Tuesday, 24 July 2018

Where is the "mole" that is sabotaging your reliability program?

Hello fellow practitioners! Apologise for missing in action for a while. I have been working on various asset management roles that have been rather frustrating. I suppose the usual time an organisation accepts that they need a Reliability/ Asset Management personnel is when they would have been pretty deep in the mud pit to get out themselves. Nothing is new when we admit that every Reliability/ Asset Management role is rather frustrating. Only weirdos like us who cannot live without a good challenge would roll ourselves into the mud pit for fun. Perhaps we have an insane definition for fun…

Yesterday, my colleagues and I were discussing the conflicting goals of reliability target against overtime payment to maintenance crew. The more reliable your plant is, the less overtime labour cost will be incurred.

I don’t want to start off on the wrong context that I am against overtime payment and portray that I put full support behind capitalism to pay the workers the least, and extract the most profit out of every hardworking family breadwinner here. This is purely a discussion from our team’s experience, and in my opinion should be managed. The billion dollar question is… How?

Culture at organisation A, we experience frontline maintenance crew collaborating among themselves to “create” urgent overtime work sustainably, either through poor workmanship, or intentional slowdown of work completion.

Notice that I mentioned culture of the organisation, instead of practice of the organisation? You’re right on the money! It is a culture issue, but which part of the culture? Whether we realise it or not, it is applicable to most if not all organisations out there. Culture is built over the years by the organisation’s LEADERSHIP. I capitalised the letters to put a strong emphasis on it intentionally. Imagine below:

Leadership at organisation B, leaders who lead by example, support sustainability, accept individuality, embrace continuous improvements. Leadership that believes in nurturing the next generation, and bringing out the best in you with committed support to train you to do your job well and give their best to groom your career aspirations.

Leadership at organisation C, seniors who boss you around, micro-managing, expect a person to work like a robot precision with no break, strong emphasis of cost cutting, hiring the cheapest, buying the cheapest, yet expect the team to deliver high reliability.

I’m sure by now you know which organisation you want to work for. Leadership makes or breaks an organisation. In reality, organisation B and C are at both extreme ends of the distribution curve. Organisation we work for probably sits somewhere in between with a combination of values from both end of the spectrum.

Every organisation will have their fair share of imperfections. It is an art to balance how much to give without turning employees into a spoilt demanding lot, and how much to hold back without compromising basic reasonable requests. I have experienced an organisation that refuses to send their employees for training purely because it costs money and the leadership believes as the employees skilled up, they would leave. What is the consequential cost to the organisation for not training them? Operating with unskilled labour? Does such organisation still have a chance surviving in an ever competitive market?

Back to the original question of how then do you improve plant reliability without incurring overtime costs? I would suggest you look into a comprehensive reliability program that involves both operations and maintenance. To have a reliably operating equipment requires more than maintenance crew doing a great job, it also require the operations crew to operate it within the constraint that present itself from time to time. With the availability of advance condition monitoring technology, most failure mechanisms can be detected, and replacement can be planned in advance, reducing unplanned downtime and thus overtime labour cost.

Identical plant availability, and reliability KPI should be shared among Operations & Maintenance, overtime payment is to be gradually reduced and finally eliminated further down the road. This will encourage team work and more collaboration between Operations & Maintenance that will lead to a more fulfilled work environment, and higher employee retention.

From another perspective, earnings as a result of overtime work reduction can be converted into incentive payments to all deserving employees. With such a scheme, an organisation can be labelled as stable, reliable and highly rated in terms of its operations and the quality of its employees who produce excellent deliveries with minimum overtime work. This would be attractive and who would leave such organisation for another job.

Feel free to share your alternative or successful experience with me! You can reach me at harry (at) wiwoweb (dot) net

Thursday, 17 November 2016

The Plant Maintenance Program

Article extract from ReliabilityWeb newsletter:

The program explains and prescribes what personnel do and who does what, how, when and why? The personnel involved are more than those in maintenance. They also include all who support maintenance, such as warehousing, or depend on maintenance services, as with production.

The success of all maintenance functions is enhanced with a program commonly understood across the entire operation. But, the most important aspect of all is to ensure that those other departments that must support maintenance or utilize its services know how. If they don’t know what maintenance wants and needs, they cannot deliver it. There is an axiom that suggests: If you want someone’s help, you must first tell them how they can help. More simply: No tell; no help.

