The Electronic Radial Alignment Gauge (ERAG) or Concentricity Alignment Tool (CAT) by: Storm Josefsberg
Many people ask, “What is an ERAG for?” When you need to measure the differential distances between two adjacent surfaces you can use an ERAG.
The Electronic Radial Alignment Gauge (ERAG) or Concentricity Alignment Tool (CAT) provides you with many benefits.
• Does away with tight wire and/or laser alignment.
• Directly measures the amount of diaphragm misalignment with the rotor in place.
• Factory and field-tested method of diaphragm alignment since 1992.
• Alignment method proven thru thousands of hours of use.
• Cost effective – often pays for itself in one outage!
• Easy to use – direct readout.
• Accommodates a wide range of turbine sizes.
• Very accurate (resolution to .0001 inch – accuracy plus or minus.0005 inch maximum).
• Durable – units rarely require maintenance even after years of service.
• Parts are readily obtained from the factory and are usually field replaceable.
So I am sure you are asking yourself…how will this tool work for my project?
Inserted into the empty packing groove, the Concentricity Alignment Tool (CAT) allows annular space variations to be displayed on a LCD display as it is pulled through the packing groove as shown.
The head “rub bars” ride on the turbine shaft and the head lever arm rides on the ID of the diaphragm. As the head is pulled through the packing groove, the lever arm follows the contour of the diaphragm ID and the dimensional variation is displayed.
Our instruments have a main body to which there is pivotally coupled a U frame whose arms extend at an angle from its base, so that as the former is pivoted in one direction, the latter will correspondingly pivot in an opposite direction.
Contact points are provided to the arms and the bottom surface of the body, and the base of the U frame is biased by a spring loaded slidable element within the body which in turn is connected to a transducer.
An ideal way to accomplish alignment is with the rotor in place so the dimension from rotor to seal carrier can be measured directly. One of the best methods of measuring between the rotor and the carrier includes an ERAG.
ERAG rental from ACQUIP, INC makes moving the instrument between two adjacent surfaces a breeze!
For more information on ERAG/CAT rental from ACQUIP, INC go to www.acquip.com
