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Pressure Seal Gate Valves -Style A-
Installation and Maintenance Instructions
Table I: Bolt Torque Figures for Packing Bolts
For System pressures < 2533 psi
Torque (ft lbs) = (24.87) x (OD2 _ ID2) x (d)
Torque (Nm) = multiply Torque (ft lbs) x 1.3558
Where:
This "Torque method" may result in more or less than 30% compression.
2.5 Periodic Valve Verification during Service
A - Normal Check
1. Verify monthly that there is no leakage from packing or in the body/bonnet area. If the leakage
has been detected from the packing, tighten nuts according to the procedure described in
Section 3.
If the leakage does not stop, follow the procedure for packing maintenance (3.1).
If the leakage has been detected from the body/bonnet, tighten the nuts (pos. 31) as indicated in
Table II.
If the leakage does not stop, follow the maintenance procedure for the replacement of the body/
bonnet gasket (3.2, 3.3).
2. Every 2 / 3 months, depending on operating frequency, verify the greasing of bearings and stem
thread.
3. For actuated valves, in addition to the above, please refer also to the warnings in the actuator
manual.
B - Preventive Actions
1. Every 3 months verify the tightness of gland bolts.
2. Every 6 months on motorized valves and every 8 months on hand operated valves, grease stem
and bearings.
3. Every 12 months check the travel of the gland follower, setting a new packing when the end of
the travel is approaching.
4. Every 4 years disassemble the critical service valves and/or actuated valves, verifying the sealing
surfaces and lap them again when necessary. Substitute the bonnet gasket and the packing,
grease the stem.
5. For the actuator, proceed as indicated in its maintenance manual.
Troubleshooting Guide
Possible Cause
Symptom
1. Gland flange nuts too loose
Stem packing leaking
2. Packing damaged
1. Gasket bolting loose
Body-Bonnet leaking
(pos 31)
2. Gasket damage
1. Valve not fully closed
Valve leaking
2. Debris trapped in valve
3. Sealing surface damaged
1. Packing is too tight
Jerky operation
2. Air supply inadequate
(for pneumatic act.)
1. Back seat damage
Back seat leaking
Emerson reserves the right to change the contents without notice
For System pressures ≥ 2533 psi
Torque (ft lbs) = (S.P./101.8) x (OD2 _ ID2) x (d)
OD = Stuffing Box Bore (ln.)
ID
= Stem Diam (In.)
d
= Gland Stud Diam (in.)
S.P. = System Pressure (psi)
Solution
1. Tighten gland flange nuts.
2. Replace packing
(See Paragraph 3.1)
1. Tighten bolting
(pos 31)
2. Replace the gasket
1. Close valve
2. Cycle and flush (with valve open)
to remove debris
3. Recondition the seat surface
1. Loosen gland nuts, cycle the
valve, retighten
2. Increase air supply pressure
1. Replace the back seat
Table II:
Bolt Torque to Ensure Tightness
of Pressure Seal Gasket
Position 31 for Gate Valves
Stud
Torque ft.lbs.
3/8
18
1/2
37
5/8
74
3/4
125
7/8
207
1
310
1 1/8
443
1 1/4
627
1 3/8
811
Important
To ensure tightness of Pressure Seal gasket,
pull up bolts must be tightened when valve is
under fully hydrostatic test pressure.
page 4
Torque Nm
24,5
50
100
170
280
420
600
850
1100
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