Maintenance is not a stand-alone effort. Any successful effort to improve maintenance performance, regardless of how, depends on the quality of the plant maintenance program. It’s important to note that it is the plant maintenance program, not the maintenancedepartment’s maintenance program. Maintenance is a service provider, dependent for success on the cooperation and support of all other plant departments and the backing of a supportive plant manager. Maintenance is not to be carried out single-handedly by maintenance. Planning, for example, is a key maintenance function and the responsibility for successful planning rests solely with maintenance. But, the planning function requires the support of numerous plant departments, like warehousing, purchasing, shops, accounting, etc. Few maintenance functions are successful without help and cooperation from other departments.

Getting Started
Only the plant manager controls all departments. Therefore, the existence of a quality plant maintenance program is the responsibility of the plant manager. However, the maintenance manager is responsible for the effective execution of the elements of the plant maintenance program. Yet, the maintenance manager depends on all other departments in order to execute the plant maintenance program. Thus, the plant manager becomes responsible for ensuring the support and cooperation of other departments, which, in turn, ensure the success of maintenance. What must the plant manager do? Based on the corporate business strategy, the plant manager, as shown in Figure 1, develops a business plan (1), assigns departmental objectives specifying responsibilities for primary operational or support activities to include interactions with maintenance (2) and specifies policies for the conduct of maintenance (3). In turn, departments acknowledge objectives and follow policies as they incorporate all experiences with merit (4) and follow principles (5) to develop internal and interdepartmental procedures (6). Procedures are then incorporated into departmental programs (7) and information systems utilized to control actions (8). Once tested, departments organize to support programs (9) and interact according to approved program details (10). Thereafter, information is used to control and manage the overall operation (11).

It follows that the best maintenance organization must be capable of executing the what, who, how, when and why of the plant maintenance program. And the best information system is the one that provides the right information to ensure efficient execution of the what, who, how, etc., specified in the program. It is reasonable to state that modern strategies, like reliability centered maintenance (RCM), cannot be successfully implemented unless there is a plant maintenance program, organization and information system to support them. It logically follows that only when a plant and its maintenance department have solidly locked down what they do, how, etc., can they confidently choose the best organization and a competent information system to carry out and control plant maintenance activities.

Figure 1
Program Development
Program definition begins at the plant manager level. This individual states how the departments should work together efficiently and productively by assigning specific objectives. The plant manager provides policies so departments are guided as they develop internal and interdepartmental procedures that make the plant’s maintenance program work efficiently.

Effective maintenance and actions that assure reliable equipment and workforce productivity don’t simply happen! They happen only after clear, logical management guidance is provided and a quality program emerges.

Program definition is a composite interaction of all departments. As they work together, maintenance crews, equipment operators, supervisors and staff personnel, like planners, warehouse personnel, or purchasing agents, should confer as the procedures for each department are being developed and interdepartmental actions confirmed. This collaboration better assures the practicality and workability of the final program.

Program education is essential and must include everyone in the plant, from worker to manager. Plant managers should make a special effort to observe the discussion between departments as they commit to procedures necessary to carry out the plant’s business plan. Questions should be answered promptly and correctly. Recommendations should be welcomed and encouraged.

Program Definition Techniques
The most effective technique for documenting the program is a schematic diagram that depicts the interaction between individuals of participating departments. The schematic is accompanied by a legend to aid understanding of the step-by-step process. While other techniques, such as flow charts, decision trees, or narratives, with diagrams might be used, none are as effective as the schematic diagram in showing people’s interactions. The schematic pinpoints ‘you’ and ‘me.’ It describes directly what ‘we’ must do, how ‘we’ will do it and the results ‘we’ should achieve. It is this ‘personal’ explanation that helps to bind people to the program.

As Figure 2 illustrates, preventive maintenance (PM) services due are shown by the information system (1). Services on equipment due (2) are either static (require shutdown) or dynamic (done while running). Static services are integrated into the weekly schedule and operations is advised of the approved, scheduled shutdown times (3). Dynamic PM services are done at the discretion of the maintenance supervisor (4). The maintenance supervisor assigns PM services to individual crew members (5). Services are performed by maintenance crew members (6) and crew members confer with operators to learn about actual equipment condition (7). Operators assist according to their instructions (8), while operations supervisors are advised of new deficiencies by the crew member (9). Deficiencies are then reviewed by the maintenance supervisor and the crew member (10) and converted into work as follows: Emergency repairs - Supervisor assigns at first opportunity (11); Work that meets planning criteria requiring planning - Supervisor forwards to planner (12); and Unscheduled repairs - Crew member enters them into the work order system as new work to be fitted in at first opportunity (13).

