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ABSTRACT for Process, Plant & Equipment UP-TIME

- Volume 2 Titles - 

Volume 3

211.           Equipment Identification tags save time.  Identifying equipment for operators and tradesmen will save time, reduce errors and promote accurate record keeping.  Equipment identification involves putting a unique number and a unique written description onto a machine. Keywords:  CMMS, computerized maintenance management system, planning, breakdown repair, reporting faults, equipment tags, catalogue.  [Contents] [TOP]

212.           Sizing liquid flow pipelines easily. Designing pipe work for liquid flow requires calculating the pressure losses along the pipe due to pipe friction. Once the losses are known the right pipe diameter can be selected.  If full engineering calculations are not possible the conservative approach is to select pipe sizes that produce a velocity of less than 3 m/sec. Keywords: pressure loss, viscosity, friction factor.  [Contents] [TOP]

213.           Confined space entry safety. A confined space is anywhere not normally meant for human habitation in which access maybe restricted and the conditions in the confinement may be inadequate to support life or could cause engulfment.  Obvious places are tanks, vessels, silos and below ground pits.  The less obvious ones are cold rooms, areas of plant sandwiched between machinery and equipment, tip truck trays and open pit mines. Keywords:  risk assessment, hazard identification, job safety analysis, safe atmosphere.  [Contents] [TOP]

214.           Magnetic flow meters.  Mag-flow meters are used to measure the flow velocity of conductive liquids. In a magnetic flow meter an electromagnet placed either side of the bore creates a magnetic field when the power is turned on.  As the conducting liquid flows through the magnetic field a voltage is developed across the liquid.  Insulated electrodes flush mounted in the wall of the meter detect the voltage.  The magnitude of the induced voltage is proportional to the liquid velocity, the length of the meter and the strength of the magnetic field.  Keywords:  electric current, isolation flanges, calibration.  [Contents] [TOP]

215.           Angular contact bearings.  They are used on shafts that encounter axial forces or combined loads (both axial and radial forces). Examples are centrifugal and helical rotor pump shafts and helical and worm gear shafts in gearboxes. Their design only permits axial forces in one direction. For alternating axial loads they must be installed as a bearing set to accommodated the forces from both directions. When set back to back, and less so when set face to face, they act to stiffen the shaft and handle larger bending moments such as overhung components or high midpoint shaft loading. Keywords: floating bearing, preload, clearance, tolerance.  [Contents] [TOP]

221.           Preventive maintenance stops breakdowns. Preventive Maintenance requires people to regularly walk around looking, feeling, listening, smelling (sometimes even tasting) and thinking about their equipment�s operating condition.  The three foundations of classical Preventive Maintenance are regular lubrication checks, drive train monitoring and equipment mounting inspections. Keywords:  work order, inspection, watch keeping, CMMS, computerized maintenance management system.  [Contents] [TOP]

222.           Fibreglass construction and repair. Fibreglass is a glass fibre reinforced plastic composite with excellent chemical resistance properties.  Its physical properties, selection of resins and glass, method of construction and fabrication and peculiar repair requirements must be appreciated when using this material.  Keywords:  laminate, backing layer, structural layer, corrosion barrier, crack repair, winding angle.  [Contents] [TOP]

223.           Shaft alignment on pumps. Shaft misalignment is one of the most common reasons for bearing and mechanical seal failures.  Rotating misaligned shafts produce vibration and complex fluctuating radial and axial loads that lead to breakdowns.  Shaft alignment is a precision maintenance requirement that requires exacting care and detail and if not performed will cause much production down time.  Keywords: axial alignment, laser alignment, dial indicator, soft foot, shaft coupling.  [Contents] [TOP]

224.           How control systems can trick operators.  Operators are required to run their plants from control panels.  They view the control panel dials, lights and readouts and from them they interpret the plant and equipment operating condition.  It is critical that every indicator on the panel be a true reflection of the equipment�s state out in the plant. Keywords: operator panel, equipment monitor, PLC, process control, plant design, operating procedures.  [Contents] [TOP]

225.           Shaft coupling selection issues. Shaft couplings are used between shafts to connect them so power can be transmitted and to allow for axial expansion. Shafts can either be aligned or intentionally inclined at an angle to each other.  When at an angle a universal joint is used to connect the shafts. When directly aligned a shaft coupling is fitted.  Keyword: shaft alignment, coupling spacer, power rating.  [Contents] [TOP]

