Tech Tips Newsletter
UE SOUND BITES . . . The Ultrasound Newsletter published by UE Systems, Inc.
Information… Product News… Advice… Dialog |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
T O P I C S
What is the P-F Curve?
|
This newsletter is dedicated to you, the reader with the goal of improving your ultrasonic inspection skills and enhancing your value to your company or clients. As always, we welcome your participation. If you have questions or seek advice about your inspection techniques or programs, or if you wish to share your experiences with others, please e-mail your contributions to us at info@uesystems.com.
What is a P-F Curve? Whether well maintained or not mechanical equipment will eventually fail. Of course, the more attention paid to predictive and preventive maintenance actions, the better the potential life expectancy. There is a life expectancy for all rotating equipment. As components all move or come in contact with something that moves, there are many conditions created in the natural motions of mechanical equipment that eventually lead to a point where it will fail. Our challenge is to be aware of any changes in operating equipment that can ultimately lead to a failure stage. Once entered, we than have the responsibility of making sure we can jump in early enough to keep the designated equipment from a catastrophic failure state causing an unplanned downtime situation. |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
The P-F curve is an illustration we have seen in technical journals and at Ultrasound World conferences that describes the “Potential for Failure of rotating equipment from early stages of failure to catastrophic failure. At Ultrasound World we were shown where along this “slope to failure” various predictive technologies lie. As it happens ultrasound technology was shown to be capable of detecting the earliest stages of failure in rotating equipment.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
Ultraprobe Tip: Spectral Analysis for Valve Inspection One advantage of ultrasound inspection is that it can detect the presence of turbulent flow related to a leak condition. When a valve leaks, turbulence is generated downstream of the valve seat. By comparing upstream to downstream, differentials in ultrasound levels can help determine if a valve is leaking. Often the procedure involves four test points: 2 upstream (points A and B) and two downstream (points C and D). For the majority of cases simply comparing upstream to downstream dB levels is sufficient. There may be instances in which valve flow modulates or, as with reciprocating compressor valves, observing a timed event might provide more information than by just observing changes in dB levels. In other instances the ability to graphically portray the image of a leaking valve can help illustrate findings in a report. Using spectral analysis can help. Record the sounds at the C test point and play them back in the time series. If a known good condition has been recorded the images of both can be used in your report. If you want to provide an image of the leaking valve, record all four test positions. When you play them back create overlays for each. Be sure to keep the sensitivity the same when recording the four test points or the sound recording comparison will not be accurate. The spectra view of the 4 is colorful and makes a great attachment in your reporting. Carlos Garza provided us with some excellent graphical representations of leaking valve conditions at Ultrasound World. You’ll find them in his presentation entitled: “Ultrasound Fundamental Technology for the Efficient Use of Steam” Comments and Contributions: Ultrasound World III was an outstanding success. The presentations provided us all with valuable information which we would like to share with you. As we mentioned above in this newsletter, you can get your copy three ways: order the CD, view on line or download from our web site: http://www.uesystems.com/ultrasound_world_III_proceedings.asp Here’s a new contest. Every month we’re going to set up a new sound for you on our web site. All you have to do is read the clue and identify it. Send us an email with your guess. All successful entries will be placed in a monthly drawing for a prize. This month’s prize is a UE Watch. Send us one of your sounds with a brief description. If we select it for use we’ll put your name up on the site to give you the recognition you deserve plus we’ll happily send you one of our famous UE shirts as a thank you. To participate in the contest, Click Here: Training Schedules: As you may know from previous newsletters, this year we are offering a more varied program. You can attend our renown Level I and Level II courses or take a specialized software course. Level I and Level II
or register on-line: http://www.uesystems.com/forms.asp?frmID=10 1-Day Software Class Ultratrend DMS & UE Spectralyzer
or register on-line: http://www.uesystems.com/forms.asp?frmID=21 More articles will be posted periodically. Please check back. If you do not wish to continue to receive this newsletter, please let us know via email. Contact us at info@uesystems.com. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| UE SYSTEMS, INC. Toll Free: 1.800.223.1325 Phone: 914.592.1220 Fax: 914.347.2181 e-mail: info@uesystems.com |
| Copyright ©1999-2007 UE Systems, Inc. All rights reserved. |