Page 417 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Steam Turbines and Turboeqanders 395

Adjusting The Trip Pin And Plunger Clearance
1. Remove the inspection plug (12, Figure 8-12) from the steam end
bearing cap:
2. Rotate the rotor shaft, by hand, until the adjusting nut (4) can be
observed through the inspection hole. This will position the
weighted end of the trip pin (1) directly above the plunger assembly
(7).
3. Latch the resetting lever and loosen the jam nut (9) on the trip lever
jackscrew (8).
4. Push the plunger assembly (7) upward and into the bearing housing,
until it is in solid contact with the trip pin.
5. Adjust the jackscrew to obtain 1/16 in. (1.6 mm) clearance between
the base of the plunger (7) and the jackscrew (8).
6. Tighten the jam nut (9) and recheck the clearance.

Caution: The jam nut (9, Figure 8-12) must be locked, at all times, to
prevent the jackscrew from vibrating loose during operation.
A loose jackscrew can render the trip system inoperative.

Adjustlng The lbrblne nip Speed

1. Remove the inspection plug (12, Figure 8-12) from the steam end
bearing cap.
2. Rotate the rotor shaft, by hand, until the adjusting nut (4, Figure 9-12)
can be viewed through the inspection hole.
3. Latch the resetting lever (11, Figure 8-4).
4. Place a non-ferrous drift pin on the adjusting nut and strike the drift
pin sharply to ensure that the trip pin (1, Figure 8-12), trip valve and
trip linkage function properly.
5. Latch the resetting lever and start the turbine. Closely monitor the
turbine speed during operation.
6. Gradually overspeed the turbine by overcoming the governor (see
Governor Operation, chapter 10).

Caution: Do not allow turbine to exceed 2 percent above the rated
(nameplate) trip speed.
7. If the overspeed trip does not function within 2 percent of the rated
trip speed, manually trip the turbine, by striking the top of the
hand trip lever. Then close the steam inlet shutoff valve.
8. When the rotor shaft stops rotating, turn the shaft, by hand, until
the adjusting nut is visible through the bearing cap inspection hole.