- All Articles
ABSTRACT for Process, Plant & Equipment UP-TIME
- Volume 3 Titles -
311. Job safety on hazardous and dangerous work. Doing a job safely is no accident! Like all good outcomes safety is a result of good planning. To help recognize safety issues before they arise on a job a Job Safety Analysis (JSA) may need to be performed. A JSA is a documented step-by-step safety action plan that lists the individual job tasks, the risks in each task, the consequences of the risk and how each risk will be managed to insure the safety of personnel. If you want safe work it needs to be planned as part of the job. Keywords: hazard analysis.
312. Process logic controller basics. A process logic controller is a computer designed for monitoring and controlling equipment. The personal computer that many people have at home is designed to accept signals from the keyboard or mouse and use instructions (software) to display the resulting effects on a screen (monitor). A PLC accepts signals (inputs) from sensors located throughout a piece of equipment or process plant. It then follows the instructions (program) within its memory and sends out commands (output) to operate equipment. Keywords: input-output card, monitor, control program, software, configuration.
313. Air compressor operation and care. Compressed air is one of the most used service fluids in industry. The article introduces the basic design concepts of an air compressor and discusses some of the common problems and solutions found in both reciprocating (piston goes up and down) and rotary screw (twin, meshed, rotating, helix) air compressors. Keywords: free air delivery, compression ratio.
314. Heat exchanger design and use. The article introduces readers to heat transfer in heat exchangers. It explains the concepts of temperature gradients across walls and parallel-current and counter-current flows. Both shell-and-tube and plate heat exchanges are discussed along with their common operational problems and remedies. Keywords: recuperative, flooding, temperature rise, heating, cooling, fouling, condensation, boiling.
315. Centrifugal pump life extension � the volute. The volute contains the process media while supporting the inlet and outlet nozzles and the bearing housing. The volute houses the spinning impeller and though it is stationary the flow and motion of the product across it caused by the impeller can lead to failures. Keywords: casing, cavitation, scouring, liner, wear ring, casting defect.
321. Gear pump operation & maintenance. A gear pump uses two meshing, toothed cogs to force liquid from the inlet of the pump through to the outlet. Being a positive displacement pump there deliver very precise quantities for each revolution and this means they have good dosing characteristics regardless of their speed or the pressure into which they discharge. Keywords: internal external teeth, pressure relief, viscosity. [Contents] [TOP]
322. Reducing wear in abrasive conditions. Abrasion is the removal of material from a surface by the movement of material across its surface. The factors affecting abrasive wear are the surface properties of the item being worn away, the abrasive properties of the material moving across the surface and the characteristics of motion. Where abrasive wear is a problem it becomes necessary to understand the mechanism of attrition. Keywords: surface abrasion, size range, particle properties, hardness, abrasion resistant coating, rubber lining.
323. Tools to focus on plant reliability. The focus of maintenance has changed from repairing equipment to keeping it running for longer between breakdowns. This requires more consideration of how to get longer running life between repairs, i.e. higher reliability, on a machine. To accomplish this a number of �tools� have been invented and developed to allow maintainers to pinpoint problems and fix them. In this article three of the most effective �tools� will be introduced. Root cause analysis, Weibull analysis and lifecycle simulation can be used to help organizations achieve proactive approaches to maintenance or adopt a �reliability based approach� to maintenance. [Contents] [TOP]
324. Using manometers for measuring pressure. A U-tube manometer is the simplest of the pressure measurement devices. Its name comes from the U-shape formed when the two ends of a flexible tube full of liquid are raised to keep the liquid from coming out the ends. A U-tube manometer is a �liquid� balance. By using liquids of different densities a range of pressures can be measured simply by measuring the height difference of the liquid columns. Keywords: process pressure, vacuum pressure, specific gravity, relative density.
325. Oil- how clean does it have to be. Clean, dry oil can extend equipment life between failure up to 8 - 10 times the normal operating life. Timken, the bearing manufacturer, reports that reducing water levels from 100 ppm (parts per million) to 25 ppm increases bearing life 2 times. British hydraulics research indicate that if solids contamination with particles larger than 5 micron (0.005 mm or 0.0002�) is reduced from the range of 5,000 � 10,000 particles per milliliter of oil to 160 � 320 particles, the machine life is increased 5 times. Keywords: iso particle count, scale number, cleanliness, oil analysis, oil sample procedure, suspended solids, filter performance.
