Heating Stage; Change-Over Stage; Joining And Cooling Phase; End Of Welding - Hürner HWT 400-M Manuel Utilisateur

4.4.4 Heating Stage

After the bead build-up stage (t
pressure must be decreased to below or equal to the level of P
The decreased pressure will then be applied for the entire duration of
the heating stage (t in the diagram), in which the component butts
2
continue to soak heat from the plate. Use the welding value tables
in the Appendix to determine the heat-soaking time (t
heat-soaking pressure (P
To reduce the pressure applied to the component, use the pressure
release regulator and observe the pressure level on the gauge.
Full contact has to be continuously established between the
heating plate and the bead, even with lower pressure. While
heating, if contact between them is lost somewhere along
Important
the circumference, welding has to be aborted and repeated.

4.4.5 Change-over Stage

After the end of the heating, or heat-soaking, stage, set the carriage
mover lever on the control terminal to its move-apart position in order
to move the carriage to the far end. Then remove the heating element
from in-between the components.
The change-over has to be followed immediately by the joining stage.
The change-over time given for your welding situation in the tables
in the Appendix (t ) must not be exceeded. If it is, welding has to be
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aborted and repeated.

4.4.6 Joining and Cooling Phase

Set the mover lever to its close-in position again to move the pipe butts
in on each other and to build the joining pressure (P
to a consistent increase. Watch the reading of the gauge. Building the
joining pressure must correspond to a linearly increasing ramp and its
duration must neither be longer nor shorter than indicated for your
welding situation in the welding value tables in the Appendix at t
Once the joining pressure is reached and has stabilized at P
pending on the applicable welding standard, the pressure will either
be kept at this level until the end of the joining stage is reached (t
or pressure will be reduced after 10 seconds to one-third of P
reduced pressure will be kept until the end of the stage t
Towards the end of the joining stage, the new joint also starts cooling
down. If the pressure has to be reduced in the course of the joining
stage (under the WIS standard or the UNI standard for PE100 with walls
thicker than 20 mm), reducing the pressure is done with the manual
pressure release regulator on the hydraulic unit.
Pipe and fitting manufacturers may include data on how long the new
joint should not be exposed to external strain. Also, the applicable
welding standard may require a minimum cool-on time (t
gram). In most cases, however, t

4.4.7 End of Welding

The welding is finished at the end of a successful joining and cooling
stage. The welder has to shut the pressure off from the pipes using
the immediate-action full pressure release valve.
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Producing Pipe Fittings/Branch-offs

When the machine is switched on prior to welding, the in-
stuctions given in Sect. 4.1 on checking-out and turning-on
have to be taken into account at all times.
Important
18
EN
in the diagram) was completed, the
1
+ P ) applicable to your welding situation.
2 t
is not relevant to the welder.
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HÜRNER HWT 400–M User's Manual
H Ü R N E R S c h w e i s s t e c h n i k G m b H
+ P .
2 t
) and the
2
+ P ) according
5 t
.
4
+ P , de-
5 t
),
5
and the
5
is reached.
5
in the dia-
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Version January 2020