Second, the main security gate leakage volume piston chamber. When the valve piston chamber leakage volume, the type (1) f1 a role in force on the small piston in the other conditions remain unchanged f1 <f2 + f3 + fm therefore refused to move the main security gate. Leakage caused by the piston chamber with a large quantity of the main reasons for their own gas-tight valves and piston rings do not meet size requirements or excessive wear of piston ring seal required less than a relationship.
For example, 3 ~ 9, the main safety valve for the piston ring furnace of the quality requirements of the edges and corners is a piston ring should be smooth, free state open space not more than 14, the assembly after the opening gap △ = 1 ~ 1.25, piston and piston chamber space B = 0.12 ~ 0.18, with the piston chamber piston ring gap for S = 0.08 ~ 0.12, piston ring contact with the piston chamber good perimeter light should be not more than 1 / 6. Requirements for indoor piston, piston inside a trench the depth of no more than 0.08 ~ 0.1mm, the ellipticity does not exceed 0.1mm, Taper degree no more than 0.1mm, should be smooth without scratches, but the disintegration of each maintenance check found the main furnace security door piston ring, piston and piston chamber maintenance order is not in conformity with the requirements of the existing piston ring gap with the piston chamber in the S ≥ 0.20, and defects in the surface of the piston chamber is even more serious, serious impact on the piston of the steam room Micronesia nature, resulting in the volume of piston chamber large steam leak.
Elimination of this shortcoming of the method is: the surface of the piston room for processing, the replacement of qualified piston and piston rings, where the impulse throttle safety device system related small throttle opening, increasing the access to the main security door into the piston chamber gas volume, where conditions permit, can also increase the impulse to increase the safety of the trip into the main security door into the piston chamber volume method to promote the main steam safety valve action.
Third, the main safety valve and safety valve matching impulse improper safety valve steam impulse flow is too small. Safety valve impulse DN is too small, resulting in inflow of the main steam safety valve piston chamber volume, piston downward movement to promote f1 enough force, that is, f1 <f2 + f3 + fm a result, the main safety valve fixed spool. This phenomenon occurred in the main impulse-type safety valve safety valve to have a replacement, as a result of ill-considered.
For example, in 2002 furnace overhaul on the 5th, it will be two weight-type impulse safety valves into two production Harbin A49H-P54100VDg20 pulse valve, the safety valve A42H-P54100VDg125 general type with spring-loaded match the use of the main security it with the Soviet Union production Dg150 × 90 × 250-type safety valve supporting the use of old-fashioned Main, such main safety valve with the A29H-P54100VDg125 type spring-loaded safety valve of this than the main DN is not only larger but also less tightness in the Boiler safety valve on the 5th set steelyard weight saturated after steelyard weight to run the main safety valve caused by the pilot refused to move. Later, we will be the disintegration of the impulse valve to be oriented with the sleeve and valve core part of the space to expand in order to increase its through-flow area, once a successful test run steelyard weight. So the main impulse safety valves and safety valves to match properly, DN smaller refusal will lead to moving the main valve.
2.4, Impulse safety valve safety valve back seat back to seat time delay
The main reason for this failure the following two aspects:
On the one hand, the main safety valve piston steam leakage amount of room size, although the impulse to block the safety valve, but in line with the piston of the steam chamber is still very high pressure to promote the downward piston force is still great Therefore, the main safety valve caused by the slow back seat, such failures occur in A42Y-P5413.7VDg100 type safety valve, because this type of relief valve piston chamber of a good seal. Way to eliminate this failure, mainly through opening of the throttle valve opening and increased expenditure to be resolved aperture, the opening of throttle opening and the increase in expenditure have made aperture in the pulse tube rapidly discharges out of steam , which reduces the pressure inside the piston to the role of movement in the piston downward thrust on the rapid decrease in the spool box set in conjunction steam up steam medium and the main thrust of its own safety valve spring under tension up quickly to Block. ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve Three way ball valve V Type Ball Valve
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