Check before installation Check the type, size, and type of commonly used valves. Which valve is used should be selected according to the purpose of the valve, the characteristics of the medium, the maximum working pressure, the maximum temperature, and the flow rate, flow rate of the medium, or the nominal diameter of the pipe.
Before installation, it should be carefully checked whether all valve types and specifications meet the design requirements. According to the valve type and the manufacturer's instructions, check if they can be used under the required conditions, if necessary, water pressure or air pressure test. In addition, it should also check whether the packing is in good condition, whether the gland bolts have enough adjustment margin, and whether the valve stem and the valve disc are to be checked for sensation and whether they are stuck or skewed. The sealing face of the valve plate must be tightly closed. For threaded connections, check the thread quality. Failed valves cannot be installed and should be stacked or marked.
When installing the valve, note that the valve cannot be buried directly to prevent corrosion of the valve stem. It can only be installed in the covered trench, and the valve should be installed in a position where it is convenient for operation, inspection, disassembly, maintenance, and operation. It is not allowed to throw the valve when carrying the valve to avoid damage and deformation. When stacking, carbon steel valves should be separated from stainless steel valves and non-ferrous metal valves. When the valve is hoisted, the steel wire rope should be hung on the connection flange between the valve body and the valve cover. Do not squat on the hand wheel or the valve stem to prevent damage to the valve stem and the hand wheel.
The valve installation position should not hinder the disassembly, maintenance and operation of the equipment, piping and valves themselves. The installation height should be convenient for operation and maintenance. Generally, it is advisable to use a valve operating handle of 1-1.2m from the ground. For valves that operate more, when they must be installed more than 1.8m away from the operation surface, a fixed operation platform should be set. When it must be installed above or below the operation surface, extend the rod or install the valve stem horizontally. Install a hand wheel or remote operation device with a transmission. The angle of the axis of the valve transmission should not be greater than 30°, and the joint should be flexible in rotation and easy to use during operation. The indication is accurate. With thermal displacement valves, the transmission shall have compensating measures.
The horizontal pipe is best to hold the valve vertically upwards or to install the valve stem in the upper half circle, but do not install the valve stem downwards. Valve stems and handwheels on vertical pipes must be installed along the direction of the operating tour line. When conditions permit, the valve should be installed as much as possible for ease of operation. Valves on towers above 4m above the ground should not be placed outside the platform for ease of installation and operation.
For directional valves, the installation direction should be determined according to the medium flow direction of the pipeline. When installing the check valve, special attention must be paid to the flow of the medium to ensure that the valve disk can be automatically opened. In important cases, an arrow should be clearly marked on the outside of the valve body to indicate the flow direction of the medium. For a swing check valve, the swivel pivot of its board should be installed in a horizontal position. For lift check valves, ensure that the centerline of the valve plate is perpendicular to the horizontal plane. If a stop valve is installed, the medium should flow from the bottom of the cabinet to the top, commonly known as low and high. When installing a plug or gate valve, allow media to flow from either end.
For valves with special requirements, be familiar with the installation requirements. If a lever type pressure reducing valve and a safety valve are installed, the center line of the valve disc must be perpendicular to the horizontal plane, and correction must be made when the tilt is found.
When a threaded connection is installed on the pipe, a union must be installed near the valve for disassembly.
The auxiliary system pipeline shall be provided with shut-off valves when entering the workshop. When the workshop is shut down for maintenance, it may be cut off from the main pipeline. The installation height of these valves is generally high and they should be arranged as much as possible in order to set a fixed operating platform.
Install the flanged valve, and ensure that the two flange faces connected to it are parallel and coaxial with the valve flange. Especially when installing relatively brittle valves such as cast iron, the damage of the valve due to incorrect installation position and non-uniform force should be avoided. When tightening flange bolts, symmetrical or criss-crossing methods should be adopted, gradually tightening several times.
Before installing the high pressure valve, the product certification and test records must be reviewed. High-pressure valves are mostly angle valves, which are often used in series with two, and the starting force is large when they are opened. The valve frame must be set to support the valves and reduce the starting stress. The installation height is preferably 0.6-1.2m.
The pipe connections on the pumps, heat exchangers, towers, and vessels shall not be subjected to the weight of valves and pipes, and valves with a nominal diameter dn > 80 mm shall be provided with brackets.
Lining, spraying and non-metallic materials require high quality and low strength. In addition to considering the process requirements, they should be arranged as much as possible to facilitate the design of the valve frame. Even a single valve should be fixed to the valve frame. When installing heavy-duty valves on horizontal pipes, consider installing brackets on both sides of the valve.
The threaded connection of the valve should be ensured that the thread is intact. The packing should be selected according to the working conditions. The position of the valve stem should meet the installation requirements when tightening the valve. When tightening, you must use a wrench to tighten the hexagonal body of the valve on the end of the pipe to ensure that the valve body is not twisted and damaged. Flange or threaded valves should be installed in the closed state.
