INSTALLATION AND MAINTENANCE INSTRUCTIONS - ORIGINAL VERSION
AVK GATE- AND SERVICE CONNECTION VALVES FOR GAS
SERIES 02, 03, 06, 36, 38 and 46
16. REPLACEMENT OF STEM SEAL NUT
The stem sealing can be replaced regardless of the position of the valve. If it is necessary to replace the stem sealing under
pressure, the following procedure must be followed. NB: No USE OF OPEN FIRE!
MAX. TORQUES
Valve
dimension
Closing
Closing torque
Free running
Rupture
Turns to
DN
torque
below 0°C
torque
torque
open
mm
Nm
Nm
Nm
Service connection valves
25
35
-
-
200
7
32
35
-
-
200
9
40
35
-
-
200
11
50
35
-
-
200
14
Gate valves
40 40 40 9 400 11
50
40
50
9
400
11
65
60
65
9
400
14
80
60
80
9
400
17
100
80
100
9
400
21
125
80
125
9
500
26
150
80
150
18
600
26
200
120
200
18
800
33
250
180
250
18
1000
37
300
200
300
18
1200
44
350
300
350
24
1400
59
400
300
400
24
1600
59/50***
450
300*/450**
450
25
1600
59*/39**
500 300*/450** 500
25
1600
59*/43**
600
500**
600
25
3200
53*/52**
* series 02 ** series 06 and 46 *** series 36
Table 2
1. Lower the pipeline pressure as much as the situation allows
2. Close the valve using the specified torque. The replacment
can also be done with the valve in open position, but then it
is required to completely isolate the valve from pressure
3. Unscrew the stem seal nut in counterclock direction and lift
it off over the stem
4. Replace the stem seal nut unit including O-rings with a new
one ordered from AVK International
5. Apply locking liquid medium strength to the stem nut
threads
6. Apply a silicone based grease to the o-rings
7. Mount the new stem seal nut by sliding it carefully over the
stem, and tighten it firmly clock wise with a torque of approx.
80 Nm
8. Open the valve and observe for leakages
9. Re-apply normal pipeline pressure while observing for leak
ages
Up to DN 400:
From DN 450:
Page 6/8
MI GateValvesGas Rev. N June 2019 GB
