What are the functions of pipeline valves?
 
How to install it?
 
What do you mean by common logos?
 
What is the maintenance of failure? Four functions of pipe valve
 
1. Cutting and release medium
 
This is the most basic function of the valve, which is usually selected as a straight-through valve with a smaller flow resistance.
 
Downward closed valve (globe valve, plunger valve) due to its winding, flow resistance is higher than other valves, so less selection. Closed valves can be used in situations where high flow resistance is allowed.
 
2. Control flow
 
Valves that are easy to regulate flow are usually chosen as control flow. A downward closing valve (such as a globe valve) is suitable for this purpose, as its seat size is proportional to the distance of the closing part.
 
Rotary valves, plug valves, butterfly valves, ball valves) and deflection type valve body (clamp valve, diaphragm valve) can also be used to throttle control, but usually only apply within the size of the valve co., LTD.
 
The gate valve is a circular seat with a disc shape, which can control the flow well only when it is close to the closing position, so it is not usually used for flow control.
 
3. Commutation flow
 
This valve can have three or more channels according to the need for a diversion. Cock and ball valves are more suitable for this purpose, so most of the valves used for commutation are selected from such valves.
 
In some cases, however, other types of valves can be used for commutation as long as two or more valves are properly connected.
 
A medium with suspended particles
 
When the medium has suspended particles, it is most suitable for the sliding of the closed part along the sealing surface with the wiping valve.
 
If close to the seat back and forth movement is vertical, then can clamping particles, so unless the valve sealing surface material allows embedded particles, otherwise only applies to basic cleaning medium. Ball valve and plug valve have a wipe effect on the sealing surface during the opening and closing process, so it is suitable for use in the medium with suspended particles. Three installation problems for pipeline valves
 
1. Pre-installation inspection
 
1. Carefully check the valve model and specifications to meet the drawing requirements.
 
2. Check whether the stem and disc are open flexibly, whether it is jammed or skewed.
 
3. Check whether the valve is damaged, and the thread of the threaded valve is correct and intact.
 
4. Check whether the seat and body combination is strong, disc and seat, bonnet and valve body, stem and disc connection.
 
5. Check whether the valve gasket, packing and fastener (bolts) are suitable for the work medium nature.
 
6. For old or long-shelved relief valves should be removed, dust, sand and other sundries should be cleaned with water.
 
7. Clear the vent cover and check the seal. The disc must be closed tightly.
 
2. General provisions of installation
 
1. The position of valve installation shall not obstruct the operation of the equipment, piping and valve body itself, disassembling and repairing, and taking into consideration the aesthetic appearance of the assembly.
 
2. Valve on horizontal pipe, stem facing up, or inclined at a certain Angle, not to be installed downward. The valve, stem and handwheel can be installed horizontally in the high-altitude pipeline, and the valve's opening and closing can be operated from a chain with a vertical low.
 
3. Symmetrical, neat and beautiful; Valves on the riser, with the process allowed, the valve handwheel is the most suitable for the chest height. Generally, it is appropriate to be 1.0-1.2 m from the ground, and the stem must be installed in the direction of the operator.
 
4. The valve on the vertical side of the vertical pipe will be the best in the center line and the net distance between the handwheel is not less than 100mm; Valves on the horizontal line should be staggered to reduce pipe spacing.
 
5. When installing heavier valves on equipment such as pumps and heat exchangers, valve supports should be installed; A fixed operating platform shall be installed when the valve is frequently operated and installed at more than 1.8 m.
 
6. The valve body has the arrow mark on the valve body and the arrow pointing to the flow direction of the medium. When installing the valve, it should be noted that the arrow points to the same as the medium in the pipe.
 
7. When installing flange valves, ensure that the two flange faces are parallel and concentric, and should not be used with double gaskets.
 
8. When installing threaded valves, a threaded valve shall be fitted with a live connection for easy removal. The installation of the live connection should consider the convenience of maintenance, usually the water flow through the valve before flowing through the live connection.
 
Iii. Installation precautions
 
1. Valve body material is made of cast iron and is brittle, so it should not be hit by heavy objects.
 
2. When handling valves, no throwing is allowed; When hoisting and hoisting valve, the rope should be attached to valve body. It is strictly prohibited to be fastened to handwheel, stem and flange bolt hole.
 
3. The valve shall be installed in the most convenient place for operation, maintenance and maintenance, and shall not be buried underground. The valve shall be installed in the hole and in the pipe in the gutter, and shall be set up to inspect the well, so as to allow the opening and adjustment of the valve.
 
4. The thread shall be kept intact, and the thread shall be twisted, covered with lead oil or wrapped in ptfe tape, and the screw shall be screwed into the hexagonal valve body at the end of the pipe.
 
5. When installing the flange valve, pay attention to tighten the connecting bolt along the diagonal direction, and the force should be even when the action is screwed, in case the gasket is running off or causing the body deformation and damage.
 
