Author Archive | Maintenance Technology

36

7:43 pm
May 15, 2017
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SAP Tips and Tricks: Manage Assets with Refurbishment Order

By Kristina Gordon, DuPont

randmWhen assets need to be refurbished or fabricated, SAP offers an order type called a Refurbishment Order. The purpose of this order is to assist sending the item to a repair shop, either on or off site; having that asset repaired or fabricated; and then receiving it back into inventory at a different valuation or cost. The new store-room inventory value will be based on the cost charged to the refurbishment work order.

Name a work order type by whatever nomenclature your company uses. In this example, we will call the refurbishment work order type WO10. When creating and executing a refurbishment work order, follow these steps from creation to closure. Note that some of the transaction codes used here are finance- and costing-based. Such steps may be designated only by your finance department.

1. Set up transaction IW81 (standard SAP transaction code for refurbishment):

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2. Fill in the needed information (note that the screen layout looks very different from a work order created in IW31):

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3. Create the operation steps for internal labor and a line with your PO information for outside services:

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4. Add the asset/material to the work-order components, then release and save the order:

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5. Once work is completed and the asset/material is ready to be returned into inventory, confirm the internal labor hours to the work order that was added in step 3, using transaction IW41.

6. Add actual overhead to the work order using transaction KG12:

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7. After time confirmations are completed and material movements have been made, TECO the work order.

8. Using Transaction IW8W, return the material back to inventory.

9. It is now time to financially settle the work order. This will also change the value of the material in inventory (Note that this screen looks very similar to the overhead calculation screen in KG12):

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Creating and executing a refurbishment order is more labor-intensive than normal work-order types. However, refurbishment orders will keep your inventory value correct and maintain complete tracking and history of the work performed on the asset. MT

Kristina Gordon is SAP PM Leader, DuPont Protective Solutions Business, and SAP WMP Champion, Spruance Site, Richmond, VA. If you have SAP questions, send them to editors@maintenancetechnology.com and we’ll forward them to Kristina.

46

6:01 pm
May 15, 2017
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Use IR Switchgear Windows Properly

IR windows provide a measure of safety and reduce labor by allowing thermographers to inspect switchgear without opening panel covers. (Photo courtesy of Fluke Corp.)

IR windows provide a measure of safety and reduce labor by allowing thermographers to inspect switchgear without opening panel covers. (Photo courtesy of Fluke Corp.)

By Jim Seffrin, Director, Infraspection Institute

In an effort to reduce the risk of injuries associated with arc flash, many sites have installed infrared (IR) transmissive windows or ports that permit IR inspections of switchgear without the need to open panel covers. Although such devices can provide a measure of safety and help to reduce labor associated with those inspections, they pose unique challenges not associated with direct line-of-sight imaging.

Switchgear windows are typically constructed of a rigid frame with a fixed IR transparent material that enables an imager to view through them. Switchgear ports consist of a rigid frame with small openings through which an imager may be sighted. Depending upon type, some feature a single hole, others incorporate metal screens containing multiple holes.

randmIR windows will always attenuate infrared energy received by the imager. While this attenuation affects qualitative and quantitative data, the greatest challenge involves temperature measurement. Accurate temperature measurements can’t be obtained through a screened port. Furthermore, the ability to accurately measure temperatures through an IR window is possible only if the following conditions are met.

• The window opening must be larger than the imager’s lens objective.
• The target must be at or beyond the imager’s minimum focus distance.
• Values for window transmittance and target emittance must be known and properly entered into the imager’s computer.
• The imager’s lens must be kept perpendicular to and in contact with the window.

When it is not possible to meet all of the above conditions, imagery should be evaluated only for its qualitative value. As always, any inexplicable hot or cold exceptions should be investigated for cause and appropriate corrective action taken. MT

Words to the Wise: Beware Hidden Electrical Danger

Getting ready for an infrared inspection of electrical equipment often requires manual preparation of switchgear components, which could be a riskier endeavor than many people might think. Unwary thermographers and other personnel can, in fact, be injured through contact with cabinets or component surfaces that have become accidentally or unintentionally energized.

Switchgear enclosures and components are generally designed to prevent their surfaces from becoming energized. Under certain circumstances, however, enclosures and other dielectric surfaces can become unintentionally energized to significant voltage levels. This potentially lethal condition can be caused by improper wiring, faulty equipment, or contamination due to dirt or moisture.

When conducting infrared inspections on or near electrical equipment, always keep the following in mind:

• Only qualified persons should be allowed near energized equipment.
• Treat all devices and enclosures as though they are energized.
• Never touch enclosures or devices without proper PPE (personal protective equipment).
• Do not lean on or use electrical enclosures as work surfaces.
• Always follow appropriate safety rules.
• Know what to do in case of an accident.

Working alone near exposed, energized electrical equipment isn’t just dangerous, it’s a violation of federal law. Thermographers who perform infrared inspections on any electrical equipment should never work alone. Since CPR can’t be self-administered, at least two people trained in first aid and CPR must always be present when working near most exposed, energized equipment. Having a second CPR-trained person along not only satisfies OSHA requirements, it may save your life.

To paraphrase a time-honored electrician’s admonishment, remember that while there are old thermographers and bold thermographers, there are no old, bold ones.

Jim Seffrin, a practicing thermographer with more than 30 years of experience in the field, was appointed to the position of Director of Infraspection Institute (Burlington, NJ), in 2000. This article is based on several of his “Tip of the Week” posts on IRINFO.org. For more information on electrical systems, safety, and other infrared-related issues, as well as various upcoming training and certification opportunities, email jim@infraspection.com or visit infraspection.com.

