Marwin Valve CF8901 Series Three Piece Ball Valve - Manual (Page 3)

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B. Inspection and Replacement
With the valve completely disassembled, clean and
examine all components.
1. Ball - The surface of the ball should be free from
any defect. If any are found, the ball should be
replaced. Using a defective ball will be extremely
detrimental to valve performance.
2. Seats - Replacement of seats is recommended.
3. Stem and Body Seals – Stem and body seals
should be discarded and replaced.
4. Remaining components of the valve - After
cleaning, carefully examine for wear, corrosion
and mechanical damage. Replace all defective
parts.
5. Clean inside of body and stem housing. Light
grease, compatible with line fluid, can be used
on ball, seals and stem surface.
Note: A spare parts list is available for this valve.
Please refer to explosion view below for
identification. Please specify specific valve number
to ensure proper parts are ordered. Marwin Valve
does not take responsibility for incorrectly ordered
spare parts.
Reassembly
A. Stem
1. Replace thrust washer (7) on stem, and then insert
the stem (6) from inside the body (1).
2. Install stem packing (8), gland bushing (19), stem
nut (13), and tighten until snug, then one-half turn.
Do not over-tighten! To avoid rotation of stem,
insert the handle through the body and ball.
3. Install lock-washer (20), handle (15) and handle nut
(14), and then tighten.
B. Ball, Seats and Seals
1. Place the stem in closed position and insert the ball,
aligning groove in ball with bottom of stem.
2. Position the ball in the open position then insert the
seats and body seals.
3. Insert the centerpiece between the end caps,
reinstall removed bolts and tighten all bolts and nuts
by hand.
4. Tighten nuts to recommended torque values using
an alternating/opposing pattern with no more than
1/4 turn on each nut before alternating.
Testing
1.
After completing the reassembly, check that valve
operates smoothly by opening and closing valve
several times
2.
If entire valve was removed from line and if facilities
are available, test the ball valve to appropriate
specifications.
Troubleshooting
A. Stem Leakage - You can eliminate leakage in the
stem area by increasing the torque on the stem nut
(13) in one-quarter turn increments. If leakage
persists, replace stem packing (8).
B. Body Seal Leakage - Check the torque of the body
bolts (9) according to Torque Table. Replace body
seals (5) if leakage persists.
C. In Line or Seat Leakage - Check to be sure valve is
in fully closed position. If leakage persists, the valve
must be disassembled and damaged parts
replaced.
Torque Table
Body Bolt & Stem Nut
Valve
Size
Bolt Size Body Bolt
Torque
(in-lb)
Max Stem
Nut Torque
(in-lb
½” 5/16-18 UNC-2B 70 - 110 90
¾” 5/16-18 UNC-2B 80 - 120 90
1” 5/16-18 UNC-2B 85 - 130 110
1-½” 7/16-14 UNC-2B 120 - 180 170
2” 7/16-14 UNC-2B 200 - 300 180
2-½” M12 x 1.75 435 - 660 260
3” M14 x 2 480 - 725 380
4” M16 x 2 560 - 840 450