Figure 2
It is always prudent to ensure that everyone in an industrial organization understands their operational, support and cooperative roles and responsibilities. When this happens, the plant maintenance effort will be successful.
Paul D. Tomlingson, retired, is a 44 year veteran maintenance management consultant focusing on heavy industry. Mr. Tomlingson is the author of eleven textbooks and over a hundred published trade journal articles. He is a graduate of West Point and received a BA in Government and a MBA from the University of New Hampshire.

6 Elements of a Good Job Description

Article extract from Reliable Plant newsletter:

A successful training program is built from clear and comprehensive job descriptions that define the expected tasks to be performed by the employee and the expected behaviors to be demonstrated by the employee.

Many organizations are reluctant to write job descriptions for fear that employees will use the document as a way to avoid taking on additional responsibilities or refuse to get involved in special projects. In actuality, a detailed job description provides the employee with important information that enables him or her to quickly acclimate to a new environment by clearly and precisely stating the expectations for task delivery and behaviors.

The elements of a good job description are briefly outlined below. While not all inclusive, these six elements are a good place to start:

  1. Task functions and responsibilities — Clearly delineate all job functions and responsibilities as they relate to the performance of the employees duties. This would include technical aspects of the position, supervisory or managerial responsibilities (if applicable), communication skills and experience requirements, and back-up functions such as "other functions as deemed necessary by circumstances."
  2. Performance standards — Indicate productivity and quality standards required for the individual to be successful in his or her new role.
  3. Job-related skills — List the level of skill, knowledge, experience and capability demanded by the job, including any technical skills; physical requirements such as repeated lifting, pulling or pushing and physical exams that must be passed prior to qualifying for the position; communication skills such as written, verbal and language requirements; and interpersonal skills such as customer interaction, strong team player skills and the ability to work harmoniously with a diverse workforce. If the job requires computer skills, indicate the hardware and software that the employee will be using and the minimal skill level and/or experience required with the hardware or software.
  4. Scope and limits of authority  Outline the areas of responsibility assigned to each person, including where duties may overlap and who is ultimately responsible for the finished product or service. Also, specifically describe the level of authority the person has over other people, the function or the product.
  5. Management expectations  It is impossible to get results unless you spell them out. These should include expectations for availability such as overtime, nights, weekends, holidays, etc.; flexibility in scheduling regarding off days; restrictions on vacation time; policies and accountabilities for tardiness and absenteeism; and expected employee behaviors regarding interaction with peers, customers, vendors, managers and others.
  6. Relationships  Clarify the reporting structure for each department or division, stating to whom the employee reports or who reports to the employee, if applicable. Also, if team or group projects are required, give an example.

Whether you make the job description available to the potential employee during the application process prior to the interview or present it during the interview, the employee should have ample time to review and reflect on the job requirements on which he or she will be expected to deliver. The preferred method is to make the job description available with the application. This gives the applicant enough time to formulate questions that he or she may want to ask during the interview.

Most importantly, once you have made the job offer, have the new employee sign the job description. This allows you to hold the employee accountable for delivering on all aspects of the job and avoid the "that wasn't in my job description" scenario. If you ultimately hire the person, the signed job description is placed in his or her personnel file.

About the Author
Deborah K. Zmorenski, MBA, is the co-owner and senior partner of Leader’s Strategic Advantage Inc., an Orlando, Fla.-based consulting firm. During her 34-year career with the Walt Disney ... 

Anatomy of an Oil Filter

Article extract from ReliablePlant newsletter:

This is the second part of a series of “anatomy” lessons within Machinery Lubrication. In this issue, the oil filter will be examined to uncover its functional and performance characteristics. Several other related topics will also be discussed, including best practices for oil filter usage, possible filter failure modes, factors for proper filter selection and how to maintain an installed filter.

By definition, an oil filter’s main role is to cleanse oil from destructive contaminants within a machine such as an engine, transmission, hydraulic system and other oil-dependent systems. In the case of automotive oil filters, canister-type filters are the most common. This filter configuration was most likely responsible for the advanced performance of oil filtration technology.

In 1922, Ernest Sweetland invented the first oil filter device for automobiles. It was named the “Purolator,” which was short for “pure oil later.” The spin-on filters common in today’s automotive industry were introduced in the 1950s and were virtually a standard by the early 1970s.