15

2:29 pm
May 15, 2017
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Final Thought: Back to Basics For a Better Future

klausblacheBy Dr. Klaus M. Blache, Univ. of Tennessee, Reliability & Maintainability Center

During a trip to Europe, several years ago, I visited the German Museum of Science and Technology in Munich (the largest museum of this type in the world). While there, I marveled, as many do, at the machinery and equipment that people have designed and built without the help of modern technology. Consider the many windmills that used to be so prevalent across the European landscape

According to Low-Tech Magazine (Barcelona, lowtechmagazine.com), at their peak, the total number of wind-powered mills in Europe was 200,000. The Netherlands alone is reported to have had 9,000 of them by 1850. Based on a capacity of about 50-hp each, that calculates out as roughly 450,000 hp to mill grain, pump water, and support other industrial uses.

The craftsmen of those early, engineered wonders were driven to do great work, mostly because their livelihoods depended on it. Today is not that different. For example, as stated in a Feb. 2015 Los Angeles Times article, The Boston Consulting Group (Boston, bcg.com) predicted that investment in industrial robots would grow 10% a year in the world’s 25-biggest export nations through 2025, up from what, at the time, was said to be 2% to 3% annual growth.

Those numbers reflect just one of many such projections that popular news outlets seem to continuously share. Regardless of automation’s actual rate of growth in industry, for purposes of reliability and maintenance (R&M), the reality is that our skilled trades need more technical knowledge to understand wireless controls, computer interfaces, machine learning with predictive technologies, big data, and digital connectivity.

A lot can be accomplished right now. It starts with getting better at doing the basics well with proven best practices. Much of this falls into the category of precision maintenance.

My 2016 study comparing the savings resulting from precision-maintenance training with those from general-maintenance training showed that the benefits of applied precision maintenance were greater by a factor of four. Precision-maintenance training teaches trades and plant-floor engineers essential manufacturing skills. Examples of such skills include asset care and operation and machine assembly and installation, plus hands-on knowledge of precision alignment, pumps and pumping systems, gearboxes, and root-cause failure analysis.

Maintenance best practices will continue to be key to manufacturing competitiveness.

Maintenance best practices will continue to be key to manufacturing competitiveness.

The payback

You recognize a skilled craftsman when you see one at work. It’s evident in how he or she takes care of every detail, checks and rechecks the work, and shows pride in doing something right the first time, every time. Sadly, for reasons such as time pressure, lack of training, and organizational culture, among others, there’s been a decline in craftsmanship over the years. I am, though, of the opinion that most personnel, if given the opportunity and an enabled work environment, want to do the best job possible. At the same time, the generally accepted number for human error in maintenance issues is greater than 50%. A thorough comprehension and application of precision maintenance can reduce that percentage.

Of course, we first have to find adequate numbers of qualified technical workers. That’s a challenge. According to the Georgetown Univ. Center on Education and the Workforce (Washington, cew.georgtown.edu), by 2020, the United States will be short 5-million workers with the necessary technical certificates and credentials to succeed in high-growth, high-demand industries.

In 1991, the National Research Council (NRC, Washington, nationalacademies.org/nrc/) investigated U.S. manufacturing competitiveness. The subsequent report stated, “…the most cost-effective increase in U.S. manufacturing capacity may well be achievable through improved maintenance practices for existing equipment.”

Fast-forward 26 years: I believe this NRC statement holds true in 2017, and will continue to hold true in industries of the future. MT

Based in Knoxville, Klaus M. Blache is director of the Reliability & Maintainability Center at the Univ. of Tennessee, and a research professor in the College of Engineering. Contact him at kblache@utk.edu.

95

2:22 pm
May 15, 2017
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Facilities vs. Factory Maintenance: Is There a Difference?

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The common denominators boil down to assurance of reliable equipment assets and successful delivery of product.

By Jeffrey S. Nevenhoven, Life Cycle Engineering (LCE)

Among reliability and maintenance (R&M) professionals, there are many opinions about the universal or, more precisely, not-so-universal nature of maintenance practices. We’ve all heard statements along the lines of “this organization is different,” “we’re not like them,” or “those best practices won’t work or fit here.” One perception shared by many working in the R&M trenches is that maintenance in a batch-processing manufacturing environment is considerably different from maintenance in a continuous-flow operation. Another common perception is that maintenance principles and practices within the world of non-manufacturing facilities differ greatly from those in a manufacturing organization. But do they really?

At first glance, those strongly held beliefs might seem justifiable. Below the surface, however, the inner workings of any organization are quite similar when it comes to R&M requirements. Why, then, do so many people contend that reliability and maintenance are handled differently within distinct organization types? A number of factors drive those beliefs, including operating environment, regulatory requirements, organizational structure, leadership style, business priorities, expectations, and past practice. On top of that, many influences figure into the perception that something will or will not work within a specific organization.

In reality, physical assets are void of emotion and thought. Regardless of location or organization type, such assets need to be operated and maintained appropriately and, in turn, be available to deliver reliable service, as required. Without reliability, business risks increase, asset-performance levels decrease, and costs escalate.

So different, but so similar

Assets, systems, procedures, departments, and workers exist to produce a product or service, regardless of organization type. In the healthcare sector, the product is patient experience. Within amusement, entertainment, and sports markets, it is fan/customer experience. Within the travel industry, it’s passenger experience. Within the education system, the deliverable is student experience. And, within manufacturing, the product is ultimately consumer experience.

Consider, for example, two starkly different environments: a healthcare operation and a refinery. On the exterior, a healthcare organization, such as a hospital, looks very different from an oil-and-gas refinery. Hospitals consist, primarily, of aesthetically appealing buildings and grounds while oil refineries consist of tanks, piping, and other industrial-looking structures. As we enter these operations, noticeable differences still exist.

