Mechanical seals and sealing systems parts are used on a variety of rotating equipment, including valves, pumps, compressors, mixers, steam turbines and other specialty equipment in the field of oil and gas, chemical processing, water, pharmaceutical and other general industries. Valve seal mainly includes gasket seal and motive seal according to its sealing parts and mechanism.
A gasket seal is a seal between two static surfaces, that is usually a gasket. Gasket-type seal including plain gasket, o-ring, packing gasket, profiled gasket, corrugated gasket and winding gaskets. Gasket materials mainly include metal materials, non – metallic materials and composite materials. Generally speaking, the metal material offers high strength and strong temperature resistance. The commonly used metal materials include copper, aluminum, stainless steel and so on. Non-metallic materials are widely used in valve system and pump and selected according to specific needs, mainly including plastic, rubber, asbestos, hemp products and so on. Composite materials mainly include laminates, composite plates, etc. used in corrugated gaskets and winding gaskets.
- Spring Energized Seal gaskets (material including PTFE, graphite, strong graphite, graphene-stainless steel, PTF-stainless steel)
- Soft O-rings (material including NBR, EPDM, VITON A, VITON B, VITON AED, HNBR)
- Soft/hard seal seats(material including PTFE, PCTFE, NYLON, NYLON PA12, DEVLON V, PPP, PEEK)
- Flexible graphite packing ring;
Motive seal mainly refers to the stem seal, that is usually packing box which is used to avoid the media leakage due to the stem movement. The basic form of packing box includes gland type and gland nut type, of which gland type is the most commonly used and the gland nut type is generally used for smaller valves, the compression force of which is limited the due to its small size.
There are plenty of materials available for packing and each packing material has its own operating conditions and temperature range, that depends on its specific conditions. Common packing including:
- Rubber O-ring
- Flexible graphite packing ring
- PTFE woven packing
- Asbestos packing
- Plastic Packing