231.           Use written work instructions to make it clear. Job procedures or job instructions are written directions given to equipment maintainers.  They reduce the chance of making an error and reduce the time spent looking for information. Job instructions offer an opportunity to insure a job is well planned, well documented and well organized. Once written they are reused forever more.  Keywords: CMMS, computerized maintenance system, job planning, corrective work , planned work, work order, training, repetitive work.  [Contents] [TOP]

232.           Centrifugal pump cavitation. Cavitation in pumps is the presence of collapsing gas bubbles in a liquid stream.  Under very low-pressure conditions the liquid vaporizes and boils. The gas bubbles collapse when they enter a region of high pressure.  It is often heard as a rumbling sound coming from the pump.  The collapsing bubbles cause mini-implosions that tear metal out from impellers and volutes.  Keywords: gas inclusion, entrained gas, vapour (vapor) pressure, suction pressure, boiling, pressure loss, high velocity, suction head, net positive suction pressure available, NPSHA, supply tank. [Contents] [TOP]

233.           Stress in metals cause failure.  Too much stress in metal will cause it to fail.  Failure can occur by putting the metal under a once-only load greater than it can take or by metal fatigue from continually loading the metal cyclically with a high load less than the breaking load.  Stress produces strain at the molecular level in the metal and discontinuities between atoms come together to form microscopic cracks. Under continued stress the cracks grow and eventually the metal parts. Keywords:  metallurgy, molecular structure, strain, Hooke�s Law, distortion, deformation, dislocation, yield stress, ultimate tensile stress, proof stress, stress reduction, heat treatment, microstructure.[Contents] [TOP]

234.           Experiences with pneumatic actuators. Pneumatic (air operated) actuators are the preferred device used to automatically open and close quarter-turn valves.   They consist of a ram moved by air pressure within a cylinder.  Long-lived actuator operation depends on the air quality, the compatibility of materials of construction, the simplicity of the design and the quality of the installation.  Keywords: valve actuator, solenoid valve, fail close, fail open, instrument air, opening torque, spring pack.  [Contents] [TOP]

235.           Locating pressure relief valves. A pressure relief valve (PRV) is used to prevent over-pressure in a vessel or pipeline.  It consists of a disk pushed onto a seat by a spring. The seat is forced open with the rising pressure and relieves the build-up. The contact faces of the seat and disk are machined smooth and accurate so no leakage occurs when the process pressure is less than the set pressure.  The set pressure is the pressure at which the valve opens.  If the pressure rises above the set pressure the force on the disk pushes the spring up and the valve vents.  Keywords:  discharge pressure, relief capacity, vent, rupture, pressure vessel, over-pressure.  [Contents] [TOP]

241.           Use words instead of code numbers on work orders.  A work order full of code numbers confuses people.  When work order type (breakdown, corrective, modification, etc) is described as Work Order Type �04� you can guarantee that no one knows what �04� is without looking it up on a list.  The best way to prevent confusion is to use word descriptors.  Keywords: CMMS, computerized management maintenance system, breakdown, corrective, work order, implementation.  [Contents] [TOP]

242.           How fluids flow in pipes. This article explains what happens to fluids flowing through pipes.  A fluid is either a liquid or a gas.  In industry they are piped from storage to the point of use.  Correct design and installation of the piping system minimizes pressure loss and improves the behavior of equipment and processes. Keywords:  pipe wall friction, surface roughness, boundary layer, laminar sub-layer, velocity, pressure loss, viscosity, density, friction factor, turbulent flow, laminar, pipe fittings, nozzle. [Contents] [TOP]

243.           Equipment and plant layout for improved maintenance.  Equipment reliability studies show that the likelihood of failure increases the more often machinery is disturbed.  The chance of something being done wrong rises every time an item of plant is worked on.  Nothing may go wrong the first time or the second time but with each additional disruption there is an increasing possibility that an error will be made.  Simple, fast and uncomplicated access to individual items of plant and equipment means higher plant availability and longer time between failures.  Keywords:  safe ease of access, crane access.  [Contents] [TOP]

244.           Capacitance level probes.  These are instruments that consist of a long rod or cable which protrude into a vessel and its contents.  The instrument sets up an electric field between the probe and the tank wall using the contents of the tank as a dielectric (a nonconductor that allows an electric field to exist within itself).  The electrical properties vary between the portion of the probe under and above the liquid.  The position of the change is detected and represents the level of the tank contents. Keywords:  tank level, level detector, level reading.  [Contents] [TOP]

245.           Spherical roller bearings. These bearings are popular because they can take very heavy loads and are self-aligning.  Their design allows them to take combined loads in both the radial and axial direction acting together.  Keywords:  misalignment, radial load, axial load, bearing housing.  [Contents] [TOP]

