Archive | November, 2002

282

1:59 am
November 2, 2002
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Information Management System Helps Meet Maintenance Goals

Augusta Service Co. Inc. (ASCI), Augusta, GA, is a maintenance organization that serves two parent companies and their subsidiaries. During the past 10 years, we have met regulatory challenges—and the unique challenges of the companies we serve—by installing, adapting, and expanding an automated system to manage the information required for predictive and preventive maintenance.

ASCI is a nonprofit company owned by DSM Chemicals North America, Inc. and PCS Nitrogen Inc. DSM is the world’s largest merchant supplier of caprolactam monomer for Nylon 6 polymer, which is used in carpets and textiles. PCS Nitrogen is the world’s largest producer of nitrogen fertilizers and its Augusta facility is the largest nitrogen fertilizer producer on the East Coast. Two other production facilities owned by DSM and one owned by W.R. Grace also operate on the 150-acre site in Augusta served by ASCI.

To serve all of these facilities, we maintain a maintenance shop with 25-person electrical and instrumentation (E&I) crews on site at each company’s main facility. A back-shift crew and several utility shops assist in providing preventive and predictive maintenance. A maintenance-engineering group provides engineering support to the parent companies through assigned area-maintenance engineers, as well as base support through its mechanical and pipe groups and E&I.

Certification and compliance top priority
ASCI purchased its automated system, DocuMint Solution, in 1992 from Loveland Controls Co., which later became part of Honeywell. Our goal was to develop a test history database to help DSM and PCS attain ISO 9000 certification.

In addition to providing a means of compiling, storing, and organizing test histories, the automated information management system captures crucial details for certification, including “as found” and “as left” test points, environmental conditions at time of calibration, NIST traceable test equipment, and out-of-tolerance specifications on field instruments and test equipment.

DSM now holds ISO 9000 (2000) certification. DSM Resins US, Inc. earned QS-9000 certification and PCS earned ISO 9002 (1994) certification. We expanded our use of the system in 1997 to address the Occupational Safety and Health Administration’s (OSHA) Process Safety Management (PSM) standard 1910, particularly to document compliance with the standard’s mechanical integrity rule.

Organizing and managing data
The organization of ASCI’s database reflects our need to manage assets for two separate companies, document history on instrumentation loops, and maintain records on individual instruments and equipment. The database hierarchy is Cost Center (a group of equipment in a particular area of the plant), Loop (all instrumentation related to a single function), and Tag ID (each instrument or piece of equipment).

Currently, the database includes 83 cost centers, more than 8600 loops, and more than 38,500 tags. It holds more than 30,000 test results—each linked to specific tag IDs and specific pieces of test equipment.

Test equipment is tracked as well. ASCI maintains three-point, one-point, and certification histories on all 340 pieces of test equipment. Prior to use, each piece of test equipment receives a one-point check for accuracy. The database also designates which test equipment ASCI should segregate for use on ISO 9000 devices. We maintain check standards for one-point and three-point checks in each instrument shop.

Each process calibrator has a test setup for every function it performs, which means ASCI tests a total of 687 functions. We maintain a test equipment function database, which designates each function of each calibrator as an individual record with a test setup assigned.

Creating shortcuts for routine tasks
We also use the software to create quarterly reports for each facility’s production staff. These reports reveal specific deficiencies related to past-due or untested instrumentation. Production staff also may use reports to plan for shutdowns, audits, and daily schedules. To expedite these and other routine information needs, we use the Fastask function of the system. Reports include:

  • Production update report: Issues a list of all delinquent or untested devices by cost center to update a specific area of the plant.
  • Cost center performance: Searches all ISO cost centers to determine the number of devices untested or past due based on date guidelines.
  • Scheduler report: Searches for tag IDs or test equipment between chosen dates to allow reports to cross reference with maintenance schedules.
  • Plant structure for ISO: Searches and displays only ISO tags, in only ISO loops, in only ISO cost centers, instead of all tags in all loops in all cost centers, which may include instruments that are not ISO quality critical instruments.

