ACTUATORS - RP SERIES
Australian Pipeline Valve - Installation, Operation and Maintenance Manual
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stated BTO torque*.
ETC - Closing torque: the torque required to reseat a closing valve. 85% of stated BTO torque*.
RTC - Running torque: the torque needed to keep the ball moving through it’s travel. 50% of stated BTO
torque*.
MAST- Maximum stem torque - refer to manufacturer.
*Average guide based on floating ball and smaller size trunnion ball valves. Large trunnion ball valves
have slightly different ratios. Butterfly and plug valves have totally different ratios.
4.4.3 Elements that Effect Soft Seated Ball Valve Operating Torque
The below factors are only for use as a rough estimating guide only and apply to smaller diameter ball
valves. Furthermore, the effects the following factors have will vary for trunnion ball valves, even in
smaller sizes. For trunnion ball valves it is impossible to provide accurate multipliers, however the below
factors will effect all types of soft seated valves in all sizes to a certain degree and should be taken into
account when specifying safety factors.
For a particular size and differential pressure, the torque of soft seated ball valves depend on many
factors. Use the torque multipliers stated below with the selected valve’s stated ‘break’, ‘end to close’
and ‘end to open’ torques as needed for your application.
Seat Material: The friction force or degree of holding force depends on the seat material type.
Fluid Type: Torque values depend on media type. Torque will become higher with dry, gasses or liquids
with solids and lower with oils. Torque multipliers are shown in the table (based on normal
temperatures).
Frequency of Operation: When a valve remains in closed position for extended periods of time, the
breakout torque increases.
Seat Material
Seat Type Multiplier
*
1
15% - 25% Glass RPTFE
1.0
Virgin PTFE
0.8
Carbon Graphite RPTFE
1.0
PEEK
2.3
Delrin
2.0
*1
- For floating ball valves up to 175 NM. For larger valves consult us.
Fluid
Fluid Type Multiplier
Gas or superheated steam, clean / dry
1.2 - 1.3
Viscous fluid
1.4 - 1.6
Liquids containing abrasive solids
1.3 - 2.0*
2
Clean / non-lubricating
1.0
Clean / lubricating
0.8
*2 - Can be higher.
Frequency
Frequency Multiplier
Once per day or greater
1.0
Once per week or greater
1.3
Once per month or greater
1.4
Once per 4 months or greater
1.5
Critical ESD services
1.8