251.           Watch keeping � added value from operators.  The watch keeper of old guarded their people and possessions.  They were found walking about looking, listening, and watching for changes that signaled danger.  Their job was to look for hazards and quickly raise the alarm before all of them were invaded and killed or captured into slavery.  With sufficient warning the home group could rally to the defense and counter-attack the enemy.  In the world of plant and equipment maintenance the watch keeper is the plant operator.  Keywords: check sheet, log book, plant performance records.  [Contents] [TOP]

252.           Bronze � use the right one for the right job.  This quarter we will talk a little about bronzes, their properties and applications. Occasionally people refer to a brass bush when in fact they want a bronze bush and could we write something on this.  Keywords:  plain bearing, brass, gun metal, phosphor bronze, aluminum bronze, copper alloy, cast, wrought, machining properties.  [Contents] [TOP]

253.           Converting from oiled to greased shaft roller bearings. The conversion of shaft bearings on a basket centrifuge from oil-bath to grease lubrication involved changing the method of shaft sealing.  Roller bearings can be lubricated by oil or grease.  The use of grease has distinct advantages in some applications. Keywords:  temperature rise, oil bath, lubrication.  [Contents] [TOP]

254.           Temperature sensing elements.  The temperature of a process is an important measure to know as it indicates whether or not the process is in control. When high temperatures exist and accurate measurements are needed thermocouples and Resistance Thermal Devices (RTD) are two commonly used industrial temperature sensing methods.  Keywords:  temperature range, instrument, response time, spanning.  [Contents] [TOP]

255.           Changing out dust bags in reverse pulse dust collectors.  The dust bags in pulse jet dust collectors require replacement if damaged and leaking or if blinded by the product.  This work procedure indicates the process and methods to use to change-out and replace dust bags and cages in a dust collector.  Keywords: tube plate, bag collar, air manifold, air plenum.  [Contents] [TOP]

261.           Components of an effective maintenance system.  If you are ever in the fortunate position of developing a maintenance system from the beginning, the list below will help you focus your efforts.  Maintenance systems in small business, develop by default and without much forethought.  This list puts together, in one place, the important components of a workable maintenance system.  [Contents] [TOP]

262.           Electric motor problems.  This article presents a basic explanation of electric motor construction and operation along with twelve problems that can be encountered with their use.  Most electric motors in industrial equipment are three phase alternating current induction motors.  Induction is the creation of an electric current across a gap. Two types of induction motors are commonly used: squirrel-cage and wound-rotor.  The names come from the way they are built.  Keywords: motor characteristics, mounting, frame size.  [Contents] [TOP]

263.           Pulse jet bag house dust collectors. A bag house dust collector is used to separate dust from a dust-contaminated gas stream.  The gas is filtered through bags made of fabric. The fabric traps and filters out the dust while the cleaned gas passes through.  The fabric consists of either woven or intertwined (felted) fibres. The bag fibre is selected for its ability to give a long working life within the internal environment of the dust collector.  In this article on pulse jet bag house dust collectors we cover twelve factors spanning their design and operation.  Keywords: dust bag, filter cake, bag retainer, venturi, pulse air.  [Contents] [TOP]

264.           Plastic pipelines for instruments and control valves. Some instruments and many actuated valves require an air supply to operate.  There are control panels that are purposely pressurized with air to stop ingress of dust or hazardous vapors.  When the supply air is lost to these items of plant the process fails or the level of risk rises dangerously.  It is sensible to buy and use high quality compressed air fittings and piping to protect against lost production time and unwanted dangers. Keywords:  air supply, threaded fittings, valve actuator.  [Contents] [TOP]

265.           Problems with peristaltic (hose) pumps. A peristaltic or hose pump consists of a rubber hose in a bath of lubricant, mounted on the inside of round track that is squeezed closed by revolving wheels or a sliding shoe.  The squashed area moves around the hose and pushes the contents through it.  Behind the moving squeezed area a vacuum is formed and draws in more of the contents being pumped.  There usually are two squeeze points 180o apart and driven through a gearbox by a motor. This article explains the operation of peristaltic (hose) pumps and gives twelve points to be aware of when using them.  Keywords:  positive displacement pump, slurry, material compatibility.  [Contents] [TOP]

271.           Have good valve decontamination practices.  In an industry where dangerous and hazardous liquids and gases are handled it is necessary to insure that all equipment removed from service for repair or inspection is properly decontaminated.  Procedures are required that involve the use of information tags warning people of the likelihood that a dangerous chemical is present and what level of decontamination was undertaken.  Keywords: danger tag, safe transport, MSDS, material safety data sheet, accident, incident report.  [Contents] [TOP]

