Your Reliability Engineering Professional Development Site
A gearbox is used to control the operating speed of industrial equipment.
It converts a high input speed to a lower output speed and so permits one driver element, such as an electric motor, to do numerous duties.
Failure of the gearbox causes the equipment and associated plant to stop.
Proper selection, care, and maintenance of gearboxes is critical to your company’s continued profitability. [Read more…]
Chemical corrosion occurs at increased rates in agitated conditions.
Typical iso-corrosion curves for alloy metals no longer apply. These curves only show corrosion rates at various chemical concentrations and temperatures in stagnant conditions.
A typical curve is shown below. The curves are available from alloy metal suppliers on request.
When metals are selected for agitated corrosive conditions the curves can only be used in a relative sense.
They help grade the metal selection but they cannot provide absolute corrosion rates. [Read more…]
A benchmark is the end distance point from the start.
In the world of maintenance, it is the name for the targets that an organization sets for itself in an improvement program.
Benchmarking is often against world-best practice and it is used to provide direction and focus in an organization’s efforts to improve.
When RAV is chosen as the benchmark it means that the annual cost of maintaining the plant will be measured against the value of the plant.
RAV is a percentage of the cost to replace the plant. The lower the RAV the more effective the maintenance effort. [Read more…]
Vibration in equipment is the result of unbalanced forces.
Out-of-balance is corrected by adding or removing material so that when the equipment is operating the unbalance is controlled to an acceptable level.
Keywords: spring stiffness, damping, center of rotation, center of mass, natural frequency, isolation mount, counterbalance, out-of-phase. [Read more…]
Coatings provide industry with low-cost solutions to difficult chemical corrosion problems.
This article covers the use of rubber, fiberglass, and epoxy linings.
Keywords: rubber lining, resin, composite glass fibers, overlap joints, adhesive, primer, corrosion barrier, repair. [Read more…]
Bridging is the name given to the self- created arch that develops just above the outlet of a bulk material silo or hopper as it empties.
A bridge forms when wall friction holds up the ends of the arch.
To overcome bridging the wall friction must be reduced or prevented from occurring. [Read more…]
Control valves regulate the flow of a liquid or gas by opening or closing internal passages.
They form part of a control loop used to control a process. The control valves respond to instructions from the controller and adjust the internal openings accordingly.
Keywords: sensor, setpoint, trim, actuator, sealing class, tuning, proportional, integral, derivative. [Read more…]
Net positive suction head losses (or why you can suck through a straw).
Pumps cavitate and run dry when the pressure leading into them falls below the vapor pressure of what they are pumping. At vapor pressure, the liquid boils into a vapor and fills the pipe.
In order to know that the pressure to a pump is always above the vapor pressure, it is necessary to calculate that the pressure losses from pipe friction and suction lift will not cause the pressure to drop under the vapor pressure.
The presence of dissolved gas in the liquid complicates the problem. [Read more…]
Pressure vessels must be regularly inspected and be maintained in a safe operating condition.
New Australian laws stipulate that all pressure vessels must have a Hazard Level rating (‘A’ highest to ‘E’ lowest) which reflects the vessel’s safety risk (see AS3920.1).
The higher the risk the more stringent the requirements for operating and inspecting the vessel.
Keywords: receiver, non-destructive testing, internal inspection. [Read more…]
Get mechanical seals working properly.
Mechanical seals are used to keep the bulk contents of rotating equipment such as pumps and compressors from escaping. They do this by sealing the shaft that protrudes from the casing.
They require quality installation and operating conditions for a long life. [Read more…]
Vibration from out-of -balance rotating equipment can be frightening.
The ground shakes, machines jump about, hold down bolts come loose and parts break.
An unbalanced rotating body will produce forces on its bearings and transmit them throughout its structure and into the foundations.
Keywords: rotor, centrifugal forces, balance quality. [Read more…]
Don’t run centrifugal pumps on the end of the curve. Pumps are designed and selected to operate near their highest efficiency point.
If they operate at the right-hand end of the pump curve the likelihood of cavitation increases.
Keywords: suction pressure, flow velocity, vapor pressure, duty point. [Read more…]
There is a good chance you can make astounding changes and achieve incredible performance improvements from your plant and equipment.
It can be done with the method used by Thomas Edison to solve his problems and make his discoveries. Improvements in the order of 20% maintenance savings with 100% on-time achievement of production plans are possible.
The method is that of continuous improvement. You start by proving it works for yourself first and then, once you are sure it works you introduce it to your people.
Keywords: continuous education
What you will learn from this article.
What you will learn from this article.