Gasket is the main sealing material for vacuum flange connection, so choosing a suitable gasket is also the key to ensure that the flange connection does not leak. Gaskets can be divided into many types according to their materials. In addition to the types of pads, the identification and selection of pads is also very important!
1. Non-metallic flat gasket-PTFE coated gasket.
1. Introduction of gaskets.
PTFE coated gasket is a kind of non-metallic composite soft cushion, generally composed of an encapsulation layer and an embedded layer. The main anti-corrosion encapsulation layer is usually made of PTFE material, and the inlay (filler) is a non-metallic material with or without a metal reinforcement layer, usually made of asbestos rubber. PTFE-clad gaskets are mainly suitable for the connection of full-planar and convex steel pipe flanges. The nominal pressure PN used is 0.6~5.0MPa, the working temperature is 0~150℃, or the corrosive medium that requires high cleanliness.
2. Pad form.
PTFE tube flange gaskets can be divided into three types according to their manufacturing methods: trimmed type (S type), machined type (M type), and folded type (F type). For machine-processed cladding gaskets, the encapsulation inner diameter can be matched with the flange inner diameter to prevent fluid turbulence from occurring on the flange surface. The bag-type shoe gasket is made of a tape-shaped PTFE film with a thickness of 0.4~0.8mm. After the two ends are heat-sealed by a heat sealing process, a U-shape is formed on the outer layer of the annular core. It is simple to manufacture and suitable for large flange sealing.
Second, the metal composite gasket.
1. The characteristics of spiral wound metal gaskets are: good compressibility and resilience; multi-channel sealing and some self-tightening; not sensitive to the defects of the flange pressing surface, not sticking to the flange cover, easy to disassemble, It is easy to center; it can partially remove the influence of pressure, temperature changes and mechanical vibration; it can maintain good sealing performance under various cyclical alternating conditions such as high temperature, low pressure, high vacuum, and shock vibration.
2. Form. According to different structures, spiral wound gaskets can be divided into four types: basic type, inner ring type, ring type with inner ring, ring type with inner ring and ring type.