By using the program’s options, ASCI further customized the information management system to meet its needs.

Equipment group searches are simplified. We assign all OSHA PSM loops separate equipment groups for location, rank values for catastrophic failure risk, and rank orders of importance and FMEA numbers, which help calculate ranking values. The loop database stores and indexes these values and orders in a searchable format. When ASCI blocks off equipment groups for calibration, technicians can search for the equipment group number, load the calibrations for all instruments in the group, and go to work.

Calibration sheets expedite turnaround maintenance. During a plant turnaround, technicians must perform hundreds or thousands of tests in a short time period. ASCI also must manually record much of the maintenance information due to the number of temporary technicians on site. To ensure collection of consistent information, we use the information management system to create calibration sheets that can be printed and attached to work orders.

Reverse trace ensures correction of inaccuracies. When we find out-of-tolerance test equipment, we can trace which process control devices the out-of-tolerance equipment calibrated. Technicians then can check and correct affected devices, if necessary.

The payback
Using this information management system, we have been able to ensure our parent companies and their subsidiaries comply with ISO certification and OSHA PSM compliance. Our ability to customize the system and manage the database effectively has also increased profitability.

In addition to supporting routine preventive maintenance, the system also helps increase the efficiency of work performed during turnaround periods.

We have more efficient maintenance schedules. Using the system to track test history such as failure rates of specific models or specific loop configurations, we can use re-engineering to protect equipment and prevent early failures, re-evaluate the tolerance specifications, or adjust the calibration intervals. The evaluations can help determine the appropriate frequency for preventive maintenance.

We can identify specific equipment makes and models that failed repeatedly or frequently drifted out of tolerance. Maintenance histories stored in the information management system provide the rationale for specifying new instrumentation or a wholesale change-out of a particular make or model. This single benefit saves production downtime and contributes to ASCI’s ability to maintain a record of 0.5 percent average production loss of maximum capacity.

The use of the information system as an interlock database has allowed ASCI to identify inoperable and out-of-tolerance interlocks, which are tested during plant outages. It is ASCI’s answer to OSHA 1910 PSM instrumentation documentation requirements for its safety interlocks. The ability of the system to track failures allows engineers to focus on technical requests with a solid historical basis for engineering changes. MT


Information supplied by Tina Spivey, an associate equipment specialist in instrumentation at Augusta Service Co., Inc., 27 Columbia Nitrogen Rd., Augusta, GA 30901; (706) 894-6147. For information on DocuMint, visit www.acs.honeywell.com

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1389

12:46 am
November 2, 2002
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The Trouble with Torque in Electrical Connections

Torque and force are not the same.

The secret to making and keeping reliable electrical connections is contained in two elements: start with clean contact surfaces, and apply high force.

Clean contact surfaces are a function of cleaning procedures, including joint compounds, and will be covered in a future article. Application of high force is the subject here.

The trouble comes about because the terms “torque” and “force” are incorrectly used interchangeably. Force is NOT torque. Force is a function of torque. The expression which describes the relationship is

F = T/K

Note that the equation has a variable, K, that includes the coefficient of friction. The higher the friction, the lower the force for the same torque. Torque is a convenient way to get at force and is usually specified in making an electrical connection. Force is considered inconvenient to measure.

Torque can be misleading

Consider the following. Suppose you are given a torque value for an electrical connection and suppose that the connection is frozen due to corrosion, arcing, etc. Obviously, the recommended torque will not assure a good connection. Thus, relying on torque to judge the quality of an electrical connection can be misleading.

Levels in uncertainty in the accompanying section “Force Variations by Methods of Tightening Connections” are taken from mechanical engineering sources and represent a rough estimate of the percent variation encountered when trying to tighten a connection using different methods.

You can see there is a wide variation in accuracy depending upon the method and that many of them are fairly inaccurate. In fact, when considering life safety, torque values are rarely mentioned.