331. Spread forces through equipment and reduce breakdowns. When a force is applied to a structure it reacts by deforming slightly. The structure is placed in a state of strain. The strain produces internal stresses. If there is insufficient strength in the structure to take the stresses it will fail. Equipment failures involving sudden breakage of parts will most likely be traced back to over stressing of the part. Keywords: stress concentration, tensile, compressive, shear, force diagram, tension, compression, fatigue, .cyclic stress.
332. Cyclone separators � an overview. A cyclone separator is used to separate larger, heavy particles from smaller, lighter particles. It does that by using a spinning column of gas to force the larger, heavier particles out to the walls of the cyclone. By changing the ratio of its dimensions they can used to remove particles larger than a selected size. Keywords: segregate, vortex, hydrocyclone, tangential inlet, dust filtration, dust filter.
333. Reliability centered maintenance � what is it? Reliability Centered Maintenance is one of the great developments in asset management. It is a methodology which studies a piece of plant or equipment in detail, predicts how it can fail, and puts into place the best maintenance strategy to prevent failure, or minimize losses from failure. Keywords: loss of function, failure pattern, failure mode, maintenance strategy, PM optimization, RCM, maintenance procedure, condition monitoring, consequence of failure, failure data, review process.
334. Electric motor current protection saves your plant. A lot of equipment failure results from just simple, plain mistakes, sometimes from unintentional forgetfulness, sometimes from �short-cut� taking and sometimes because of ignorance of the consequences. The result is plant destroyed at great cost and inconvenience. But for plant being driven by an electric motor use of under and over current protection is something that can be done very cheaply to protect it from being run outside of its design 'envelope'. A current transformer is placed around the electrical cables leading to the motor. The transformer is connected to a monitoring device that alarms when the current is outside preset limits. Keywords: motor load, overload, motor characteristic. [Contents] [TOP]
335. Creative disassembly. It would be rare for a machine to fail and not give some material or historical evidence of why it has failed. This material evidence must be looked at and some experiential opinion will be offered for the cause. Often the answers are already there. This process of Creative Disassembly is an important element of gathering the data that identifies the cause of premature failure. Keywords: Overhaul, shutdown, strip down, repair. [Contents] [TOP]
341. Set-up tank agitator gearboxes for long life at low cost. Agitated vessels and tanks are common throughout the process and chemical industries. A properly sized agitator with correct proportions to suit the tank will deliver well-mixed product. A correctly sized gearbox with well-chosen bearings and bearing arrangements will need only regular lubrication while giving years of trouble free service. Keywords: bending forces, bearing configuration, mounting support, tank baffle, vapor seal, radial load, thrust load, stool.
342. Holiday detection in above-ground tank bottom lining inspection. An important evaluation of bottom linings after application to aboveground storage tanks (AST) is holiday (i.e., discontinuity, �pin holes�) detection. Linings are principally applied to AST�s to prevent internal corrosion that may be severe. Therefore, any holidays must be detected and repaired prior to the newly lined tank being returned to service. Keywords: dry film thickness, spark testing, low voltage wet sponge test, tank lining.
343. Root cause analysis answers your problem. Root Cause Analysis (RCA) is a step by step method that leads to the discovery of a fault�s first or root cause. Every equipment failure happens for a number of reasons. There is a definite progression of actions and consequences that lead to a failure. An RCA investigation traces the cause and effect trail from the end failure back to the root cause. Much like a detective solving a crime. Keywords: failure mode, fault finding, fault tree, cause tree, events.
344. Control loops � masters of automatic control. A control loop senses, monitors and adjusts a process to maintain it within preset requirements. The loop consists of instruments, computers and computer-controlled equipment that interact to make continuous fine adjustments. Keywords, feed back, feed forward, process variables, open loop, closed loop, tuning. [Contents] [TOP]
345. Gluing plastic pipes so you can trust them. Adhesive joined plastic pipes have been known to separate at the glued joint. The joining of plastics using glue requires the glue to �hook� into a clean, rough surface. The article explains the preparation procedure to use and the reasons behind its use. Keywords: PVC pipe, ABS pipe, solvent, cement, glued joint, contact surface area, chemical bond.
351. Is your scrubbing tower working? A wet scrubbing tower is used to clean odors, particles, mists and vapors from a gas stream. The gas is forced through the tower. As it moves from inlet to outlet it is washed and cleaned. The washing is done with suitable chemicals that remove the active components in the gas flow. The gas is cleaned to environmentally acceptable levels and discharged to atmosphere. Keywords: packed tower, packing, fill, mist eliminator.