Inside the hospital, we observe doctors, nurses, patients, and other healthcare professionals at work. At the refinery, we see operators, crafts, engineers, and other industry specialists performing their duties. One facility encompasses exam, emergency, and operating rooms, labs, registration desks, and waiting areas, while the other encompasses control rooms, repair facilities, material storage areas, and production equipment and environments.

Once we look beyond the exterior differences, though, similarities become more noticeable. Despite one organization focusing on patient health and the other on refining crude oil, both share a long list of common business practices, have comparable organizational structures, and utilize physical assets. Both are delivering a product, and both require reliable, well-maintained equipment to do it.

Healthcare operations, such as hospitals, fall under the category of facilities maintenance, or facility management, while refineries in the oil-and-gas industry fall under the factory-maintenance category. Despite the differences in form, fit, and function, these operations are very much alike when it comes to sustaining maintenance requirements. After all, the maintenance processes and practices to ensure that the HVAC system in a hospital is operational and reliable are similar to the efforts required to ensure the reliability and operation of a refinery’s cooling system.

The HVAC system in a hospital’s operating room requires the utmost care and reliability. Temperatures and airflow must be regulated within specific parameters throughout the entire surgical procedure to help prevent infection and promote healing of a patient. If the HVAC system is not working reliably, entire operating suites can be shut down, resulting in canceled surgeries, reallocation of patients to other hospitals, and even possible litigation and damage to reputation.

The process of refining crude oil into consumer fuels and other products entails several chemical-process steps that generate enormous amounts of heat and pressure. The cooling-water system, which is associated with a cooling tower, helps control these extreme temperatures and pressures by transferring heat from hot process fluids to the cooling system. Much like the HVAC system, the cooling tower is a critical asset that requires reliable operation. Unless it performs reliably, product delivery, product quality, energy consumption, the environment, and employee safety can be severely compromised.

Have the parallels between these different types of organizations become clearer?

Maintenance 101

A hospital HVAC system and a refinery cooling tower incorporate mechanical, electronic-control, transmission, and power systems, all of which need to be maintained properly. To achieve this, facility-maintenance departments and their factory-maintenance counterparts need to ensure that the following foundational methods are established and functioning well. Think of these methods as “focusing on the fundamentals” or “the blocking and tackling” of maintenance:

Asset-care program. Most assets within any organization require some level of preventive care. This includes routine cleaning, lubrication, inspection, and adjustment to maintain reliable operation which invariably includes time-based and condition-based maintenance. This should all be documented and monitored through the maintenance strategy program.

Work-management system. The work-management system encompasses the framework, infrastructure, processes, and resources needed to manage asset-care activities, reactive or proactive. It provides the means to identify, prioritize, perform, document, and report work.

Planning and scheduling function. The planning and scheduling function defines the what, how, who, and when for proactive-maintenance work activities. The collective effort of planning and scheduling aims to minimize asset downtime, improve workforce efficiency and, reduce maintenance-induced failures.

Stores (MRO) inventory-management function. To effectively fulfill its mission, the maintenance function requires reliable and prompt material support. A proficiently managed MRO (maintenance, repair, and operations) inventory storeroom contributes to improved equipment reliability, workforce efficiency, and cost control.

Reliability engineering. The reliability engineering function is responsible for driving out sources of repetitive failure. Its mission is to provide leadership and technical expertise required to achieve and sustain optimum reliability, maintainability, useful life, and life-cycle cost for an organization’s assets.

Computerized maintenance-management system (CMMS). Proactive-maintenance organizations use data to effectively handle work activities, report performance, track costs, and enable continuous improvement efforts. The CMMS automates these processes, captures data, and provides information required to enable resource productivity and asset reliability.

Universal application

Regardless of where an asset resides, reliability depends on core reliability and maintenance fundamentals that span all industries and organizational types. Whatever the assets may be, i.e., motors, pumps, compressors, robots, conveyors, boilers, elevators, escalators, pelletizers, utilities, mobile equipment, fire-suppression systems, rotary-tablet presses, chillers, rolling mills, roadways, buildings, you name it, all require specific amounts of downtime for proactive preventive- and predictive-maintenance activities, including, but not limited to, replacement of wear parts, rebuilds, upgrades, and other improvements. Levels of maintenance may vary by organization type, but the fundamental requirement for it is universal. MT

A senior consultant with Life Cycle Engineering, Charleston, SC, Jeff Nevenhoven helps clients align organizational systems, structures, and leadership styles with business goals. Contact him at jnevenhoven@LCE.com.


learnmore2“Alignment Connects Individuals to Organization Objectives”

“Managing Your Value Stream”

“Get to the Root of the Cause”

“Profiles Reveal Reliability Trends”

109

6:14 pm
May 10, 2017
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Don’t Neglect Electrical Equipment Maintenance

Human error and improper maintenance, akin to operating a car and not checking the oil, can lead to catastrophic results to equipment and personnel involved.

Human error and improper maintenance, akin to operating a car and not checking the oil, can lead to catastrophic results to equipment and personnel involved.

Electrical equipment that is not properly maintained is notNFPA 70E compliant and, therefore, dangerous to personnel and business operations.

By James Godfrey, CESCP, Craft Electric & Maintenance

Since the release of the 2015 edition of NFPA 70E, “Standard for Electrical Safety in the Workplace,” there seems to be a tremendous push by companies to achieve compliance, and rightfully so. As noted in this standard, more than 2,000 people each year are admitted to burn centers with severe arc-flash burns.

