Page 418 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

396 Major Process Equipment Maintenance and Repair

9. partially pry the “U” lock staple away from the trip body until the
adjusting nut is free to turn.
10. lbrn the adjusting nut to change the trip speed. Turning the nut
counterclockwise will decrease the trip speed. Turning the nut
clockwise will increase the trip speed.
11. Push the “U lock staple into the trip body, and check that the trip
pin (1, Figure 8-12) moves feely. (Be sure staple is firmly
seated.)
12. Start the turbine and check the trip speed. Continue to make trip
adjustments until the turbine trips at the rated (nameplate) trip
speed.

Dlsassembly, Rip Valve
1. Place the trip valve in the tripped position and disconnect the closing
spring (14 and 49, Figure 8-4) from the resetting lever (1 1).
2. Remove the cap screws (4) from the valve cover (3) and lift the trip
valve assembly (17) and cover from the steam chest body (1).
3. Remove nut (15), spring (41), bushing (43) and spring seats (40 and
42) from the valve stem.
4. Turn the valve stem out of connection (46) and remove the valve
assembly (17) from the cover (3).

Guide Bushing Replacement
1. Disassemble the trip valve as described under “Disassembly, Trip
Valve” Section.
2. Drive the bushings (16, Figure 8-4) out of the valve cover (3) w3h a
non-ferrous drift pin.
3. Clean and de-burr the valve cover.
4. Press new bushings into the valve cover and lock them in place by
staking the cover.
5. Assemble the valve as outlined under “Assembly, Trip Valve” Sec-
tion.

Assembly, Trip Valve

1. Clean the sealing surfaces on the valve cover flange and steam
chest body.
2. Insert the valve stem into the lower guide bushing (1 6, Figure 8-4) and
push the valve stem through the valve cover.
3. Turn the valve stem into and through connection (46) and replace
spring seats (40 and 42), bushing (43), spring (4 1) and locknut (1 5).