352. Metering and dosing pump operation. Any positive displacement pump can be used as a metering or dosing pump. The purpose of these pumps is to inject a known volume of liquid into a process stream. The primary requirement is that over a given period of time the pump consistently delivers the same amount of liquid. Keyword: gear pump, piston pump, helical rotor pump, diaphragm pump, peristaltic (hose) pump, additive, dosing rate. [Contents] [TOP]
353. Flow meters � don�t believe what they tell you. A flow meter is an instrument that measures the amount of fluid (liquid or gas) that passes through it. The meter in the pipe is the detecting device and increases the count when a specific quantity of fluid passes by. There are several types of flow meters in common use. They include magnetic flow meters, vortex flow meters, mass flow meters, turbine flow meters, rotor blade meters, paddle flow meters, and ultrasonic flow meters. Usual the quoted accuracy on the flow meter specification sheet is for water at 20 oC. However when the meter is installed in a process application it is unlikely that the meter will meet the quoted accuracy without site-specific calibration. Keywords: calibration, certified test equipment, flow meter accuracy.
354. Plant compressed air waste control. Every compressed air system will eventually develop leaks from connectors and redundant pipelines. Compressed air is very expensive to make. It is necessary to institute regular inspections for air leaks and fix them immediately. Keywords: pressure loss, energy loss, air compressor, pressure switch.
355. Work within the design limits. Once equipment or a process is allowed to run outside it's design limits it will fail quickly. The only way to get long-lived, well operating plant and equipment is to keep its individual components working within their service limits throughout their life. Keywords: training manual, procedures, operator manual
361. Non-destructive testing of welds. Welding processes and methods can introduce contaminants and metallurgical defects into the weld. If a weld is required to withstand severe loading conditions and stresses it is critical to insure its quality meets minimum standards. Welds can be tested by destructive and non-destructive techniques. Most production is tested by use of non-destructive methods. The most common non-destructive tests to check welds are Visual Inspection, Liquid Penetrant, Magnetic Particle, Eddy Current, Ultrasonic, Acoustic Emission and Radiography. Keywords: NDT, quality control, non-conformance, verification, weld procedure.
362. Dust control concepts. Industrial dust is the result of material escaping from the confines of a process or a storage location. The size of the problem depends on the dust�s characteristics and the means of its distribution. The best policy to control dust is to not let it escape from where it ought to belong. There are simple techniques that can be used to manage dust and prevent it from becoming a major health and environmental problem once the mechanism of creation and distribution are under stood. Keywords: bulk material handling, dust collector, stock piles, transfer points [Contents] [TOP]
363. Electric motor variable speed drives operation. Alternating current electric motor speeds can be changed by the use of a frequency converter. This device changes the frequency of the alternating current to the motor. This then changes the rotating speed of the motor�s internal magnetic field. The speed of the rotor responds accordingly and so allows for variable speed control of connected items. When these devices are used there are several issues that need to be addressed to insure successful selection and long-term operation. Keywords: VSD, precise speed control, over-speed, motor controller, frequency inverter.
364. Rolling bearing vibration detection. Roller bearing vibration measurement is one of the major condition monitoring tools in regular use. By measuring the velocity, acceleration and frequencies emitted from a rolling bearing it is possible to tell its condition and the likelihood of imminent failure. The technology is well established and well proven but requires a good understanding of equipment vibration characteristics before a user can draw good interpretations from the results. Keywords: out of balance, vibration analysis, bearing life
365. 5 Whys method of root cause analysis. It's important when resolving a problem that you address the problem and not a symptom of the problem. Determining the real problem is called finding the root cause. There are special techniques for determining the root cause of a problem. One technique known as "The 5 Whys." Keywords: failure mode, failure analysis
371. Rotating shafts under bending stress. It is common to transmit motion using rotating shafts. The shafts are mounted in bearings and turned by force through a drive arrangement. The shafts usually also carry a load. These loads cause bending and the shaft reacts by producing counter stresses within itself. Provided the reactive stresses are within the shaft�s strength range it will take the load. But if the stresses are greater than what the shaft can take it will bend. Even if the stresses are below the load limit but fluctuate, it is possible that the shaft will break from fatigue. The point of highest stress can be found by looking at the arrangement of the shaft supports and loads and calculating the forces and stresses. Keywords: Bending moments, tensile stress
