Centering Pin Diaphragm Alignment

Existing positions of diaphragms are first measured relative to specified reference bores. To make these measurements , 10 to 20 adhesive-backed targets are placed directly in each of the diaphragm and reference bores . A set of images that include all the bores are then made using Mechtell's photogrammetry camera. Photogrammetry software is then used to accurately determine the locations of all targets relative to each other.

Once target positions are determined, the targets in each bore are used to create a cylinder. The center of the cylinder created from the targets in a bore represents the position of that bore and the diaphragm. An advantage of multiple targets in each bore is that any outlier targets that might occur due to local surface imperfections or other anomalies will be identified and discarded.

The measured diaphragm and reference bore positions plus any desired offsets for rotor sag and similar variances are entered into a purpose built spreadsheet. This spreadsheet calculates the shim changes needed to move the diaphragm to the desired position.

After needed shim changes are made, the new diaphragm positions can be checked using a similar process.

If desired, diaphragms can easily be centered on the existing rotor position rather than reference bores. This only requires that the position of the rotor be measured before it is lifted from the lower half of the cylinder, a quick and easy process.

Turbine Diaphragm Centering Pin Diagram Turbine Diaphragm Centerline Coordinate System