What is the correct force? When a connection is tightened, the joint electrical resistance drops as the force increases, up to a certain point. Beyond that certain amount of force, a marked decrease in resistance no longer occurs; the resistance remains fairly constant even with increased force. That certain amount of force is the minimum value of force needed.

In bolted connections, I have found that the forces associated with SAE Grade 5 hardware produce this correct value.

Applying proper force
To assure you are applying the proper force in a connection, there are a few methods which can be utilized:

•Low and consistent K factor by the use of lubrication. You can produce repeatable, high forces in the connection. To safely use lubricants, run tests in the shop before applying on the job.

A well-lubricated fastener is stressed to a higher force for the same torque than an unlubricated one. Check that the fastener does not fracture at the higher force. Having conducted tests, then apply the selected torque to the lubricated threads.

•Belleville washers. These are not always required in electrical connections and are often questionable. The washer must flatten at the proper force and many applications do not use a high enough force. In addition, since the bow in the washer is difficult to see, Bellevilles are sometimes installed upside down. If a proper high force is utilized in the connection, I have found that a Belleville is usually not necessary.

But a Belleville is an excellent force indicator and therefore can solve the force/torque dilemma. If you choose a Belleville that flattens at the desired force, you then can proceed with implementing the connections and not worry about a torque value.

•Direct tension indicators. As mentioned previously, in mechanical connections where life safety is a subject of concern (e.g., buildings, bridges, etc.), torque is not mentioned. Instead measurement of force is required.

A common procedure is the use of direct tension indicators. These are washer-like devices that feature protrusions (bumps) which flatten as a function of force applied to the connection. A feeler gauge is used to announce when the proper force is reached. Later inspection is simple through the use of a feeler gauge. Since the indicators are designed for use with steel, make sure the bumps are put against a hardened steel washer, not a copper or aluminum bus.

These devises are available for 1/2 in. hardware and larger. It is possible to use the 1/2 in. indicator with smaller hardware by requesting the force/gap characteristics from the manufacturer and then selecting the proper feeler gauge for the desired force. Make sure the gauge is narrow enough to fit between the bumps. MT


Norman Shackman, P.E., is based in Kent. CT. He conducts in-house seminars on electrical connections and can be reached at http://home.earthlink.net/~elecon/ or (860) 927-4067.

Force Variations By Methods Of Tightening Connections

Method Percent variation (+/-) in force
Feel (experienced installer)* 35
Torque wrench* 25
Turn of nut (snug tight, then 1/2-2/3 turn more)* 15
Lubricated assembly* 10
Belleville washer** 5
Direct tension indicator** 5
*depends on K

**independent of K

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3738

10:17 pm
November 1, 2002
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Managing Spare Parts

Proven, controversial, and new approaches are part of an effective asset management program.

Proper planning and control of spare parts inventory is a critical component of an effective asset management program. If the right parts are not on hand when needed for routine maintenance or repairs, downtime is prolonged. If too many parts are on hand, the enterprise absorbs excessive costs and the overhead of carrying the inventory.

There are tried and true strategies to manage spare parts in support of effective asset management, along with some that can be considered questionable, and a variety of new and innovative practices. Advanced enterprise asset management (EAM) solutions support the proper implementation of these capabilities. Following are examples of each.

Proven strategies
Item search.
It can be frustrating to a maintenance planner who is not familiar with item numbers to locate the appropriate part in a computer system. Nouns and qualifiers are a way of simplifying a search. A noun is a simple, meaningful name for the item, for example “pump.” The qualifier adds more detail, such as “hydraulic.” A search on this combination will bring up all hydraulic pumps in the stock item master file.

An assortment of captions and a detailed item description can provide an increasingly narrowed search that considers make, model, size, formulation, capacity, etc. If the part can be substituted with an alternate or equivalent part, that reference also should be stored in the stock record.