Aside from the automotive industry, oil filtration is an integral part of equipment within a wide variety of industries, including aerospace, power generation, oil refining, manufacturing, mining, etc. Although most current oil filter designs come in canister or cartridge types, several variations in size, filter media, dirt-holding capacities and flow arrangements are available. For this reason, it is important that filters and filtration systems are selected to meet the needs of the application and with cost, performance, ease of use and environmental conditions in mind.

Oil Filter Types

Oil filters can be characterized by the method in which the contaminants are filtered or the method in which the oil flows through the housing. One technique used to control contamination in filters is through surface-type media. This is the type of filter used in automobiles. In depth-type filters, the filter media are designed to hold much higher levels of contamination and provide a more circuitous path for lubricant contaminants to become trapped.

Other possible contamination control methods include magnetic and centrifugal filtration. Magnetic filtration utilizes rare-earth magnets or electromagnets to attract and collect ferrous particles as the oil passes through a magnetic flux region. Centrifugal filtration works by integrating a rapidly rotating cylinder to produce a centrifugal force for contamination separation from the oil.

Oil filters can also be categorized by the oil flow design. As its name implies, a full-flow filter will draw all of the oil through the filter media. On the other hand, a bypass filter only requires a fraction of the oil flow for sufficient flow rates within the system. The application’s oil flow and contamination control requirements will determine which design is the best option. Another alternative is the duplex filter system, which contains two side-by-side filters in parallel to allow one of the filters to be replaced during uninterrupted operation.

With typical canister-type filters, it is standard for oil to flow from the outside in. This means that the oil travels through the cylindrical filter media from the outward-facing surface into the inner core. However, in some cases the flow direction is reversed, with the oil coming into the filter through the core and pushed outward through a unique pleat design. This is intended to improve flow handling and distribution as well as reduce filter element size.

Filtration Mechanisms and Filter Media

A filter’s primary function is to remove and retain contaminants as oil flows through the porous component called the media. The media operate under several types of filtration mechanisms, including:
  • Direct Interception and Depth Entrapment – Particle blockage on the media due to the particles being larger than the taken passages within the media.
  • Adsorption – The electrostatic or molecular attraction of particles between the particles and the media.
  • Inertial Impaction – Particles are impacted onto the filter media by inertia and held there by adsorption as the oil flows around.
  • Brownian Movement – This causes particles smaller than 1 micron to move irrespectively of the fluid flow and results in the particles being adsorbed by media in close proximity. It is much less prevalent, especially in viscous fluids.
  • Gravitation Effects – These allow much larger particles to settle away from fluid flow regions when there is low flow.

In addition, filter media can be designed to capture particles through two distinct methods:
  • Surface Retention – Contaminants are held at the surface of the media. This provides an opportunity for the contaminant to become trapped as it comes in contact with the media surface.
  • Depth Retention – Contaminants are held either at the surface of the media or within the labyrinth of passages within the “depth” of the filter media. This creates several opportunities for contaminants to become trapped.

The graph below shows how depth-type filtration is more efficient in capturing smaller particles when compared to surface-type filters. This can be attributed to the deeper media providing more chances for the particles to be trapped along with the adsorptive and Brownian movement effects being more predominant in depth-type filters. While these characteristics are beneficial, depth-type filters tend to have higher differential pressure across the media as a result of the increased flow restriction from the deeper filter media.

Particle size retention characteristics of
depth-type and surface-type filter media.

Filter Media Types and Dirt-Holding Capacity

In the September-October 2012 issue of Machinery Lubrication, Wes Cash explained how the porosity of the filter media plays a role in how well the filter can retain captured particles. This is known as the dirt-holding capacity. As pore size goes down, to maintain a low differential pressure across the media, the pore density must go up to account for the oil volume in contact with the surface. The filter depth and size also influence the dirt-holding capacity. Another factor is the filter media material. There are three primary types of filter media:

  1. Cellulose - Comprised of wood pulp with large fibers and an inconsistent pore size.
  2. Fiberglass (Synthetic) - Comprised of smaller, man-made glass fibers with a more consistent pore size.
  3. Composite - Comprised of a combination of cellulose and fiberglass material.

Cellulose media are advantageous because they can absorb some water contamination. However, these types of media tend to fail more rapidly than synthetic media in acidic and harsh oil conditions. Nevertheless, the primary reason synthetic filter media are preferred is their more consistent porosity and smaller fiber size, which contributes to higher dirt-holding capacity and longevity of the filter.

