The hot water boiler circulating pump is an important auxiliary equipment of the boiler, which is responsible for supplying water to the boiler during the boiler operation. If there is a water leakage failure, it is very complicated to check. In view of this phenomenon, I will introduce the solution for the leakage of the hot water boiler circulating pump regulating valve:
1. Adding sealing grease method For valves that do not use sealing grease, consider adding sealing grease to improve the sealing performance of the valve stem.
2. Adding packing method In order to improve the sealing performance of the packing to the valve stem, the method of adding packing can be used. Usually it is in the form of double-layer and multilayer mixed fillers, and simply increasing the number, such as increasing from 3 to 5, the effect is not obvious.
3. Replacement of tetrafluorocarbon fillers, which are widely used by graphite filler method, because their working temperature is in the range of -20～+200℃. When the temperature is at the upper and lower limits and changes greatly, its sealing performance will be significantly reduced, aging fast, and life span short. Flexible graphite filler can overcome these shortcomings and has a long service life. Therefore, some factories all changed the tetrafluoroethylene packing to graphite packing, and even the newly purchased boiler pump regulating valve also replaced the tetrafluorocarbon packing with graphite packing for use. However, the use of graphite packing has a large hysteresis, and some creeping phenomenon occurs at the beginning, which must be considered.
4. Change the flow direction and place P2 at the end of the stem. When △P is larger and P1 is larger, sealing P1 is obviously more difficult than sealing P2. Therefore, the method of changing the flow direction can be adopted, changing P1 at the stem end to P2 at the stem end, which is more effective for valves with high pressure and large pressure difference. For bellows valves, sealing P2 should usually be considered.
5. The lens pad sealing method is used to seal the upper and lower covers, and the valve seat and the upper and lower valve bodies are sealed. If it is a flat seal, under high temperature and high pressure, the sealing performance is poor, causing leakage, you can switch to the lens gasket to seal, and satisfactory results can be obtained.
6. Up to now, most of the sealing gaskets are still made of asbestos plates. Under high temperature, the sealing performance is poor and the service life is short, causing leakage. In this case, spiral wound gaskets, shaped rings, etc. can be used instead, which are now adopted by many factories.
7. Tighten the bolts symmetrically and adopt thin gasket sealing method. In the boiler pump regulating valve structure with ring seal, when thick gaskets with large deformation (such as winding sheets) are used, if the compression is asymmetrical and the force is asymmetrical, It is easy to damage, tilt and deform the seal, which seriously affects the sealing performance. Therefore, in the maintenance and assembly of such valves, the compression bolts must be tightened symmetrically (note that they cannot be tightened at one time). It would be better if the thick gasket can be changed to a thin gasket, which is easy to reduce the inclination and ensure sealing.
8. Increase the width of the sealing surface to prevent the flat spool from jumping when it is closed and reduce its leakage. The flat spool leaks out. The flat spool (such as the valve plug of the two-position valve and sleeve valve) is on the seat There is no guiding and guiding curved surface inside. Because the valve core is subjected to lateral force when the valve is working, from the inflow side to the outflow side, the larger the valve core fits the gap, the more serious this unilateral phenomenon, and the deformation and disagreement , Or the valve core sealing surface chamfer is small (usually 30 chamfers to guide), so when close to closing, the chamfered end surface of the valve core sealing surface is placed on the valve seat sealing surface, causing the valve core to jump when closing, or even not close at all Circumstances greatly increase the valve leakage. The simplest and most effective solution is to increase the size of the valve core sealing surface, so that the minimum diameter of the valve core end surface is 1～5mm smaller than the valve seat diameter, and there is enough guiding effect to ensure that the valve core is guided into the valve seat and maintained Good sealing surface contact.
