Archive | Reliability & Maintenance Center

108

6:58 pm
February 10, 2017
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Obsolete Inventory? Deal with It.

randmObsolete. Everyone who has ever purchased a computer knows what that means. It describes your computer within a month or so of your purchase.

When the discussion turns to a plant’s MRO inventory, Roger Corley of Life Cycle Engineering (LCE.com) says it’s an entirely different type of conversation. That’s because some items are never used, yet continue to collect dust and take up valuable storeroom real estate. He has some tips for dealing with this obsolescence, starting with how to identify it.

Identifying obsolete MRO inventory, in Corley’s opinion, is the easy part, especially if a good set of parameters has been established. Most large storerooms, he says, apply these factors:

• items with movement (receipts or issues) in 3+years

• items that aren’t identified as critical spares

• items that aren’t on an active asset’s BOM (optional).

Up-front planning can ease your site’s identification and disposal of obsolete MRO items.

Up-front planning can ease your site’s identification and disposal of obsolete MRO items.

With these parameters in place, most inventory systems can quickly generate a list of obsolete items—something that should be done annually to make it easier to manage the following years’ lists.

According to Corley, the more difficult (politically charged) challenge associated with obsolete MRO items is their disposal. That’s why storeroom managers must be involved in a site’s budget-preparation process. For one thing, there will need to be a line item in the budget for disposal of inventory. In addition, since writing off unused inventory can be damaging to a company’s bottom line, it’s crucial to prepare (and obtain approval) for doing so ahead of time.

Another issue involves disposing of what personnel believe “belongs” to them. As Corley put it, “I’ve seen maintenance supervisors and managers dig in their heels when a storeroom manager begins removing what they think of as ‘their’ MRO items.” His advice to storeroom managers is to take great care to ensure important items that might have been left off the list of critical spares aren’t eliminated from inventory. Some front-end work on the part of storeroom managers can smooth the process. Such work includes:

• investigating the history of the proposed item considered for disposal

• grouping items into specific operating areas on site and scheduling meetings to review (tip: buy lunch to get participation)

• allowing area managers to present a case for inclusion of a critical spare and being prepared to offer solutions such as vendor-stored inventory.

Once a list is developed and agreement among stakeholders reached, the obsolete items must be removed from inventory and disposed of. Corley notes that this phase will be less painful in plants that have investment-recovery departments. Smaller operations will sometimes list the obsolete inventory on bidding sites or, in the case of metals, recover money by scrapping items.

“Either way,” he cautioned, “sites shouldn’t expect to get anywhere near what the initial investment was when the items were purchased. In the case of scrap, they’ll recover pennies on the dollar. As for companies with multiple plants, it’s important for sites to check with other locations regarding possible use of obsolete items before disposing of them.”

To Corley’s way of thinking, dealing with obsolete MRO inventory, including identifying and disposing of it, needn’t be viewed as a daunting task. “That is,” he said, “if the process is managed properly and homework is done before the items are removed.”  MT

—Jane Alexander, Managing Editor

Roger Corley is a Materials Management subject-matter expert with Life Cycle Engineering, Charleston, SC, and a certified facilitator for Maintenance Planning and Scheduling with the Life Cycle Institute. For more information, email rcorley@LCE.com and/or visit LCE.com.

48

6:39 pm
February 10, 2017
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Infrared Inspections Of Installed Motors

By Jim Seffrin, Infraspection Institute

randmDespite the important role they play in facilities, electric motors often tend to be out of sight and out of mind—until they fail. Infrared thermography can be a cost-effective diagnostic tool for detecting problems within these systems.

Many infrared (IR) inspection programs focus on motor control circuits, but overlook the actual motors. Infrared inspections of a motor’s bearings and stator should be performed monthly by an experienced, certified IR thermographer that thoroughly understands the theory and operation of electric motors.

Here are the basic steps for performing this type of inspection:

1. Inspect motor casing for localized hotspots that may be indicative of short circuits within motor windings.

2. Qualitatively compare individual motors to similar motors under similar load.

3. When possible, qualitatively compare inboard and outboard bearings for each motor. If a large Delta T is present, it may be indicative of misalignment or a rotor balance problem. If both bearings are hot, the bearings may be worn or improperly lubricated.

4. Additionally, a thermographic inspection of the electrical connections within the motor junction box should be performed annually. This may be done in conjunction with a regularly scheduled IR inspection of the facility’s electrical system.