372. The Big Bang � starting and stopping equipment under load. When a machine starts-up its parts move from zero speed to operating speed in a short time (the reverse when stopping). During this short period the biggest forces that the machine experiences act on its components. If during the start-up or slow-down the product or process loads are added to the machines own self-loads the forces acting on the machine�s parts are horribly magnified. If these impulse forces exceed the machine�s design allowance, or cause gradual fatigue, then the stressed parts will shatter without warning. Key words: inertia, kinetic energy, momentum, torque [Contents] [TOP]
373. Orifice plate meter flow measurement. An orifice meter is a circular piece of metal plate placed between flanges in a pipe. In it is a square-edged round hole machined 0.5 to 0.8 pipe diameter in size. Pressure tapping points are placed either side of the plate at specified distances. The orifice causes a flow restriction and produces a pressure drop from one side of the hole to the other. The amount of pressure difference is proportional to the flow of fluid through the hole. The flow is calculated from the pressure difference and flow areas using accurate mathematical formulas. Keywords: differential, static pressure
374. 6 secrets of trouble-free lubrication success. Grease and oil are the key lubricants used throughout industry to reduce friction between metal parts. Lubricants can only reduce friction if their immediate environment sustains their lubricating properties. Once the operating conditions are known a suitable lubricant with the right properties can be used. When the lubricant is in place it is necessary to maintain the environment and the machine to the specified design standards and protect it from changes to the design conditions. There are six key factors to address for trouble-free life where grease or oil lubrication is used on machinery. Keywords: viscosity, film thickness, contamination [Contents] [TOP]
375. The 5 s method of operation. A Five S program focuses on having visual order, organization, cleanliness and standardization throughout the workplace and the operation. It is a structured method to put operators and maintainers in control of what they do. Keywords: sort, systemize, standardise, self-discipline. [Contents] [TOP]
381. Moving slurries about. Slurry is solid particles in a liquid. Concentration can vary from mostly liquid to mostly solid. Slurries are usually transported through pipe work using pumps, pressurized gas or steam. Different concentrations and different particulate produce different flow characteristics. Successful slurry transport requires knowledge of the particulate, its transport behavior in the liquid at different concentrations and speeds, the nature and friction effects of the pipe work system and selection of the right motive method for the application. This article provides information for transporting slurries of up to 60% solids concentration. Keywords: Dense phase transport, rheology, viscosity. [Contents] [TOP]
382. Belt conveyor tuning. A belt conveyor is a moving surface used to transport product from one end to the other. In its basic form it consists of a driving head pulley, a tail pulley, the moving belt, support rollers, cleaning devices, tensioning mechanisms and a structural frame. Though simple in concept its many components need to work together as a system to get the best performance and operating life. Critical to that is an understanding of how to care for a belt conveyor and tune it for successful operation. Keywords: materials handling, bulk material transport [Contents] [TOP]
383. Effect of process changes on electric motors. This article explains the effect of changing process loads on AC induction electric motor performance. The motor�s behavior is a response to the load imposed on it by the equipment connected to it. The equipment�s behavior is itself a response to the duty and service it has to perform. Where the equipment duty and service is adjustable by the operator, or fluctuates as the process changes, the motor will react to those changes. When the changes are so excessive that they are beyond the motor�s ability to handle them the motor stops and the equipment or process stops with it. Keywords: squirrel cage motor, overload [Contents] [TOP]
384. Pump life extension � the impeller. A spinning pump impeller provides the means to draw incoming product through the pump, energize it, and then force it out under pressure. The impeller coverts the electrical energy from the motor into hydraulic energy of the liquid. It does this by taking the liquid into the center of the impeller and flinging it outward at high speed. To efficiently continue to do this the impeller must remain in the same condition as it was when first installed. If the impeller deteriorates the conversion from electrical to hydraulic energy becomes inefficient. Power is wasted, flow and pressure fall and the pump cannot do its designed duty. Keywords: impeller design, delivery pressure, delivery head [Contents] [TOP]
385. Equipment criticality - How do you decide what level and type of maintenance to use on an individual item of plant and its sub-assemblies? Not all equipment is equally important to your business. Some are critical to production and without them the process stops. Others are important and will eventually affect production if they cannot be returned to service in time. While other items of plant are not important at all and can fail and not affect production for a very long time. Keywords: risk based maintenance, preventive maintenance. [Contents] [TOP]
391. Heat transfer basics. Heat is energy and its nature is to flow from a state of high excitement to one of low excitement. Heat is transferred from a hot place to a cold place by convection, conduction or radiation. This article explains the three modes of heat transfer and provides simple examples of each. Methods to reduce and increase heat transfer are also presented. Keywords: emissivity, black body, absorptivity, reflectivity, transmissivity,
