Structural features

1. Core of forged steel valve body: The material advantage of high pressure and high strength
Material selection and performance The valve body and valve cover are made of forged carbon steel (A105), chromium-molybdenum steel (F11/F22) or stainless steel (F304/F316), formed through forging processes (free forging or die forging). The material has high density (grain refinement), no casting defects (such as pores and sand holes), and its tensile strength is 30%-50% higher than that of cast valve bodies. The compressive strength reaches PN25-PN420, making it suitable for high-pressure pipelines (such as oil and gas transportation, main steam pipelines in power plants). It has a wide temperature resistance range. A105 is suitable for -29 ℃ to 425℃, F22 for -29 ℃ to 593℃, and F316 for -196 ℃ to 816℃, meeting the requirements of harsh working conditions such as high temperature and deep cold. ​
Valve body structure design The structure of "integral forging and welding assembly" is adopted (some small diameters are formed by integral forging), and the wall thickness of the valve body is designed in accordance with ASME B16.34 or GB/T 12224 standards. The wall thickness of high-pressure models (PN100 and above) is 50%-80% thicker than that of cast valves of the same diameter (for example, the wall thickness of DN100 and PN100 models is 32mm). The valve body chamber undergoes 100% non-destructive testing (UT/RT flaw detection) to ensure there are no internal cracks. The hydrostatic test pressure is 1.5 times the nominal pressure, and the air tightness test pressure is 1.1 times the nominal pressure. It is suitable for the transportation of flammable, explosive and toxic media. ​
2. Welded connection structure: A reliable guarantee for high-pressure sealing
Welding methods and standards: The butt welding connection (BW) is adopted. The form of the welding end is "bevel type" (conforming to ASME B16.25 or GB/T 12224 standards). The bevel Angle is 30°-35°, and the thickness of the blunt edge is 1.5-3mm, which is convenient to form a fully penetrated joint when welding with the pipeline. The welding strength is consistent with that of the valve body. There is no risk of bolt leakage in flange-free connections. Some models support "socket welding" (SW, small diameter DN15-DN50), where the medium does not come into contact with the weld seam during welding, and are suitable for pure media (such as aviation fuel, high-purity gas). ​
Welding protection design: The inner wall of the welding end is treated with "thickened transition" to prevent material embrittlement caused by the heat-affected zone of welding. After welding, high-pressure models need to undergo "stress relief heat treatment" (holding at 600℃-650℃) to reduce welding residual stress and prevent weld cracking during long-term operation. The surface of the valve body is marked with the size of the welding groove and the heat treatment requirements, guiding on-site standardized welding and adapting to the long-term high-pressure operation of industrial pipelines. ​
3. Gate plate and sealing structure: Precise matching of high-pressure hard seals
Gate plate type and material: Wedge gate plates (single gate plate or double gate plate) are adopted, and the material matches the valve body (for example, valve body A105 corresponds to gate plate A105 13Cr surfacing, and valve body F316 corresponds to gate plate F316 Stellite surfacing). The sealing surface is surfacing with hard alloy (such as 13Cr, Stellite 6 or nickel-based alloy), with a surfacing layer thickness of 3-5mm and a hardness of HRC≥50. Through precision grinding processing, the sealing surface roughness Ra is ≤0.8μm, forming a metal-to-metal hard seal. Leakage ≤0.01×DN mm³/s (conforming to API 598 VI grade standard), suitable for high-pressure and high-scouring media (such as high-pressure steam, oil and gas containing particles). ​
Sealing compensation design: The double gate plate model is equipped with an "intermediate top wedge" (made of alloy tool steel). The elastic deformation of the top wedge compensates for the wear or temperature deformation of the sealing surface, ensuring reliable long-term sealing. Single gate plate (elastic wedge type) ADAPTS to the processing error of the valve body sealing surface through the slight deformation of the gate plate itself (such as the design of the gate plate slot), and the sealing specific pressure is uniform when closed, which is suitable for working conditions with large temperature fluctuations (such as the inlet and outlet of chemical reaction vessels). ​
4. Valve stem and opening and closing mechanism: Stable transmission under high-pressure conditions
Valve stem structure: Open stem design is adopted (a few high-pressure models have concealed stem). The valve stem material is 2Cr13, 304 or 316 stainless steel (surface chrome plating or nitriding treatment, hardness HV≥800), the thread is trapezoidal thread (precision GB/T 5796.3 grade), the pitch is 2-5mm, suitable for slow opening and closing under high pressure. The valve stem is connected to the gate plate through a "T-slot anti-loosening pin", with a fit clearance of no more than 0.05mm. There is no transmission gap, avoiding the gate plate from shifting and causing sealing failure. ​
Packing seal system The multi-layer flexible graphittic-metal jacketed gasket combined packing is adopted (the high-pressure model is equipped with a "stuffing box cooling sleeve"). The depth of the stuffing box is 30%-50% deeper than that of the ordinary gate valve (for example, the depth of the stuffing box of the PN100 model is 45mm), and it is evenly pressed by the cover bolts to form a "stepped seal". The leakage of the medium along the valve stem is ≤1×10⁻⁶ mL/s (conforming to API 622 standard); Some models are equipped with a "packing injection valve", which can replenish sealing grease online and is suitable for continuous production pipelines that cannot be shut down. ​
5. Auxiliary structure and working condition adaptation: Detailed optimization for harsh scenarios
High-pressure opening and closing assistance: Large-diameter, high-pressure models (DN200 and above, PN100 and above) are equipped with "gearboxes or hydraulic drive devices", achieving effort-saving operation through deceleration and force increase (manual operation torque ≤300N). The electric model is equipped with an "explosion-proof electric actuator" (Ex d IIC T6), featuring an internal torque sensor and travel limit. The control accuracy of the opening and closing torque is ±5%, making it suitable for flammable and explosive working conditions (such as oilfield wellheads and LNG transportation). ​
Maintenance and monitoring design: The valve body is equipped with a "pressure detection interface" (NPT thread), allowing for the installation of a pressure gauge to monitor the pressure inside the valve in real time. A "wear indicator rod" is installed at the top of the gate plate. The wear condition of the sealing surface can be indirectly judged by the height of the valve stem's rise and fall, which is convenient for planning maintenance in advance. The cryogenic model (-196℃ and below) features a "cold insulation layer covering groove" on the valve body to prevent freezing of the valve stem packing due to cold loss, making it suitable for the transportation of liquid natural gas and liquid oxygen.