, Asset Performance Management Solutions, a key member of the Invensys Process Systems (IPS) Global Marketing Group. Prior to joining Invensys four years ago, Cooper was the president of Indus Canada.

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6:00 am
November 1, 2007
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Planned Maintenance Activities Revitalize An Aging Plant

Teamwork is truly a key ingredient in the juiced up production and maintenance efforts at this facility.

The Ocean Spray Cranberries Inc. [OSC] Bordentown, NJ facility was getting a bit “long in the tooth.” Originally constructed in the late 19th century as a Worsted Wool plant and then converted by OSC in 1946, it operated for many years with minimal preventive maintenance. Over time, the facility began having difficulty meeting its obligations. In August 2004, newly appointed plant manager Tim Haggerty and corporate continuous improvement manager Jerry Langley invited Charles Brooks Associates, Inc. (CBA) to conduct a maintenance benchmarking evaluation and help develop an action plan to improve the overall performance of the facility. This process had been used in other OSC facilities for a number of years with great success. Over the course of the next two years, the Bordentown plant began making remarkable improvements in both production and maintenance performance.

During the initial benchmarking by CBA back in 2004, the facility scored 466 out of a possible 1000 on a worldclass maintenance scale. Specific opportunity areas were identified during the survey and recommendations were communicated to the management team during the wrapup meeting. The team was encouraged to:

  • Develop and communicate a coordinated plan for asset care improvement.
  • Develop effective metrics for measuring maintenance contribution to plant performance.
  • Restructure the maintenance function to support the operations.
  • Improve the utilization of Maximo:
    • Capture of maintenance costs
    • Analysis of asset performance data
  • Determine if assets were capable of performing at required levels (and upgrading if necessary).
  • Evaluate maintenance skills and provide the required high-impact training.
  • Determine the appropriate maintenance approach for each asset, including center-lining.
  • Improve the execution of the planned maintenance process:
    • Level 1 (Operators’) PMs
    • Maintenance PMs
    • Overhauls

1107_pmactivity1The local OSC management team began to evaluate its staffing and processes immediately after the benchmarking and discovered that it was not prepared to take the plant to the next level. At that point, plant manager Haggerty chose to move the facility out of the reactive maintenance mode into a planned maintenance mode through a series of staff moves and strategic hires.

A plant-wide strategy
In September 2005, Charles Brooks Associates began providing interim maintenance management by assigning Dan Simpson to the facility on a full-time basis. A thorough analysis was made of all hot-fill bottling equipment to determine what steps were required to bring the facility up to acceptable standards. OEMs and vendor representatives had been contracted prior to Simpson’s arrival to conduct complete technical evaluations of their equipment.

The result of the evaluations was a plant revitalization strategy that identified over $325,000 in parts that were required. One fact was evident: the equipment was not receiving the preventive maintenance attention it required. The following month (October 2005) the plant conducted its first “revitalized” maintenance down day. The postmortem revealed the following:

  1. Hourly employees from both production and maintenance completed a great deal of very necessary work.
  2. The planning process and the presentation of THE PLAN from the maintenance department needed improvement.
  3. More and better interaction with production operations was needed. Production participation in the preventive maintenance (PM) process needed to be expanded to enhance equipment knowledge and increase available PM resources.
  4. There was a definite need for a “make ready” meeting prior to the down day kickoff, as well as a need for a process to allow the team’s progress to be tracked throughout the day.
  5. It was determined that critical equipment (filler, capper, labeler, case packer) must receive preventive care during every down day, both from production and maintenance.

As time went on, each and every down day was evaluated and improvements were made before the next down day was scheduled. The maintenance team included the maintenance manager, maintenance supervisors, maintenance planners and hourly employees who had specific technical knowledge of the critical equipment. Twelve-hour maintenance down days were scheduled every week for each of the packaging lines.

Delivering via a reshaped program
When new technical services manager, Herb Nielson, came onboard, he began to reshape the technical team, including the maintenance operation. One notable change was the assignment of Phil Camerota as permanent maintenance manager. Camerota had a background in aircraft maintenance with the U.S. Air Force—he definitely understood the importance of prevention. His experience with aircraft coupled with his plant experience gave him a full appreciation of what could be accomplished.

To support the planned maintenance effort, two maintenance planners were assigned to work with the existing Maximo maintenance management software. Tom Krepp and Warren Bell assumed the roles as maintenance planners, conducting both pre- and post-down day meetings. Down day schedules were prepared and monitored, assigning work orders to individuals on an hour-by-hour basis. By continuously monitoring the progress of the down days, resources could be shifted from one activity to another to ensure that the most critical activities always were completed.

1107_pmactivity2To address the technical skill needs of the maintenance department, Chris Guldner of CBA worked with the OSC maintenance team to develop and implement a skills evaluation process. The process included supervisory observations, self evaluations and the use of the Minimizer, a device for evaluating mechanical and electrical ability. The results of the skills evaluations were used to create individual development plans for maintenance personnel.

Working with the new production manager, Bill Garcia, the maintenance team has been able to signifi- cantly improve the performance of the packaging assets of the facility. The cooperation between maintenance and production has improved, and the results show it:

  • 25% improvement in bottling throughput efficiency performance
  • 25% reduction in unplanned downtime
  • 24% increase in bottling output (cases/day)
  • 1,068,240 additional cases produced in a 5-month period due to increased line efficiencies.
  • $1,068,240 of additional available sales volume

Haggerty, Nielson and Camerota all recognize that none of this progress could have occurred had it not been for the buy-in and support of the front-line mechanics, electricians and controls technicians. As Haggerty says, “All of those individuals are professional in their own right, and as such have been looking for a professional, specific, process to follow. These people have always wanted to do the right job, with the right equipment and parts, but past decision-making put them in a position of having to do the ‘best job they could with whatever they had available.’ This new focus and drive has really made a significant step improvement, not only in the operations, but in the daily work life of each maintenance employee.”

The sweet taste of success
While a great deal has been accomplished, there is much left to be done as the facility strives to become a world-class bottling facility. The OSC team at Bordentown has accepted the challenge and is moving ahead implementing new tools, conducting additional training and exploring creative ways to improve asset performance.

In July 2006, Charles Brooks Associates once again conducted a maintenance benchmarking of the Bordentown plant. The survey revealed the percentage of maintenance work that was planned in advance had increased from less than 20% in 2004 to 71% in 2006. Maintenance personnel are now recording over 90% of all hours worked on work orders and maintenance schedules are being honored. Production and maintenance managers meet every day to discuss asset performance and the top three downtime causes are analyzed. The Bordentown facility improved its overall maintenance score by 39% and recorded “best in class” in the areas of planning and scheduling and maintenance procedures.

Bordentown plant manager Tim Haggerty has spent 33 years in container manufacturing and beer/ juice packaging, including 27 years with Coors and 6 years with Ocean Spray Cranberries, Inc.

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