STI RTQ Series, Instruction Manual, Page: 15 / 44

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Manual 5300, rev. 09 06/2020 – RTQS
11
Fig. 4 – Assembling of the actuator on the valve
Important To guarantee the correct transmission of torque 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 actuator and
bracket (or flange) [1] and from bracket (or flange) and valve flange [2].
- tighten the bolts fixing the bracket (or flange) to the bottom flange of the actuator
with the torque specified into the following Table 1.
- tighten the bolts fixing the bracket (or flange) to the bottom flange of the actuator
with the torque specified into the following Table 2, provided that the valve maker
verifies and guarantees the correct transmission of required valve torque.
Table 1
Table 2
Actuator
ISO 5211
flange
Bolts
Tightening
torque (Nm)
(1)
Bolts
Tightening torque
(Nm)
(1)
Bolts
Tightening torque
(Nm)
(1)
RTQS-01 F25 8 x M16 180 M10 40 M36 1.800
RTQS-02 F30 8 x M20 340 M12 70 M42 3.000
RTQS-03 F35 8 x M30 800 M16 180
RTQS-04 F40 8 x M36 1.800 M20 340
RTQS-05 F48 12 x M36 1.800 M24 550
RTQS-06 F60 20 x M36 1.800 M27 700
RTQS-07 F60 20 x M36 2.200 M30 800
RTQS-08 F80 20 x M42 3.000 M33 1.200
(1) The torque values in Tables 1 and 2 have been calculated considering the standard bolting made in Carbon
Steel according to ASTM A320 grade L7/ASTM A193 grade B7 for bolts/screws and ASTM A194 grade 4 for
the nuts. Alternative bolting in Stainless Steel are permitted i.e. ASTM A193 B8M (Class 2 or 2C) for
bolts/screws and ASTM A194 grade 8M for the nuts, provided that yield strength of bolts/screws is not less
than 450 MPa.
Bottom flange of the actuator [1]
Connection with the valve [2]
Bracket (or flange)