(1) Jammer jamming The jamming performance is that the gate jamming is stuck on the side of the cavity guide rail of the valve body, even separated from the stem, which is mainly caused by poor design and manufacture, such as the contact width of the guide rail is too short or too long, and the surface of the guide rail is rough. When the gate stuck in the valve seat, while the valve stem forced on the mention, often appear T-slot gate fracture or deformation, to avoid the "abnormal boost" factor, and another two reasons for the temperature difference and closing force is worth noting. Typical temperature difference conditions such as the valve closed in the cold state after the hot and then open, due to expansion of the valve stem expansion and expansion to further compress the gate, increasing the closing moment of the gate, leading to wedge gate. Such as hot off, cold open, due to the thermal deformation of the valve seat on both sides caused by the crotch width becomes larger, the contraction of the cold becomes smaller, resulting in wedge gate. The above two conditions, such as with the "closing force" is too large, that is too tight, such as improper electrical drive debugging or improper use of force-enhancing mechanism such as wrenches or levers, the occurrence of wedge gate increases the chance of occurrence. Cracking (or bottom deformation) Crack split mainly occurs in the Z944 / Z964 parallel plate structure products, the bottom of the gate directly hit the bottom of the valve occurs, and more due to improper debugging electric valve electrical installation, the closing stroke is not set Limit or limit failure is extremely prone. (3) Sealing surface Crack sealing surface cracks mainly in the alloy steel valve, often due to unreasonable technology. Reasonable material selection and reasonable control of welding process parameters can be avoided.