272.           Metal corrosion basics. The article explains the metal corrosion process including the basic chemistry of how metal loss occurs. Methods to control corrosion are also listed and explained.  Metal corrosion is a chemical reaction between a metal surface and its environment. Corrosion can occur in a gaseous (dry) environment or a damp (wet) environment.  It is the result of an electrical process in which electrons are exchanged between the corroding metal atoms and the acceptor element atoms. Corrosion control involves stopping or minimizing the loss of electrons between the components involved in the process.  Keywords:  dry corrosion, wet corrosion, surface area, differential aeration, stagnation, pitting, stress corrosion, galvanic, microbiological, crevice.  [Contents] [TOP]

273.           Vee-belt drives.  The article discusses the use of vee-belt drives. It covers some basic theory of friction drives and lists 11 factors to be considered when using vee-belt drives. A friction drive connects two shaft-mounted pulleys by a belt that is drawn taut enough to grip each shaft and turn them. The belt is pulled tight to create friction with the pulleys.  As the drive pulley turns, the belt moves the connected driven pulley.  Keywords: belt tension, friction drive, coefficient of friction.  [Contents] [TOP]

274.           Water hammer and how it is controlled.  When a control valve or manual valve is shut fast in a full pipeline of moving liquid, the liquid comes to a sudden stop. If the pipe suddenly starts banging and thrashing about you can be sure a water hammer was created.  Water hammer can cause great noise and damage. The pressure surge can deform pipes and valves and start leaks.  Keywords: momentum, pressure wave, valve stroke speed, opening time.  [Contents] [TOP]

275.           Helical rotor pumps � benefits and limitations.  The article presents the benefits of using helical rotor pumps as well as the important factors to consider for a long working life when they are used. Helical rotor pumps consist of a rotor shaped like an elongated corkscrew, which turns inside a stator. The rotor sits inside the stator void and a cavity is formed between the rotor and stator.  As the rotor turns, the cavity moves from one end of the pump to the other.  Keywords: progressive cavity, wiggle pump, mono pump.  [Contents] [TOP]

281.           Predictive maintenance � what is it?  The practice of maintenance has been developing for the past 300 years.  Since the start of the Industrial Revolution machinery and their control systems have played a critical part in our ability to produce consumer and industrial goods. Over that time different maintenance philosophies have developed in response to changing technology and increasing costs.  The progression in philosophies started with breakdown maintenance (BM), then to time based maintenance such as preventive maintenance (PM) and shutdown maintenance. More recently condition based maintenance (CM) has become significant.  The next step is predictive maintenance.  Keywords:  equipment monitoring, process variables monitoring.  [Contents] [TOP]

282.           Vertical bulk liquid storage tank construction and maintenance.  Bulk liquid storage tanks are constructed to contain large volumes of content.  The nature of the content and the amount involved can impose major hazard and risk.  For this reason bulk liquid storage tanks must be constructed and maintained to high standards.  The article reviews the requirements for building and maintaining vertical, bulk liquid storage tanks. Issues, which affect the care of large storage tanks as well as common problems, are reviewed.  Keywords:  chemical storage, tank floor, statutory inspections.  [Contents] [TOP]

283.           Metal fatigue failure. Metal fatigue is the common name used to describe the unexpected failure of metal parts by progressive fracturing while in service.  The article is a basic introduction to the mechanism of metal fatigue failure. An introduction into accepted theories is provided and relevant design practices to reduce metal fatigue are presented and explained.  Keywords:  cyclic failure, stress concentration factor, microstructure, micro crack, alternating stress, stress relieve, stress point, cycles to failure, infinite life.  [Contents] [TOP]

284.           Proximity switches.  A proximity switch is the common name for a range of detectors that generate an electrical signal when a physical mass cuts through their sensor field.  Upon detection of an object the electrical signal is sent to a controlling device and is used to monitor and control the operation of the equipment. Keywords:  target, position switch.  [Contents] [TOP]

285.           Chain drives � some experiences in-the-field.  Chain drives involve the use of roller chain to turn a driven sprocket connected by the chain to a driving sprocket.  They are used when precise speed ratios are required between the driver and driven shafts. A chain drive allows no slippage. An example is on a gearbox driving a conveyor.  Chain drives are also used when a large amount of power is required through the drive.  For example the drive on large rotating kilns. Keywords: link, pitch, duplex, triplex chain, stretch, jockey wheel, overload protection, chain link.  [Contents] [TOP]

