Automatic Recycle Valve Technical Article

Automatic Recirculation Valves Installation

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Automatic Recirculation Valves Installation

16 Sep 2014/  /  in Automatic Recycle Valve Technical Article

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.

  1. Outside diameter of the connecting piping
  2. Inside diameter of the connecting piping
  3. Material of the connecting piping
  4. 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.