Boiler Pressure Vessel Safety Valve common failer and debug method
1、 safety valve leakage
1} Oxide skin, scale, debris and others fall on the sealed surface, it can be used to manually discharge (steam) purge or disassemble clean.
2} sealing surface mechanical is damaged or corrosive. the method of Abrasive grinding or turning can be used to repair or replace.
3） Spring failure due to a large loading or spring elastic reduction because of corrosion, they should be replaced spring.
4）The stem bends or core and seat bearing surface deflects, we should identify the reasons, re-assembly or replace stem and other parts.
Lever-type safety valve lever and the fulcrum occur deflection, the valve core and valve seat bear force unevenly, we should correct the leverage centerline.
2、 Safety valve is not acted under adjusted starting seat pressure
1） The safety valve adjustment is improperly, when adjusting pressure, neglecting the actual working media features and working temperature effects, it is required to re-adjust. In the hot state of continuous adjustment would not be more than three times. Otherwise, the error of the starting seat pressure is larger, and can not act under the normal debugging pressure.
2）The sealing surface is adhered and rust due to medium contamination or crystal; it is needed to blow wash safety valve, and in severe need to grind valve core, valve seat.
3）The gap between the stem and the bush is too small, the expansion stuck when heated; it is appropriate to increase the gap between stem and bush.
4） adjusting or maintaining improperly, spring type safety valve spring shrink tightly or tight is not enough, lever type safety valve rusty plate is too heavy or too light, and need to re-adjust the safety valve.
5） The valve channels are blocked by blind plug and other obstacles; we shall promptly remove obstructions.
6） If spring is permanent deformation, we should replace the spring.
7） safety valve selection is proper, such as the back-pressure big fluctuations occasion, choosing a non-balanced safety valve and so on, need to replace the corresponding type safety valve.
3、 safety valve does not get to full open state
1） The safety valve selected nominal pressure is too large, spring rigidity is also too large, need to re-use safety valve.
2） The regulating ring is improper adjusted, need to be re-adjusted.
3） The disc friction is too large in the guided sleeve, needs cleaning, grinding or replacing parts.
4） The safety valve exhaust pipe is set improperly, gas (vapor) flow resistance is large, need to re-adjust the discharge pipe.
4、 disc oscillation
1） The gap between regulating ring and disc is too large, need to be re-adjusted.
2） The safety valve emissions is much larger than the container required volume, should be re-selection, to match it.
3） The safety valve inlet pipe cross-sectional area is too small or resistance is too large, so that the exhaust (steam) supply amount is short, need to replace or adjust the safety valve inlet pipe.
4） The discharge pipe resistance is too large, should be adjusted to reduce the resistance of pipeline.
5、 the disc can not back seat in time
1） Frictional resistance of disc in the guided sleeve is large, gap is too small or a different axis, is in need of cleaning, grinding or replacement parts.
2）The disc open and back seat mechanisms are not good, should be redirected. To spring-type safety valve, through the adjustment of the spring clamping force to adjust its opening pressure; by adjusting the position of down adjustable ring to adjust its back seat pressure.
3） The vertical degree of safety valve is excessive, it is required to re-look vertical.
4） The boiler pressure vessel safety valve seat sealing surface cracks. When the safety valve never has opened seat after debugging, it may be cold shock produced by rain water from the exhaust pipe into the body and the high temperature media, leading to the seat sealing surface cracks. Recommending installing rain cover on the exhaust outlet. Meanwhile eliminating the valve seat sealing surface cracks, if necessary, replace the safety valve.
In short, the safety valve is a key component of boiler pressure vessel, also is a failure-prone components. The control of boiler pressure vessel safety valve is from the safety valve selection, installation, commissioning, operation, maintenance and the whole repair process of quality control, safety supervision, if an error occurs in one part, it is likely to cause boiler pressure vessel accidents. In recent years, boiler pressure vessel accidents always happen due to valve problems. Thus, for boiler pressure vessel safety valve, only strict control from selection, installation, commissioning, operation maintenance and repair in all processes, earnestly implement the requirements of standards and procedures, that can ensure its safety valve will be able to take-off pressure relief and its equipment safety when boiler pressure vessel is in the over-pressure state, so as to ensure boiler pressure vessel safety and economic operation.
