Page 422 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

400 Major Process Equipment Maintenance and Repair

Adjustments

1. Inspect the governor linkage, valve stem and bushings for loose fit-
tings or excessive play before attempting any adjustments. Replace
as necessary.
2. With the governor valve, governor servo motor or actuator, and
linkage fully assembled:
a. Turn the valve stem (20, Figure 8-4) from the connection (36)
until the valve is fully seated.
b. Adjust the jam nut (37) so the distance between the jam nut and
connection (36) is equal to the valve travel dimension shown on
fige
c. Screw the valve stem into the connection until the jam nut con-
tacts the face of the connection.
d. Lock the jam nut by tightening it against the connection.

Inspect the governor valve stem (20) and guide bushings (22, 28) for
wear and replace as necessary.
Remove the packing follower (25, Figure 8-4) and replace the valve stem
packing (23, 34) if excessive steam leakage is evident. (See details A and B,
Figure 8-14.)

Note: Do not overtighten the packing follower (25, Figure 8-4). The
governor valve stem can bind in the valve cover and result in
erratic speed control.

Lubricate the governor linkage pins with high temperature, water resistant
silicone grease.

Assembly (Refer to Figure 8-4)
1. Chill the valve seat (27) with dry ice (C02) and press it into the
steam chest body (1).

Note: The number of ribs (either 3 or 4) found on the valve cage
body depends on the size of the steam chest and governor
valve. Position these ribs to allow the inlet steam flow be-
tween them (Figure 8-12). Do not confuse these ribs with guide
bushing ribs. Do not weld blocks (29) to the governor valve
seat (27). This may distort seating surfaces.

2. Weld blocks to the steam chest (1 80" apart) to secure the valve seat.
3. Place the governor valve stem (20) in the valve cover (21, 35).
4. Replace connection (36) and jam nut (37) on the valve stem (20).