Turbine Soft seal ball valve
Overview
The ball valve evolved from the plug valve. Its opening and closing part is a sphere. The ball is used to rotate the axis of the valve stem 90° to achieve the purpose of opening and closing. Ball valves are mainly used on pipelines to cut off, distribute and change the flow direction of media. Ball valves designed with V-type openings also have good flow regulation functions. The ball valve not only has a simple structure but also has good sealing performance. Moreover, within a certain nominal size range, it is small in size, light in weight, consumes less material, has a small installation size, has a small driving torque, is easy to operate, and can easily open and close quickly. It is one of the valve types that has developed rapidly in the past ten years. . Especially in industrially developed countries such as the United States, Japan, Germany, France, Italy, Spain, and the United Kingdom, ball valves are widely used, and the varieties and quantities used continue to expand, and are moving towards high temperatures, high pressures, large diameters, high sealing properties, and long-term use. With its long life, excellent regulating performance and multi-function in one valve, its reliability and other performance indicators have reached a high level, and it has partially replaced gate valves, globe valves and throttle valves. With the technological advancement of ball valves, they will be more widely used in the foreseeable short term, especially in oil and gas pipelines, refinery cracking units and the nuclear industry. In addition, ball valves will also become one of the leading valve types in large and medium diameter, medium and low pressure fields in other industries.
The advantages of ball valves are:
1) It has the lowest flow resistance (actually only equivalent to a section of circular pipe of the same nominal size).
2) Because it will not get stuck during operation (when there is no lubricant), it can be reliably used in corrosive media and low-boiling point liquids.
3) Complete sealing can be achieved within a larger pressure and temperature range.
4) Quick start-up can be achieved. The opening and closing time of some structures is only 0.05-0.1s to ensure that it can be used in the automated system of the test bench. When the valve is quickly opened and closed, the operation will be impact-free.
5) The spherical closing piece can be automatically positioned at the boundary position.
model representation method
Additional codes for ball valves: V indicates that the valve core has a V-type structure, D indicates low temperature, B indicates insulation, P indicates eccentric structure, U, S and DY mostly indicate top-mounted type;
Ball valve name code: Q means ball valve; Ball valve drive code: 2 means electro-hydraulic, 3 means turbine, 6 means pneumatic, 7 means hydraulic, 9 means electric, manual has no code; Connection mode code: 1 means female thread, 4 means flange type, 6 means welding, 7 means clamping type;
Structural type code: Floating type: 1 means straight flow channel, 2 means Y-type port, 4 means L-type port, 5 means T-type port; Trunnion type: 0 means hemispherical straight-through, 6 means four-way flow channel, 7 means straight-through flow, 8 means L-type port, 9 means Y-type port;
Seal material code: B babbitt alloy, F fluorine rubber, F46 fluorine lining, H alloy steel, J rubber lining, M Monel alloy, N nylon plastic, Monel P, Y hard alloy, W valve body direct processing;
Pressure grade code: 16 means the pressure is 16 kilograms (1.6Mpa) and the maximum pressure can reach 64Mpa; 150LB means the American standard pound pressure, and the maximum pressure level can reach 2500LB (150LB=1.6MPA/300LB=2.5-4.0mpa/400LB=6.4 mpa/600LB=10mpa); 5K represents daily pressure, the maximum pressure is 63K;
Valve body material code: A titanium and titanium alloy, C carbon steel, I chromium molybdenum steel, P stainless steel, S plastic.
difference between metal seal and soft seal
Metal Sealing Ball Valve:
It uses a metal valve seat, mostly stainless steel + hard alloy, which requires relatively high processing precision and process technology. It has a wide range of uses and can be used in normal temperature, low temperature, and high temperature and high pressure working conditions.
It can withstand high temperatures, resist wear and tear, and has good mechanical properties. The disadvantage is that this seal has poor sealing performance. (Generally, it is recommended to use metal-sealed ball valves for media that contain solid particles or are abrasive, and have a temperature higher than 250 degrees.)
Generally it is level V, and the highest level can be level VI. Soft seal valves: generally Class VI.
Soft Sealing Ball Valve:
Cheaper and lower cost
Valve seats are divided into several types such as fluorine plastic, rubber, and resin, and are mostly used in normal pressure, normal temperature, and normal pressure and low temperature conditions.
It is easy to achieve better sealing effect, and is resistant to corrosion, acid and alkali; the disadvantage is that it is not resistant to high temperatures, the sealing surface is easy to wear, and the mechanical properties are relatively poor. (Used for normal temperature and pressure situations with high sealing requirements or with corrosive media and no particles.)
Poor wear resistance. After being used for a period of time, if there are solid impurities in the liquid medium, the valve seat may be worn, resulting in increased leakage and reduced sealing performance.
Functions
The opening and closing part of the ball valve is a round sphere with a hole. The ball core is used to rotate 0-90° back and forth around the axis of the valve stem to open or close the valve. Ball valves have many functions. They are generally used for switching, cutting off or regulating media in pipelines. Among them, the three-way ball valve can flexibly cut off, distribute and change the flow direction of the medium. The sealing surface of the ball valve is usually in a closed state with the spherical surface, so it is not easily eroded by the medium. It is easy to operate, has a simple and compact structure, and can be used in working conditions with water, natural gas, acid, solvents, etc.
maintenance
Having a longer service life and maintenance-free time will depend on several factors: normal operating conditions, maintaining a harmonious temperature/pressure ratio, and reasonable corrosion data
Note: When the ball valve is closed, the fluid pressure in the valve body still exists. Before servicing, remove line pressure and leave valve in open position Before servicing, disconnect the power or air supply
1. Packing lock If the packing culvert is slightly leaking, the valve stem nut must be tightened. Note: Do not lock, usually 1/4 ring to 1 ring, the leakage will stop.
2. Replace the valve seat and seals A. Disassembly Leave the valve in the half-open position to flush any hazardous materials that may be inside and outside the valve. Close the ball valve, remove the bolts and nuts from the flanges on both sides, and completely remove the valve from the pipe. Disassemble the driving device in sequence - actuator, connecting bracket, anti-loosening washer, stem nut, butterfly shrapnel, wear-resistant sheet, and valve stem packing. Remove the body bonnet connecting bolts and nuts, separate the valve bonnet from the valve body, and remove the valve bonnet gasket. Make sure the valve ball is in the "off" position, which will make it easier to remove it from the valve body, and then remove the valve seat. Gently push the valve stem downward through the middle hole of the valve body until it is completely removed, and then remove the O-ring and packing ring.
NOTE: Use caution to avoid scratching the stem surface and the valve's packing seal.
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