ABC and XYZ analyses. The generally accepted 80:20 rule illustrates that approximately 80 percent of any storeroom’s volume is associated with only 20 percent of the items in inventory. It is important to pay extra attention to that critical 20 percent.

ABC and XYZ codes are commonly used to identify those parts. The codes are assigned based on value or quantity of stock movement, and each code will have an associated “upper limit.” Highest value parts, for example those that cost more than $5000 each, can be assigned the ABC code of “A,” and fastest moving parts can be assigned an XYZ code of “X.”

Automatic replenishment. Automating the thought process related to reorders has generated proven savings. Suggested reorder functionality creates requisitions based on reorder points (ROP) and reorder quantities (ROQ) that are stored in the inventory record. Once inventory levels for a part fall below the reorder point threshold, a suggested reorder is placed for the reorder quantity, which in turn creates a requisition. This saves time and prevents the delays and errors that can occur with manual purchasing processes.

When a simple ROQ value is not enough, an economic order quantity (EOQ) algorithm can be used to calculate the right quantity of a spare part to purchase when replenishment is needed. The EOQ can consider volume discounts, the cost of placing an order, carrying costs, and other factors.

Vendor service levels. Capturing supplier service level data within the inventory record helps bring to light the most efficient, dependable, and cost-effective vendors. Preferred suppliers can be identified based on historical lead times, pricing, quality, number of short- or over-shipments, how often goods are received damaged, frequency of backorders, and other criteria. Preference can be given to these vendors in the procurement process.

Where used. A view of where a part is used, for example on which assets a certain ball bearing is installed, provides benefits to both the plant floor and storeroom. This view enables inventory personnel to understand how extensively a part is used throughout the operation, and helps the maintenance planners to determine the item number and quantity of parts installed on an asset.

Multi-stores capability. Taking where-used one step further, a multi-stores capability enables an enterprise-wide view of spare parts inventory that is stored at more than one warehouse or off site by a third party. In a multi-plant environment or when maintenance departments are distributed, visibility into inventory at the various storerooms permits monitoring of parts availability and service-level agreements across the enterprise as a whole or on an individual basis.

Controversial methods
Just-in-time (JIT) replenishment is a popular but sometimes controversial concept of storing minimal inventory in the warehouse and replenishing it only when and as needed╛just in time. Although enabling significant carrying cost savings, there are risks involved. The best replenishment formulas cannot predict an emergency breakdown, a vendor going out of business, a carrier going on strike, or a sudden shortage of raw materials. Being too conservative in stocking levels can result in the inability to repair equipment in a timely manner or to keep the production line running.

In asset management, the criticality of a part determines whether it is a candidate for JIT. A criticality code in the EAM inventory record can be used to identify these items.

Lean manufacturing is a similar concept with a broader scope. Lean manufacturing means doing more with less, cutting time to market, and eliminating unnecessary processes. This impacts maintenance and the storeroom by stressing improved efficiencies, better planning, and reduced costs╛and running an operation with far less inventory.

A comprehensive lean manufacturing program can be costly to implement, but a number of steps can be taken to support lean inventory levels. EAM inventory analysis tools, catalog management, and automatic replenishment can be used to reduce on-hand inventories, track where individual items are used, how they are used, and where they are stored, so that inventory maintained is matched to inventory needed.

New approaches
Purchasing through the Internet is an effective means of acquiring indirect items and hard-to-find, inexpensive, or short-notice spare and replacement parts. Almost all OEMs, brokers, distributors, manufacturers, and machine shops have Web ordering capabilities. Most companies are now purchasing indirect materials online, about half are purchasing direct materials online, and about a third use industry exchanges and e-marketplaces such as Pantellos and Enporion for utilities and ChemConnect for chemicals and plastics.

An e-procurement solution that is tightly integrated with a company’s EAM system checks to see if the item is already in stock, automates the approval of purchase orders, and alerts the buyer to exceptions. By negotiating better prices and terms with e-sourcing, companies have been known to save 10-15 percent on direct goods and 20-25 percent on indirect goods and services, while slashing sourcing cycle times.

