Commonly used valve overall layout requirements of five types of commonly used valve advantages and disadvantages analysis, must be collected!

Commonly used valve overall layout requirements of five types of commonly used valve advantages and disadvantages analysis, must be collected!

General layout requirements:
1. The valve should be located in a place that is easy to access and easy to operate and maintain. Valves on a row of pipes should be centrally arranged. Pipeline valves below ground level shall be located in valve Wells.
2. The center of the valve handwheel on the riser is generally 1.2m away from the operating surface, and should not exceed 1.8m.
3. For the valve on the horizontal pipe, the valve stem direction can be determined in the following order: vertical upward, horizontal and downward tilt 45 degrees, vertical downward is not allowed.
4. The center of the valve arranged around the operating platform should not be more than 450mm from the edge of the operating platform.
5. The horizontal installation of the open rod type valve, when the valve is opened, shall not affect the passage.
6. Parallel layout of the pipeline on the valve, the center line should be as far as possible, the net distance between the handwheel should not be less than 100mm, can be staggered layout.
7. The valve on the bottom pipe of the tower, reactor, vertical vessel and other equipment shall not be arranged in the skirt. 8. The valve should be installed as close as possible to the dry pipe or equipment, and the valve connected to the pipe mouth of the equipment should be directly connected, and the valve on the pipe connected to the highly toxic medium equipment should be directly connected to the pipe mouth of the equipment.
9. For the horizontal branch pipe led from the dry pipe, a cut-off valve should be set in the horizontal pipe section near the root.
Common valve layout requirements
1 stop valve
A Handwheel and handle operated globe valves can be installed anywhere in the pipeline
B Handwheel, handle and valve transmission mechanism are not allowed to be used for lifting
C When installed, the flow of the medium should be consistent with the direction indicated by the arrow on the valve body
If D is less than or equal to DN100, the design is generally based on low input and high output. If D is greater than or equal to DN125, the design is generally based on high input and low output
E Straight-through globe valves are installed in horizontal pipelines
2. The gate
A Manual single gate valve can be installed at any position.
B Double gate valves shall be installed upright, i.e. stem in vertical position with handwheel on top.
3. The throttle valve
A As the throttle valve is operated frequently, it should be installed in a convenient position, either in horizontal or vertical pipelines
4. Check valve
A straight through lift check valve should be installed in the horizontal pipeline; Vertical lift check valves and bottom valves are installed in vertical pipelines, and the medium flows from bottom to top.
B Check VALVES SHOULD NOT BE LOCATED DIRECTLY downstream OF PIPE bends or ELBOWS to avoid eddy CURRENTS FROM media FLOWING THROUGH them
C SWING CHECK VALVES ARE INSTALLED IN UNRESTRICTED POSITIONS, USUALLY IN HORIZONTAL PIPELINES, BUT CAN ALSO BE INSTALLED IN VERTICAL OR INCLINED pipelines.
D The bottom valve should be installed at the bottom of the water pump suction pipe
E During the design process, the damage to the valve, piping or equipment caused by the water hammer pressure when the valve is closed should be considered.
5. Butterfly valve
A Butterfly valve with spanner can be installed anywhere in pipe or equipment.
B Butterfly valve with transmission mechanism should be installed vertically or according to the product instructions
6. Ball valve
A Ball valve with wrench operation can be installed anywhere in the pipe or equipment
7. The diaphragm valve
A Diaphragm valve is not suitable for vacuum pipes and equipment
B Diaphragm valve with handwheel can be installed anywhere in the pipe or equipment
8. The relief valve
A Requirements for inlet pipe layout
* The safety valve shall be installed in a vertical upward position. Otherwise, the consent of the manufacturer should be obtained.
* Safety valves should be installed as close as possible to the equipment or system being protected.
* The inlet pipe for installing the safety valve should be short and straight. The minimum cross-sectional area of the inlet pipe shall not be less than the cross-sectional area of the inlet of the safety valve. For high pressure and large displacement occasions, the inlet pipe at the entrance should be large enough rounded radius; Or it has a tapered channel whose entrance cross-sectional area is approximately twice the exit cross-sectional area.
* When the relief valve is discharged, the pressure drop in the inlet pipe, that is, between the protected equipment and the relief valve, should be as small as possible. In no CASE SHALL THE PRESSURE DROP EXCEED 3% OF the SETTING PRESSURE OR 1/3 OF THE GREATER ALLOWABLE opening/CLOSING PRESSURE difference, whichever IS LESS. If the pressure drops too much, the relief valve frequency will jump.