NFPA 70E states that an arc-flash risk assessment shall be performed and shall determine if an arc-flash hazard exists. Arc flash is the result of an arcing fault that bridges the air gap between conductors such as phase to phase, phase to neutral, or phase to ground. In an article published in Safety and Health Magazine (August 2009) the most common cause of arc-flash accidents is human error. However, such things as the accumulation of conductive dust inside an enclosure and equipment failure, most likely the result of inadequate maintenance, can also cause these arc-flash events. In short, if electrical-equipment maintenance is neglected, something is going to blow. When that happens, it can be catastrophic.

OSHA CFR 1910.303(b)(1) states that electrical equipment shall be free from recognized hazards that are likely to cause death or serious physical harm to employees. Simply put, condition of maintenance must be considered. NFPA 70E states that electrical equipment shall be maintained in accordance with manufacturer instructions or industry-consensus standards to reduce the risk associated with failure.

The term “industry-consensus standards,” typically refers to a standard that has been accepted as recommended practice such as NFPA 70B, “Recommended Practice for Electrical Equipment Maintenance.” This standard addresses such things as development and implementation of an electrical preventive-maintenance (EPM) program, recommended intervals for maintenance, testing and test methods, reliability-centered maintenance (RCM), and acceptance testing.

When having an arc-flash risk assessment performed and not addressing the maintenance component of an electrical safety program, some assumptions must be made. These include, but are not limited to, equipment that is operating properly, equipment that has been properly maintained, and condition of maintenance, as well as opening times of over-current protective devices.

If an arc-flash risk assessment has been performed, then the amount of incident energy must be observed before removing equipment covers.

If an arc-flash risk assessment has been performed, then the amount of incident energy must be observed before removing equipment covers.

NFPA 70E states that over-current protective devices that have not been properly maintained can cause increased opening times, thus increasing the incident energy in the event of a fault in the electrical-distribution system. This creates a major safety concern for personnel and their interaction with energized electrical equipment, as well as lost revenue due to equipment failure. As a result, careful consideration must be given to the development and implementation of an effective electrical-safety program to maximize benefit and minimize cost. The arc-flash risk assessment can be a costly endeavor and the results obtained can be misleading or inaccurate because of improper or inadequate maintenance.

Surprisingly, a high percentage of facilities are not OSHA and NFPA compliant and have little knowledge of what it takes to be compliant in the area of electrical safety. Furthermore, some are doing very little in terms of electrical-equipment maintenance and are satisfied with having infrared scans done on the electrical panels because it has been recommended by their insurance company. Infrared thermography is very effective at identifying heat-related issues, but does not satisfy the requirement to maintain electrical equipment in accordance with manufacturer instructions or industry-consensus standards.

Infrared technology generally requires a direct line of sight to the target area, which raises another safety concern. Pursuant to the NFPA 70E requirements, the level of risk must be assessed before removing equipment covers and exposing energized conductors and circuit parts. To properly assess the risk, such things as available fault current and opening times of over-current protective devices must be considered.

Available fault current is the amount of current that may be present at any point in the electrical system as a result of a short or fault condition. If a fault were to occur in the electrical system as a result of equipment failure or human error, the equipment affected may not be rated to handle the fault current and this could be catastrophic. If an arc-flash risk assessment has been performed, then the amount of incident energy (typically expressed in calories/cm2) must be observed and personal-protective equipment selected and put on before removing equipment covers.

At this point, a decision must be made, based on personnel risk, to open or not open equipment and expose energized conductors and circuit parts. If it is determined that removing equipment covers could expose personnel to an unacceptable risk, the equipment should be de-energized before performing any type of preventive maintenance. An infrared scan would be ineffective in this case.

When doing any work on electrical systems, proper personal-protection equipment is essential.

When doing any work on electrical systems, proper personal-protection equipment is essential.

Maintenance considerations

An effective preventive- and proactive-maintenance program should take into consideration safety, the age of the equipment, operating environment, and the criticality of the asset. If infrared scanning is the only form of preventive-maintenance approach that’s been employed, equipment reliability and safety have been compromised. That type of situation should be of great concern to plant managers, maintenance managers, technicians, and other employees.

As outlined in NFPA 70B, several available maintenance and testing options are specific to the targeted equipment. Take, for example, low-voltage service-entrance equipment, often referred to as switchgear. Some of the maintenance recommendations outlined in NFPA 70B include energized/de-energized inspection and de-energized cleaning. While the equipment is in a de-energized state, all bolted connections and cable terminations should be torqued, in accordance with manufacturer specifications.

During de-energized maintenance, molded-case/insulated case circuit breakers should be exercised manually to keep the contacts clean and help the lubrication perform properly. This simple maintenance procedure is often overlooked, and breaker failure is a common result. In addition, breaker testing (primary and secondary injection) and protective relay testing are also recommended. These and other factors must be considered when determining what compliance means and developing an electrical-safety program that satisfies the OSHA and NFPA requirements.

We’ve heard that, “an ounce of prevention is worth a pound of cure.” This phrase should have significant meaning when management is struggling with how to comply with the latest regulations imposed by OSHA as it relates to safety in the workplace.

Among the several elements that make up an effective electrical-safety program, electrical-equipment maintenance is one that cannot be ignored. When the decision is made to have an arc-flash risk assessment performed, consider the condition of maintenance of the electrical equipment and the affect it will have on the results of the risk assessment. This will ensure that employees stay safe and assure management that money appropriated is well utilized. The result of a well-administered electrical-safety program will reduce life-safety risk, cut business interruptions, and extend the life of electrical equipment. MT

Jay Godfrey, CESCP, has more than 25 years of experience in the electrical-contracting industry and is a licensed electrical contractor in Georgia. Godfrey is OSHA trained, NFPA certified and, for the past eight years, has been working as a preventive-maintenance and electrical-safety consultant with Craft Electric & Maintenance, Atlanta.