Because no complicated analysis is required, infrared inspections typically can be performed rapidly and at a fraction of the cost of other types of motor testing. Infrared can also detect evidence of misalignment at lower thresholds than those detectable by vibration analysis and motor-current signature analysis. MT

Words to the Wise: Stick to Facts

0217rmcinfraWhen used as a preventive/predictive maintenance tool, infrared (IR) thermography can detect and document evidence of thermal patterns and temperatures across the surface of an object. The presence of inexplicable thermal anomalies or exceptions is often indicative of incipient failures within inspected systems and structures. Because thermography alone can’t determine the cause of an exception, other diagnostic tools must be employed.

Some thermographers, however, provide opinions as to the cause of exceptions without the benefit of confirming test information. Such opinions are frequently accompanied by elaborate recommendations for repair. When those observations/recommendations are incorrect, they can cause repair efforts to be misdirected.

Unless a thermographer has performed, or has access to, confirming tests, it’s unwise to provide opinions regarding the cause of exceptions and offer suggestions for repair. Lacking confirming test data, a prudent thermographer should make only one recommendation: “Investigate and take appropriate action.”

This simple recommendation can be applied to any thermographic inspection and serves to avoid unnecessary liability by eliminating guesses and sticking to facts.

— J.S.

Jim Seffrin, a practicing thermographer with 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 one of his “Tip of the Week” posts on IRINFO.org. For more information on infrared applications, as well details on upcoming training and certification opportunities, email jim@infraspection.com or visit infraspection.com.

31

9:28 pm
February 9, 2017
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Ensure Clean, Dry Compressed Air

randmWhen it comes to compressed-air systems, equipment performance is only as good as the quality of the air itself. Unfortunately, the high-pressure air that these systems produce is wet and dirty. Air dryers and filters keep a compressed-air system operating efficiently, but only if they are properly maintained.

All atmospheric air contains some moisture and dirt. No matter how small the amount of contaminants initially, they are concentrated when the air is compressed. As the air heats up, its ability to hold water vapor increases. When the air begins to cool as it travels downstream, the vapor condenses into liquid.

Possible consequences of that condensation include, among other things, leaking seals, rusty or scaling pipelines, premature wear of moving components, and similar problems that can lead to subpar operation, equipment failure, and even damaged finished product. Plant personnel can prevent many of these headaches by selecting the right types of air dryers and filters to remove the liquid and particles and by performing regular maintenance on these
components.

Compressed-air experts at Mazeppa, MN-based La-Man Corp. (laman.com) offer several tips regarding air dryers and filters. Keep them in mind.

—Jane Alexander, Managing Editor

Types of dryers

Most compressors incorporate an aftercooler to reduce the temperature of the compressed air. Air dryers are often installed to further reduce the moisture content. There are four major types of air dryers:

• refrigerated

• chemical or deliquescent

• regenerative or desiccant

• membrane or mechanical.

Condensation in compressed-air systems can lead to a multitude of ills, including equipment failure and damaged finished product.

Condensation in compressed-air systems can lead to a multitude of ills, including equipment failure and damaged finished product.

The simplest, most economical dryer is the membrane or mechanical type. It uses a textile filter made up of thousands of individual fibers to trap large particles and cause moisture to form large droplets (coalesce). These particles and droplets collect at the filter’s base and are drained off. Water vapor passes through the filter to a sweep chamber, where it is vented.

Mechanical systems are typically installed at the point of use (unlike desiccant-type dryers that are placed near the air compressor to capture water vapor). At this point, air temperature has cooled sufficiently to permit water droplets to form and be captured by the system.

Impact of air filters

Mechanical filters work with compressed-air dryers to remove water and other contaminants from the compressed air and prevent component contamination. Three types of filters are typically used:

• particulate

• coalescing

• adsorption.

Particulate filters are typically made of a fine mesh glass fiber, plastic fiber, or woven wire cloth. They remove large particles using centrifugal force, while smaller particles are strained out. The filter is rated by the largest-size particle it will allow to pass. These types of filters work hand in hand with coalescing filters.

Coalescing filters are high-efficiency filters that use a fine stainless-steel mesh or woven fiber cloth (such as a cotton co-knit) to remove water and lubricants from the compressed air. They are often installed downstream of a particulate filter.

Adsorption filters use activated carbon to remove gaseous contaminants from compressed air. They adsorb the oil vapor into the pores of the carbon granules and must be replaced once saturated with collected oil. They are point-of-use filters, which should be supported upstream by a coalescing filter. Typical uses for adsorption filters include sanitary environments, such as paint spray booths, clean rooms, and food and beverage manufacturing.

