Determining the correct maintenance strategy for industrial production assets poses a problem for many plant asset managers and reliability and maintenance engineers.
Identifying the source of vibration by following the amplitude: the case of a company that thought the problem was a pump impeller, but, in fact, the problem was over 15-ft away and not a pump at all.
"An ounce of prevention is worth a pound of cure" may have been coined by process and plant engineers tired of repairing or replacing pumps. Pumps are often the most under-serviced pieces of equipment in process automation when it comes to maintenance and prevention best practices. Unfortunately, nothing moves without the humble pump, and a process becomes inefficient when a pump doesn't operate properly or completely shuts down. Many times the pump manufacturer is seen to be the problem, when in fact the process or the surrounding equipment configuration is the cause.
Last month we reviewed the pump selection criteria for a closed loop circulation system (Vp-Vf). This month we will take a look at a similar application that adds some elevation to the equation.
One of the major contributors to unbalance in rotating machinery is eccentricity. When we disassemble parts, we must also reassemble them. Even if the reassembly requires heating to shrink-fit the elements back together, we probably balanced them in a balancing machine where tolerances due to fit-up on mandrels or roundness of journals may possibly far exceed the heavy spot tolerances that the target standard of balance allows.
Pumps are sent to rebuilding and remanufacturing companies because buying new can be expensive and require long lead times. For instance, a 39 in diameter, 1,000 lb bronze impeller may cost $28,000 and take many weeks to deliver. In these cases, the impellers involved in an overhaul are often built back up to the required specifications and rebalanced.
Even when a redundant pumping system is in place, it can be advisable to monitor the condition of the operating units in critical applications where maintaining production depends on motor-pump reliability.
A dangerous misconception exists regarding the "Arc Rating" of infrared (IR) windows or viewing panes. Many reliability and maintenance professionals are under the impression that an IR window will protect them in the event of an arc blast. Others believe that installing IR windows will turn non-arc-rated switchgear or electrical equipment into "arc-rated" cabinets. Neither is true. Both misconceptions need to be corrected because they present safety concerns.
Interpretation of equipment clues can help diagnose problems before failure occurs
Many items must be considered when designing pump station control systems with power requirements, level control method and control panel location often among the most important.
The installation of an AC drive with an advanced software tool has dramatically cut call-outs for blockages at an Irish county council pumping station.
Of the technologies available for condition monitoring of rotating equipment, the quickest return on investment is from vibration analysis. For the novice, vibration data seems complex and is generally difficult to assess compared to other techniques. Once trained, however, the novice can recognize the patterns and diagnose a machine problem.
When it comes to pressure and flow, variable speed pumping applications can be divided into three basic categories. Constant pressure-variable flow (Cp-Vf) attempts to keep pressure relatively constant over a range of flows. Constant flow-variable pressure (Cf-Vp) tries to achieve the opposite by using varying pressure to keep flow constant. Variable pressure-variable flow (Vp-Vf) applications can accommodate a change in both.
Although the use of transmitters in pressure measurement is growing, mechanical pressure gauges are still used on most systems as local pressure display to back up electrical readings. The selection and installation of these gauges can be difficult in certain locations. Harsh conditions that can require special consideration include vibration, pressure pulsation, overpressure, corrosive media and extreme process and ambient temperatures. This article is designed to address harsh conditions with best practice recommendations to extend gauge life and provide for the safest installation possible.
How a monitoring alarm system with control and shutdown capabilities prevented costly pump damage and environmental hazards and made the job of the pump operator safer and easier.
With the wide use of variable frequency drives in the pump industry and increasing unit size, it is becoming more difficult to design mechanical systems free from natural frequencies within operating speed range. If such an occurrence is allowed in the field, a resulting resonance condition threatens to significantly impact performance and longevity of the equipment.
In the oil and gas industry, custody transfer transactions involve transporting physical substance from one operator to another, including transferring raw and refined petroleum between tanks and tankers, tankers and ships and other transactions. An accurate account of the amount of material transferred is of great value to both the company delivering the material and the eventual recipient. This is especially true in bunker fuel oil delivery since a ship's bunker contributes to the ship's operating cost.
Back in the old days, level control had little or nothing to do with saving energy. In fact, it was often a necessary evil. Today, that is no longer true - the VFD offers the potential for power savings in lift station applications that range from a few hundred gallons per minute to those that have to move thousands of gallons each minute.
Growing infrastructures are creating more complex problems for municipalities than ever before, forcing them to search for a diverse range of system solutions to issues involving energy savings, maintenance savings and total life cycle cost analysis.
What Are Your Vibration Monitoring Goals?
Identifying goals before starting is key to designing a process tailored to specific needs. What are you hoping to accomplish by monitoring vibration? How would you like to acquire data? What are you going to do with the data? These important questions should be addressed before moving forward.