The importance of safe valves is beyond doubt, and how to correctly install the valve determines whether the valve can be used safely. Different valves, different use of the environment, the valve installation needs to pay attention to different content, the following is the valve installation needs to pay attention to the twenty-seven!
1. Rising stem gate valves can not be directly buried to prevent corrosion of the valve stem, and can only be installed in the covered trench, the valve should be installed in the operation, inspection, dismantling, maintenance, and operation of the location of the convenience.
2. Handling valves are not allowed to throw, so as not to damage and deformation of stacking, carbon steel valves with stainless steel valves and non-ferrous metal valves should be separated. Valve lifting, steel wire rope should be chained to the valve body and the valve cover of the connecting flange, do not chained to the handwheel or valve stem, to prevent damage to the valve stem and handwheel.
3. Valve installation location should not interfere with the equipment, piping and the valve itself disassembly, maintenance, and operation of the installation height should be convenient for operation and maintenance, generally to the valve operating handle from the ground 1-1.2m is appropriate.
Operation of more valves, when they must be installed from the operating surface of more than 1.8m, should be set up a fixed operating platform, when they must be installed above or below the working surface, should be set up to extend the pole or the stem horizontal installation, while installing a handwheel with a transmission device or remote operating device. The angle between the axes of the valve transmission device should not be greater than 30 °, and its joints should be rotating and flexible, easy to use when operating, and accurate instructions.
Valve with thermal displacement, the transmission device should have compensation measures.
4. Horizontal pipeline is best to the valve vertical up or the valve stem installed in the upper semicircular range, but shall not be installed with the valve stem down vertical pipeline valve stem, handwheel must be installed in the direction of the operating circuit line. The valve should be installed as centrally as possible to facilitate operation. Higher than 4m above the ground on the tower area pipeline valves should not be set outside the platform to facilitate the installation and operation.
5. For directional valves, the installation should be based on the pipeline medium flow direction to determine the direction of its installation, such as the installation of globe valves, should make the medium from the cabinet disc below the flow to the top, commonly known as the low into the high out. Installation of plug, gate valve, allowing the medium to flow from either end. Installation of check valves, must pay special attention to the direction of flow of the medium to ensure that the valve disc can be opened automatically, important occasions but also in the valve body outside the marked arrow, indicating the direction of flow of the medium.
For the rotary check valve, should ensure that the rotary pivot of the plate is installed in a horizontal position. For lift check valve, should ensure that the centre line of the valve disc and the horizontal plane vertical.
6. For special requirements of the valve, to be familiar with the installation requirements such as the installation of lever-type safety valves and pressure reducing valves, must make the valve disc center line and the horizontal plane perpendicular to each other, found that the tilt must be corrected.
7. Installation of loose joints pipeline installation of threaded connections on the valve, near the valve must be installed loose joints for disassembly.
8. auxiliary system piping into the workshop should be set up to cut off the valve when the workshop parking maintenance, can be cut off from the main pipeline. The installation height of these valves is generally high, should be arranged together as far as possible, in order to set up a fixed operating platform.
9. Installation of flange connection of the valve to ensure that the two flanges connected to the end face and valve flange parallel and coaxial. Especially when installing valves made of brittle materials such as cast iron, it should avoid damage to the valve caused by incorrect installation position and uneven force. Tighten the flange bolts, should be used symmetrical or cross-crossing method, several times gradually tighten.
10. Installation of high-pressure valves, must review the product certification and test records of high-pressure valves are mostly angle valves, the use of the two often in series, open the start-up force is large, must be set up to support the valve and reduce the start-up valve stress, and its mounting height of 0.6-1.2m is appropriate.
11 machine pumps, heat exchangers, towers and containers on the pipe interface should not bear the weight of the valves and pipelines, the nominal diameter of dn> 80mm valves should be added support.
12. Lining, spraying and non-metallic materials ask the door itself the quality of large, low strength, in addition to consider the process requirements, it should be done as far as possible to centralise the arrangement, to facilitate the design of the valve frame even if it is a separate valve should be fixed on the valve frame. Horizontal pipeline installation of heavy-duty valves, to consider installing brackets on both sides of the valve.
13. Installation of threaded connection of the valve should ensure that the threads are intact according to the working conditions of the choice of packing, tightening in place when the position of the valve stem should meet the installation requirements. When tightening, you must use a spanner to bite firmly screwed to one end of the pipe on the valve hexagonal body to ensure that the valve body is not screwed deformation and damage. Flange or threaded connection of the valve should be installed in the closed state.
14. Welding valves and pipelines connected to the bottom of the weld sealing weld is appropriate to use argon arc welding welding to ensure that its internal smooth and clean welding valve should not be closed to prevent the sealing surface overheating and deformation. If the sealing material is not resistant to high temperatures, before welding to remove the sealing material to prevent welding high temperature damage to the sealing material.
15. Side-by-side pipeline valves, the net distance between the handwheels shall not be less than 100mm, in order to reduce pipeline spacing, side-by-side arrangement of the valve is best staggered arrangement.
16. Cryogenic valves should be positioned before the cold state as far as possible to do the opening and closing test, the requirement of flexible without jamming phenomenon.
17. Safety valve connections should be elbow (or tee and other accessories) to avoid direct impact of the fluid valve; in addition to ensure that the safety valve in the operation of the non-frost, so as to avoid failure at work.
18. It is strictly prohibited in the valve installation when the valve stem as scaffolding climbing.
19. High-temperature valves 200 ℃ or more due to the installation of the valve at room temperature, and normal use, the temperature rises, the valve bolt thermal expansion, the gap increases, so it must be tightened again, called the “hot tight”, the operator should pay attention to this work, or else it is easy to leakage of the valve and other events.
20. When it is cold in winter, the water valve is closed for a long time, the water behind the valve should be excluded after the steam valve stops steam, but also to exclude condensate. The bottom of the valve is like a drain switch, you can open it to drain.
21. Non-metallic valves, some hard and brittle, some lower strength, operation, open and close the force can not be too large, especially not to make violent. Also pay attention to avoid object knocking.
22. Globe valve should be installed with the flow direction of the valve body marked on the same arrow (can not be installed in reverse) so that when the valve is closed, the pressure is added to the top of the cone, and the packing is not loaded. However, the infrequent opening and closing and the need to strictly ensure that the valve does not leak in the closed state (such as heating valve), according to the needs of conscious reverse loading, in order to make it tightly closed with the help of medium pressure.
23. Large size gate valve (DN200-500MM), pneumatic control valves should be installed vertically to prevent the spool of the greater self-weight and bias to one side, increasing mechanical wear between the spool and the liner, resulting in leakage.
24. When tightening the compression screws, the valve should be in a slightly open state, so as not to crush the sealing surface of the top of the valve.
25. After all the valves in place, should be made again to open and close, flexible without jamming phenomenon is qualified.
26. large air separation tower in the bare cold, in the cold state of the connection valve flange pre-tightened once, to prevent the valve at room temperature does not leak in the valve leakage phenomenon occurs at low temperatures.
27. New valves in use, the packing should not be pressed too tightly to the extent of no leakage, so as to avoid the valve stem pressure is too great, wear and tear to speed up the opening and closing of the effort. Valve installation is the most important, the quality of the installation affects the normal operation of the future.