* The inlet pipe is generally provided with a CB bracket
* When the isolation valve is installed at the safety valve inlet, it should not violate the relevant provisions of laws or specifications.
* The safety valve should not be installed at the dead end of the long horizontal pipe section, so as to avoid accumulation of solid or liquid materials at the dead end, affecting the normal operation of the safety valve
B Discharge pipe layout requirements
* The cross-sectional area of the discharge pipe shall not be less than the cross-sectional area of the safety valve outlet. When MULTIPLE RELIEF VALVES DISCHARGE INTO A MAIN LINE, THE CROSS-SECTIONAL AREA OF THE DISCHARGE LINE SHALL BE SUCH THAT THE TOTAL DISCHARGE FROM ALL RELIEF VALVES THAT MAY DISCHARGE INTO IT SIMULTANEOUSLY IS ACCEPTABLE.
* The discharge pipe is generally equipped with GL bracket
* Any conditions that could lead to obstruction of the discharge line should be prevented. If necessary, a drain hole should be provided to prevent rain, snow, condensate, etc. from accumulating in the drain pipe.
* The discharge and drain of the safety valve should be guided to a safe place. Special attention should be paid to the discharge and thinning of dangerous media.
* When the isolation valve is installed at the outlet of the safety valve, it should not violate the relevant provisions of laws or specifications.
9. Pressure reducing valve
A Pressure reducing valve should not be set close to rotating equipment or easy to be affected, and should be considered to facilitate maintenance
B Pressure reducing valve should be installed on the horizontal pipeline
C The outlet of the pressure reducing valve should be provided with a reliable support to avoid vibration damage during decompression
Attached: Taishan remote operation valve layout requirements
A The relatively large space between the two universal nodes is 3M
B The maximum installation Angle of universal joint is 25 degrees
C Try to keep the universal joint at the same Angle and in the same plane
D The distance between the valve and the surrounding objects is required to be 500mm(this rule is difficult to implement, and can be relaxed according to the actual situation)
Five types of commonly used valve advantages and disadvantages analysis, must be collected!
Gate valves
Gate valve refers to the closing parts (gate) along the vertical direction of the axis of the channel to move the valve, in the pipeline is mainly used as a cut off medium, that is, fully open or fully closed use. Generally, gate valves cannot be used to regulate flow. It can be applied to low temperature pressure can also be applied to high temperature and high pressure, and according to the different material of the valve. But the gate valve is generally not used for conveying mud and other media in the pipeline.
Advantages:
Small fluid resistance;
② the torque required for opening and closing is small;
③ can be used in the medium flow to the two directions of the ring network management road, that is to say, the flow of the medium is not restricted;
(4) When fully open, the sealing surface is eroded by the working medium than the stop valve;
⑤ The body structure is relatively simple, and the manufacturing technology is good;
⑥ The structure length is short.
Disadvantages:
(1) the size and opening height are large, and the required installation space is also large;
② In the process of opening and closing, the sealing surface is relatively friction, friction loss is larger, and even easy to cause abrasion phenomenon at high temperature;
③ The general gate valve has two sealing surface, to the processing, grinding and maintenance increased some difficulties;
(4) Long opening and closing time.
Butterfly valve
Butterfly valve is a disc type opening and closing parts reciprocating around 90 to open, close and adjust the fluid channel of a valve.
Advantages:
(1) Simple structure, small volume, light weight, consumables, not used in large diameter valve;
② rapid opening and closing, small flow resistance;
(3) can be used for medium with suspended solid particles, according to the strength of the sealing surface can also be used for powder and granular media. It can be applied to the two-way opening, closing and adjustment of the ventilation and dust removal pipeline, and is used in the gas pipelines and waterways of metallurgy, light industry, electric power and petrochemical systems, etc.
Disadvantages:
① The range of flow regulation is not large, when opened up to 30%, the flow will enter more than 95%;
② Due to the structure and sealing material of butterfly valve, it is not suitable for high temperature and high pressure piping system. General operating temperature below 300℃, PN40 below;
③ The sealing performance is poor compared with the ball valve and globe valve, so it is used in places where the sealing requirement is not very high.
