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Valve installation knowledge and precautions
Valve installation requirements Valve installation quality is good or bad, a direct impact on the use of the valve, therefore, should be the introduction of construction units and production units attach great importance to the valve installation instructions should be in accordance with the valve and the relevant provisions. The construction process should be carefully checked and carefully constructed. Before the installation of the valve, the pressure test should be carried out after installation, carefully check the valve specifications, model is consistent with the drawings, check the valve parts are intact, opening and closing valve is flexible and flexible, sealing surface without damage, etc., Can be installed. When the valve is installed, the operating mechanism of the valve should be about 1.2m away from the ground for operation, and should be aligned with the chest. When the center of the valve and the hand wheel from the ground when operating more than 1.8m, should operate more valves and safety valves to set the operating platform. Valve more pipes, valves as much as possible concentrated in the platform for easy operation. For more than 1.8m and infrequently operated single valves, sprockets, extension rods, moving platforms, and moving ladders may be used. When the valve is installed below the operating surface, should be set to extend the rod, the valve should be set to the well, for safety reasons, wells should be stamped. Valve on the level of the valve stem, the best vertical up, not the valve stem down to install. Stem down installation, inconvenient operation, inconvenient maintenance, but also easy to corrode the valve accident. Do not skew the landing valve installation, so as not to operate inconvenient. Side-by-side pipeline valves, there should be operation, maintenance, disassembly of the vacancy, the clearance between the hand wheel is not less than 100mm, such as tube spacing is narrow, the valve should be staggered. On the opening of a large, low strength, brittle large and heavy valve, the valve before installation to set the valve support to reduce the starting stress. When installing the valve, the pipe closer to the valve uses pipe wrenches and the valve itself uses an ordinary wrench. At the same time, the installation, to make the valve in a semi-closed state, to prevent the valve rotation and deformation. The correct installation of the valve should be in accordance with the internal structure of the media flow direction, the installation of the valve structure in line with the special requirements and operational requirements. In particular, pay attention to the requirements of the media flow valve should be installed according to the requirements of the process. Valve layout to be convenient and reasonable, the operator easy access to the valve, the valve stem for the lift valve, to leave room for the operation of all valve stems should be installed upward and perpendicular to the pipe. Valve connection surface installation and installation of the end of the threaded connection of the valve should be threaded into the appropriate depth of the valve, screwed into the over-deep pressure valve seat, will affect the valve seat and the gate with a good fit, screwed into the light, Will affect the seal of the joint reliability, easy to introduce leakage. At the same time thread sealing material should be used to tetrafluoroethylene raw rubber tape sealant, be careful not to give sealing material to the valve cavity. For the valve connected to the end of the flange, first find the connecting face of the flange, the cover perpendicular to the pipeline, and the bolt holes to be aligned. Valve flange should be parallel with the pipe flange, flange clearance moderate, should not appear wrong port, tilt and so on, the flange between the heart gasket should be placed in the middle, can not be skewed, bolts should be evenly tightened. Prevent compulsory connection tightening when the valve is installed, resulting in an additional residual force. Before installation, it is necessary to completely remove the dirt on the inner wall and the outer thread of the pipe. To remove the burrs, foreign matter and other substances that may hinder the flow of the medium and the operation of the equipment, blow away the dirt, slag and other debris from the pipe before the pipe is connected. Prevent damage to the valve sealing surface or block the valve. Install the welding end of the connection valve, the group should be welded to both ends after the spot welding valve, open the valve, and then press the welding process card welding seam, the appearance of the weld after the weld and the quality of the internal weld inspection to ensure non-porosity , Slag inclusions, cracks, etc., if necessary, the weld should be over-checked ray or overweight valve installation Heavy installation of the valve (DN> 100), the application of lifting tools or equipment, lifting rope should be tied in the valve flange Or bracket, should not be tied to the valve handle lever, so as to avoid damage to the valve. What are the general requirements for valve installation? A: The general requirements for installation of the valve, the most appropriate installation height, the level of the valve on the pipeline, stem direction as follows: (1) The valve should be located in easy to access, easy to operate, maintain the place. Valves on a row of pipes (such as pipes leading to and from the installation) should be centrally located and considered to be equipped with operating platforms and ladders. Parallel arrangement of valves on the pipeline, the centerline should try to get together. The clear distance between the handwheel should not be less than 10Qmm, in order to reduce the pipe spacing, the valve can be staggered layout; (2) the valve should be installed in the operating position should be easy to operate, the most appropriate installation height of 1.2m from the operating surface up and down. When the valve hand wheel center height exceeds the operating surface 2m, for centralized valve group or frequent operation of the separate valve and safety valve should be set to platform, for infrequently operating separate valves should also take appropriate measures (such as sprocket, Extension rod, activity platform and activity ladder, etc.). The chain of the sprocket should not interfere