How to install a check valve
Threaded check valves are divided into spring-loaded and non-spring-loaded. Spring-loaded check valves can be installed in any position, while non-spring-loaded check valves are installed on a vertical pipeline with flow from bottom to top or on a horizontal pipeline.
A strainer filter is recommended to be installed before the check valve of all types except for ball valves, in order to protect against abrasive substances present in the flowing medium.
The body of the check valve should not be subjected to bending, twisting, stretching, or compressing loads from the connected pipeline.
The check valve allows flow only in one direction, and the working direction of the flow is indicated by an arrow on the valve body - follow the correct installation according to the technological scheme.
Do not damage the paint coating on the valve body, as it serves not only a decorative function but also provides protection against corrosion.
Sequence for packing a threaded connection
1. Take a flax fiber string with enough threads so that its twisted diameter is approximately equal to the depth of the thread. The length of the string should provide for 1.5-2 times more windings than the number of thread turns.
2. Starting approximately 50-70 mm from the beginning of the string, slightly twist it, place it in the first thread turn, and, holding it with your hand, tightly wind a long branch of the string clockwise, placing it in each thread turn.
3. When reaching the end of the thread, continue winding with a second layer, shifting the turns to the beginning of the thread. The length of the second layer winding should be approximately equal to 2/3 of the thread length.
4. Wind the remaining end of the string (50-70 mm) similarly clockwise, from the end of the thread to its beginning.
5. Apply a layer of sealant to the winding surface.
6. Tighten the connecting elements by hand. With correct packing, the assembled element should turn 1.5-2 full rotations.
7. Continue tightening the element with a wrench or a torque wrench. In case the assembled element needs to be in a specific position, complete tightening it in the necessary position of the element.
With proper packing, during tightening, the force should not exceed the tightening torque listed below:
| DN15 | DN20 | DN25 | DN32 | DN40 | DN50 | DN65 | DN80 | DN100 |
|---|---|---|---|---|---|---|---|---|
| 70 Nm | 95 Nm | 120 Nm | 150 Nm | 190 Nm | 230 Nm | 280 Nm | 350 Nm | 400 Nm |
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