392. Fired packaged boiler basics. Steam boilers not used for power generation and of smaller size and energy output are termed packaged boilers. The heat source is usually either electric coils or a burning fuel. When a flame is used to heat the water it is known as a fired packaged boiler. Fired boilers are considered efficient steam generators with about 85% of the available energy converted to steam. They can be of water-tube or fire-tube design. Boilers incorporate many key aspects of heat transfer to create steam from water. This article describes how fired boilers work and their key components. Keywords: steam generation, hardness, feed water
393. Conductivity meter operation and use. The electrical conductivity (and its opposite, resistivity) of water based solutions indicate its electrical current carrying ability. High conductivity occurs when many charged atoms and ions are in the water. This typically means the presence of dissolved metals, salts, acidic or alkali chemicals. Conductivity probes are used to measure the total level of charged particles present. This article explains how conductivity probes work and their application in boiler water treatment and management. Keywords: TDS, totally dissolved solids, [Contents] [TOP]
394. Lubrication cleanliness and filtration. When oil in gearboxes become contaminated there is a rapid loss of bearing operating life. It is critical that metal particles, dirt, sand, oxidization products, etc be removed from the oil before they gouge and tear-up the finely tolerance machine parts. Oil replacement, contamination prevention and oil filtration are common practices religiously adopted by the best in the equipment reliability management business. This article explains the fine requirements for successful contamination control to insure long trouble-free equipment life. Keywords: Beta rating,
395. The 9 great benefits of a CMMS. A computerized maintenance management system (CMMS) is the maintenance department�s most important tool. It provides insight into the behavior of the facility�s individual assets, i.e. the plant and equipment. For a CMMS to be of use it must be used as an information �bank� that can be investigated. There are 9 really good reasons to use a CMMS. And each one of them alone makes a CMMS worth having. Keywords: asset management, preventive, preventive, [Contents] [TOP]
3101. Mechanical level sensor types and use. In some process situations mechanical level sensors are the best choice for the environment or are stipulated by law (as in boilers). To operate these devices requires the physical contact of the process being measured. They provide solid indisputable proof that a process condition has been achieved. Provided the mechanical mechanism is connected and working properly, these devices provide the most believable proof that a level in a vessel, tank or silo is actually what the instrument is saying it is. Keywords: rotating, pendant, vibrating,
3102. Membrane and leaf filtration overview. One method to clean particles from a liquid or gas is to pass it through a filter. The filter is a screen that traps and holds the contaminants on its surface while allowing the fluid to twist its way past the build-up and screen. The screen can be used until the back-pressure from the collected contaminants choke it so severely that the fluid flow falls drastically. At that point the screen must be cleaned. This article explains how membrane and leaf filtration processes work and the critical factors that produce successful filtration results. Keywords: filter cake, pressure-leaf filtration, filter aid, pre-coat
3103. Bag house dust bag selection. The dust bags within a bag house must handle the process conditions they experience. The choice of bag materials is usually based on the cheapest fabric that will handle the conditions for a minimum of 3 to 5 years� operation. The selection of the bag materials requires a good understanding of the process temperature, moisture content, chemical reactions with the bag fibre, dust loading effects and behaviour of the dust bags in operation. Keywords: pulse jet dust collector,
3104. Tracking belts on bucket elevators and short belt conveyors. Flexible flat belts are used on bucket elevators and belt conveyors to carry loose, bulk product. The belt is stretched tight from head drum to tail drum and the friction generated on the turning head drum is used to drive the belt and carry the product. The belt must run true on the end pulleys (drums) and stay within the sides of the equipment structure. If the belt runs off the drums, buckets will be destroyed and belt edges frayed. In the worst cases the belt runs off the pulleys resulting in a breakdown repair. Proper and long-lived tracking of belts is critical for trouble-free operation. Keywords: belt alignment,
3105. Budgets � what to do and how to use them. Budgets represent plans or expectations for the future! They are a means to plan, forecast, coordinate and control the activities needed to achieve the business� objectives. The budget document contains the amount of money that has been allocated to achieve those goals and the timing of its spending. Budgets cover the planned use of men, materials, external resources and management effort that is expected to be sufficient to hit the targets. Once the budget is finalized it becomes a tool to feedback how the actual progress is going compared to what was expected. Key words: cost control, cash flow, zero based budgeting, variances.