Mobile computing is becoming more sophisticated and is increasingly popular in the storeroom. Warehouse personnel can conduct cycle counts without halting operations by automating parts identification with bar codes. Wireless technology can capture inventory through bar codes and transmit the data in real time to the corporate network. Critical material availability is easier to track, resulting in timelier asset management.

With a wireless system, real-time information flows throughout each key process in the warehouse, including receiving, put-a-way, picking, issues/returns, and bin movement activities. For one energy company that implemented mobile asset management, errors were slashed, pick time was cut by one-third, on-time picks were improved from 64 percent to 98.89 percent, and overhead costs were reduced by 20 percent.

Key performance indicators (KPI) are increasingly popular decision support tools. For example, an EAM solution can calculate a KPI on inventory turns by dividing inventory expenditures by average inventory level. When problem areas are flagged, notification can be sent automatically to the plant and storeroom managers for escalation. Other supply chain KPIs can include vendor performance, obsolescence, items available but not used, supplier pricing, and more.

Supplier relationship management (SRM) is the newly branded concept of developing and managing long-term relationships with suppliers of specialized equipment and replacement parts. In asset-intensive industries, some suppliers enjoy a near-exclusive position because of the uniqueness of their replacement parts.

These relationships support the automatic electronic procurement of required parts, offsite storage of parts, or onsite storage with vendor ownership. SRM requires establishing the two-way visibility of parts requirements and availability, which is built into advanced EAM solutions.

Vendor-managed inventory (VMI), where suppliers own raw material inventory until needed, is a strategy that reduces inventory and administrative costs, while meeting the demand for parts and equipment. The collaborative capabilities within advanced EAM solutions support the two-way visibility and transaction flow required by this strategy.

Outsourced asset management and maintenance follows the trend of using partners for the execution of noncore businesses. In asset-intensive companies, the extensive infrastructure and deep knowledge base required to manage certain strategic assets can be beyond their capacity. Collaborative commerce (c-commerce) and Internet-enabled collaboration within enterprises now supports remote asset monitoring and proactive maintenance services. Advanced EAM solutions can support this business model by providing the ability to share the necessary real-time information within and outside the enterprise.

Clearly, effective spare parts management plays a critical role in asset maintenance, which in turn keeps the operation running. A combination of tried and true inventory and warehouse strategies, strategically aligned with new and controversial methods that are properly implemented, can result in tremendous benefits for the enterprise. MT


Sheila Kennedy is research director at Indus International, 3301 Windy Ridge Parkway, Atlanta, GA 30339; (770) 952-8444

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268

8:52 pm
November 1, 2002
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Snooping Around Outside the Fence

bob_baldwin

Robert C. Baldwin, CMRP, Editor

I‘ve never been to a bad conference, one where I came away with nothing of value. Even when the conference is peripheral to maintenance, or completely outside the field, there are usually some ideas that can be adapted to improve your situation or at least trigger ideas about a new way of approaching familiar problems.

Getting outside the fence to mingle with people in different or associated fields pays dividends. It is like benchmarking outside your field to find world-class processes that can put you ahead of your competitors. Remember: If you always do what you’ve always done, you’ll always get what you always got.

I took some time recently to attend the conference and exhibition produced by ISA-The Instrumentation, Systems, and Automation Society. Although the event, held in Chicago October 21-24, 2002, touched on some asset management topics, I was most intrigued by some ideas presented in a couple of process control oriented sessions.

Dick Morley, best known as the father of the PLC, chaired a wide-open discussion with the audience and panel members Shuzo Kaihori, president and CEO, Yokogawa Corporation of America; Jim Pinto, JimPinto.com; Ken Crater, Control.com; and John Berra, executive vice president, Emerson Process Solutions.

