1.
Fit valves with detachable pipe connection elements – using suitable
connection fittings – directly into the pipe system.
®
Valve is installed.
6.4
Valve with Welded Ends
This section describes the welding procedure for the valve housing.
Warning!
Spring tension in the valve
Danger of injury when opening the clamp connections on the actuator or on
the housing as the released spring pretension will suddenly lift the actuator.
► Therefore, release the spring tension before detaching the clamp
connection by pressurizing the actuator with compressed air at max. 6 or 7
bar (depending on the type of positioner) or by mechanically adjusting the
control cone.
Notice
Welding distortions
The control valve can be damaged by distortion due to welding and when
the position of the grooves is altered.
► Before starting any welding work, remove all built-in parts from the valve.
► To ensure that a proper weld is formed when the valve is welded into the
pipe, make sure that the root side of the weld is protected against oxidation
by forming gas.
► Use welding filler if necessary.
Carry out the following steps:
1.
Release the spring tension.
2.
Remove the valve insert, see chapter .
3.
Weld the housing, without sealing rings, into position, ensuring that the
connection is free of stress.
4.
Fit the housing into place and tack it.
5.
To avoid welding distortions, always seal the housing before welding.
6.
Flush the housing with forming gas from the inside to push the oxygen out of
the system.
7.
Weld the housing into the pipe system; use welding filler if necessary. When
technically possible, use the WIG-Orbital welding process with pulse
configuration, according to guidelines EHEDG documentation. 35.
8.
Passivate the seam after welding.
9.
Assemble the valve and depressurize the actuator.
10.
Fit the seals.
®
The valve disk is lowered.
®
Install the valve with welded ends.
Assembly and installation
Valve with Welded Ends
430BAL011074EN_5
08.11.2021
31