PERMALIGN®

MONITORING POSITIONAL CHANGES (THERMAL GROWTH)

Category:

Description

The PERMALIGN laser system measures and monitors alignment changes, commonly referred to as “Thermal Growth”, of rotating machinery during operation. It can measure the absolute move of a machine or the relative move between coupled machines. It may be used for permanent monitoring or for just the necessary time to determine positional change from cold to hot or vice versa. The user may obtain printout of numerical data, graphics and plot curves of positional changes over time of any monitored equipment. Contrasting with other monitoring methods, PERMALIGN allows you to determine what movements have thermal origin and what movements are caused by dynamic influences, pipe strain or load variations, etc.

PERMALIGN is the only linearized LASER MEASURING system with a resolution of one micron throughout the entire detector range of 0.630″. The system permits accurate measurement of parallel and angular movement at distances of up to 30 ft. Temperature variations and vibration do not diminish accuracy.

Collected measurement data can be trended, analyzed and archived with the WINPERMA PC SOFTWARE.

arrow Order No. B-2 (includes PC SOFTWARE)

“HOT” ALIGNMENT CHECKS ONLY
TELL HALF THE STORY!

Hot alignment checks are often unsuccessful because of delays in installing measuring devices on the equipment which has just been shut down.
Even when good planning and organization allowed you to take readings within minutes of shutdown, these readings only address the so called “Thermal Growth”. Often the effects of thermal growth on alignment had been calculated fairly accurately and the “hot alignment”check confirmed them, but still, excessive vibration persists and continues to be traceable to misalignment.
The problem is that MACHINERY MOVES during operation for reasons unrelated to thermal effects.
Dynamic rather than thermally induced movements may cause machinery to operate misaligned. Since these dynamic effects disappear before the machinery stops rotating, hot alignment checks cannot measure them.
The non-thermal moves, both vertical and horizontal, are often as large or larger than the thermal moves but much more difficult to calculate. In our experience the dynamic moves are usually ignored.
These movements can be caused by FOUNDATION PROBLEMS, by pipe strains and stresses, loose anchor bolts or changes in the load, etc. Whatever the cause or causes, almost the only way to determine the movements is continuous computerized monitoring of the alignment.
When coordinated with records from the control room it often becomes clear why and how the machinery changed position. Proper “cold” alignment targeting thus becomes feasible and significant operational improvements are usually achieved.
Aside from the well known consequences of less wear on bearings, seals, couplings, etc. it is sometimes possible to increase the load for the equipment and last but not least, power consumption will reduce and result in savings which are a multiple of the cost of the monitoring equipment.
Several monitoring systems have been on the market for many years using dial indicators or proximity probes, etc. and now, fully automatic laser systems are available with suitably large measuring range. PERMALIGN using the principle of a prism reflected beam is not affected by temperature variations and measures accurately even at very high vibration levels.

“Our Machinery Analysis Team began using the PERMALIGN system two years ago to assure that our high speed, critical rotating machinery is ‘running’ with accurate SHAFT ALIGNMENTS. Alignment related problems with our high speed turbomachinery have been solved using this technology. Experience with this system has pointed out the following: 1) Conventional ‘hot checks’ do not provide an accurate measure of the actual ‘running’ alignment condition for steam turbine applications. 2) Loads from the piping, etc. can contribute significantly to the running alignment condition. In summary, the PERMALIGN system provides an economical way to accurately measure the ‘thermal growth signature’ of critical rotating machinery.”

Leave a Comment