The main performance specifications: steel gate valve opening and closing parts is, the direction of movement of the fluid direction perpendicular to the gate, gate can only be fully open and fully closed, can not be adjusted and the throttle. Ram has two sealing surface, the two most common mode of sealing surface to form a wedge gate valve, wedge angle with the valve parameters vary, usually 50, the medium temperature is not high for 2 ° 52 '. Wedge gate valve can be made into a whole, called the rigid gate; can also be made to produce small quantities of deformation gate in order to improve its process, to make up the sealing surface angle deviations arising during processing, this gate board called the flexible gate. Types of cast steel gate valve, according to the sealing surface configuration can be divided into wedge gate-type valve and parallel gate-type valve, wedge gate-type valve can be divided into: single-gate type, double plate and flexible gate type; parallel gate-type valve can be divided into single-gate type and double plate. Divided by the threaded stem position can be divided into two clear shot valve gate and dark bar. When the cast steel gate valve is closed, the sealing surface can only rely on media pressure to seal, which rely on the sealing surface of the medium pressure to ram pressure to the other side of the seat to ensure the sealing surface, which is self-sealing. Most of the valve is sealed by force, that is, when the valve is closed, to rely on external pressure to force the gate valve to ensure the tightness of the sealing surface. Cast steel gate valve with the valve stem linear movement, called the lift rod valve (also called clear shot valve). Often movements are trapezoidal threaded rod through the valve guides and valve nut on the rotary motion into linear motion, which is the operating torque thrust into action. Open the valve, when the gate valve lift height equal to the diameter of the 1: 1 times, the fluid channel is completely smooth, but at run time, this position is not monitored. Actual use, is the apex of the stem as a sign that the fixed position, as its fully open position. Temperature appears to consider locking phenomenon, usually open to the vertex position, and then rewind 1 / 2-1 circle, as the position of the valve fully open. Therefore, the fully open position of the valve, according to gate position (ie, travel> to determine. Some valve stem nut located at the gate, handwheel drive stem rotation, leaving the gate to upgrade, this valve called the rotating rod valve or valve called the dark bar. valve features a compact structure, reasonable design, the valve rigid, channel flow, flow resistance coefficient. sealing surface of stainless steel or tungsten carbide, long service life. the use of asbestos flexible graphite or graphite, reliable sealing, light and flexible operation. can be a variety of standard pipe flanges and flange sealing surface forms to meet various project needs and user requirements. Widely used in pipeline in petroleum, chemical, water, fire station and a variety of systems. [ 1] applicable conditions Medium: 1, steel gate material code "C": water, oil, steam (temperature ≤425 ℃) 2,304 stainless steel valve material code "P": Class nitrate (temperature ≤200 ℃) 3 316 stainless steel valve material code "R": acetic acid class (temperature ≤200 ℃) 4, WC6, WC9 chromium molybdenum steel gate material code "I": water, oil, steam (temperature ≤595 ℃), etc ...... the design, manufacture standard design and manufacture standard: GB / T 12234-2007 standard length of the structure: GB / T 12221-2005 standard Flange: GB / T 9113 pressure and temperature rating: GB / T 12224-2005 test inspection standards: GB / T 13927-2008