The gate should not be inverted (that is, the handwheel is down), otherwise the medium will be retained in the cover space for a long time, easy to corrode the stem, and for some process requirements taboo. It is extremely inconvenient to replace packing at the same time. Open STEM GATE VALVES, DO NOT INSTALL underground, otherwise due to damp corrosion of the exposed stem. Lift check valve, installation to ensure that the valve disc vertical, so that the lift flexible. Swing check valve, when installed to ensure that the pin level, in order to swing flexible. The pressure reducing valve shall be installed upright on the horizontal pipe, and shall not tilt in any direction.
1 Direction and position
Many valves are directional
For example, globe valve, throttle valve, pressure reducing valve, check valve, etc., if installed in reverse, it will affect the use effect and life (such as throttle valve), or does not work at all (such as pressure reducing valve), and even cause danger (such as check valve). General valves with directional markings on the body. If not, it should be correctly identified according to the principle of valve operation.The valve chamber around the globe valve is asymmetrical, fluid to let it from the bottom to the top through the valve port, so the fluid resistance is small (determined by the shape), open labor-saving (due to the medium pressure up), closed after the medium pressure packing, easy to repair, this is why the globe valve can not install the truth. Other valves have their own characteristics.Valve installation position must be easy to operate. Even if the installation is temporarily difficult, it is necessary to consider the long-term work of the operator. Better valve handwheel and chest alignment (generally 1.2 meters from the operating floor), so that the opening and closing of the valve is less effort. Floor valve handwheel should be facing up and not tilted to avoid awkward operation. The valve of the wall machine depends on the equipment, and the operator should also be left standing room. To avoid the operation of the sky, especially acid and alkali, toxic media, otherwise it is not safe.The gate should not be inverted (that is, the handwheel is down), otherwise the medium will be retained in the cover space for a long time, easy to corrode the stem, and for some process requirements taboo. It is extremely inconvenient to replace packing at the same time. Open STEM GATE VALVES, DO NOT INSTALL underground, otherwise due to damp corrosion of the exposed stem. Lift check valve, installation to ensure that the valve disc vertical, so that the lift flexible. Swing check valve, when installed to ensure that the pin level, in order to swing flexible. The pressure reducing valve shall be installed upright on the horizontal pipe, and shall not tilt in any direction.
2 Construction Work
Installation and construction must be careful, do not hit the valve made of brittle materials.
Before the installation
All valve types and specifications shall be carefully checked for compliance with design requirements.(CHECK whether they CAN BE USED IN THE REQUIRED conditions according to the valve model and factory instructions, and perform water or air pressure tests if necessary.)In addition, it should also be checked whether the packing is intact, whether the gland bolt has enough adjustment allowance, and to check whether the stem and disc are sound, whether there is stuck and skew phenomenon.The sealing surface of valve disc must be closed tightly, and the quality of thread should be checked for threaded valves. Unqualified valves shall NOT be INSTALLED and shall be separately stacked or marked.
Debris in the valve.The installation processWhen LIFTING THE VALVE, THE ROPE SHOULD NOT BE TIED TO THE HANDWHEEL OR STEM TO AVOID DAMAGE TO THESE PARTS. It SHOULD BE TIED TO THE flange.The line to which the valve is connected must be cleaned.Compressed air can be used to blow iron oxide filings, sand, welding slag and other sundries. These debris, not only easy to scratch the sealing surface of the valve, the large particles of debris (such as welding slag), but also can block the small valve, so that its failure.When INSTALLING THE SCREW VALVE, THE SEALING PACKING (WIRE AND aluminum oil OR PTFE RAW material belt) should be wrapped on the pipe thread, do not get into the valve, so as to avoid the valve memory volume, affect the medium flow.
When installing flange valves, pay attention to tighten the bolts symmetrically and evenly. The valve flange and the pipe flange must be parallel, the clearance is reasonable, lest the valve produces excessive pressure, even crack. For brittle materials and not high strength of the valve, special attention should be paid. The valve to be welded with the pipe shall be spot welded first, then the closed part shall be fully opened, and then welded dead.
3 Protection Measures
Some valves must also have external protection, which is heat preservation and cold retention. The insulation layer is sometimes mixed with hot steam lines. What kind of valve should be heat or cold, according to the production requirements.In principle, where the valve medium to reduce the temperature is too much, will affect the production efficiency or frozen valve, people need to keep warm, even mix heat; Where the valve is bare, adverse to production or cause frost and other adverse phenomena, people need to keep cold. Insulation materials are asbestos, slag wool, glass wool, perlite, diatomite, vermiculite, etc.; The cooling materials are cork, perlite, foam, plastic and so on.
4 Bypass and meter
Some valves, in addition to the necessary protection facilities, also have bypass and instrumentation. A bypass is installed. Easy to repair the trap. Other valves, also installed bypass. Bypass installation depends on valve condition, importance, and production requirements.