45

7:25 pm
April 13, 2017
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Surge Vessels Address Hydraulic Shock

Properly implemented surge vessels can optimize pump/piping-system performance and address hydraulic shock.

By Frank Knowles Smith III and Steve Mungari, Blacoh Fluid Controls Inc.

Damage to pumps and piping systems from hydraulic shock, also known as water hammer, can often result in catastrophic failure, along with expensive repair and downtime. 

In the world of petrochemical processes, hazardous conditions resulting from pump damage or line breaks can also bring about significant liability concerns, along with very negative publicity. With many plants and facilities currently in operation without protection against hydraulic shock, what can be done from a maintenance, repair, and operations (MRO) standpoint to avoid this inevitable problem? 

The issue

Under steady-state conditions, a plant’s pumping system will tend to operate near the nominal working pressure unless there is change of flow velocity. This change is defined as hydraulic shock and immediate mitigation efforts are needed to prevent damage from occurring. 

This fluid acceleration or deceleration can be attributed to several likely causes, with the most common being from either “pump trip,” or sudden valve closure. A pump trip, generated by sudden loss of power to the pump station or by a pump stop without warning, can drop the working pressures near the pump’s discharge side to negative levels and cause possible vapor-pocket collapse.

The sudden valve closure from electrical, hydraulic,  or mechanical failure, or from human action, can result in a dramatic increase in pressure at the inlet side of the closed valve. That pressure increase is experienced as high-velocity (potentially exceeding 4,000 ft./sec.) transient pressure waves that will oscillate throughout the piping network unless the transient wave energy can be suppressed. 

Pipes that shake violently, even occasionally with restrained piping, and with loud banging noises are the ones typically experiencing hydraulic shock. Pumps and motors are also likely to be damaged concurrently as the transient-pressure energy waves travel back through the pump until the check valve slams shut.    

Weak points in the piping network, such as flange connections and pipe elbows, tend to bear the brunt of the pressure wave’s damaging effect and are often the first to break.    

In a single-pump system, several transient-mitigation options are available to address the transient wave’s effects. Some of the most popular are surge vessels, air-release/vacuum valves, pressure-relief valves, surge-anticipator valves, and vacuum breakers. Even with an existing facility or pipeline, space is often readily available to accommodate which specific pieces of mitigation equipment are necessary to solve the problem. However, what does the facility do when the plant is pumping in series?

Case in point

A large oil-industry customer, involved with a chemical-process application, was looking for a way to protect their pumping system infrastructure from damage and repair expenses, along with reducing lost product costs from the breaks. 

For their application, a booster pump (which requires a minimum of 100 psi NPSH (net-positive suction head) is located approximately 10,000 ft. from a high-pressure injection pump. When power is lost at the booster pump’s location, with the high-pressure pump operating, a transient negative-pressure wave is generated. 

This wave causes a sudden pressure drop at the booster pump’s discharge side and travels at approximately 4,000 ft./sec., making contact with the high-pressure pump. In this situation, it’s important to protect the high-pressure pump from cavitation damage and maintain a minimum 100 psi NPSH on the booster pump.

Monitoring and protecting

Should the high-pressure pump trip when the booster pump is running, a high-pressure “up surge” transient pressure wave will be created at the inlet flange of the high-pressure pump. High pressure can also bypass the check valve and cause additional damage.

A properly sized surge vessel, with the sizing calculated through the use of computer surge-analysis software at the high-pressure pump, will accept energy from the pump trip. It will also be able to accept energy (compress vessel gas volume) on a high-pressure pump trip. 

On the high-pressure pump trip, the flow will stop, based on the system demand, and will pump dynamic head. However, there is a concern of reversal of flow back through the high-pressure pump from the up-surge transient wave due to check-valve closing time. 

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Fig. 1: Negative-pressure transient wave. Graph shows a transient negative-pressure wave on a pump’s discharge side that occurs when power is lost to a booster pump. Green shows booster-pump pressure and red shows high-pressure-pump pressure.

A properly sized surge vessel will accept the transient energy, but check-valve closing time will vary,  based on factors such as type of valve and pipe size. With the specific closing time a critical factor to the accuracy of the results from the computer surge analysis, this must be properly entered into the analysis. The results of the analysis can be verified at the time of commissioning using a report from a transient pressure-monitoring system, with the data being read and recorded at a minimum of 100 times/sec.

Fig. 2: Pressure variation without a surge vessel. Fig. 2 shows pressure variation in a system that is not equipped with a surge vessel. Green is the booster-pump pressure and red is high-pressure-pump pressure.

Fig. 2: Pressure variation without a surge vessel. Fig. 2 shows pressure variation in a system that is not equipped with a surge vessel. Green is the booster-pump pressure and red is high-pressure-pump pressure.

When evaluating how to size a surge vessel to deliver energy, or to keep the high-pressure pump’s NPSH correct in time to de-energize, further computer surge analysis is needed. In this example, the graph in Fig. 2 shows the booster pump tripped (pressure shown in green) while the high-pressure-pump suction pressure is shown in red. In monitoring the liquid level and pressure in the high-pressure pump’s suction-stabilizer surge vessel, the high-pressure pump can be successfully de-energized in 15 sec.

Fig. 3: Surge-vessel pressure at booster pump. Figure 3 shows the pressure inside of a surge vessel at the booster pump.

Fig. 3: Surge-vessel pressure at booster pump. Figure 3 shows the pressure inside of a surge vessel at the booster pump.

