Pipeline ball valve design

Pipeline ball valve design

The design and manufacture of pipeline ball valves, the emphasis on safety and reliability, is by no means excessive. And this idea should be implemented in the whole process of ball valve product design, process specifications, parts processing, type testing, product testing, quality control, after-sales service. Whether it is long-distance pipeline or urban pipe network are energy supply lines, is a national economic lifeline. Global underground oil and gas transmission pipelines and pipe networks, like the ground transmission and distribution grid, are the basis for the survival of urban industries and civilian populations. Without this energy supply line, modern urban functions are stopped immediately. 1 body design can be divided into all-welded body design and split body design. All-welded body design has a cylindrical structure and spherical structure, cylindrical structure is a double weld, the heat input during welding large, complex residual stress, axial and radial deformation. Spherical structure is four welded splicing, and now due to advances in technology, the use of left and right body hot forging molding, welding can be welded in the middle, reducing the line energy input and reduce axial and radial deformation. Split structure generally by the valve body and left and right connectors. The connecting body and the valve body are connected by bolts. The thickness of the connecting flange and the connection strength of the bolts should be analogically designed according to the flange with the equivalent diameter of the valve body. The connection strength must prevent the stress of the pipeline from causing loose connection and failing the sealing. Valve body and connector face to face contact with no gap in the middle. Seal must meet the fire safety requirements, the use of rubber O-ring and wound metal gasket combination seal. The material of the valve body is forgings, the temperature above -29C ° is selected from ASTM A105; the following is used from -29C ° to ASTM A350 LF2. For welded bodies, there shall be special restrictions on the chemical composition, carbon content, carbon equivalent, sulfur, phosphorus and other elements of A105 or LF2 materials. Forgings by three standard forgings acceptance, do 100% non-destructive testing, weld color inspection and ultrasonic testing. Most of the gas pipeline valve body is the A105, ball A105N. Most of the valve body of the oil pipeline is A105, ball 316. 2 Sealing seat and sealing seat with a combination of sealing structure, the metal-metal initial "seal" to block the entry of solid particles; with rubber, PTFE plastic, nylon, PEEK and other soft seal as a secondary seal to ensure zero leakage . However, due to accidental introduction of foreign matter in the pipeline damage to the soft sealing material, the pipeline ball valve is equipped with emergency sealing agent injection system to obtain temporary sealing requirements. Sealing rubber ring with round, triangular or other special shape. Valve companies have their own design structure and process measures to prevent the rubber ring is blown out during the switching process (Blow out) or cut. For Class900 pounds or more, should be used explosion-proof (AED) characteristics of the material as the O-ring material. PTFE seals, generally cylindrical inlay structure can also be made of barbed combo structure, designed to ensure that the seal is not blown and lead to seal failure. The sealing seat is made of the same material as the valve body, electroless nickel plated and spring-loaded to ensure the initial seal pressure. The spring can be a coil spring, a plate spring or a disc spring made of Inconel X-750. The inlet and outlet seat symmetrical two-way seal design. The piston-type self-sealing medium can be designed as "Single piston action", pressure self-sealing seat structure and Double Piston effect double sealing structure according to customers' requirements. Single-piston effect that is imported seal, the outlet end of the cavity automatically discharge pressure. 3 DBB function design DBB function design refers to whether the valve is open or closed, the valve chamber pressure relief discharge, the upstream end and the downstream end of the valve seat should be both closed (Double Block & Bleed), and from the discharge valve to allow online Valve seat sealing performance test, without affecting the pipeline operation. 4 Emergency seal system design Emergency seal system by the injector (Injector) and check valve (Check Valve), respectively, installed in the valve body, the valve seat at the outside of the test and valve packing outside. The emergency seal system can be used to prevent or reduce the leakage of the valve seal seat in the pipeline. The sealant must be cleaned and rinsed prior to injection. There are specially manufactured cleaning agents and sealants. The cleaning agent or sealant is dispensed manually or electrically Inject syringe port and follow the instructions provided by the valve supplier for cleaning and emergency sealing operations. Fire safety and anti-static design has been described in the support shaft, seal seat chapter, anti-static structure design, measured at 24VDC, the resistance does not exceed 10 ohms. 5 Valve operation Valve operation, manual, worm gear, pneumatic (double acting or spring reset), high pressure pneumatic (direct use of pipeline gas), electric, hydraulic (double acting or spring return) and gas-liquid interaction. The gas-liquid linkage enables both local and remote control, in conjunction with a satellite-controlled SCADA system. When the rate or duration of downstream pressure drops exceeds the setpoint (ie, the pipeline is burst), the emergency shut-off valve is automatically shut off with Save an acute pressure accumulator for manual operation. 6 pipeline ball valve connection end design connector according to customer requirements, there are flanged and welded ends. Flange connection should be convex or annular groove, the size, tolerance and finish, and drilling, flange face, countersunk, holes and so on should be the following standard DN600 and below, according to ASME B16.5, of which DN550 press MSS-SP44; DN650 Above A series of ASME B16.47 welded ends shall be as specified in 434.8.6 of ASME B31.4 or ASME B31.8. 7 Bolt Fasteners 8 Direct Buried Design Directly buried underground valves are all-welded valve body line ball valves. The valve stems are required to be extended according to customer's requirements. The long part of the valve stems should be designed to be firm and resistant to ground loading. All valve bodies Connecting pipe, sealant injector, the bottom of the drain valve, safety relief devices are connected to the surface, take over and valve body welding. Then the long rod design, the long axis around the curve and the transmission link with the gap should be controlled to prevent the switching process, the ball can not be accurately in the off or open position, resulting in transmission errors. 9 Line Ball Valves Scope of Supply According to API Standard 6D and the line ball valve manufacturer's equipment capabilities, the scope of supply for the product is: Class100-600 pounds of DN1 / 2 "-60" Class900 pounds of DN1 / 2 "-36" Class1500 pounds Class DN1 / 2 "-16" Class2500 Class DN1 / 2 "-12" On special occasions, foreign pipeline ball valve suppliers can provide Class150-600 pounds maximum diameter to DN72 "Class900 pounds maximum diameter to DN40" Class1500 pounds Maximum diameter to DN36 "Class2500 pounds maximum diameter to DN24"