5 Packing replacement
Stock valve, some packing has not been good, and some do not conform to the use of media, which needs to replace the packing.Valve factory can not consider the use of thousands of different types of media, packing box is always filled with ordinary root, but when used, must let the packing in the medium to adapt.When replacing packing, press in round by round. Each ring seam to 45 degrees is appropriate, ring and ring open 180 degrees. The packing height should consider the leeway for the gland to continue pressing, and now it is necessary to let the lower part of the gland press the packing chamber to an appropriate depth, which can generally be 10-20% of the total depth of the packing chamber. For demanding valves, the joint Angle is 30 degrees. The seam between the ring and the ring is staggered 120 degrees.In addition to the packing, but also according to the specific situation, the use of rubber O-ring (natural rubber resistant to 60 degrees Celsius weak alkali, butadiene rubber resistant to 80 degrees Celsius oil crystal, Fluorine rubber resistant to a variety of corrosive media below 150 degrees Celsius) three stacked polytetrafluoron ring (resistant to strong corrosive media below 200 degrees Celsius) nylon bowl ring (resistant to 120 degrees Celsius ammonia, alkali) and other forming filler. A layer of TEflon raw material tape can improve the sealing effect and reduce the electrochemical corrosion of the valve stem. When pressing the seasoning, turn the stem at the same time to keep all around evenly, and prevent too dead, tighten the gland to force evenly, can not tilt.
Hot air valve installation and use requirements and how to maintain installation and use technical requirements
1. The hot air valve can only be installed and used with the stem perpendicular to the ground, and the debugging should also be carried out under the condition of the stem perpendicular to the ground;
2. The ventilation direction of the hot air valve and the inlet and outlet direction of the cooling water must conform to the direction of the installation diagram. When installing the hot air valve, the wind arrow should point to the hot air main pipe. When the hot air valve is used as a combustion valve and flue valve, the wind arrow should point to the hot blast stove; When the hot air valve is used as a backflow rest valve, the wind arrow should point to the hot air main pipe; When the hot air valve is used as a mixed air shut-off valve, the wind arrow should face away from the hot air main pipe. (When the hot air valve is used as the installation method of the above mentioned valves * When the nameplate name is still hot air valve, and the nameplate name is clearly the name of the above valve, the wind arrow indicates the direction of the medium.)
3. Before debugging, clean the sealing surface of the valve body and valve plate with cotton yarn to prevent the sealing surface from being scratched. Before operation, add lubricating oil to each oil point, sprinkle graphite powder or grease to the floating sealing part;
4. After installation, check the tightening of bolts in the valve body, valve cover, valve stem seal and other parts to ensure no air leakage and smooth falling of valve plate. Manually start the valve at low speed to confirm the normal operation of the mechanism before starting the test run;
5. The pipe installation of the valve is the whole installation (excluding the transmission device). The lifting point is the lifting lug on the valve body (4 are located in the round flange, the lifting lug on the valve cover is strictly prohibited for overall lifting), the transmission device is installed on the valve after the overall installation of the valve;
6. The valve pipe flange between the application of ceramic metal gasket coated with high temperature sealant seal, prevent air leakage;
7. When the valve is opened, the lower part of the valve plate should be more than 100mm higher than the upper side of the valve channel (debugging method: lift the valve plate to the upper limit and then drop 50mm as the valve plate opening position). The valve cooling water should be unblocked, the outlet temperature is lower than 40℃;8. Before the valve installation, the transmission frame and the valve body should be packed and stored separately, and then the whole installation will be performed on site. Tighten the valve body and the transmission device according to the position of the installation interface during installation, and tighten the valve close to the switch position after installation and adjustment. When the valve is in test operation, it should be started manually before power. (Note: When installing the hydraulic transmission valve, both sides of the cylinder piston have free stroke when the valve is open and closed, and then fix the stroke switch after adjustment. Rack and pinion hydraulic transmission valve should adjust the position of cylinder piston according to the limit position of valve plate stroke, and then hang the chain). Operation should be smooth without collision and impact stuck phenomenon.
Valve service repair and maintenance
1. Check the sealing performance of the valve once a week when it is closed, judge the sealing effect of the valve by hand and ear feeling, and report and deal with any problems in time;
2. Check the cooling water temperature, water pressure and external leakage before and after work, and eliminate any problems in time;
3. When opening and closing the valve, attention should be paid to the stable running condition, and problems should be dealt with in time;
4. Fill lubricating oil and grease twice a week to prevent the lack of oil and burn damage of moving parts;
5. It is strictly prohibited to use under the condition of insufficient cooling water and water cut off;6. Regularly check and clean up the sediment in the valve, and deal with abnormalities in time;
7. Please read the electric device manual provided with the electric valve for the electric device instructions.
Other Factors
1. The valve shall be stored and transported with the sealing surface of the valve placed below and the arrow of the wind vane facing up (when the nameplate name is flue valve, backflow air rest valve and mixed air cut off valve, the arrow of the wind vane facing down) and the valve stem firmly fixed in the closed position to prevent the sealing surface from being damaged by vibration;
2. The transmission device shall be disassembled by the manufacturer after qualified installation and debugging.
original source: https://www.likvchina.com/news/installation-points-and-characteristics-of-hot-air-valve-installation-and-operation-requirements-and-how-to-maintain-2/
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