The pressure drop to the high-pressure pump’s minimum NPSH will keep the pump protected. Figures 3 and 4 show the change in pressure inside the surge vessel placed at the booster pump and at the high-pressure pump.

Fig. 4: Surge-vessel pressure at high-pressure pump. Figure 4 shows the pressure inside of a 106-ft3 surge vessel at a high-pressure pump.

Fig. 4: Surge-vessel pressure at high-pressure pump. Figure 4 shows the pressure inside of a 106-ft3 surge vessel at a high-pressure pump.

By making use of computer surge analysis to correctly assess the conditions with the booster and high-pressure pump conditions, the customer was able to understand how properly sized and placed surge vessels can assure optimize operational performance by confirming proof of design with transient monitoring of pressure and flow.

With the surge vessels properly located, potential damage to the pumps and piping network from hydraulic shock was eliminated. As a result, considerable time and equipment cost savings were realized.RP

Frank Knowles Smith III is executive vice president of the Surge Control team at Blacoh Fluid Controls Inc., Riverside, CA (blacoh.com). He has three decades of academic, design, and application experience. Steve Mungari is the business development manager at Blacoh. He has more than 20 years of process-control experience in the areas of fluid measurement and control technologies.

489

6:23 pm
April 13, 2017
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Maintenance Efficiency: Understand It To Drive It

Various factors and measurements affect an organization’s ability to improve workforce efficiencies.

Worker of oil and gas refinery

By Al Poling, RAM Analytics LLC

It’s a given: Maintenance is the largest fixed cost in manufacturing. Maintenance-workforce efficiency has a profound effect on that cost and, in turn, overall business performance. Can that efficiency be improved and, if so, how?

The common metric used to measure this efficiency is wrench time. Research on wrench time has revealed maintenance workforce efficiencies ranging from 18% to 74%. In other words, inefficient maintenance operations will spend exponentially more on maintenance labor than the most efficient operations to complete the same amount of work.

To illustrate the significant financial impact of maintenance workforce efficiency, a highly efficient operation with 74% wrench time spends $100 million/yr. on maintenance labor. A highly inefficient maintenance operation would spend more than four times that amount (or more than $400 million annually) to complete the same volume of work. Translation: The inefficient maintenance operation would waste $300 million a year due to inefficiency.

Critical factors

Numerous factors influence effective use of maintenance labor resources. At the top of any list, however, is a well-defined maintenance-work process. This type of process describes, in detail, each step of maintenance work from identification through execution and closure. Despite claims to the contrary, there is effectively only one universally used maintenance workflow. The five major components are identification, planning, scheduling, execution, and closure:

Identification is the timely pinpointing and prioritization of maintenance work. These activities are performed by equipment operators who use a well-defined work-prioritization matrix or by maintenance coordinators who base priorities on business and related needs.

Planning is formal organization of the work to be done, including scope assessment and identification and procurement of the labor and materials required to complete the job.

Scheduling includes setting the optimum time period in which to complete the planned work. It takes into account the overall resources required at the site and attempts to level the resource load to use normally available maintenance resources.

Execution is the actual hands-on work performed by skilled maintenance craft personnel. This includes company personnel and contract maintenance workers.

Closure involves capturing work history, including critical information on failure modes used to facilitate reliability analysis.

Failure to have or follow a well-defined maintenance-work process results in chaos and, therefore, grossly inefficient resource utilization.

Tools and prep

The next factor that influences maintenance-labor efficiency is the availability of tools and materials required to complete the assigned work. Without that availability, work can’t be completed in a timely manner.

Wrench-time studies consistently reveal that traveling for tools and materials is the most common barrier to maintenance-workforce productivity. If highly skilled (and costly) maintenance-craft personnel have to spend time retrieving tools and materials, it will take significantly longer to complete the work, including possibly delaying completion. It’s troubling why so many organizations depend on highly skilled maintenance resources to perform such mundane work (material and tool transport) rather than assigning those tasks to less costly storeroom and/or delivery personnel.

Next in line as a detrimental impact on maintenance-workforce efficiency is the interface with operations. Equipment must be prepared in advance of maintenance work. Examples include equipment decontamination, lockout/tagout, and work permitting. If these types of tasks aren’t performed in a timely manner, wrench time will suffer. Paying highly skilled maintenance workers to stand around while operators perform such work—that should have been done in advance—is absurd. Yet, as wrench-time studies show, this is a common occurrence in today’s plants.

The culture effect

Empirical evidence suggests that particular work environments, or cultures, are more prone to maintenance workforce inefficiency. At the top of this list is an environment in which unreliable equipment reigns. In this type of reactive environment, it is virtually impossible to achieve high levels of maintenance-workforce efficiency. Unplanned failures, by their very nature, don’t facilitate planning and scheduling, leading to extremely inefficient and expensive reactive corrective work. As if this weren’t bad enough, it is invariably the value of lost production and subsequent lost profit that causes the greatest economic harm to the site and business. Sadly, these costs are often overlooked.

The next environment most prone to maintenance workforce inefficiency is one where maintenance labor costs are low. Southeast Asia, for example, experiences severe inefficiencies—often at appalling levels. In those regions, it’s not unusual to find human labor being utilized instead of equipment. For example, you might find large numbers of maintenance workers with shovels doing the work that a single bulldozer could complete in short order. Sometimes, though, this is by design, i.e., to create more jobs to support a growing middle class. Nonetheless, while it’s an expensive way to operate, the costs can be more easily absorbed due to exponentially lower-skilled maintenance-craft wages.

Surprisingly, highly reliable operations represent yet another, although not necessarily obvious, area where maintenance inefficiencies can be found. In such environments, the business is typically enjoying very high profit margins as a result of achieving maximum production with existing assets.

