Page 421 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Steam Turbines and Turboexpanders 399

Caution: The clearance between the resetting lever (1 1) and the
auxiliary resetting lever cam (10) should be 1/16 to 11s in.
(1.5 to 3 mm) with the trip valve in the closed position.
This clearance will prevent the cam shaft from bending
and hampering the trip operation.

Governor Velve
Warning: Close all isolating valves and open drains to depressurize
turbine casing and steam chest before performing main-
tenance on the governor valve or its linkage.

The governor valve (1 8, Figure 8-4), located in the steam chest body (l),
regulates the steam flow through the turbine. The valve is positioned through
mechanical linkage, by the speed governor.

Governor Valve Dmssembly (Refer to Figure 8-4)

1. Remove the linkage connecting the governor valve to the governor.
2. Remove bolts (26, Figure 8-4) from the valve cover (21, 35) and pull
the cover and valve (18) away from the steam chest body (1).
3. Remove the valve stem connection (36) and jam nut (37) from the
valve stem (20) and remove the stem from the cover assembly.
4. The valve seat (27) has a shrink fit in the steam chest. Wlded
blocks in the steam chest prevent valve seat movement. These
blocks (29) must be removed by chipping or grinding before remov-
ing the valve seat.
5. Chill the valve seat (27), by packing with dry ice (COz), and pull
the seat from the steam chest with a puller.
6. Remove the valve seat bushing (28) by driving it from the valve seat
with a nonferrous rod. Replace the bushing by pressing it into the
valve seat. Stake the valve seat to lock the bushing in place.

Clearances

1. The governor valve must move freely at all times. A smooth sliding fit
is necessary between the valve stem (20, Figure 8-4) and the packing
(23,34), and between the stem and guide bushings (22,28).
2. The governor lever and linkage should also be smooth sliding fits.
The governor valve travel should be set in accordance with the
value shown on Page ii. The governor valve has a maximum travel
of 1h in. (13 mm).