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STI S.r.l. – Via Dei Caravaggi 15, 24040 Levate (BG) – ITALY www.imi-critical.com
Manual 5021, rev. 00 10/2015 – SC/VHS - 9 -
Important
To guarantee the correct transmission from the actuator to valve stem
without phenomena of slip it is important to remove any trace of oil and/or
grease from the mating surfaces of valve and actuator or bracket and tighten
the nuts fixing the bolts with the torque specified into the following Table 1
Table 1
Threading Tightening torque (Nm) Threading Tightening torque (Nm)
M8 20 M24 550
M10 40 M27 800
M12 70 M30 1200
M14 110 M33 1400
M16 150 M36 1800
M20 300
The torque values in Table 1 have been calculated considering the materials ASTM A320 grade L7/ASTM
A193 grade B7 for screws or tie rods and ASTM A194 grade 4 for the nuts.
Alternative bolting permitted i.e. ASTM A193 B8M (or B8M3) for tie rods and ASTM A194 Gr.8M for the
nuts, provided that yield strength of screws or tie rods is over than 450 Mpa.
5.6.3 Hydraulic Connections
Warning
Check that the values of hydraulic supply available are compatible with those reported on
the identification plate of the actuator.
Use pipes and connections appropriate as for type, rating, material and dimensions.
The connection should be made by qualified staff.
- Properly deburr the ends of rigid pipes.
- Properly clean the interior of pipes sending through them plenty of the supply fluid used in the system.
- Carry out the flushing operation before assembling the pipes.
- Mould and fasten the connection pipes so that no irregular strains at entries or loosening of threaded
connections occur.
- Make the connections according to the operating diagram.
- Check the absence of leakages from hydraulic connections. If necessary tighten the nuts of the pipe-
fittings.
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