Flowserve V-377 R4 Edward Valves - Manual (Page 37)

37
Flow Control Division
Edward Valves
21. On stop valves, the disk and disk-nut
assembly is attached to the stem. On
stop-check (non-return) valves, the pis-
ton-disk assembly is not attached to
the stem and must be removed sepa-
rately. See step 22.
22. Screw 1/2”-13 bolts (3/8”-16 on
sizes 5” and smaller) into the thread-
ed bosses or nuts provided in the pis-
ton. The piston now can be lifted
from the valve. Occasionally, a vacu-
um may be formed by the cooling
fluid in the pipe line below the valve.
Until relieved, this vacuum will pre-
vent removal of the piston. Since the
piston must be removed through the
pressure-seal area of the bonnet
bore, use caution to avoid marring
the sealing surface in any way.
23. The bonnet end opening should be
kept covered whenever possible.
Type III Pressure-Seal Bonnets –
Piston-Lift Check Valves
See Illustration No. 25 on page 35.
1. Remove the cover/cover retainer.
2. Screw an eyebolt into the tapped
hole in the cover.
3. Fasten a chain hoist to the eyebolt
and pull up just enough to eliminate
all slack in the hoist.
4. Remove all cover stud nuts or cap
screws.
5. Remove the cover retainer.
6. Mark the body, cover and gasket
retainer segments with adjacent prick
punch marks so that their relative posi-
tion can be restored on reassembly.
7. With clean rags and an air hose,
thoroughly clean the top of the valve
and all exposed surfaces of the cover
and gasket retainer segments. This is
important.
8. Slack off on the chain hoist to permit
the cover to slip down into the valve
body. If necessary, tap lightly to
loosen. If the cover resists all attempts
to force it into the valve body, high-
pressure fluid may be trapped in the
bonnet cavity (and downstream) of
the check valve. The cover will drop
easily when this pressure is relieved.
Lower the cover until it rests on top of
the valve piston.
9. With a copper or brass drive pin or
a clean hardwood block, drive the
gasket retainer segments downward
to the bottom of the retainer groove
(about 1/16”) in the body.
10. Remove the gasket retainer segments.
11. Lift the cover back into contact with
the pressure-seal gasket, again using
the chain hoist.
12. Replace the cover retainer, using
shims to provide additional clearance
for further upward movement of the
cover.
13. Use three or four nuts in a uniform
spacing on the bonnet studs to pull
the cover and gasket out of the body.
All nuts or screws should be turned
uniformly, a fraction of a turn at a
time, using a star pattern. It is possi-
ble to damage valve parts by cock-
ing the cover, so uniform turning of
the nuts is very important.
14. Lift out the cover assembly. During
this process, mark the spacer ring
and pressure-seal gasket at points
(other than the sealing surfaces) cor-
responding to previous marks on the
body and cover (see step 6). In lay-
ing the parts aside for inspection, it is
imperative that they be placed care-
fully on a bed of rags or other soft
material to avoid marring any
machined surface, particularly any
seating and sealing surfaces.
15. Screw 1/2”-13 bolts (3/8”-16 on
sizes 5” and smaller) into the thread-
ed bosses or nuts provided in the pis-
ton. The piston can now be lifted
from the valve. Occasionally a vacu-
um may be formed by the cooling
fluid in the pipe line below the valve.
Until relieved, this vacuum will pre-
vent removal of the piston. Since the
piston must be removed through the
pressure-seal area of the bonnet
bore, this must be done very carefully
to avoid marring the sealing surface
in any way.
16. The bonnet end opening should be
kept covered whenever possible.
Disassembly Procedures for Bonnet Types
(continued)