Light Duty Spinning

The principle of metal spinning process is to cover the processed metal blank (tube blank) on the mandrel, while the blank is pressed at the end of the mandrel by the tail, and rotates with the mandrel along the spindle, and the rotary wheel moves along the mandrel.
Generally speaking, light automatic spinning machines have structural advantages similar to ordinary lathes. However, in order to meet the requirements of the above spinning process, large spinning machines usually have the following 11 core advantages.
1. The automatic spinning machine bed, main shaft, and transmission system, rotating wheel frame, tailstock and other parts should have sufficient rigidity, and also have a heavier worktable, a thicker guide rail, and a thick wall bearing support And cabinets.
2. The horizontal and longitudinal feed mechanisms of the rotary frame are mostly driven by hydraulic transmission or a combination of mechanical and hydraulic pressure to generate sufficient spinning pressure and balance step-less speed regulation to meet process requirements.
3. Ordinary automatic spinning machines usually use one rotary wheel, but there are multiple auxiliary forming wheels (flanging wheel, curling wheel, etc.). The number of rotating wheels or rotating frame of the powerful automatic spinning machine is 2 to 3 (the general type is 2, and the cylindrical part spinning machine is mostly 2 to 3), and is symmetrical to the spindle axis. Balancing the radial force during spinning, reducing the bending deflection, deflection, and vibration of the spindle and core mold provides a prerequisite for improving the accuracy of spinning parts. This correspondingly requires the rotary wheel to have a higher horizontal (such as a special spinning machine for cylindrical parts) or a longitudinal (such as a general-purpose automatic spinning machine) synchronous feed accuracy. However, a rotary wheel is used for the light and powerful automatic spinning machine.
4. The main shaft has sufficient transmission torque and power. According to the specific process requirements, it can meet the constant torque or constant power adjustment. In addition, it is best to make the spindle speed and the longitudinal feed speed of the rotary wheel steplessly adjustable. On the one hand, it can meet the arbitrary selection requirements of the spinning process; on the other hand, it can maintain the surface rotation speed of the core mold during the spinning process. Possibility of constant feed per revolution.

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