The structure of gate valve and its application is introduced

Gate valve is a common product in the valve valve, gate valve, there are four main structure elastic single ram wedge gate valve, double wedge type gate valve, with the parallel type of spring preload double sluice gate and take the top piece of parallel type double ram gate open. NI in the gate diameter DN is generally above 80 mm, nuclear grade 1 gate valve body must adopt forgings, only nuclear grade 2 and 3 of the gate valve body are allowed to use the casting, but due to the casting quality is not easy to control and guarantee, so often or use forgings. To prevent outside medium leakage, gate valves are normally used double packing with led tube leakage, and a disc spring pre-tightening device to prevent loose packing. Driven by the way, which has two kinds of manual and electric, used for electric gate valve electric actuator motor should be considered the rotational inertia of the impact on the closing force, USES the motor with brake function, in case of overload. Body and bonnet flange bolt connection with blocks and the pressure from the two forms, but more common flange bolt connection application, because this kind of structure is beneficial to add a lip seal welding, sealing is more reliable. Four kinds of gate structure is different, have different performance. Elastic single ram wedge gate valve has the seal structure is simple, the characteristics of the solid and reliable, but manufacturing requirements on disc and body sealing surface with strict Angle error, in the primary loop system use morer. Double wedge type gate valve structure is the normal terms of structure, thermal power plant due to the wedge Angle of double plate can change automatically, sealing is reliable, maintenance is convenient. With the parallel type of spring preload double gate valve has the advantage that the disc in closing load cannot jump, but at the same time brings spring force make the gate when opening and closing always don't release the seat, sealing surface wear relatively larger, at the same time more disc sealing parts, assembly of inconvenience. Parallel with the top piece of open type double sluice gate valve used by top piece make two disc along the inclined plane stagger method to make gate valve shut, sealing is reliable, but there are also disc sealing parts many questions. In addition to the above four kinds of structure, there are two kinds of packing of gate valve. One kind is reported abroad hydraulic gate valve, with the aid of its own water pressure forces the pistons to open or close the valve. Due to the piston through the stem directly connected to the gate, so there is no packing seal, can avoid funnelled outside. But the piston and cylinder seal hard to do not leak, so how to maintain the stability of the pressure needs to take measures in the control system. Another is designed and developed by our country successful full enclosed electric gate valve, the valve adopts the special screen closed motor, work by immersion of the inner planets retarding mechanism made gate opening and closing movement, with rolling screw pair, but no packing, thus reducing the energy consumption, and to ensure running safety and simplify maintenance has a good effect. The disadvantages of the two gate structure is more complex, the cost is higher. The following main gate valve type and the applications of a list: 1, high-power graphite moderated reactor nuclear power plant and back ( The main) Application of electric double gate wedge gate valve, nominal pressure PN10. 0 mpa, DN800mm nominal diameter, working temperature 290 ℃. 2, welding connection hydraulic double ram parallel gate valve, nominal pressure PN17. 5 mpa, working temperature 315 ℃, nominal diameter DN350 ~ 400 mm. 3, fast reactor nuclear power plant elastic plate gate valve with frozen solid packing. 4, water & ndash; Water power reactor units with internal pressure from the sealed cover wedge gate valve, nominal pressure PN16. 0 mpa, DN500mm nominal diameter. 5, light water coolant and back ( The main) Application of electric double gate wedge gate valve, nominal pressure PN45. 0 mpa, temperature 500 ℃, DN500mm nominal diameter. 6, high-power graphite moderated boiling water reactor nuclear power plant heat element refueling machine with double ram parallel gate valve with flow guide hole, the nominal pressure PN8. 0 mpa, open or close the valve can only be in the pressure drop for delta P≤ 1. 0 mpa. 7, the stroke unit with a butterfly spring wedge gate valve, flange used bolt connection, USES the seal welding. Eight, of the steam turbine unit and process pipe (on the road The main) Used welding connection electric elastic plate gate valve, nominal pressure PN2. 5 mpa, working temperature 200 ℃, nominal diameter DN100 ~ 800 mm.