What is a floating ball valve?
The ball of the floating ball valve is floating. Under the action of medium pressure, the ball can produce a certain displacement and press tightly on the sealing surface of the outlet end to ensure the sealing of the outlet end.
Floating ball valve is generally connected by flange or butt welding. The ball of the floating ball valve has only the upper valve stem, and the ball can be slightly displaced. The floating ball valve can be provided with an anti-static structure. The spring plunger type electrostatic lead-out device is used to form an electrostatic channel directly between the ball and the valve body of the floating ball valve (for ball valves with DN ≤ 25) or between the ball and the valve body through the valve stem (for ball valves with DN ≥ 32). Thus, the static electricity generated by the friction between the ball valve and the valve seat can be led to the earth through the valve body.
In production practice, the inconsistency of parts caused by machining error will cause the assembly torque of ball valve to not reach the ideal control value. It is an important link to control the torque of ball valve to reasonably determine the dimensional tolerance and geometric tolerance parameters of moving pair and sealing pair in the design and effectively control the machining error of parts in the machining process. For ball valves that cannot meet the requirements of torque control value in one-time assembly, they need to be adjusted.
Product features of floating ball valve
The floating ball valve has the characteristics of reliable valve seat sealing, complete fire-proof structural design, reliable sealing of valve stem, natural anti-static structure, structural design to prevent misoperation, support platform for installing driving device, etc.
Reliable sealing of valve seat
Floating ball valve adopts elastic sealing ring structure design. When the medium pressure is small, the contact area between the sealing ring and the ball in the floating ball valve is small, and a large sealing specific pressure is formed at the contact between the sealing ring and the ball to ensure reliable sealing. When the medium pressure is large, with the elastic deformation of the sealing ring of the floating ball valve, the contact area between the sealing ring and the ball increases, so the sealing ring can bear large medium thrust without damage.
Fire protection structure design
In case of fire at the use site of floating ball valve, when the valve seat sealing ring, valve stem upper sealing gasket, valve stem sealing filler and middle flange sealing gasket made of non-metallic materials such as polytetrafluoroethylene are decomposed or damaged at high temperature, ball valve can effectively control the internal and external leakage of the valve with the help of specially designed metal to metal auxiliary sealing structure.
Reliable sealing of valve stem
The valve rod of floating ball valve adopts the anti blow out structure design, which can ensure that the valve rod will not be blown out by the medium even in extreme cases such as abnormal pressure rise in the valve chamber and failure of the packing pressing plate. The valve rod adopts the bottom mounted structure design with sealing. The sealing force of the reverse seal increases with the increase of the medium pressure, so it can ensure the reliable sealing of the valve rod under various pressures.
The valve stem adopts V-shaped packing sealing structure, which can effectively convert the pressing force and medium force of the packing gland into the sealing force of the valve stem.
The traditional packing gland is improved into a two-part structure design of packing pressing plate and packing pressing sleeve. The packing pressing sleeve and packing pressing plate are in spherical contact to ensure that the packing pressing sleeve is always vertical. A Teflon bushing is set inside the packing pressing sleeve, which avoids the scratch and wear of the valve rod and packing pressing sleeve, and reduces the operating torque of the valve.
According to the needs of users, the packing pressing mechanism loaded by disc spring can be used to make the sealing of valve stem packing more reliable.
According to user requirements, the ball valve can be equipped with anti-static structure. The spring steel ball (or plunger) electrostatic extraction device is used to form an electrostatic channel directly between the ball and the valve body (for ball valves with DN ≤ 25) or an electrostatic channel between the ball and the valve body through the valve stem (for ball valves with DN ≥ 32). Thus, the static electricity generated by the friction between the ball and the valve seat can be led to the ground through the valve body to prevent the fire or explosion hazards that may be caused by static sparks.
A 90 ° switch positioning piece with lock hole is set, which can be locked as required to prevent misoperation. The part where the handle is installed at the head of the valve rod adopts flat design. When the valve is opened, the handle is parallel to the pipeline. When the valve is closed, the handle is perpendicular to the pipeline, which can ensure that the opening and closing indication of the valve will not be wrong.
Setting of driving device installation platform
The floating ball valves of Yaang are equipped with a support platform for installing the driving device. Through the support of the driving device, it is convenient to install the worm gear transmission device, pneumatic device or electric device.
Specification for floating ball valves
Design and manufacturing standards: API 6D, API 608, BS 5351, GB/T 12237;
Structural length standard: ASME B 16.10, GB/T 12221;
Connecting flange standards: ASME B 16.5, GB/T 9112 ~ 9124, Hg/T 20592, Hg/T 20615, JB/T 74 ~ 90, JIS B2238;
Test and inspection standards: API 598, GB/T 13927, GB/T 26480, JB/T9092, ISO 5208.
Floating ball valve VS fixed ball valve
The ball of floating ball valve is floating. Under the action of medium pressure, the ball can produce a certain displacement and press tightly on the sealing ring at the outlet end to ensure the sealing at the outlet end. It is a one-sided forced sealing.
The ball of the fixed ball valve is fixed and does not move after being pressurized. Therefore, the two sealing rings shall have sufficient preload to ensure sealing in design, which is a double-sided forced sealing. Thrust or sliding bearings are usually installed on the upper and lower valve stems connected with the ball.
The design of floating ball valve shall focus on whether the sealing ring material can withstand the medium load of the ball. Because the ball bears the load of the working medium and is transmitted to the outlet sealing ring, this floating ball structure is widely used in medium and low pressure ball valves. In addition, the design shall also consider the large torque required for the operation of large-diameter ball valve.
China Floating Ball Valves Manufacturer www.sfutube.com supplies Low temperature floating ball valve and low temperature fixed ball valve for industrial use, in kinds of materials such as carbon steel, stainless steel, alloy steel, etc.