English to Chinese: Valves General field: Tech/Engineering Detailed field: Mechanics / Mech Engineering
Source text - English API6D High performance pipeline ball valve series-RMD-GWB forged steel full weld G type trunnioned ball valve
RMD-GWB full weld ball valve has various kinds of advantages, for example, it is simple in structure, light in weight, high in strength, easy in operation. All the types of ball valves are fire safe in design with no need of maintenance. This type of ball valve has reliable performance, low cost and ling lifespan without malfunction. All these make it an ideal choice for pipeline contractor.
Unique body structure
The body of RMD-WBG ball valve is full welded, selects high quality forged material, and adopts the advanced forged forming technology to form two semi-spheres which are welded into a whole in the middle of the body. This welding technology differentiates the RMD-GWB ball valve form others, and makes the valve more spherically, so the valve structure is more compacter, lighter and stronger. Besides, the middle direct welding realize highly accurate valve body manufacturing, makes fully and completely sealing between the seat and ball. The full welding instead of bolts completely avoids the outside leakage, so RMD-GWB ball valve is the ideal product for under-ground, offshore working platform and under-sea equipments.
Adopting fixed plates or trunnion to support the ball
The top and bottom of the ball is supported by upper and lower fixed plates or stem and trunnion, and the ball is accurately placed in the center of the ball valve to achieve complete seals and precise movements. When plate adopted, the force exerted by the medium to the ball is distributed via the plate to the left and right bodies, so that the stem does not bear the blending moment from the medium, but only the torque from the ball rotation during the opening/closing of the valve. The low-friction PTFE Teflon composite bearings installed between the ball axis and fixed plate and between the stem and the trunnion can absorb ball moving action caused by the pressure of the medium. This structure brings stable actions and easy operations for the RMD-GWB ball valves, and the required operation torque can be reduced, so smaller actuators can be used, and the cost is cut down.
Unique seat sealing structure
RMD-GWB type ball valve seat is floating structure, means the seat can move along the medium direction, so that the seat can fit against the ball all the time.
（Ⅰ）Double piston effect structure seat
Seat design is special double pistons effect structure, it can ensure the seal wherever the medium flows into the ball valve.
（Ⅱ）Seat multistage seal structure
As following graphic instruction, on seat bearing ring, set two soft sealing rings(A and B)and metal sealing spherical surface which can seal with the ball. Seat ring A is spring loaded, which seals the surface with the ball tightly to the surface to form an initial seat;When there is pressure generated from medium, the piston force is generated to make seal ring A elastically deformed and seal ring B fit the surface of the ball surface due to the piston effect caused by area difference, thus the second seal forms. When the medium pressure is rising. It will generate huge pressure to seal ring A and seal ring B, so the two seals have a greater elastic deformation, then metal seal ball surface compact with ball surface to form the third level of metal to metal seal.
（Ⅲ）Secondary seat seal device
As the above graphic instruction, the secondary seal device(seat grease injection valve)can be chosen according to the actual working condition, medium requirement, seal requirement, etc. Seat ring grease injection valve is a one-way valve, installed on the body, which can prevent the leakage and inject grease under the outside force. When secondary seal is required, there is a grease injecting channel and hole on the seat ring. The grease can form a seal between the seat and the ball, and then stop the leakage.
Extension stem and sleeves design
All RMD high performance pipeline ball valve can be of extension stem design to be used underground according to users' requirements. There are no special requirements for the length of extension stem, but the detailed length must be clearly confirmed when ordering, such as H and H1 in the right graphic.
If sleeve is required, RMD can meet clients' requirements, but the details of the sleeve must be clearly confirmed when ordering, such as dimension (L1 in the right graphic),material and sleeve pipe grade, etc.
RMD can supply ball valve accessories according to clients' requirements, such as: discharge tube, auxiliary sealing grease injection tubes, etc., but it must be clarified when ordering.