IOM-POSR-2
10
21. Using a sharp, flat-edged tool, clean the gas ket
fac ings and all surfaces where a metal-to-
metal joint occurs on the body (1), bonnet (2),
cylinder (3) and cylinder head (4).
22. Remove body (1) and bonnet (2) from vises
and solvent clean. Solvent clean all loose
parts to be reused.
23. Inspect all surfaces for wear. Replace all parts
that have excessive wear. Replace seat ring
(5) and plug-stem assembly (7) as a set. Hone
cylinder (3) if slightly grooved.
24. Lap plug-stem assembly (7) together with seat
ring (5) using a suitable lapping com pound. Do
for new re place ment parts as well as reused
parts (5, 7). Clean parts of lapping compound
with suitable solvent and let dry.
25. Place cleaned body (1) back into vise.
26. Place new seat ring gasket (6) into body (1)
cavity.
27. Insert the plug-stem assembly (7) through
the bonnet (2) and check clearance between
stem (7) and hardened bushing (18) with a
wire gauge. Normal clearance is .001–.002"
(.025–.050 mm). If excess clearance is due to
wear in stem (7), replace plug-stem assembly
(7). If clearance is due to bushing wear, place
bon net (2) under a hydraulic press and “press
out” the bushing (18); “press in” a replacement
bushing. If new bushing seems “loose” after
pressing in, place four small tack welds along
the bushing (18) OD on top of bonnet (2)-to-
bushing (18) joint, taking care to not overheat
the bushing (18) and distort.
28. Place bonnet (2) back into the second vise
held as previous.
29. Determine correct orientation of seat ring (5)
from Figure 9 herein.
(DO NOT INSTALL
SEAT RING (5) UPSIDE DOWN
.) Insert plug-
stem assembly (7) threaded end through seat
ring (5) and bonnet (2) bushing (18). Push seat
ring (5) into the “cage” portion of the bonnet
(2).
30. Place TFE ring gasket (13) onto upper side
of bonnet (2) and onto shoulder.
31. Place a thin film of lubricant onto the cylinder
(3) inside wall at the wear points of the piston
seal (12). Wipe excess lubricant away with a
clean, dry cloth.
32. Place cylinder (3) into a strap support and lift
with an overhead hoist. Swing cylinder (3) over
threaded end of plug-stem assembly (7) and
lower into the shoulder of bonnet (2), taking
care to protect ring gasket (13) of previous
article 30., above. Align match marks and
apply duct tape to hold cylinder (3) to bon net
(2).
33. Place piston (8) with recess for piston spring
(14) face down on flat surface.
34. Position a small section of the seal (12)
cir cum fer ence around the top recess of the
piston (8). Apply an equal amount of thumb
pressure on opposing sides of the seal (12) as
the seal (12) is pressed around and over the
top of the piston (8) into the recess. NOTE:
Install seal (12) with opening of U-Cup facing
upwards.
35. Place piston spring (14) into recess of piston
(8).
36. Rotate stem (7) until the tool of previous article
13., this subsection, can be inserted through
hole of stem (7). Leave the tool in the hole.
37. Carefully slide piston (8) with captured piston
spring (14) into cylinder (3). Insert a rod or
similar tool into the center hole of the piston
(8), and simultaneously lift and move into the
cylinder (3) deeper. Using fingers of one hand,
push the plug-stem assembly (7) together from
the plug (7) end. Lift piston (8) onto threaded
portion of plug-stem assembly (7) as far as
possible, removing tool when nec es sary. Place
hand into cylinder (3) and push the piston (8)
until the piston spring (14) begins to compress.
38. Place temporary eyenut onto threaded end
of plug-stem assembly (7). Finger-tighten
eyenut until piston spring (14) is slightly under
com pres sion.
39. Place a rope, cable, etc., through the eyenut
and rig for overhead lifting. Simultaneously,
loos en the grip of the vise on the bonnet (2),
lift the cylinder (3) with its hoist, and lift the
partial internals subassembly (IS) with its hoist.
Con tin ue the lifting slowly until the internals
sub as sem bly (IS) is vertical. Release the strap
support from the cylinder (3). Fully release the
vise’s grip.
40. Place a round wooden peg about 2" (50 mm)
tall with flat ends, and small enough to fit within
the seat ring (5) onto a flat work surface. Swing