Of course, it’s human nature for people to focus on what’s important and overlook anything that’s deemed less so. Thus, in a highly reliable production environment, as profits rise, maintenance-cost management can take on a lower sense of urgency. In extreme cases, the inherent inefficiency can lead to anywhere from tens to hundreds of millions of dollars in unnecessary maintenance expense. Interestingly, this situation may also occur in less-reliable operations when the market is tight and profits are high. (It’s not uncommon for managers to remove any maintenance cost controls as long as sales demands are satisfied.)

In both of those scenarios, however, maintenance inefficiency will only be tolerated as long as profit objectives are being met. As soon as market conditions change, pressure will once again be applied to maintenance cost and, subsequently, to maintenance-workforce efficiency. The reaction to this often-sudden change can be quite ugly as arbitrary rules with the potential for unintended consequences, e.g., discontinuing proactive maintenance as a way to reduce maintenance labor costs, are put in place.

Effective measuring

In an ideal production environment, skilled maintenance resources are used efficiently and effectively. As the father of statistical process control W. Edwards Deming advised, “You can’t manage what you don’t measure.”

To ensure that maintenance resources are being efficiently and effectively utilized, they must be measured. Although not used extensively today, the early 20th century methodology of maintenance-work sampling provides an effective means to measure wrench time. (Despite exaggerated claims by some that this sampling is akin to Frederick Taylor’s infamous time and motion studies of the late 19th century, it is not.)

Maintenance-work sampling is simply a statistical tool that, when used effectively, can measure maintenance-workforce productivity. Identification and elimination of barriers to productivity can significantly increase the value-added contribution of existing maintenance resources. Work sampling is the process of capturing and analyzing a statistically valid number of random observations to determine the amount of time, on average, that workers spend in various activities throughout their normal workdays. Non-value-added activities are then targeted for reduction and/or elimination using root-cause analysis.

The maintenance-work sampling approach is based on the proven theory that the percentage of observations made of workers doing a particular activity is a reliable measure of the percentage of total time actually spent by the same workers on the activity. The accuracy of this technique is, naturally, dependent upon the number of observations. To achieve a 95% confidence level in the results, approximately 3,000 observations must be made and recorded. While this might seem excessive, a single trained observer can collect that number of observations during a week of single 8- or 10-hr.maintenance work shifts.

Keep in mind that maintenance-work sampling makes it possible to measure utilization of work groups and the overall maintenance workforce. Key opportunities that warrant attention can be isolated and examined. A good example is that of travel time involved in obtaining requisite maintenance tools and materials and delivering them to where they will be used. That time can be accurately measured and a cost assigned simply by taking the number of total hours consumed by the activity and multiplying by the hourly rate.

Additionally, with maintenance-work sampling, unique factors that affect maintenance wrench time can often be identified. For instance, if inadequate means of communication exist between a work group and the supervisor, valuable time can be wasted tracking each other down. Radios or mobile phones, can solve this problem.

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The accompanying charts (Figs. 1 and 2) are based on a real-world case study where work sampling was leveraged to identify and eliminate maintenance-workforce inefficiencies. Figure 1 depicts a decline in non-value-added activities, while Fig. 2 depicts an increase in value-added activities.

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As these charts show, initial measurement of the site’s maintenance-workforce wrench-time revealed a mere 28% value-added work (wrench time). Through the systematic reduction and/or elimination of non-value-added activities over the course of three years, the wrench time rose to 74%. What really matters here, however, is the recovery of the value of time that was being wasted, as shown in Table I. (Efficiency gains can also be measured in terms of full-time-equivalents, as shown in Table II.)

As part of its development and publication of standard reliability and maintenance metrics, the Society for Maintenance and Reliability Professionals (SMRP, Atlanta, smrp.org) published its work-management metric, 5.6.1 Wrench Time, in 2009. The stated objective of this metric is “to identify opportunities to increase productivity by qualifying and quantifying the activities of maintenance craft workers.”

The Society also published the SMRP Guide to Maintenance Work Sampling, in 2012. As one of three co-authors, I can state definitively that the intent of this publication was to educate younger reliability and maintenance professionals who had not been exposed to maintenance-work sampling. Although adoption has been slow, several companies are beginning to include this sampling methodology as a valued component in their reliability and maintenance tool kits. Ironically, sites are often introduced to maintenance-work sampling by maintenance contractors who want to demonstrate the efficiency and effectiveness of the skilled maintenance-craft personnel they provide.

(Editor’s note: SMRP’s Guide to Maintenance Work Sampling is a simple “how to” document that includes statistical tables designed to help users understand the correlation of the confidence level associated with a number of observations. The guide can be purchased for a small fee at SMRP.org. The co-authors donated their time to the development and publication of this document and receive no royalties from its sale.)

Last words

While it might be enticing to simply reduce the number of skilled maintenance craft workers on site as wrench time increases, a more prudent path may be to redeploy resources and invest in failure-prevention activities and/or infrastructure.

Increased wrench time may also provide an opportunity to reduce overtime as resources become available and/or to reduce the reliance upon third-party maintenance resources. With today’s critical shortage of skilled maintenance workers, however, displaced workers would likely be able to secure employment elsewhere.

In summary, maintenance wrench time plays a significant role in measuring efficient utilization of skilled maintenance-craft personnel. This valuable metric can be used by any manufacturing operation to ensure that it is realizing the greatest return possible from its investment in human capital. MT

Al Poling, CMRP, has more than 36 years of reliability and maintenance experience in the process industries. He served as technical director for the Society for Maintenance and Reliability Professionals from 2008 to 2010. Contact al.poling@ramanalytics.net.