Bottom line: Using—and maintaining—filters dramatically improves the performance and extends the life of compressed air systems. MT

For more information on solutions that remove water, oil, and contaminates from compressed air systems, visit La-Man Corp. at laman.com.

143

9:45 pm
January 13, 2017
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Use Catalog Profiles, Failure Codes to Analyze Assets

By Kristina Gordon, DuPont

randmDetermining why an asset failed during production is a critical function, not only for general reporting, but to measure asset costs and make informed decisions about future use. The SAP system provides an effective means of documenting the key aspects of damages, causes, tasks, and activities. Catalog profiles are used to group attributes together and allow maintenance personnel to document asset failure in the maintenance notification.

Q: What defect codes exist in the SAP catalog profile and how do you turn them on?

A :  Catalog profiles are created based on a company’s general business practices. Each company will have its own standards and naming convention and they should be followed in this setup to maintain consistency and avoid confusion.

The SAP catalog structure goes from catalog to code group to code. Each of these must be set up in the IMG (implementation guide), which is a SAP configuration. A catalog profile should be created such that it describes the equipment at a level that helps identify the possible failures associated with its particular equipment group.

Once the catalog and failure codes are configured, they are assigned to equipment masters. This will connect a catalog profile and corresponding damage or failure code to a specific equipment type, and then allow the proper failure code to be selected and added to the notification for that asset, as seen in the example below.

1701rmcsap01p

As shown in the equipment-master screen (next column), the equipment description is R/V, with some identifying characteristics (identification number 531503, in this case). The catalog profile (bottom of the screen) states the profile number with the description “Valve, Safety Relief.”

1701rmcsap02p

In the work-order notification generated for the equipment above, the object part goes into a more granular description of the catalog profile, “Disk”.

1701rmcsap03p

Finally, the failure code for the damage can be selected. In this example, the inspection produced a “Worn” result.

SAP includes the following key transactions for viewing failure-analysis results:

• MCI5: Damages, based on damage, cause, and activity

• IW67: List of tasks completed for the damages

• IW69: List of items with damage, cause, and other catalog details

• IW65: List of activities with damage, cause, and other catalog details.

Knowing the failure rate can optimize PM intervals and improve failure response and work practices. MT

Kristina Gordon is SAP Program Consultant at the DuPont, Sabine River Works plant in West Orange, TX. If you have SAP questions, send them to editors@maintenancetechnology.com and we’ll forward them to Kristina.

206

9:40 pm
January 13, 2017
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Properly Align Variable-, Fixed-Pitch Sheaves

Aligning sheaves on equipment with multiple V-belts is more complex than aligning them on machines designed with single belts.

Aligning sheaves on equipment with multiple V-belts is more complex than aligning them on machines designed with single belts.

Variable-pitch sheaves are frequently used in air handlers. According to a blog post by Stan Riddle of VibrAlign (Richmond, VA, vibralign.com), they allow design engineers to increase or decrease the speed of the driven machine and, thus, provide:

• changes in motor amp draw to maximize efficiency

• increased or decreased static pressure and air flow.

Normally, a design engineer will specify the use of a variable-pitch sheave on the driver and a fixed-pitch sheave on the driven machine.

Performed on a single-belt machine, proper sheave alignment is simple, if a good sheave-alignment tool is used. When multiple belts are used, as they often are, proper sheave alignment can become more complex. A variable-pitch sheave can be adjusted to increase/decrease the sheave diameter. However, doing so also changes the sheave width, depending on the adjustment.

In his post, Riddle referred to a customer who was attempting to perform a sheave alignment on an air handler. The unit’s motor had a variable-pitch sheave, but the fan sheave was fixed. The customer stated that he could align one belt, but not the other.

As Riddle described it, the customer was struggling because the width of the fixed-diameter sheave was 1 5/8 in., but the width of the variable-pitch sheave was 2 3/8 in. Consequently, only one set of grooves could be aligned, meaning the other was out of alignment.

The key to properly aligning a variable-pitch sheave to a fixed-pitch sheave on equipment with multiple V-belts is to split the difference between the diameter widths of the two sheaves. In this example, splitting the difference between sheave-diameter widths of 2 3/8 in. and 1 5/8 in. would result in a 3/8-in. offset at each groove.

The key to properly aligning a variable-pitch sheave to a fixed-pitch sheave on equipment with multiple V-belts is to split the difference between the diameter widths of the two sheaves. In this example, splitting the difference between sheave-diameter widths of 2 3/8 in. and 1 5/8 in. would result in a 3/8-in. offset at each groove.

