Usually caused by valve leakage due mainly to the following three conditions:
One is that the impurities fall to the sealing surface, the sealing surface of the pad to live, resulting in a gap between the spool and the valve seat and valve leakage. Eliminate this failure is to remove falling to the sealing surface dirt and impurities, generally in the boiler ready to shutdown the size of repair, the first to do door safety test run mound, if found that leakage stopping furnace after overhaul, if furnace after running the ram test and found that the security gate leakage is estimated to be caused by this situation, run mound after 20 minutes after the cooling and rudder run time, on the sealing surface erosion.
Another case is the sealing surface damage. The main reasons for the damage of the sealing surface are the following: first, the material of the sealing surface is poor. The main security gate due to years of maintenance, the main safety valve core and valve seat sealing surface generally has a very low research, dense cover of hardness is also greatly reduced, resulting in sealing performance degradation, eliminate the phenomenon, the best approach is the original sealing surface turning down, then according to the drawing requirements and re welding process, improve the surface hardness of the sealing surface. Attention in the processing process must ensure that the processing quality, such as the sealing surface cracks, and other defects must be turned down after the re processing. The spool valve seat must meet the requirements of the drawing. At present, the valve core sealing surface of YST03 general steel welding rod is better. Two is poor quality, valve seat grinding can not reach the quality standard requirements, to eliminate the failure of the method is based on the degree of damage by grinding or turning the grinding method to repair the sealing surface. The
Another cause valve leakage was due to improper assembly of parts or the wrong size. Valve seat in the assembly process is not completely on the face or the combination of light transmission phenomenon, or the valve seat sealing surface is too wide is not conducive to sealing. Elimination method is around the check valve with the gap size and uniformity, to ensure the center hole of the valve core and sealing the surface of degrees, the space does not allow inspection departments up spool; according to the requirements of the drawings appropriate to reduce the width of the sealing surface to achieve an effective seal.