The sealing welding of welding seams between welded valves and pipes should adopt argon arc welding to ensure that the inside of the welding is smooth and smooth. The valve should not be closed during welding to prevent overheat deformation of the sealing surface. If the sealing material is not resistant to high temperatures, the sealing material must be removed before welding to prevent the welding heat from damaging the sealing material.
The flow direction of the shut-off valve should be consistent with the arrow marked on the valve body (can not be reversed), so that when the valve is closed, the pressure is applied to the cone on the top of the valve, and the packing is not loaded. However, valves that do not open and close frequently and that need to be strictly secured in the closed state (such as a warming valve) can be consciously reversed according to demand, so that they can be closed by means of medium pressure. Large-sized gate valves (DN200-500MM) and pneumatic regulating valves should be installed vertically to avoid biasing one side due to the larger weight of the valve core and increasing the mechanical wear between the valve plug and the sleeve, causing leakage. When tightening the compression screw, the valve should be in a slightly open state to avoid squeezing the valve top sealing surface. After all the valves are in place, they should be opened and closed once again, and no sticking phenomenon is acceptable. After the bare air cooled, the large air separation tower pre-tightens the flange of the connecting valve in the cold state to prevent the valve from leaking at a low temperature at the normal temperature without leakage. When the new valve is in use, the packing should not be pressed too tightly so as not to leak, so as to prevent the stem of the valve from being pressed too much, which causes the wear to increase, and it is difficult to open and close.
For valves on side-by-side pipelines, the net distance between the handwheels must not be less than 100mm. To reduce the pipeline spacing, valves arranged side by side should preferably be staggered.
Before the cryogenic valve is positioned, it should try to open and close the test in the cold state, which requires flexibility and no jamming.
Safety valve connection should be elbow (or three links and the like), to avoid direct impact on the valve fluid; also to ensure that the safety valve in the operation is not frost, so as to avoid failure during work. It is forbidden to climb the valve stem as scaffolding when the valve is installed.
High temperature valve above 200 °C, because the valve is installed at room temperature, and after normal use, the temperature increases, the valve bolt is heated to expand, the gap increases, so must be tightened again, called "heat tight", the operator should pay attention to this work , otherwise it is prone to events such as valve leakage. When the winter is cold, the water valve is closed for a long time and the water behind the valve should be excluded. After the steam valve has stopped steaming, condensate should also be excluded. The bottom of the valve is like a drain switch, which can be opened to drain. Non-metallic valves, some hard and brittle, some low strength, operation, the opening and closing force can not be too large, in particular, can not make Mengjin. Also pay attention to avoiding object collisions
Before installation, it should be carefully checked whether all valve types and specifications meet the design requirements. According to the valve type and the manufacturer's instructions, check if they can be used under the required conditions, if necessary, water pressure or air pressure test. In addition, it should also check whether the packing is in good condition, whether the gland bolts have enough adjustment margin, and whether the valve stem and the valve disc are to be checked for sensation and whether they are stuck or skewed. The sealing face of the valve plate must be tightly closed. For threaded connections, check the thread quality. Failed valves cannot be installed and should be stacked or marked.
When installing the valve, note that the valve cannot be buried directly to prevent corrosion of the valve stem. It can only be installed in the covered trench, and the valve should be installed in a position where it is convenient for operation, inspection, disassembly, maintenance, and operation. It is not allowed to throw the valve when carrying the valve to avoid damage and deformation. When stacking, carbon steel valves should be separated from stainless steel valves and non-ferrous metal valves. When the valve is hoisted, the steel wire rope should be hung on the connection flange between the valve body and the valve cover. Do not squat on the hand wheel or the valve stem to prevent damage to the valve stem and the hand wheel.
The valve installation position should not hinder the disassembly, maintenance and operation of the equipment, piping and valves themselves. The installation height should be convenient for operation and maintenance. Generally, it is advisable to use a valve operating handle of 1-1.2m from the ground. For valves that operate more, when they must be installed more than 1.8m away from the operation surface, a fixed operation platform should be set. When it must be installed above or below the operation surface, extend the rod or install the valve stem horizontally. Install a hand wheel or remote operation device with a transmission. The angle of the axis of the valve transmission should not be greater than 30°, and the joint should be flexible in rotation and easy to use during operation. The indication is accurate. With thermal displacement valves, the transmission shall have compensating measures.
The horizontal pipe is best to hold the valve vertically upwards or to install the valve stem in the upper half circle, but do not install the valve stem downwards. Valve stems and handwheels on vertical pipes must be installed along the direction of the operating tour line. When conditions permit, the valve should be installed as much as possible for ease of operation. Valves on towers above 4m above the ground should not be placed outside the platform for ease of installation and operation.