with traffic. Dangerous medium pipes and equipment valves shall not be installed in the height range of the head to avoid bruising the human head, or direct damage to the human face due to leakage of the valve; (3) the partition valve equipment and equipment Spout directly connected or close to the device. Valves connected to equipment with extremely hazardous and highly hazardous toxic media shall be connected directly to the equipment tank mouth and shall not be operated with sprockets; (4) Accident handling valves such as fire service water valves, fire safety steam valves, etc. Should be distributed, and to take into account the safety of the accident operation. This type of valve to be arranged in the control room. After the safety wall, the plant door, or with the accident at a safe distance between the zone; in case of fire accidents, the operator can safely operate; (5) In addition to the process has special requirements, the tower, the reactor, vertical container (6) from the main pipe on the horizontal branch of the shut-off valve, should be located near the root of the horizontal section; (7) lift check valve should be installed In horizontal pipe, vertical lifting check valve should be installed in the pipe flow from the bottom of the vertical pipeline. Swing check valve should be preferentially installed in the horizontal pipe, pipe can also be installed in the vertical flow of media from the bottom up; the bottom valve should be installed in the installation of centrifugal pump suction height, optional butterfly check valve; (8) arranged around the operating platform valve hand wheel center from the edge of the platform should not be greater than 450mm, when the stem and hand wheel into the platform above And the height is less than 2m, it should be so that it does not affect the operator's operation and access; (9) underground pipeline valve should be located in the trench or valve well, if necessary, should set the valve extension rod. Fire water valve wells should be clearly marked; (10) The horizontal pipe valve, stem direction can be determined in the following order: vertical upward; horizontal; 11) Stem horizontal rod valve installation, when the valve is opened, the stem shall not affect traffic. Check valve installation needs attention (1) installation location, height, direction of import and export must meet the design requirements, pay attention to the flow direction of the medium should be consistent with the direction of the arrow marked by the body, the connection should be firm and tight. (2) The appearance of the valve must be checked before installation. The nameplate of the valve should meet the requirements of the current national standard "General Valve Marking" GB 12220. For the working pressure is greater than 1.0 MPa and the main pipe to play the role of cut-off valve, the installation should be carried out before the intensity and tightness test, qualified after the standard use. Strength test, the test pressure of 1.5 times the nominal pressure, the duration of not less than 5min, valve housing, packing should be no leakage as qualified. Tightness test, the test pressure of 1.1 times the nominal pressure; test duration in line with the requirements of GB 50243. (3) aetv One-way valve: Do not subject the check valve to heavy loads in the pipeline: Support it independently of the pressure exerted by the piping. Valve installation of technical requirements 1, directional. General valve body has a logo on the direction of the arrow that gas flow forward direction. Must pay special attention, may not be installed. Because there are a variety of valves require one-way flow of gas, such as safety valve, pressure reducing valve, check valve, throttle, etc., for the cut-off valve for ease of opening and maintenance, but also requires gas from bottom to top through the valve seat, When the cock is installed, it is not restricted by the circulation direction. 2, the installation location. Valve to long-term operation and maintenance considerations, as much as possible to facilitate operation and maintenance, but also pay attention to the appearance of the assembly beautiful. Valve handle direction can be vertical upward, you can also tilt to an angle or horizontal, but the hand wheel can not be down, to avoid Yang Lian operation; landing valve hand wheel is best Qi chest high, easy to open and close; In the ground, to prevent the stem from corrosion. Some valves have special installation requirements. For example, the pressure reducing valve should be mounted upright on a horizontal pipe without tilting. The lifting check valve requires the valve disc to be vertical. The swing check valve requires the horizontal pin. In short, according to the principle of the valve to determine its installation location, otherwise the valve can not work effectively, or even ineffective. 3, the cocks installed. Check the model number, identify whether damage, remove the thread cover and threaded thread too much grease and debris, check the cock sealing performance. The gas cock in the installation must pay attention to appropriate force, according to the size of the cock size selection of different specifications of pipe wrenches or wrenches for installation. 4, Threaded valve installation, the valve company should ensure that the thread intact; wrench can do a full time wrench, do not use pipe clamp, to avoid damage to the body appearance. 5, flange-type valve installation, you must ensure that the two flange sections parallel to each other and in the same axis, tighten the bolts should be cross-shaped, so that the valve end surface force uniform. 6, the flange and the threaded valve should be installed in the closed state. Butt valve and pipe connection, the weld should be argon welding welding, to ensure internal cleaning, welding, the valve should not be closed to prevent deformation. 7, under normal circumstances, the valve and corrugated expansion joints directly connected, it should be based on the valve and corrugated expansion joints and flanges and gaskets size, the pipes on both sides of the cut off, leaving the installation location. 8, lifting the valve, the rope can not be tied in the first round or stem to prevent damage, should be light, soft, can not collide. When placed on the pier, according to the required elevation pad, pad flat. Under the valve must have a solid pier or bracket to hold the valve does not allow the valve to hang stress.