This example of a depth-type filter has an element that requires
oil to pass through 114 millimeters of filter media
for maximum particle filtration. (Courtesy Triple R)

Understanding the Beta Rating

Oil filters are rated by a technique called the beta rating. In his Machinery Lubrication article “Understanding Filter Efficiency and Beta Ratios,” Jeremy Wright explained the methodology behind the beta rating in more detail. In short, the beta ratio is calculated by dividing the number of particles larger than a certain size upstream of the filter by the number of particles of the same size downstream of the filter. Every filter will have multiple beta ratios for different particle size limits such as 2, 5 or 10 microns.

Best Practices for Oil Filter Usage

Storage - Filters can fail long before they are to be used for their intended purpose. Therefore, proper filter storage and handling are essential. Ensure filters are kept clean, cool and dry, and always follow the first-in/first-out rule.

Installation - Even if a filter installation seems simple and routine, refer to the manufacturer’s recommendations for proper procedures. A classic mistake is over-tightening. Most recommendations suggest that a three-quarter turn after seal contact is optimal. Over- or under-tightening can inhibit the seal’s longevity and effectiveness. Confirm that connections, seals and ducts are fitted appropriately and are free of contaminants.

Avoiding Pre-fill - In most cases, you do not want to pre-fill your oil filters before installation. In diesel engines, it is recommended that a pre-lube system be installed instead in order to counteract changes from dry-start conditions.

Choosing Correctly - Many filters and filter housings are designed to be interchangeable, so just because a particular filter fits doesn’t mean it is the correct filter. Make sure each filter is replaced with the right filter. This may not necessarily be the one found on the machine, as an incorrect filter might have been used during the last filter change.

Training - Proper training must be conducted for all personnel involved with changing filters. Remember, a task that seems straightforward to most people may not be for a new employee.

Filter Failure Modes

Channeling - During high differential pressures, filter media passages can enlarge to a point where unfiltered oil can pass through without an efficient contaminant capture. In addition, any particles that were previously contained within the filter in line with the enlarged passage may now be set free.

Fatigue Cracks - In cyclic flow conditions, cracks can form within the filter media, allowing a breach of oil to pass through unfiltered.

Media Migration - Media fibers can deteriorate and produce new contaminants made up of filter material. This may be caused by improper placement of the filter housing or an inadequate fitting of the filter, which can generate damaging vibrations. Embrittlement from incompatible oils or extremely high differential pressures can also result in media disintegration.

Plugging - During operation, filter media can become fully plugged by exceeding the dirt-holding capacity. Plugging can occur prematurely if excessive moisture, coolant or oxidative products like sludge are present.

61%of lubrication professionals say filter plugging is the failure mode seen most frequently in oil filters at their plant based on a recent survey at machinerylubrication.com

Factors for Proper Oil Filter Selection

Structural Integrity - Arguably the most critical factor, structural integrity relates to a filter’s ability to prevent the passage of oil through an unfiltered flow path. The International Organization for Standardization (ISO) has established procedures for testing fabrication integrity, material compatibility, end load and flow fatigue. These tests can reveal defects such as improper sealing of seams and end caps or breaks in the media from high-flow conditions, as well as the effects of high temperatures on the filter element.

Contamination (Dirt-Holding) Capacity - This refers to the amount of contaminants that can be loaded onto the filter before the filter’s efficiency is limited.

Pressure Loss - This involves the overall differential pressure lost from the filter’s placement on the system. The pressure loss will be influenced by the filter media’s porosity and surface area.

Particle Capture Efficiency - This is the overall effectiveness of the filtration mechanisms within the filter media to extract and retain contaminants from the oil.

System/Environment - The characteristics of the system and environment in which the filter will be installed must be considered, including the contamination expectations, flow rates, location, vibration, etc.

Maintaining Installed Filters

The best way to prevent filters from reaching their dirt-holding capacity is to avoid contaminants in the system from the beginning. The fewer external contaminants that ingress, the fewer contaminants that are generated internally (particles produce particles). Use the following guidelines to maintain installed filters:

  • Ensure proper breathers are installed to prevent contaminants and moisture from entering the system.
  • Keep seals and cylinders clean and dry by using appropriate wipers and boots.
  • Select the appropriate oil grade and additive package to counter contaminant ingression and internal friction.

Analyzing the Filter

A filter not only is a trap for the machine’s undesirables but also a concentration of clues as to what’s occurring within the machine. Particles within the oil may be so highly diluted that practical analysis can become a daunting challenge. However, the particles trapped in the filter may be so plentiful that they can be easily visible to the naked eye.

Metal contaminants are a primary indication of an issue within the machine. Although some amount of metal contaminants can be expected, an unusual amount should be recognized by trending the filter’s visual appearance after each oil change. Cutting open the filter and suspending a strong magnet over it can aid in pulling out the metal contaminants to more easily distinguish them.

