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Keeping the World Flowing

ASSEMBLING ACTUATOR ONTO THE VALVE

7.1 General

Before proceeding, read and follow the health and safety
information in section 2.

Before assembling the actuator on the valve, verify that the
valve is well fixed and able to support the weight of the
actuator.

The assembling of the actuator onto the valve can be
performed by using an adapter and a coupling joint between
the actuator and the valve. The bracket utilised to interface
the actuator and valve (damper, or other quarter-turn
device) must be designed with close tolerance that permits
near perfect concentric alignment between the center axes
of the actuator shaft and driven shaft of the device being
automated.

Improper adaptation of the bracket and coupling

to the actuator can cause unnecessary friction and
premature failure. Misalignment can certainly lead to
poor performance and inaccurate control.

The vane floats on its spring-loaded seals inside actuator
housings. Avoid all end loading to the actuator shaft. End
loading will force the vane to interfere with casings and will
damage the actuator. This event commonly occurs when
proper clearance is not provided for the coupling to float
between the actuator shaft and the driven device. When
bolting the assembly together, if it is necessary to force the
two components together with the coupling fitted between
the shafts, chances are you have an end-loading problem.

The assembly position of the actuator must be in accordance
with the actuator design, plant requirements and the valve
model.

In order to assemble the actuator onto the valve, proceed as
follows:

• Verify the coupling dimensions of the valve flange and

stem; they must meet the actuator coupling dimensions.

• The actuator shaft end machined for NAMUR adaptation

has a flat side indicating the position of the vane.
Actuators are shipped with the vane in the mid-position
of the stroke. Move the vane to position end-stop that
corresponds with the rotation desired to rotate the driven
device.

• Clean the coupling flange of the valve and remove

anything that might prevent a perfect adherence to the
actuator interface. Grease has to be completely removed.

• Apply anti-seize grease to the valve stem to facilitate

assembly.

• Lift the actuator according instructions reported in

paragraph 5.2.

• If possible, place the valve stem in a vertical position to

facilitate assembling - in this case the actuator must be
lifted while the coupling flange is kept in the horizontal
position.

• If the assembly is done using an adapter and a coupling

joint, assemble the coupling joint onto the valve stem
before proceeding with the assembly of the actuator.

• Lower the actuator onto the valve so that the valve

stem (or the coupling joint) slips in the actuator without
exerting any force and only with the weight of the
actuator.

Hands must be kept away from the valve-actuator

coupling area.

• Fix the actuator to the valve by means of threaded

connections (bolts, stud bolts and nuts).

• Tighten the bolts or nuts to the recommended tightening

torque of the connecting stud bolts, in accordance with
the size and material characteristics of the bolts installed
by the customer.

See Table 1: Recommended Tightening

Torque.

The actuator must be supported until it is fully

coupled with the valve stem and until the fixing bolts
are correctly tightened.

After the actuator has been assembled on the valve, check
for possible damage to the paintwork and repair if necessary,
according to the Rotork paint specification. Ensure that the
coupling will slightly float up and down on the actuator and
driven shafts. This check will guarantee concentricity between
the actuator shaft and driven device.

Table 1: Recommended Tightening Torque

Actuator

Size

Bolt Size

Torque

Imperial*

Metric**

Imperial

Metric

KT-03

10-24/8-32

M5/M4