Due to the flammable and explosive characteristics of liquefied natural gas medium, it is necessary to analyze the anti-static measures comprehensively when designing the ultra-low temperature valve of liquefied natural gas. Especially for the seat of PCTEF material, there is a hidden danger of electrostatic accumulation. Electrostatic friction sparks can make liquefied natural gas explosion.
A conducting device shall be set between the valve body and stem, and between the shutoff and stem, so as to draw out static electricity and avoid safety accidents. For metal-sealed cryogenic valves, no conducting devices may be provided, but the resistance values of the shutoff, stem and body should meet the standard specification.
ZJCLV, one of the cryogenic ball valves manufacturers, it’s cryogenic valves is fully in strict accordance with the lasted API version. For more information, click on the website: www.clvvalve.com.
API 6D Ball Valve
Ball valves are becoming more and more popular, especially in working environments that require valves with low flow resistance. There are different types of ball valves according to different classification methods.,There are cryogenic ball valve and high temperature ball valve according to the temperature classification. This article will introduce these two kinds of ball valves for you.
Cryogenic Ball Valves
1. What are Cryogenic Ball Valves?
The cryogenic ball valve has a ball and includes a Polytetrafluoroethylene body. Cryogenic ball valves are built to help transport and store cryogenic gasses safely and efficiently, and also work great during transportation due to the ability to function efficiently in pressure settings as high as 52 bar (750 psi) and temperature as low as -196°C (-320°F).
2.How does It Work?
Cryogenic ball valves are kept in a natural closed position to keep cryogenic gasses or other medium secure and safely contained. A cryogenic ball valve is generally designed to react to high pressure which pushes the valve into the open position to allow the gas or other media to flow readily through. Such open flow will continue until the pressure again decreases, at which point it will swing back nd become seal with a special metal seat bubble-tight shutoff to prevent any leaking.
3. Structural Characteristic
(1)Lip-ring pressure relief
(2)Back pressure relief seal struchure
(3)Trunnion ball valve bi-directional seal
(4)DBB self-relief seat
4. Design Features
(1)Meets ASME B16.5, ASME B16.34, API598.
(2)Face-to-tace dimensions meet ASME B16.10 long series.
(3)Gear actuator is standard on 8-24″(200-600mm)SB-150/300 and 6-12″(150-300mm)SB-600 valves.
(4)Memory Seal seats compensate automatically for wear and fluctuations of pressure and temperature.
(6)Blow out-proof stem.
(7)Stem bearing reduces side thrust.
(8)Multiple solid PTFE of chevron type stem seal(adjustable).
(9)Live-loaded thrust washer prevents galling and provide seconcary stem seal.
(10)Fully enclosed stainless steel wound gasket.
(11)Pressure relief hole design for all ball.
High Temperature Ball Valve
1. What are High Temperature Ball Valves?
High temperature ball valves are valves that can work at very high temperatures above 400°C. High-temperature ball valves should be made of very strong metallic materials that have high melting point. Therefore, the key is the materials while selecting a high-temperature ball valve. The most common metallic material that guarantees reliable working when used to make high temperature ball valve is carbon steel and stainless steel which have high melting points of 1425 oC to 1540°C to 1400 oC to 1530°C respectively. High temperature ball valves are either manual or operated using an actuator. The valves are connected to the pipeline by using bolts and nuts or through the welding method.
2. How does It Work?
High temperature ball valve consists of a ball with a bore at its middle section. The high temperature ball valve is operated by using a handwheel, hand lever, or actuator. The handwheel and hand lever are used for manual valves while the actuator is used for actuated ball valves. The handwheel or actuator is connected to the ball through a component known as the stem.
The rotational force is transmitted to the ball through the valve stem which makes the ball bore be rotated and be in line with the pipeline. Once the ball bore in the high-temperature ball valve becomes collinear with the pipeline fluid flows as it is not blocked by the ball. To close the high temperature ball valve, the hand lever or handwheel, or actuator rotates in the opposite direction to the direction it rotated when it was opening. This makes the ball bore of the high temperature ball valve to rotate and become perpendicular to the pipeline. In this case, the ball blocks the fluid from the pipeline and thus the high temperature ball valve is said to be in a closed state.
(1) High temperature ball valves can withstand high temperatures without being distorted by thermal heat.
(2) These valves are versatile as they can be used to serve in different applications.
(3) They can be cleaned, repaired, and inspected.
(4) Easy to operate.
(5) These valves are strong enough to withstand high pressure.
(6) They have a perfect seal free from fluid leakage.
(7) High temperature ball valves can be operated manually or by using an actuator.
(1) High temperature ball valves are not suitable for throttling applications.
(2) These valves close and open quickly which makes them generate water hammers and overpressure problems.
(3) High temperature ball valves must be installed vertically.
(4) Cavities around seats and balls tend to cause blockage due to solids which can increase opening/closing torque and or cause valve failure.
Both cryogenic ball valves and high temperature ball valves are widely used in different working environments.