For directional valves, the installation direction should be determined according to the medium flow direction of the pipeline. When installing the check valve, special attention must be paid to the flow of the medium to ensure that the valve disk can be automatically opened. In important cases, an arrow should be clearly marked on the outside of the valve body to indicate the flow direction of the medium. For a swing check valve, the swivel pivot of its board should be installed in a horizontal position. For lift check valves, ensure that the centerline of the valve plate is perpendicular to the horizontal plane. If a stop valve is installed, the medium should flow from the bottom of the cabinet to the top, commonly known as low and high. When installing a plug or gate valve, allow media to flow from either end.
For valves with special requirements, be familiar with the installation requirements. If a lever type pressure reducing valve and a safety valve are installed, the center line of the valve disc must be perpendicular to the horizontal plane, and correction must be made when the tilt is found.
When a threaded connection is installed on the pipe, a union must be installed near the valve for disassembly.
The auxiliary system pipeline shall be provided with shut-off valves when entering the workshop. When the workshop is shut down for maintenance, it may be cut off from the main pipeline. The installation height of these valves is generally high and they should be arranged as much as possible in order to set a fixed operating platform.
Install the flanged valve, and ensure that the two flange faces connected to it are parallel and coaxial with the valve flange. Especially when installing relatively brittle valves such as cast iron, the damage of the valve due to incorrect installation position and non-uniform force should be avoided. When tightening flange bolts, symmetrical or criss-crossing methods should be adopted, gradually tightening several times.
Before installing the high pressure valve, the product certification and test records must be reviewed. High-pressure valves are mostly angle valves, which are often used in series with two, and the starting force is large when they are opened. The valve frame must be set to support the valves and reduce the starting stress. The installation height is preferably 0.6-1.2m.
The pipe connections on the pumps, heat exchangers, towers, and vessels shall not be subjected to the weight of valves and pipes, and valves with a nominal diameter dn > 80 mm shall be provided with brackets.
Lining, spraying and non-metallic materials require high quality and low strength. In addition to considering the process requirements, they should be arranged as much as possible to facilitate the design of the valve frame. Even a single valve should be fixed to the valve frame. When installing heavy-duty valves on horizontal pipes, consider installing brackets on both sides of the valve.
The threaded connection of the valve should be ensured that the thread is intact. The packing should be selected according to the working conditions. The position of the valve stem should meet the installation requirements when tightening the valve. When tightening, you must use a wrench to tighten the hexagonal body of the valve on the end of the pipe to ensure that the valve body is not twisted and damaged. Flange or threaded valves should be installed in the closed state.
The sealing welding of welding seams between welded valves and pipes should adopt argon arc welding to ensure that the inside of the welding is smooth and smooth. The valve should not be closed during welding to prevent overheat deformation of the sealing surface. If the sealing material is not resistant to high temperatures, the sealing material must be removed before welding to prevent the welding heat from damaging the sealing material.
The flow direction of the shut-off valve should be consistent with the arrow marked on the valve body (can not be reversed), so that when the valve is closed, the pressure is applied to the cone on the top of the valve, and the packing is not loaded. However, valves that do not open and close frequently and that need to be strictly secured in the closed state (such as a warming valve) can be consciously reversed according to demand, so that they can be closed by means of medium pressure. Large-sized gate valves (DN200-500MM) and pneumatic regulating valves should be installed vertically to avoid biasing one side due to the larger weight of the valve core and increasing the mechanical wear between the valve plug and the sleeve, causing leakage. When tightening the compression screw, the valve should be in a slightly open state to avoid squeezing the valve top sealing surface. After all the valves are in place, they should be opened and closed once again, and no sticking phenomenon is acceptable. After the bare air cooled, the large air separation tower pre-tightens the flange of the connecting valve in the cold state to prevent the valve from leaking at a low temperature at the normal temperature without leakage. When the new valve is in use, the packing should not be pressed too tightly so as not to leak, so as to prevent the stem of the valve from being pressed too much, which causes the wear to increase, and it is difficult to open and close.
For valves on side-by-side pipelines, the net distance between the handwheels must not be less than 100mm. To reduce the pipeline spacing, valves arranged side by side should preferably be staggered.
Before the cryogenic valve is positioned, it should try to open and close the test in the cold state, which requires flexibility and no jamming.
Safety valve connection should be elbow (or three links and the like), to avoid direct impact on the valve fluid; also to ensure that the safety valve in the operation is not frost, so as to avoid failure during work. It is forbidden to climb the valve stem as scaffolding when the valve is installed.
High temperature valve above 200 °C, because the valve is installed at room temperature, and after normal use, the temperature increases, the valve bolt is heated to expand, the gap increases, so must be tightened again, called "heat tight", the operator should pay attention to this work , otherwise it is prone to events such as valve leakage. When the winter is cold, the water valve is closed for a long time and the water behind the valve should be excluded. After the steam valve has stopped steaming, condensate should also be excluded. The bottom of the valve is like a drain switch, which can be opened to drain. Non-metallic valves, some hard and brittle, some low strength, operation, the opening and closing force can not be too large, in particular, can not make Mengjin. Also pay attention to avoiding object collisions
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