The solution

Riddle wrote that the solution to the customer’s problem was simply to split the difference between the width of the two sheave diameters, as shown in the following equation:

2 3/8 in. – 1 5/8 in. = 3/4 in. ÷ 2 = 3/8 in. offset on each groove

randmRiddle also noted that it’s important to keep in mind this approach will probably not align the components sufficiently to eliminate sheave and belt wear. In fact, such wear can’t be eliminated. Still, when it comes to aligning multiple V-belts on an equipment system, splitting the difference between the diameter width of a variable-pitch sheave and that of a fixed-pitch sheave to which it is aligned will make the belts wear evenly.

Variable-pitch sheaves are normally used to balance a system and achieve proper static pressure and speed. When that’s determined, according to Riddle, the variable-pitch sheave should be replaced with a fixed-pitch sheave of the proper diameter to match the desired speed and pressure. Once both sheaves are fixed-pitch, proper alignment can be achieved. MT

—Jane Alexander, Managing Editor

Stan Riddle, a technical trainer for VibraAlign, has spent more than 36 years aligning industrial machinery. For more information from him and other technical experts with the company, visit vibralign.com.

73

9:35 pm
January 13, 2017
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Ramp Up Your Network Security

Industrial-control-system networks may seem secure, but there are opportunities for unwanted access at just about any level and component.

Industrial-control-system networks may seem secure, but there are opportunities for unwanted access at just about any level and component.

It’s inevitable that the Industrial Internet of Things (IIoT) will continue to grow, with more and more devices connected to networks by the minute. Achieving operational efficiency of those networks, however, is not without problems—including cyber-security threats. Such threats are raising serious concerns throughout industrial operations. What are the best ways to deal with them? Yiwei Chen of Moxa Inc. (moxa.com, Brea, CA) points to the IEC62443 Standard as a good place to start.

IEC62443 is constantly evolving to provide up-to-date security guidelines and a list of best practices for different parts of a network. It also includes information for those with different network responsibilities. The ultimate goal of the standard is to help improve network safety and enhance industrial-automation and control-settings security. According to Chen, to protect their networks from internal and external threats, it’s paramount for operators to understand IEC62443. This understanding will help them deploy devices with adequate security features to protect networks from internal and external threats.

Just what types of cyber threats can arise, and what options do your operations have for combating them? Chen provided several tips.

— Jane Alexander, Managing Editor

Prevent intrusions and attacks.
The first step in preventing unauthorized access to devices on a network is to implement a password policy. Remember, however, that while password policies are effective to some degree, as the number of users and devices on a network increases, so does the possibility of the network being breached.

Protect sensitive data.
All devices on a network must support and enforce data encryption when data are transmitted. This will virtually eliminate the risk of data being stolen during transmission. The reason data integrity is so important is because it guarantees data accuracy and that information can be processed and retrieved reliably and securely when needed.

randmAudit security events.
Networks must constantly be monitored, and every event that takes place on them should be recorded for possible analysis later. Although several security precautions can be taken to prevent cyber attacks, in the event one were successful, detecting it in real time would be difficult.

Visualize network security status.
Software that visualizes network security status allows operators to monitor any abnormal or potentially damaging activity. This type of software can also help network operators prevent problems before they arise, by allowing personnel, with a quick glance, to verify the correct settings are applied to each device. The security features that are typically covered can include password policies, encryption, log-in credentials, and data integrity.

Ensure correct configuration.
Human error can cause a wide range of problems, including improperly functioning networks, lost data, and creation of significant network vulnerabilities for attackers to exploit. Networks with incorrect configurations can be manipulated by internal staff or outside forces that have gained unauthorized access. Note: Cyber attacks resulting from human error are the most common way that networks are compromised. MT

To learn more about network security and Moxa’s wide range of solutions for ensuring it, visit moxa.com.

123

9:27 pm
January 13, 2017
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Improve Your Chemical-Pump Maintenance

Maintenance missteps in chemical-pumping applications can be catastrophic.

Maintenance missteps in chemical-pumping applications can be catastrophic.

Regardless of the industry, in chemical-pumping applications, it’s important to understand how the chemical reacts to heat, pressure, and flow. Just as crucial is the need to consider all system components in these applications. One maintenance misstep could be catastrophic.

