Bell & Gossett HS 601G Pilot Operated Pressure and/or Temperature Steam Regulators Series 2000 - Manual (Page 17)

SPRING PILOT REPAIR
Disassembly
1. Isolate the main valve from the steam line. Make
sure the internal pressure is 0 psig (0 bar) and allow
the valve to cool to prevent injury.
2. Disconnect the copper tubing lines and feedback line.
Disconnect the pipe union and remove the pilots from
the main valve. If more than one pilot is used,
unscrewing the 1/4" NPT pipe nipples should separate
them.
3. Mount spring pilot in vise with adjusting spring up.
4. Release compression on adjusting spring (2) by
loosening adjusting nuts (1) an equal amount.
5. Remove diaphragm nuts (3) and lift off cowl (4). Lift
out diaphragm assembly (5, 6 & 7).
6. Disassemble diaphragm assembly by removing
diaphragm screw (7) from pressure plate (5).
7. Remove blind flange bolts (16) and take off blind
flange (15). Remove screen (12) and gasket (17).
8. Hold the pusher plate (8) and remove stem nuts (14).
Lift out stem assembly (8 & 11) and valve spring (9).
The disc (13) will drop off.
9. If the seat ring (10) requires replacement, remove it
from pilot body with a socket wrench.
Spring Pilot Inspection
1. Examine the seat and disc sealing surfaces for nicks
or other signs of damage by pipeline debris. Slight
imperfections may be removed by lapping the
surfaces together. Otherwise the seat and disc must
be replaced.
2. Examine the stem for build-up of pipeline contami-
nants or erosion. Remove any build-up with a wire
brush and polish with very fine crocus cloth. Work
carefully to avoid bending the stem.
Spring Pilot Seat Lapping Operations
Lap sparingly using 500 grit lapping compound and
light pressure. Heavy grinding may cause galling,
wide sealing surfaces and a grooved disc, all of
which tend to produce leakage.
Refer to lapping procedures in "Seat, Disc and Stem
Replacement" below. After the sealing surfaces are
lapped in, disassemble and clean all parts.
Seat, Disc and Stem Replacement
1. Clean the body threads of old sealing compound
using a wire brush. Apply new sealing compound
(Copalite or equal) to the shoulder of seat ring. Let
stand until tacky before installing in pilot body.
2. Lap in stem to disc joint with lapping compound.
3. Secure disc (13) to stem (11) with a stem nut (14).
Insert this assembly into pilot body (omit valve spring).
4. Apply lapping compound to the disc and lap in the
seat to disc joint. The stem is slotted for rotation with
a screwdriver.
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1/8 NPT
1/4 NPT
5. When lapping is complete, use a clean cloth to wipe
the disc (13), seat ring (10) and stem (11).
6. Screw pusher plate (8) on stem (11). Holding disc
against its seat, adjust the pusher plate (8) so that
dimension C = 11/64" (4.4mm). A pilot travel setting
gage is supplied with each repair kit.
7. Remove stem nut, being careful not to disturb the
pusher plate adjustment. Lift stem out the top of the
pilot. Grind off stem projection B flush with upper
surface of the pusher plate.
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