Cashco 988-MB - Manual (Page 6)

6 IOM-988/989-BODY
D. Trim and Packing Removal and Replacement for
Units with Internal Live-Loaded Packing; Opt-STD
or Opt-KRI: (See pg. 19 for Item # identifi cation.)
1. Remove (AA) as described in Sub-Sec tion V.B.
Leave (BA) in vise with plug/stem (3) upwards.
2. Continue to loosen stem packing (6) by rotating
pack ing nuts (15) CCW to just short of disengage-
ment from packing studs (14). DO NOT REMOVE
PACKING NUTS (15).
3. Remove all bonnet stud nuts (17).
4. Lift bonnet (2), plug/stem assembly (3), cage (10)
and all packing zone parts up and out of the body
- grasp stem (3) to prevent from falling. Lay these
parts down horizontally on a workbench. NOTE:
Seat ring (11) (and seat retainer (23) and soft seat
insert (24) for com po si tion/soft seated de signs)
may also pull out with the above parts assembly.
5. Remove both stem nuts (52).
6. Withdraw plug/stem (3) out through bottom of the
bon net (2) and packing (6). Hold cage (10) to
pre vent from dropping. Set parts (3, 10) aside.
7. Place bonnet (2) into a second vise with the pack ing
zone on top.
8. Remove the packing nuts (15).
9. Remove packing fl ange (4) and fol low er (5).
14. Examine plug/stem (3) in critical fi nish zone where
con tact is made with the packing (6). It is desirable
to re store the surface of the stem (3) to a #4 Ra μ-in
surface fi nish; metal removal should not exceed
0.001 inch material. A deeply scratched or pitted
stem should be replaced.
15. Examine plug/stem (3) for wear around the seating
area. Ex am ine seat ring (11).
a. Plug head of stem assembly (3) for metal
seat ed design may be hand lapped using
suit able lap ping compound. If hand lapping will
not re store sur fac es to an acceptable de gree,
then re place ment of plug/stem assembly is
rec om mend ed.
b. For composition seated design, if plug/stem
as sem bly is wear damaged, the stem should
be re placed.
16. Examine the inner surface of the bonnet’s (2)
stuffi ng box. It is desirable to restore the surface
of stuffi ng box to a #8 Ra μ-in surface fi nish; metal
re mov al should not exceed 0.001 inch material. A
deep ly scratched or pit ted bon net (2) should be
replaced.
17. Examine packing follower (5) for corrosion. Re-
place if corroded:
a. Replace follower bushing (26) with new bush-
ing.
b. Replace wiper ring (22) with new wiper ring.
18. Turn attention to the body (1) and remaining parts
yet there in. Remove seat ring (11) (and seat re-
tain er (23) and soft seat in sert (24) for com po si tion/
soft seated de sign) if not already removed. Discard
used soft seat in sert (24); always use a new soft
seat insert upon re as sem bly. If seat ring (11) or
seat retainer (23) are damaged, replace.
19. Examine gaskets (12,13) to see if leakage oc-
curred. Re move and discard both the seat ring
gasket and bonnet gas ket. Always use new gaskets
upon reassembly.
20. Remove body (1) from vise. Solvent clean all loose
parts with suitable solvent. Determine parts to be
re placed due to wear and/or corrosion. Clean seat
ring (11), cage (10), and seat re tain er (23).
21. Place body (1) into vise with body/bonnet fl ange
face up.
22. Place a new seat ring gasket (13) into position.
23. Note correct orientation of seat ring (11) and place
inside the body (1).
24. For composition/soft seat design, position a new
soft seat insert (24) and the seat retainer (23) into
position on top of seat ring (11).
25. Place new bonnet gasket (12) on the body’s bonnet
fl ange face.
10. Using a sharp, hooked-end, pick-type tool, hook and
pull the packing rings (6) up and out of the bon net’s
(2) stuffi ng box in di vid u al ly. Examine for excessive
wear. Discard old pack ing.
11. Remove bonnet (2) from vise and invert to al low
pack ing washer (7), packing spacer (9) and pack ing
spring (21) to slide out of the bonnet’s stuffi ng box.
12. Solvent clean all parts to be reused, including bon-
net (2). Examine any parts for wear and cor ro sion.
Replace any corroded or warn parts.
13. Examine plug/stem (3) at lower guide bushing (8)
area for wear. If there are signs of ex cess wear,
guide bushing (8) should be replaced:
a. Place the bonnet (2) on a bench press. Press
the guide bush ing (8) out of the bonnet and
discard.
b. Rotate bonnet (2) end-for-end. Place a new
guide bush ing (8) into position and press fully
into the bonnet.
c. Reclean bonnet with suitable solvent.
CAUTION
Take extreme care to not mar internal wall surface of the
bonnet (2).