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Inspection and Maintenance — GEK 107048
Operation 8 — How to Take Turbine Clearance Checks
1. It is suggested that turbine clearances be taken under the guidance of your General Electric Com-
pany Field Service Representative. The need to closely monitor the internal gas turbine clear-
ances is critical. On every removal of the turbine casing, the internal clearances called for on In-
spection Form PGS/GT-FF-6105 should be determined. Any clearances not within specified
tolerances, as indicated on the "unit clearance diagram," in the Reference Drawing section of this
Service Manual, should be reported before any parts are removed to the General Electric Compa-
ny Field Service Representative in case "rechecks" are needed. The data will be compared to the
units original clearance data so that a determination for corrective action, if any, can be made.
The clearances listed below should be taken and recorded on Inspection Form PGS/GT-FF-6105.
a. First stage nozzle support ring to first stage nozzle segment support pad clearance B1, B2.
b. First stage nozzle clamp clearances (E).
c. Axial rotor clearances 1F1, 1A1, 2F1, 2A1, 3F1, 3A1.
d. Axial seal clearances 1F3, 1F5, 2F3, 2A3, 3F3, 3A3.
e. Axial diaphragm to turbine wheel clearance 1A4, 2F4.
f. Radial seal clearances 1F2, 1F4, 1A2, 2F2, 2A2, 3F2, 3A2, 3A4.
g. Bucket tip clearance (1R).
h. Diaphragm radial seal clearance 1PH, 2PH.
i. Rotor set points "A," "A" compliment, set point "B," "B" compliments (includes 2PA).
j. First stage nozzle support ring shim "D".
k. Shroud to bucket clearances 2SA, 2B, 2S, 3SA, 3B, 3S.
l. Axial clearance support ring set dimension ("C").
Note: The use of proper tools for taking clearance measurements is an impor-
tant factor in obtaining correct readings. See the Standard Practices
section in this Service Manual.
Left Side And Right Side (Definition)
1. The left side of the machine by definition is the left hand side when the observer is facing the
compressor inlet and looking downstream (direction of air low) toward the generator load cou-
pling end.
CAUTION
String tie all hand tools to the wrist to avoid loss in the
turbine.
Hot Gas Path Inspection — Disassembly Procedures
HGP-D-11
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