Ball valve
Ball valve is evolved from the plug valve, its opening and closing part is a ball, the use of the ball around the axis of the valve stem rotation 90 to achieve the purpose of opening and closing. Ball valves are mainly used to cut off, distribute and change the direction of medium flow on the pipeline. The ball valves designed as V-shaped openings also have good flow regulation function.
Advantages:
(1) with low flow resistance (actually 0);
② Because it will not get stuck at work (without lubricant), it can be reliably used in corrosive media and low boiling point liquid;
(3) In a large range of pressure and temperature, can achieve complete sealing;
④ Fast opening and closing can be realized. The opening and closing time of some structures is 0.05-0.1s, so as to ensure that it can be used in the automation system of the test bench. Fast opening and closing valve, operation without impact;
⑤ Spherical closing parts can be automatically positioned on the boundary position;
⑥ the working medium is sealed reliably on both sides;
⑦ in fully open and fully closed, the ball and the valve seat sealing surface and medium isolation, so high speed through the valve medium will not cause the erosion of the sealing surface;
⑧ Compact structure, light weight, it can be considered as a reasonable valve structure for low temperature medium system;
⑨ Symmetrical valve body, especially welded valve body structure, can withstand the stress from the pipe well;
⑩ The closing parts can withstand the high pressure difference when closing. The ball valve of the fully welded body can be buried in the ground, so that the inner parts of the valve will not be eroded, and the upper limit of service life can be up to 30 years. It is the ideal valve for oil and natural gas pipelines.
Disadvantages:
(1) Because the main valve seat sealing ring material is PTFE, it is inert to almost all chemical substances, and has the comprehensive characteristics of small friction coefficient, stable performance, not easy to aging, wide range of temperature application and excellent sealing performance. However, THE PHYSICAL CHARACTERISTICS OF TEFLON, INCLUDING A HIGH COEFFICIENT OF EXPANSION, SENSITIVITY TO COLD FLOW, AND POOR THERMAL CONDUCTIVITY, REQUIRE THAT SEAT DESIGN BE MADE AROUND THESE CHARACTERISTICS. Therefore, when the sealing material becomes hard, the reliability of the seal is damaged. Moreover, Teflon has a low temperature resistance grade and can only be used under the condition of less than 180℃. Above this temperature, the sealing material will age. In the case of long-term use, it is generally not used at 120℃.
(2) its regulating performance is worse than the globe valve, especially the pneumatic valve (or electric valve).
Globe valve
Globe valve: A valve in which the closing member (disc) moves along the center line of the seat. According to this movement of the disc, the change of the valve seat through the valve is proportional to the disc stroke. Due to this kind of valve stem open or close stroke is relatively short, and has a very reliable cut off function, and due to the change of the valve seat through the stroke of the disc is proportional to the relationship, very suitable for flow regulation. Therefore, this type of valve is very suitable for cutting or adjusting and throttling.
Advantages:
(1) In the opening and closing process, because the friction between the disc and the valve sealing surface is smaller than the gate valve, so the wear resistance.
The opening height is generally * 1/4 of the seat channel, so much smaller than the gate valve;
③ usually there is only one sealing surface on the valve body and disc, so the manufacturing technology is good and easy to maintain;
④ Because the filler is generally a mixture of asbestos and graphite, it has a high temperature resistance. Steam valves are generally used with stop valves.
Disadvantages:
(1) Because the flow direction of the medium through the valve has changed, so the small flow resistance of the globe valve is higher than most other types of valves;
② Due to the longer travel, the opening speed is slower than the ball valve.
cock
Plug valve: refers to the closing part into a plunger shaped rotary valve, through the rotation of 90 so that the valve plug on the channel port and the valve body on the channel port is communicated or separated, open or close a valve. The plug can be cylindrical or conical in shape. Its principle is basically similar to ball valve, ball valve is developed on the basis of plug valve, which is mainly used in oil field exploitation, but also used in petrochemical industry.
Advantages:
1, for frequent operation, quick opening and closing, light.
2, fluid resistance is small.
3, simple, relatively small size, light weight, easy to maintain.
4, sealing performance is good.
5, limited by the installation direction, the flow of the medium can be arbitrary.
6, no vibration, small noise.
Disadvantages:
1. The cover is too large, which causes too much torque and is not flexible enough.
2. Influence of body weight, limited caliber size.
3, in actual use, if the use of large size valve, you must use the inverted cock structure, easy to affect the sealing effect.