Jim Raiders, senior technology engineer for Akzo Nobel Pulp and Performance Chemicals Inc., Chicago, offered the following advice for keeping chemical-processing pumps well maintained and reliable. MT

—Michelle Segrest, Contributing Editor

Common maintenance issues and solutions

• Wet-side seal integrity. Select materials and pump designs that offer improved hydraulic flow and the ability to prevent wet-area wear.

• Lubrication. Improve pump-sealing techniques to allow a wide range of operating conditions, without losing containment.

• Cavitation/inadequate flow conditions. Use self-contained lubrication systems and isolate the lubrication systems from process-chemical exposure.

• Corrosion. Use self-contained relief devices on positive-displacement pumps.

• Motor failure. Make better material selections, i.e., opt for quality materials instead of low-cost units.

• Improper mounting of pumps that creates secondary vibration nodes leading to pumping-system damage. Choose motors with improved insulation, bearings, and fan designs.

randmImportant preventive-maintenance steps

Regular inspections

Flow verifications

Vibration analysis and baselining

Power usage/thermal image baselining

Consideration of improved pump location in the process area.

Maintenance best practices

Use double mechanical seals with seal-guard monitoring for rotating pumps.

Place dosing pumps in a containment area to keep them protected from spills and sprays.

Place covers on rotating units for protection from processes.

Use power-line monitoring for loading indication of motor/pump wear.

Mount equipment properly with anchoring, grouting, and grounding.

Locate pumps in well-lit areas, if possible, for ease of monitoring.

Helpful tools

Vibration analysis

Offline and installed monitors

Thermal imaging

Process flow monitoring

CIP (clean-in-place) systems for automated cleaning when systems are offline.

For information about Akzo Nobel chemical-processing products and services, visit akzonobel.com/corporate-product/chemical-industry.

114

9:20 pm
January 13, 2017
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Choose to Fuse (And Why)

Designed as sacrificial devices in electrical systems, fuses protect costlier components in those systems from the damaging effects of overcurrent. They can also make control systems UL- and NEC-compliant.

Designed as sacrificial devices in electrical systems, fuses protect costlier components in those systems from the damaging effects of overcurrent. They can also make control systems UL- and NEC-compliant.

Fuses are sacrificial devices that help protect costlier components in an electrical system from the damaging effects of overcurrent. (They can also help make control systems UL- and NEC-compliant.) To be sure, there are many other solutions for protecting electrical gear from overcurrent, including circuit breakers and protective relays. Information from Cumming, GA-based AutomationDirect (automationdirect.com), though, lists 10 reasons why end users also should consider fusing.

— Jane Alexander, Managing Editor

Safety
Overcurrent protective devices that have tripped are often reset without first investigating the cause of the fault. Electromechanical devices may not have the reserve capacity to open safely when a second or third fault occurs. When a fuse opens, it’s replaced with a new fuse, meaning the protection level is not degraded by previous faults.

Cost-effective
Fuses typically are the most cost-effective means of providing overcurrent protection. This is especially true where high fault currents exist or where small components, such as control transformers or DC power supplies, need protection.

randmHigh interrupting rating
With most low-voltage current-limiting fuses (< 600 V) having a 200,000-A interrupting rating, users are not paying a high premium for a high-interrupting capacity.

Reliability
Fuses have no moving parts to wear out or become contaminated by dust or oil.

North American standards
Tri-National Standards specify fuse performance and the maximum allowable fuse Ip and I²t let-through values. Peak let-through current (Ip) and I²t are two measures of the degree of current limitation that is provided by a fuse.

Component protection
The high current-limiting action of a fuse minimizes or eliminates component damage.

Extended protection
Overcurrent-protective devices, with low-interrupting ratings, are often rendered obsolete by service upgrades or increases in available fault current. Updated NEC and UL standards are fueling the need to install potentially expensive system upgrades to non-fused systems.

Selectivity
Fuses can be easily coordinated to provide selectivity under overload and short-circuit conditions.

Minimal maintenance
Fuses do not require periodic recalibration. That is not the case with some electromechanical overcurrent-protective devices.

Long life
As a fuse ages, the speed of response will not slow down or change. A fuse’s ability to provide protection will not be adversely affected by the passage of time. MT

Fuses 101

Fuses consist of a low-resistance metal or wire that is used to close a circuit. When too much current flows through the low-resistance element of the fuse, the element melts and breaks the circuit. This keeps the excessive current from continuing down the circuit to more expensive equipment.

For more information on a range of automation-related topics and solutions, including current-limiting fuses that meet UL and NEC codes, visit automationdirect.com or library.automationdirect.com.

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