Type BM9
11
Overpressure Protection
The recommended maximum allowable pressures are
stamped on the slam-shut valve nameplate.
Upstream overpressure protection shall be provided
if the inlet pressure is likely to go higher than the
maximum operating inlet pressure (P
umax
).
Downstream pressure after slam-shut valve’s
intervention shall stay within the allowable pressure
range to avoid anomalous backpressures that can
damage the slam-shut controller.
Downstream overpressure protection shall also be
provided if the slam-shut valve outlet pressure is likely
to go higher than the PS of the slam-shut controller
(differential strength type).
Slam-shut valve operation below the maximum
pressure limitations does not preclude the possibility of
damage from external sources or debris in the line.
The slam-shut valve should be inspected for damage
after any intervention.
Underpressure Protection
▲
WARNING
In order for the Underpressure Shutoff
(UPSO) of slam-shut valve to be
triggered, the downstream pipe pressure
must drop below the UPSO setpoint.
In the case of a downstream line
break, numerous factors can prevent
the downstream pipe pressure from
decreasing below the slam-shut valve’s
UPSO setpoint. These factors include
the distance of pipe to the break, the
diameter of the pipe, size of the break
and the number of restrictions, such as
valves, elbows and bends, downstream
of the regulator and/or slam-shut
valve. Due to these factors additional
protections should be installed to stop
flow in the event of a line break.
Table 5.
Torque Specifications
(1)
KEY
PART NAME
TORQUE
DN 200 / NPS 8
DN 250 / NPS 10
DN 300 / NPS 12
N•m
Ft-lbs
N•m
Ft-lbs
N•m
Ft-lbs
4
Bolt (End cap)
25 to 28
18 to 21
50 to 54
36.9 to 39.8
80 to 85
59 to 63
20
Locknut
22 to 25
16.2 to 18.4
22 to 25
16.2 to 18.4
22 to 25
16.2 to 18.4
Hex Screw (Locknut)
Initial: 1.5
Final: 4.5
Initial: 1.1
Final: 3.3
Initial: 1.5
Final: 4.5
Initial: 1.1
Final: 3.3
Initial: 1.5
Final: 4.5
Initial: 1.1
Final: 3.3
21
Screw Rod
80 to 100
59.0 to 73.8
80 to 100
59.0 to 73.8
80 to 100
59.0 to 73.8
30
Nut
90 to 100
66.4 to 73.8
90 to 100
66.4 to 73.8
90 to 100
66.4 to 73.8
40
Screw (Ring, Clamping)
7 to 8
5 to 5.9
6.3 to 8
4.6 to 5.9
6.3 to 8
4.6 to 5.9
49
Bolt (Seal Ring)
- - - -
- - - -
- - - -
- - - -
4 to 6
3 to 4.4
50
Cam Roller
10 to 12
7.4 to 8.9
10 to 12
7.4 to 8.9
10 to 12
7.4 to 8.9
52
Screw (Bonnet)
2.5 to 2.9
1.8 to 2.1
2.5 to 2.9
1.8 to 2.1
2.5 to 2.9
1.8 to 2.1
62
Nut (Bonnet)
140 to 150
103.3 to 110.6
140 to 150
103.3 to 110.6
140 to 150
103.3 to 110.6
70
Nut
20 to 22
14.7 to 16.22
20 to 22
14.7 to 16.22
20 to 22
14.7 to 16.22
101
Lower Cover
40 to 50
29.5 to 36.8
40 to 50
29.5 to 36.8
40 to 50
29.5 to 36.8
105
Screw
3 to 5
2.5 to 3.7
3 to 5
2.5 to 3.7
3 to 5
2.5 to 3.7
114
Nut
30 to 40
22.1 to 29.5
30 to 40
22.1 to 29.5
30 to 40
22.1 to 29.5
115
Handle
20 to 30
17.8 to 22.1
20 to 30
17.8 to 22.1
20 to 30
17.8 to 22.1
33
(2)
Type PRX Pilot Plug
NPT Thread
(3)(4)
37
Main Valve Plug
38
(2)
Special Connection
74
Main Valve Fitting Elbow
74
(2)
Controller Silencer
75
Fitting Tee
- - - -
End Connections
1. Overtightening may be detrimental to the sealing function of the joint.
2. Optional parts according to customer requirement.
3. Joints should be tightened beyond the hand-tight engagement position.
4. Advancing the joint past hand-tight creates interference between external and internal thread flanks, produces a seal (with the use of a sealant), and helps prevent loosening of the joint.