If the machine is suspected to have an issue, the filter should not be discarded, as this would be similar to throwing away key pieces of evidence. Maintain the filter in the same condition as when it was removed and have it analyzed by the manufacturer or a laboratory.

Filter Disposal

Oil filters are not designed to be dumped into any wastebasket. Increasing regulations by the Environmental Protection Agency dictate proper filter disposal. While each type of oil filter may have its own requirements, common practices include oil draining, crushing or incinerating the filter. Many disposal services or filter distribution centers will accept used oil filters at little or no cost.



Fitch, E.C., An encyclopedia of contamination control, 1980s
Fitch, E.C., “How to Select Fluid Power Filters,” The BFPR Journal, 1979, 12, 3, 197-201
Erosion Control, Equipment World Magazine, December 1991
Filtration Manual, PTI Technologies Inc., 1990
Pall Corporation, Ultipleat SRT Filter Brochure, Nov. 2007
Triple R Oil Cleaning Products, Product Brochure, 2013

About the Author
  Bennett Fitch is a technical consultant with Noria Corporation. He is a mechanical engineer who holds a Machine Lubricant Analyst (MLA) Level III certification and a Machine Lubrication ... 

The Risks of Cutting Maintenance Costs

Article extract from ReliablePlant newsletter:

In our competitive environment, every manufacturer struggles to do more with less and to find capital for "nonproduction" areas, such as maintenance, safety, training, housekeeping and human resources. If done in a short-sighted fashion, the employer learns through painful experience the sacred law of "unintended consequences."

A recent magazine article detailed the harm to production and profits that resulted from gradually shifting almost all maintenance functions to production employees. You're probably thinking, "I wouldn't do that," but many employers have eliminated certain housekeeping workers and relied upon production employees to clean up their area or machine.

Let me share some of my experiences where "nonproduction" functions were neglected:

At one company, management of change (MOC) was overlooked as conveyors were modified and used machines and lines were added. Overstretched plant engineering and maintenance departments missed the new point of operation and other areas requiring guarding. Interlocks were not connected. Holes were left in boxes and panels. Lockout training was not updated. No annual evaluation of lockout was connected, and training was not revised. After an injured line employee complained to the Occupational Safety and Health Administration (OSHA), the agency issued hundreds of thousands of dollars in citations and penalties relating to guarding, lockout, training and electrical violations. Even worse, the company has significant "repeat" citation OSHA exposure throughout its many plants.

At another plant, the overall safety responsibility was shifted to a production supervisor (or maintenance or lab director, etc.), and the plant safety manager was laid off. The supervisor/safety manager responded to the loudest voice (the production manager) and the seemingly most urgent matters (getting product out the door). A worker was killed but not "directly" because of safety lapses (a poor safety culture was a factor), and OSHA learned that new hires had not received proper training. Written policies looked good until the company terminated the safety manager, so the decline in compliance was even more glaring. The poor pseudo safety manager was so underwater that he never acted on the recommendations from the last three yearly audits by the insurer, so OSHA cited the employer for numerous willful citations.

A third company didn't feel that it could retain additional experts and relied on its own staff and its general mechanical contractors to select and install new food production lines. These individuals were actually solid people, but they did not have experience with the process hazard analysis (PHA) experience in selecting and operating lines with combustible dust issues. After several hundred thousand dollars in OSHA citations and retrofitting costs, the organization now wishes it had spent the money on a full-time safety manager and used a consulting engineer with combustible dust experience to address system design and management of change issues.

These are safety and engineering-related "unintended consequences." Don't get me wrong. I embrace the lean movement and realize that sometimes you have to select the "least bad option," but you must also think ahead.

About the Author
Howard Mavity has practiced law for nearly 30 years and is the founder of the Fisher and Phillips Workplace Safety and Catastrophe Management Practice Group. He ... 

Thursday, 10 November 2016

Oil Condition Monitoring Using Electrical Conductivity

Article extract from Reliable Plant newsletter:

Electric conductivity is a measure of a fluid’s electrostatic chargeability. It usually is expressed in picosiemens per meter (pS/m). In addition to the type of fluid, conductivity also depends on the concentration of movable charge carriers. For example, pure distilled water is only slightly conductive. However, if the water contains impurities such as salts, acids or bases, then its conductivity increases.

