The DATIAN automatic recirculation valves
are best installed directly on the outlet of the pumps for which they are
meant. The valve layout is mainly based on the pump curve. Ensure that the
valves are installed on the right pumps. The flow direction is indicated on the
valve nameplate. This nameplate is riveted to the valve body. On this nameplate
you will also find the valve’s commissioning- or fabrication number. This
number is unique and therefore different for each valve. This ensures that the
valves can always be related to the right pump. In case of spare parts
requirements always refer to this number.
As a standard the valves are supplied as a
complete unit and can be installed directly after receipt. Normally the
connections are flanged but upon request we can also supply the valves with
butt weld ends. The packing which are required between the valves and the
piping are not part of our scope of supply. These packing can be supplied as an
option. This is also the case with the bolts and nuts. Depending on the weight
of the valves and the installation position the valves can be installed by hand
or with the help of a tackle.
Before installing the valves one must make
sure that the system is without pressure. The pumps must be switched off and
the lines must be drained and clean. Isolating valves should be closed to
prevent eventual backflow from other lines or tanks. The flange covers of the
valves must be removed before installing. Make sure that no foreign materials
drop into the valves after removal of the covers. If the valves are installed
after a long storage time it is advised to check them on possible rust. Clean
the valves if necessary.
Valve for vertical installation (main flow
upwards) with flanged connections:
Lift the valve by hand or with a tackle on
top of the pump outlet flange. Make sure that the right flange packing is
correctly positioned between the valve inlet flange and the pump outlet flange.
The lifting strap shall be slung around the
valve outlet flange. Do not use the bypass flange to lift the valve. The flange
bolts should be tightened crosswise.
Now connect the flange of the main process
line to the valve outlet.
Finally the bypass piping is connected to
the valve bypass flange.
(Note
that the valve internals can be inspected/removed „inline“).
In case of horizontal installation it is
most practical to use two straps, one around each main
flange, to position the valve in front of
the pump outlet flange. Connect the valve to the pump and the piping as
described above.
The valve bypass connection must be
orientated in a horizontal or vertically down position to prevent the
settlement of possible dirt on the moving parts of the valve. The valve bypass
connection should not be installed in a vertical upwards position. The weight
of the check valve would tend to pull it out of its seat.
It is not always easy to install the valve
directly on the pump outlet. In those cases where the distance between pump
outlet and valve inlet is less than 1.5 meter the valve inlet can be connected
directly to the piping coming from the pump. If this distance is bigger the
planned location must be indicated in case of order so that it is taken into
account with the design (especially with low pressure systems the distance in
vertical direction can influence the valve layout considerably). Valves ordered
for horizontal installation should not be installed vertical ,and vice versa
,without consulting us.
Minimum straight pipe length after the
valve: 10 x d (d= internal valve outlet diameter).
Minimum distance before reducing or
enlarging the pipeline diameter : 4 x d.
For valves with welding connection, it is
important to check the dimensions and material selection of all the connections
before installing them. Check if the weld edges are without damage.
With the order for valves with welding
connection, the following data must be available.
•Outside
diameter of the connecting piping
•Inside
diameter of the connecting piping
•Material of
the connecting piping
•Weld edge
preparation and directives for weld-grooves (figure number).
Based on the above data the valves are
supplied with welded on connection pieces so that they can be welded directly
into the pipeline. The bypass connection is always flanged. The welding work at
site is no part of our scope of supply.
When hoisting valves with weld connection, special
care is required because the hoist-straps cannot be hooked around a flange and
an exact positioning is required for the welding work. For the rest the
instructions are as with flanged valves.
Once the valves are installed the system
can be pressurized to check on possible leakage.
The maximum test pressure is depending on
the pressure rating of the valves and the valve material (ANSI or DIN
standards). After the pressure test the valves are ready for start-up.
