What are the stem sealing methods for stainless steel ball valves?

The stem sealing methods for stainless steel ball valves are mainly divided into two categories: packing seals and mechanical seals. Different sealing methods are suitable for different working conditions and can be selected according to parameters such as pressure, temperature, and medium. Packing seals are the most commonly used stem sealing method. They are simple in structure, low in cost, and easy to maintain. They mainly consist of a stuffing box, packing, and gland. The packing is usually made of materials such as polytetrafluoroethylene (PTFE) or graphite. The gland compresses the packing, making it tightly fit against the valve stem to achieve a seal. This sealing method is suitable for medium and low pressure, normal temperature conditions, such as domestic water supply pipelines and general industrial pipelines. However, the sealing performance is greatly affected by packing wear, requiring periodic packing replacement. Mechanical seals are a high-precision sealing method with a complex structure and higher cost. They mainly consist of a rotating ring, a stationary ring, and a spring. The pressure of the spring makes the rotating ring and stationary ring fit tightly together to achieve a seal. They have excellent sealing performance, low leakage, and are wear-resistant, high-temperature resistant, and high-pressure resistant. They are suitable for high-pressure, high-temperature, and highly corrosive media and scenarios with extremely high sealing requirements, such as pipeline systems in the chemical, power, and petroleum industries. In addition, there are combined sealing methods that combine the advantages of packing seals and mechanical seals to improve sealing reliability and are suitable for more demanding working conditions.