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5:18 pm
April 13, 2017
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‘Spring Cleaning’ For Your Fuse Inventory

Improve safety and reap cost savings through smart, streamlined ordering and stocking.

Sometimes it pays to take a fresh look at routine tasks. A major manufacturer of refrigeration and air-conditioning products was contacted by its electrical-equipment distributor regarding the site’s fuse orders. The production operation had hundreds of fuses in its storerooms—numbers that represented a $22,000 burden sitting in inventory.

Over time, those storerooms had accumulated fuses from a variety of manufacturers. For maintenance personnel, the natural impulse is to replace a blown fuse with one of the same brand, type, and rating. While this seems like the safest approach, it leads to unintended duplication in a storeroom. What’s more, workers continue to reorder fuses that may have become obsolete and/or they don’t update to more modern, safer types.

Seeking to determine how much of their current fuse inventory was really needed, managers at the site generated an electronic spreadsheet of such items in their storerooms and asked the electrical distributor to forward it to Chicago-based fuse supplier Littelfuse (littelfuse.com) for analysis. The results were, in simple terms, shocking.

The fuse vendor supplied a consolidated inventory list that reduced the number of SKUs by 37%—from 224 to 164. Several fuses, which may have been on the shelves for 10 to 15 years, were older styles that didn’t provide maximum safety and equipment protection. After managers cleaned out the old and confusing array of fuses and adopted the recommended consolidated fuse inventory, they were able to project a savings of approximately $6,000/year. 

Those savings, however, didn’t include the cost of downtime avoided by switching to indicating fuses that are more quickly identified when outages occur. Nor did the calculation factor in the labor savings from being able to quickly find a needed fuse on the shelf, or the potential costs of inadequate protection from the use of obsolete fuses.

A simple table posted in the storeroom allowed personnel to cross-reference old fuse types and brands with the new types they should use. To top it off, the vendor printed customized bin labels with the plant’s part numbers, reorder numbers, and barcodes for all fuse sizes.

Plants depend on hundreds of fuses, in panels such as this one, to protect workers and equipment.

Plants depend on hundreds of fuses, in panels such as this one, to protect workers and equipment.

Now, it’s your turn

Whether you work with a supplier or do it on an in-house basis, here are the steps for cleaning up your site’s fuse inventory.

1. Inspect for damage. Look for fuses that are not clearly marked and discard them. Issues such as flooding from storms or broken pipes can also damage fuses. If the sand or filler material inside the fuse gets wet, it may not safely quench the arc, and may never completely dry out. When in doubt, throw it out.

2. Identify outdated fuses. Print out your fuse inventory and highlight old fuse types such as Class H (renewable) and even Class K5 fuses.

Unfortunately, some workers still think that renewable fuses can be “repaired” and put back into service, but this is definitely not recommended. They have a low short-circuit interrupting capacity of just 10,000 A. They provide no current limitation, and there is no way to control what a worker will use as a replacement element. These fuses are truly obsolete, and UL prohibits renewables in new applications.

Also called “one-time” fuses, Class K5 fuses were an improvement over renewables. They are tamperproof, and have a higher interrupting rating of 50,000 A, but they provide no current limitation.

Class RK5 fuses are rated to 200,000 A and provide current limitation. They don’t provide the level of current limitation that the newer Class RK1 fuses offer. Current limitation is extremely important. It is used to reduce the danger of arc-flash hazards so that workers can wear less PPE. Current limitation also improves the short-circuit current rating (SCCR) and simplifies selective coordination. 

3. Consolidate. Give your inventory printout to your preferred fuse vendor and ask for a consolidated inventory list. The vendor will know which modern fuses to substitute for older types, know which types fit which fuse holders, and be able to cross-reference with other suppliers. Based on the experience of Littelfuse, typical savings for a large manufacturer range from $18,000 to $30,000.

4. Upgrade to indicating fuses. Indicating fuses are a common-sense way to decrease downtime. When a fuse opens, the maintenance worker can quickly identify which fuse or fuses need to be replaced. In contrast, when indicating fuses are not used, significant downtime can occur and personal safety can be jeopardized.  

When one or more fuses blow and shut down a system or production line, maintenance workers will often ignore OSHA and NFPA 70E safety requirements and go into a live panel to meter each fuse to determine any that have opened. This extremely dangerous approach can create a significant safety hazard for the worker and anyone else nearby. Best-case scenario, the worker de-energizes the system and then pulls the fuses to check for those that have opened. This process, though, can be time consuming and lead to increased downtime. The opened-fuse visual indication of indicator fuses helps eliminate–or at least significantly reduces–these potential issues.

5. Get organized. Some fuse vendors will print bin labels with the facility’s part numbers, reorder numbers, and barcodes. These can be customized to work with your company’s asset-tracking system.

Effective consolidation and organization of a site’s fuse inventory provides many benefits.

Effective consolidation and organization of a site’s fuse inventory provides many benefits.

Bottom line

Any time of year is a good time to “spring clean” your fuse inventory. The benefits are numerous. Sites can decrease downtime by standardizing on indicating fuses that allow open fuses to be identified quickly. Modern fuses simplify selective coordination that can greatly limit the scope and potential magnitude of an outage.

Furthermore, by using current-limiting fuses, operations help protect equipment and workers from faults and dangerous arc flash. In addition to reduced downtimes, better system coordination in the event of a fault, and lower arc-flash hazards due to optimal current-limiting protection, considerable cost benefits can be realized.  MT

Information in this article was supplied by Dave Scheuerman of Littelfuse, Chicago. Learn more at littelfuse.com/MROPlus.

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