Your Reliability Engineering Professional Development Site
A listing in reverse chronological order of these article series:
The very best asset managers have maintenance under control.
Their entire organization’s systems and methods are tuned to preventing unplanned stoppages. They only do that which has first been thought through and prepared for.
But most importantly they understand the key factor to excellent asset care and work toward it continuously and energetically.
Keywords: preventative maintenance, reliability-centered maintenance, RCM, total productive maintenance, TPM. [Read more…]
Weld preheating is the purposeful application of heat to warm metal to a desired temperature prior to welding.
Preheating slows down the cooling rate of the weld and gives the metal more time to form a good microstructure, release internal stresses and dissipate hydrogen from the weld.
Keywords: thickness, weld puddle, cooling rate, temperature. [Read more…]
When a bolt and nut is tightened to draw the bolt head and nut together it stretches the shank, deforms the threads and loads the object trapped between the bolt head and nut.
The bolt shank acts like a spring being pulled apart and it tries to return to its unloaded condition.
The amount of tension developed in the shank is dependent on the number of turns of the nut.
The size of the torque required to turn the nut has little to do with the tension applied to the bolt shank.
Rather the amount of torque needed to turn the nut reflects the slipperiness of the threads.
Keywords: bolt tension, yield stress, the coefficient of friction.
This article covers some of the problems that can occur with bucket elevators and provides possible remedies.
Bucket elevators lift bulk materials from one level to another.
They are used on powders, granules, grain, chip shaped products and lumpy materials.
They function well when designed properly for the duty, and used as designed. [Read more…]
Many equipment breakdowns and stoppages occur because of improper clearance between holes and shafts.
The shaft is too tight in the hole; the center of the hole is not at the center of the shaft making it off-center; one part is loose on another and slips out of place or does not seal as it should. [Read more…]
Entropy is a thermodynamic concept that represents chaos and degradation. It occurs naturally in any physical system and will naturally grow (i.e.: become more chaotic) if we don’t do something to arrest its growth. Doing something requires the expenditure of energy, so energy is what counters entropy. We don’t speak of these thermodynamic terms and concepts in everyday language and conversation, but they are at work behind the scenes. We are well advised to remain aware of them and act accordingly or nature will steadily and relentlessly increase the state of chaos in which we exist. [Read more…]
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…]
Our simple 3 legged stool model from part 1 will deliver high performance at low cost and risk – i.e.: high productivity. It is important however to keep the legs intact! Doing so requires a bit of investment. In thermodynamic terms we need to put some energy into the system to keep the entropy from growing. That energy is investment in maintenance and the payoff comes in the form of steady, predictable revenues with a high margin for profit. Those words should be music to accountants’ ears. [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…]
We all want high productivity – maximum output for the least input, the most blast for our buck! We know that high payback will entail a level of risk, but again, we want to minimize our downside risks and maximize the opportunities that may be available to us. We need practical ways to achieve this. Good Capital Asset Management™ will deliver that – how? Well, here’s a simplified scientific explanation of how that works. [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…]
Let me first say that this is not a slam against accountants or the accounting profession. This is intended to help put what they do in perspective and to show the similarity of what they do with what we, as maintainers, do. [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…]
We know that there are no “quick fixes” or “silver bullet solutions” when it comes to improvements in maintenance management. In my last article I pointed out that many separate conditions and events must come together properly to achieve “schedule success” – i.e.: the high level of compliance to a schedule of planned work as produced by your planners. That list of includes: [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…]