Sealing and hardfacing
Graphite
Flexible graphite (packing, gaskets)
A sealing material pressed from expanded natural graphite. Used for stem packing and body gaskets in steam, high-temperature and fire-safe valves.
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- TEMPERATURE
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- TEMPERATURE
- −200 … +450 °C
- COST
Chemical composition
Carbon ≥ 95–99% (depending on grade); low-chloride/low-sulphur grades are chosen for nuclear and stainless service.
Mechanical properties
The values in this section are being verified.
Service temperature
−200 °C+450 °C−200−1000100200300400500600700800
450 °C in air (oxidizing atmosphere); 650 °C in steam and inert atmospheres.
Media suitability GENERAL TREND
Water
Steam
Mineral oil
Fuel, aliphatic HC
Ozone, outdoor
Dilute acid
Caustic
Ketones, esters
Emsal assessment. The final choice is made from corrosion tables, taking concentration, temperature, chloride content and flow velocity into account.
Strengths and weaknesses
Strengths
- Very high temperature and fire resistance
- The standard packing in steam service
- Highly chemically resistant
Weaknesses
- Degrades in strong oxidizers (nitric acid, concentrated sulphuric acid)
- Galvanic corrosion with stainless steel: an inhibited grade is required
- Brittle, needs care during installation
Manufacturing and use
- ECONOMY
- Medium.
- MANUFACTURING METHODS
- Expansion + pressing · Braided packing (wire-reinforced)
- TYPICAL VALVE PARTS
- Stem packing · Body-bonnet gasket · Spiral wound gasket filler
Used in 1 Emsal product
- 130Flanged gate valveStem seal
Source: —. Values compiled and verified by Emsal Vana; for binding values, refer to the current edition of the standard and the material certificate.