291.           How accounting policies affect maintenance costs.  Accounting decisions can greatly affect maintenance costs.  Two examples are the decision to purchase items as maintenance or capital and how to number plant asset items.  Keywords:  tax deduction, asset number, equipment number, depreciation, capital expenditure.  [Contents] [TOP]

292.           Safety shower installations. Safety showers and eyewash stations are installed when dangerous goods are present.  The shower installation has to meet recognized standards like American National Standard Z385.1.  The article notes the key requirements for safety shower installations and discusses some practical issues.  Keywords: water supply pressure, water spray pattern.  [Contents] [TOP]

293.           Cooling water towers. There are two types of cooling water towers: natural draft and mechanical draft.  A cooling water tower is used to remove heat from incoming hot water and reduce it to a lower temperature.  It does that by evaporating off some of the hot water.  The evaporated water takes away the heat.  Exactly the same process occurs when your body sweets to keep you cool. You cool off even faster if there is a breeze blowing. Keywords:  forced air draft, evaporation rate, relative humidity, heat exchange.  [Contents] [TOP]

294.           Static electricity basics. Static electricity is the build-up of opposite polarity (positive and negative) electrical charges on two different substances in contact by the movement of one surface across the other. The spark that can occur from static build-up is the result of the opposite charges neutralizing themselves when the electrical field between them becomes strong enough to overcome the gap resistance.  Static can occur on both conducting (such as metal pipes) and non-conducting (such as rubber) materials. Examples are moving liquids, gases carrying particulate, conveyor and vee-belts, printing equipment, on rubber and plastic items, during dry cleaning, on moving road vehicles and airplanes.  Keywords: electrically neutral, recombining electrical charges, earthing points. [Contents] [TOP]

295.           O-ring design, operation and use. Properly designed o-ring grooves and properly installed o-rings stop the passage of pressurized liquids or gasses.  O-rings are made of elastomeric materials such as rubbers and plastics.  Flexibility while being deformed under pressure is their greatest sealing advantage.  They deform under pressure and then return back to their original shape once the pressure is removed.  Keywords: cross-section shape, elastomeric, shaft seal, pressure tight.  [Contents] [TOP]

2101.       What is life cycle costing?  Life cycle costing (LCC) is a way of analyzing purchase choices and coming up with a justification to purchase a piece of equipment.  If the analysis is done right and all factors are addressed, and the information is good, you would select the item that cost the least amount to own (buy and use) over its working life. This piece of equipment would perform its service at the lowest total cost to the organization than any other comparable item.  Keywords: accounting decision, equipment life cycle, cost of ownership, capital cost.  [Contents] [TOP]

2102.       Steam trap operation and selection. The article covers the operation of steam traps and how they work.  Their duty is to remove condensate from steam piping to insure only vapor is sent through the pipeline.  Steam is a greatly used medium in industry.  Its use ranges from heating process and domestic fluids through to driving turbines by the expansion of the vapour.  Yet the steam trap at the bottom of a drop leg is easily forgotten. Keyword:  condensate recovery, discharge rate, air blinding, air venting. [Contents] [TOP]

2103.       Hazardous areas for dusts and flammables. Many explosions in the processing, manufacturing and bulk materials handling industries involve flammable gases or vapors and explosive dusts or fibres.  Such chemicals are known as hazardous materials.  The article provides a basic overview of the design requirements and maintenance practices for electrical equipment in hazardous areas. Keywords:  explosive range, hazard assessment, zone classification, explosion protection, surface temperature, pressure wave, explosive range.  [Contents] [TOP]

2104.       Using pH meters. A pH meter is used to determine if a liquid is acidic or alkaline.  It is important to know if a chemical is corrosive to human tissue and engineering materials so that appropriate protection can be provided. The pH is the measure of the amount of free H+ ions in a solution. The measure of pH ranges from 0 at the acid end to 14 the base end.  Each full division is ten times stronger than the previous division (a logarithmic scale).  Keywords:  reference electrode, neutral, hydrogen ion.  [Contents] [TOP]

2105.       Sealing threaded pipe connections. Threaded connections on process chemicals and utilities piping can be difficult to seal.  Leaks from threaded joints in steam and compressed air lines are common.  The article examines how pipe threads are designed and work and what to consider in achieving proper sealing of treads.  Keywords: thread profile, pitch, thread cavity, threaded pipe, pipe fittings screwed connections.  [Contents] [TOP]

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