Lubricants are normally only slightly conductive and therefore can work as insulators in transformers or switches. However, oils can also conduct electric current. Their conductivity is dependent on several different factors, including the base oil, additives and polarity.

Oil Conductivity

The more polar a lubricant is, the less refined and more conductive it is. Based on the manufacturing method and level of refining, the American Petroleum Institute (API) has classified base oils into five groups (see Table 1).
The lightly refined, mineral-oil-based base oils of Group I represent the simplest option and previously accounted for the largest proportion of lubricant production. Over the last few years, that proportion has been in steady decline, as the more refined base oils of Groups II, III and IV are increasingly being utilized for modern lubricants. This trend of using more refined base oils and synthetic alternatives is based on the fact that they generally have better characteristics such as higher aging stability. However, while the higher-quality base oils have many advantages, there are concerns over some of their changed properties, which can lead to problems, especially when unfavorable combinations occur. One such consequence is varnish, which can be due to the base oil’s altered dissolving performance with regard to aging and reaction products. Another consideration is component and lubricant damage, which can be caused by electrostatic discharges. The lubricant’s conductivity is an important factor in the charge buildup, and conductivity is dependent on the type of base oil used (see Table 2).

Table 2. Conductivity of oils and synthetic fluids at 23 degrees C (73 degrees F)
Along with the base oil, additives have a significant effect on an oil’s conductivity. The higher the proportion of metal-organic additives, the higher the lubricant’s conductivity. A prime example would be metal-organic additives such as those frequently used in zinc dithiophosphate (ZnDTP). As a proven multi-purpose additive in engine and hydraulic oils, ZnDTP improves wear and corrosion protection while simultaneously functioning as an antioxidant. However, zinc is considered to have dangerous health implications, so ZnDTP should be largely avoided. This means that the oil’s conductivity decreases and the risk of static charging increases.

A lubricant’s conductivity not only is influenced by the base oil and the additive package but also depends on temperature. The higher the temperature, the higher the oil’s conductivity. Unfortunately, there is no linear correlation between the two parameters, as each oil type has its own conductivity/temperature relationship. Furthermore, at a constant temperature, conductivity still changes during operation due to additive reactions, wear metals, reactions with metal surfaces, water and the formation of aging and oxidation products.

Electrostatic Charges

Although monitoring conductivity so far has been unable to achieve much success in the area of sensor technology, it is gaining significance with regard to electrostatic charges and discharges in lubricant and hydraulic systems.

Figure 1. The relationship between lubricant conductivity and temperature
In oil-circulating systems, electrostatic charges generally can occur if there is friction in the flow between the oil and the surfaces surrounding it. The strength of the static charge depends on many different and partly interconnected factors. The energy density, which builds up in the system and leads to subsequent discharges, is contingent on the oil’s conductivity and volume flow. The more oil that flows through a circulation pipe and the lower the oil’s conductivity, the greater the potential for an electrostatic charge.

Oil can be especially electrostatically charged if:
  • It is formulated with a base oil from Group II or III.
  • It contains no polarizing (zinc-containing) additives.
  • The conductivity of the new or old oil is less than 400 pS/m.
  • It is fed into pipes that are too small.
  • It is moved with too high a flow velocity.
  • It produces friction in poorly designed filter elements.
  • Pipes and hoses are not grounded.
  • The oil level has dropped too low.
  • It contains high proportions of undissolved air (bubbles).

Electrostatic Discharges and Possible Consequences

If the level of electric charge in the system becomes too great, an electrostatic discharge (ESD) will occur. In such cases, microsparks or sparking results. Typically, a crackling or clicking sound will be heard near the filter or in the tank. If the charge is high enough, the discharge could be repeated several times in quick succession. Discharges primarily take place in areas with vastly different material combinations. Modern filters with a high proportion of plastic are often affected.

The microsparks caused by a static charge can lead to temperatures approaching 1,000 degrees C. This can be extremely dangerous if the fluids are even slightly flammable. In addition, if hydrocarbon vapors have formed in the tank ventilation area, the system could spontaneously combust. However, when discharge sparks occur within a turbine or hydraulic oil-circulation system, they are normally smothered very quickly by the oil. Nevertheless, these mini-explosions can burn holes in filters or even seriously damage the oil due to increased sludge buildup.