One of the questions from the floor asked what could be done to stop the IT bulldozer from overrunning the process control field. One answer: it is probably inevitable. However, it was suggested that process control engineers prepare to take what they need from the change. The issue is not what department is in charge, but the results and value to the enterprise.

That exchange reminds me of the fear some in our community have about process control taking over condition monitoring and asset management. It really doesn’t matter, in my opinion, as long as assets get managed to the level required by the enterprise.

In another session, Béla Lipták, author/editor of the three volume Instrument Engineers Handbook, told an intriguing story in his keynote lecture about being invited to a seminar at Harvard University to provide insight into process control techniques for participants who were dealing with social and economic issues. They were looking to process control for solutions. What Lipták imparted to the group is a fundamental tenet of his field—you must first understand the process before you can control it.

Which brings us to maintenance. There are too many people, inside and outside the profession, simply looking for answers to problems instead of trying to understand the process. MT

rcb

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236

8:50 pm
November 1, 2002
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The Dumbing-Down of Vibration Analysis

The dumbing-down of vibration analysis may be described best as “the exploitation of human weakness.” The following examples are not all inclusive, but they may help in understanding the problem:

  • Advertising, education, and living have ingrained in us to get the cheapest. I think almost everyone knows that the cheapest is not always the most economical.
  • A lot of people want something that is quick and simple and do not want to be bothered with facts about adequacy for the job. This has contributed to manufacturers adding features to aid in analysis. These features may not be effective because they keep changing. Some examples are demodulation, high frequency methods, etc.
  • Many people believe everything they see in print. Many articles and papers have been written that purport to explain the various features. The first two or three paragraphs indicate an explanation is forthcoming; however, around the fourth paragraph the subject is changed to something else and the explanation never occurs.
  • In some cases, management has abdicated its responsibility to the bargaining unit.
  • The large advertising budgets and sales forces of some bearing and instrument manufacturers have capitalized the market for their products.
  • Most training courses spend too much time on how to operate equipment, software, setting alert and alarm levels, and how to set up and run a route. These courses spend very little time on actual diagnosis of problems. Some courses even teach things that are not correct. Once people have been trained in these methods, it is often difficult to change their minds.
  • Certification testing is based on the above courses. Certifying vibration analysts when there is no consensus on what the data means creates a false impression for management, a sophomoric attitude in some of the certified, and improves the cash flow for the certifying organization.

Vibration analysis is the science of breaking down vibration into the various constituents to identify all problems in the machine. Constituents of vibration are the time signal; frequency spectrum; each frequency: harmonic, sub harmonic, side band; along with the phase relationship and amplitude of each. Some applied technology must be used.

For example, the FFT produces some frequencies that cannot be generated by the machine. This causes the amplitude in the frequency domain to be understated.

Engineers and technicians that have been trained in vibration analysis can, and have, developed rules to follow for accurately diagnosing machinery problems. When all problems are accurately diagnosed and the cause identified, priorities can be assigned. Then the worst problems can be repaired on a scheduled outage and the cause eliminated. Your machines then could operate until the next outage without a failure.

The next logical step is to develop rule-based expert diagnostic software that can, and does, diagnose problems 24/7 without human assistance. This also has been accomplished. The proven results of this type of vibration analysis program are increased run time, profits, and employee efficiency. Improved product quality and reduced down time also have been achieved.

The following recommendations may be helpful in achieving the above benefits:

1. Review the vibration course content before sending people to it. If the content does not include instructions on how to diagnose problems, the course should be avoided.

2. The importance of analyst certification should be downplayed until there is a consensus on what the data means.

3. If training on how to operate equipment/software is needed, the manufacturer may be the best source.

4. Evaluate the equipment you are using. If it is outdated, replace it.

5. Avoid being “locked in” to one manufacturer because there may not be a single company in the world that knows everything there is to know about vibration analysis.

6. Do not place so much emphasis on history data because with today’s hardware, software, and technology, problems can be accurately diagnosed without history data. MT
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