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page 5
Rovalve S20
Installation and Maintenance Instructions
5. Instruction for repacking Rovalve S20
Tools and materials required:
1. Open end wrenches or sockets to fit packing gland hex nuts and 4-Post yoke hex nuts.
2. Square braided packing suitable for application.
-ROVALVE standard packing is special TEFLON impregnated synthetic (AFPL).
3. Knife, to cut packing.
4. 3/8" x 2" flat bar approximately 2' long with rounded end.
5. Tool with radius end to fit inside of packing box.
CAUTION
Follow required safety procedure and policies. Assure line is not pressurized before loosening
packing and removing valve. Use proper lifting and support techniques when moving valve
and or valve subassemblies.
Prepare Valve
1.
Relieve pressure on valve or remove valve.
2.
Close the valve.
3.
Disconnect the gate lifter.
4.
Raise stem or rod to the fully raised (open) position, providing clearance, or if desired, the
entire actuator assembly may be pulled up and away from valve.
a) After step 3, remove top plate hex nuts and washers from 4-Post yoke.
b) Pull valve stem and entire actuator assembly, excluding 4-Post yoke up and away from
valve, set aside.
6.
Remove packing gland hex nuts, packing gland, and old packing.
Installation of New Packing
If valve is equipped with SM636 packing, see note 2 before starting.
1.
Cut packing to exact length for each row (See Table D). Starting on either side of the gate
install the packing all-around the gate one row at a time.
2.
Tamp packing into packing box, even and flat using flat bar or other suitable tool.
3.
Add next row, alternating sides of the gate where the ends of the packing meet against each
other. (Ends of packing must not line up. If they do premature leakage could occur.) Complete
by adding the number of rows required.
4.
Reassemble packing gland to valve by sliding it down gate, aligning bolt holes with gland
studs.
5.
Tighten packing gland until the top row of packing is slightly compressed.
6.
Reassemble the actuator assembly, attach lifter to gate.
7.
Slowly charge line, stop when packing leak is evident or until normal pressure is reached.
8.
Retighten packing gland bolts only enough to stop the leakage, do not overstress the bolting.
9.
If normal pressure has not been achieved, continue to add pressure and adjust packing gland
until normal pressure has been reached.
10. Check gland bolts and snug all packing gland nuts.
Note 1:
Important, do not tighten packing gland bolts any more than required to stop packing
gland leaks after line pressure is applied.
Note 2:
SM636 packing is triangular in shape, 1/2" (equilateral) on a side and about 2-1/2" long. It
can be broken into pieces to conform to the shape of the packing box. Install one (or two)
row(s) of Self Mold #636 as appropriate for the size valve. See Figure 2. Make sure that
all voids are filled.
Note 3:
High-temperature packing may not reach full pliability until normal temperature is
achieved. Packing may require readjustment as temperature changes.
Figure 9
Figure 10
Valves with SM636 packing
Body
Gate
Packing
gland
Packing
Table D Packing Sizes
Valve
Number
Cross
Cut
Size
of Rows
Section
Length
2
3
3/8
6 3/8
3
3
3/8
8 3/8
4
3
3/8
10 3/8
6
4
3/8
14 3/4
8
5
3/8
19 1/4
10
4
3/8
23 3/4
12
4
3/8
28 7/8
14
4
1/2
27 1/4
16
4
1/2
35
18
4
1/2
38 5/8
20
4
1/2
42 5/8
24
4
5/8
51 1/2
30
4
5/8
64 1/2
36
4
5/8
77
