Your Reliability Engineering Professional Development Site
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.
Roll mills, drum dryers, kilns, ball mills and rotating reactors usually turn on metal tyres and trunnion rollers.
Eventually, the tyres and rollers wear out or fatigue and require repair or replacement.
Usually, the equipment manufacturers keep material specifications as proprietary information and one is forced to buy the parts from them. [Read more…]
What you will learn from this article.
Fixing plant and equipment about which you know little is daunting.
Here are a few ideas to help you successfully fault find failed equipment. [Read more…]
Some quality paradigms are expensive.
Quality is a mindset! When a wise man is given the chance to buy quality items he does so because quality pays for itself.
A quality item lasts longer, runs better and looks good when others fade. To change the way you think about quality takes a lot of experience with using poorer options. When you are sitting down with your head in your hands wondering what can be done to get costs down, to get production up and how you are going to hit the key performance indicators, remember the importance of quality equipment, quality systems, quality training and your quality mindset!
Keywords: quality control [Read more…]
What you will learn from this article:
Chemical corrosion can destroy the containment materials in contact with a process.
Means exist to mitigate and even prevent chemical corrosion. This article focuses on several such methods.
At times chemical corrosion is acceptable and one need only allow for it by using thicker materials. An example is the storage of sulphuric acid in mild steel tanks at ambient conditions and concentrations [Read more…]
What you will learn from this article.