IOM-POSR-2
9
cylinder (3). Move the flat tool fully around
the bonnet-to-body joint to ensure being fully
loosened.
8. Install the temporary eyenut (supplied with
Parts Kits “A” or “B” for 2"–4" sizes) onto the
threaded end of the plug-stem assembly (7).
Eyenut size is:
that the outer diameter edge of the bonnet (2)
can be secured in the vise, and the plug-stem
assembly (7) oriented horizontally. When
se cured, slacken overhead hoist cable, rope,
etc., to allow removal.
11. Remove temporary eyenut from end of plug-
stem assembly (7).
12. Place a support strap around the cylinder (3)
and attach to overhead hoist. Place the strap
into “tension” with the hoist by removing “slack”
in strap.
13. Insert a “round” tool (rod, Allen key wrench,
Phillips-end screwdriver, etc.) through the hole
located in the stem portion of the plug-stem
assembly (7), just above the plug por tion.
NOTE:
It may be necessary to place a wrench
on the stem nut (15) to rotate the plug-stem
assembly (7) enough to allow access for the
round tool through the “cage window” of the
bonnet (2) and through the stem (7) hole.
14. Loosen stem nut (15) by rotating CCW (viewed
from nut end), allowing tool of previous article
to secure the plug-stem assembly (7) from
rotating. Fully remove stem nut (15).
NOTE:
There will be noticeable friction in removal
of nut (15) as piston spring (14) relaxes
(elon gates). The spring (14) will be fully relaxed
before the stem nut (15) is fully removed.
15. Pull cylinder (3) horizontally outwards to
re mov al, moving overhead hoist as necessary.
Set cylinder (3) aside.
16. Using a needle-nose pliers, grasp outside lip
of seal (12), lift seal (12) up and pull out of
recess over end of piston (12).
NOTE:
Seal (12)
should be replaced with every dis as sem bly.
17. Remove piston (8) and piston spring (14).
18. While holding seat ring (5) with fingers,
with draw plug-stem assembly (7). Seat ring
(5) will be released from capture.
19. Remove all three of the TFE gaskets (13) and
discard. These gaskets may be stuck to the
cylinder head (4), cylinder (3), bonnet (2) or
body (1). If any of these gaskets (13) were
leaking, determine by inspection the possible
reason for the leakage.
20. Remove seat ring gasket (6) from body (1)
cavity and discard.
FIGURE 3
Hanger Bracket
Main Body Size
Nominal Eyenut Size - Inch
2"
1/2" – 13 UNC
3"
1/2" – 13 UNC
4"
5/8" – 11 UNC
NOTE:
For the 1" and 1-1/2" main valve (MV)
body sizes, fabricate a hanger bracket with
sheet metal similar to Figure 3 below.
9. Using an overhead hoist with the cable,
rope, etc., fastened through the temporary
eyenut, pull the internals subassembly (IS)
and cyl in der (3) upwards and out of the body
(1). The internals subassembly (IS) consist of
the fol low ing parts:
(2)
bonnet
(5)
seat
ring
(7)
plug-stem
assembly
(8)
piston
(12)
piston
seal
(13)
one-ring
gasket
(14)
piston
spring
(15)
stem
nut
10. Position the hoisted internals subassembly
(IS) and cylinder (3) above a second vise with
leaded jaws. Lower the suspended parts such
Fabricated Sheet Metal
Hanger Bracket
16 Ga. Min.