6. Valve should be kept closed during installation. For threaded valves close to the wall, it is often necessary to remove stem disc and handwheel to turn the valve. Remove the valve when it is disassembled and then remove the valve. 6 common installation ways of piping valves
 
1. Gate valve
 
The gate valve is also called gate valve, which is used to control the open and closed valve by changing the cross section to adjust the pipeline flow and the opening and closing line. Gate valves are used to make full - or closed-operation lines for fluid media.
 
The gate valve installation generally has no directional requirements, but cannot be inverted.
 
Two. Globe valve
 
The valve is used to control the open valve. By changing the gap between the disc and the seat, change the size of the channel section to regulate the flow of the medium or truncate the medium. Installation of the globe valve must pay attention to the flow of the fluid.
 
Installation of the globe valve must comply with the principle that the flow in the pipeline through the valve hole, commonly known as "low in advance", do not install the reverse.
 
Third check valve
 
Check valve is also called the non-return valve, check valve, is a kind of valve under the action of pressure difference before and after automatic opening and closing of valve, its role is to make the medium flow in one direction, only do the medium reverse back and stop the flow.
 
Check valves are in different structures, such as lifting, swing and butterfly. Lift check valve also has horizontal and vertical.
 
When the check valve is installed, attention should also be paid to the flow of the medium.
 
Iv. Pressure-reducing valve
 
Vertically mounted pressure-relief valve unit, usually set at the appropriate height of the wall. The horizontal installation of the pressure-reducing valve group, generally installed on the permanent operating platform.
 
2. The applied steel sections are mounted on the outside of the two control valves (often used as globe valves), which constitute the bracket, and the bypass pipe is also stuck on the bracket to find the right one.
 
3. The pressure-reducing valve shall be installed on the horizontal pipe and shall not be tilted. The arrow on the valve body shall point to the direction of the flow of the medium and shall not be reversed.
 
4. The globe valves and high pressure pressure gauges shall be installed on both sides to observe the pressure change before and after the valve. The pipe diameter of the pressure reducing valve shall be 2 # - 3 # after the inlet pipe diameter of the valve, and the bypass pipe shall be installed for servicing.
 
The pressure tube of the diaphragm pressure valve shall be connected to the low pressure pipe. The low pressure pipe shall be installed with the safety valve to ensure the safe operation of the system.
 
When steam decompression, the drain pipe should be set. The piping system with high degree of purification is required, and the filter is set before the pressure-reducing valve.
 
7. After the installation of the pressure-reducing valve group, the pressure reducing valve, the relief valve shall be tested, washed and adjusted, and the adjustment shall be made.
 
8. When flushing the pressure-relief valve, close the pressure reducer inlet valve and open the flushing valve for flushing.
 
5. Steam trap
 
1. The cut-off valve (globe valve) shall be set before and after, and the filter shall be set between the steam trap and the front truncation valve to prevent fouling in the condensate from blocking the trap.
 
2. A check tube should be set between the trap valve and the rear truncation valve to check whether the drain valve is working normally. If the check tube is opened in a large amount of steam, the steam trap is broken and needs to be serviced.
 
3. The bypass pipe is set to discharge a large amount of condensation water at startup, and reduce the displacement load of the trap.
 
4. When the hydrophobic valve is used to remove the condensate of hot equipment, it should be installed in the lower part of the hot equipment, so that the water pipe can be returned vertically to the hydrophobic device to prevent the water from being stored in the heat equipment.
 
The position should be as close to the drain as possible. If the distance is too far, the thin pipe in front of the trap will be stored in air or steam.
 
6. Consider hydrophobic problems when the pipeline is too long.
 
Vi. Safety valve
 
1. Before installation, the product must be carefully checked to verify whether there is a certificate of conformity and product description to clarify the pressure condition at the time of delivery.
 
2. The relief valve shall be arranged near the platform as far as possible for inspection and maintenance.
 
3. The relief valve should be installed vertically and the medium shall flow from the bottom, and check the vertical degree of the stem.
 
4. Normally, the relief valve cannot be set up before and after the relief valve to ensure the safety and reliability.
 
5. Relief valve relief: when the medium is liquid, it is generally discharged into the pipe or closed system; When the medium is a gas, it usually goes out into the open air.
 
6. The oil and gas media generally can be arranged in the atmosphere, and the outlet of the relief valve should be higher than the surrounding tallest structure, 3m, but the following situations should be enclosed in a closed system to ensure safety.
 
7. The diameter of the population pipeline should be equal to the inlet pipe diameter of the valve; The discharge pipe diameter shall not be smaller than the outlet diameter of the valve. The discharge pipe shall be used for outdoor use, and the pipe shall be installed in the pipe, so that the pipe shall be exported to the safe zone.
 
8. When the valve is installed, the opening diameter of the valve shall be the same as the nominal diameter of the relief valve when the valve and equipment and the pipe are connected to the open hole.