Effects on Turbine and Hydraulic Oils

In recent years, electrostatic charges and discharges have been occurring more frequently in turbine and hydraulic oil systems. Several developments are responsible for this, including:
  • Modern hydraulic fluids and turbine oils have become increasingly less conductive because of the global trend to use modern base oils and additives. Previously, turbine oils were based on relatively conductive, lightly refined Group I base oils. Currently, more oxidation-resistant, better refined Group II base oils or even partly synthetic Group III base oils are being used, especially for gas turbine oils. These oils are considerably less conductive. In addition, turbine oils normally contain very few metal-organic additives, which help to prevent the formation of unwanted deposits (varnish).
  • New systems feature a more compact design with a considerably smaller tank capacity and a proportionally larger displaced volume.
  • Oil purity requirements have increased. This in turn has led to higher filtration rates.
  • The filtration intensity and electrostatic charge properties of the oil (resulting from filtration) have increased.
  • The oils’ low conductivity, which often is far below 1,000 pS/m in certain conditions, has resulted in an increased tendency for electrostatic charging.

Measuring Conductivity to Prevent Damage

In order to prevent damage from electrostatic discharges, more than just the conductivity of new oil must be identified. The parameter is also important for older lubricants, especially when dealing with larger quantities, if nothing is known about the used oil or a burning smell or soot particles are noticeable. Therefore, some oil analysis laboratories now offer conductivity measurements at different temperatures. The process has been tested for several years and is conducted in accordance with ASTM D2624. It originally was developed for inspecting airplane kerosene to avoid accidents caused by jet fuel charging.

As mentioned previously, oil’s conductivity value is measured in pS/m. If the conductivity is more than 400 pS/m at 68 degrees F (20 degrees C), there is little risk of damage to the oil or the system from electrostatic charges. However, if the value is lower, there is a very real possibility that the phenomenon could occur.

If an oil with an increased ESD risk is being used, grounding the entire system is not a viable option. The voltage inside the system cannot be discharged through a grounding wire. Fortunately, there are several other approaches for prevention.

4 Ways to Prevent Electrostatic Problems

  1. Install special stat-free filters instead of conventional filter cartridges. These filters can discharge or even prevent the charge from occurring.
  2. Use an oil with a different makeup and higher conductivity value.
  3. Choose or modify the system’s material combinations so microspark formation is prevented despite an electrostatic charge.
  4. Optimize flow diameter, tank hold times or tank volumes to minimize the charge potential.

Stay Focused to Sustain Reliability

Article extract from Reliable Plant newsletter:

A terrorist with a bomb passes through airport screening undetected on Christmas day. If not for a failure to detonate, many lives would have been lost.

When this brazen attack occurred, one of the things made evident was that many of us had let our guards down since 9/11. We had grown less interested than we once were.

I recognize this in a related area of my professional life. When I am not working on maintenance systems, part of my consulting practice is in "food defense," the concept of keeping the bad guys from intentionally contaminating our food supply.

There was significant interest in this topic after 9/11, as you might imagine. I regret to share with you that today there is far less interest, at least in the United States. Paradoxically, workshops I have taught in Peru, Thailand, Panama and the Caribbean have received considerable interest from their governments, universities and food industry (factories).

I have a couple of theories why corporate America is so short-sighted. One is that our public-company, quarterly-results-driven world trains us to think and work short term instead of long term. The other is related to a term no longer in vogue but recognizable to all of us in manufacturing: the "flavor of the day."

I think this phenomenon has gotten worse in our current downsized economy. We have cut beyond the fat into the bones of our organizations. We have let so many people go that we can barely do our daily work and certainly don’t have the means to pursue more than one or two improvement initiatives.

So we went from responding to the airline terror of 9/11 and food terrorism concerns to the bird flu preparations, to the swine flu response and to the economic downturn. At each juncture, we left behind an unfinished plan or a newborn program left to die of atrophy. This was without malice but also without the energy and resources to keep multiple programs sustained.

We have seen the same with industrial plant maintenance. The total productive maintenance and condition-based maintenance initiatives of the 1980s were never finished or sustained. They were replaced with the proliferation of product forms in the booming 1990s, the packaging initiatives of the early 2000s, the "green" initiatives of recent years and the cost-saving cuts of the past few years. As a result, many of our maintenance programs have failed to advance in the last 20 years.

We need to learn from the airlines, which have largely sustained robust maintenance and reliability programs (albeit under Federal Aviation Administration regulation). We cannot let our guard down — not in our preparations against terror in the skies, not in our defense of the food supply and perhaps, with less life-threatening drama, not in our maintenance and reliability initiatives.

About the Author
Ned Mitenius, PMP, began his career supervising a submerged nuclear reactor. He has spent the last 20-plus years in the food manufacturing industry, saving companies like Minute Maid, Ocean Spray ...