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Description
High efficiency graphite sealing rings, moulded to precise density and dimensions. Manufactured from expanded high purity graphite foil without the use of binders, elastomers or fillers.
Also available as Wire Reinforced Supagraf® with internal reinforcement of stainless steel wire, orientated in all planes for high loads; as Passivated Supagraf®, containing a corrosion inhibitor to minimise galvanic action; and as highest purity Nuclear Grade Supagraf®.
Typical applications
Valves and high speed rotary pumps for virtually all industries and fluid media. The rings are particularly recommended for systems handling high-temperature steam, demineralised water, potable water, heat transfer media, petroleum products, inorganic and organic acids, alkalis, hot waxes and oils.
Specifications (plain Supagraf®)
Prime features
Chemical properties
Chemically inert within the range pH 0-14. Extractable chloride ion content typically 25ppm, sulphur <100ppm for standard grade. Chloride ion content <10ppm, sulphur <60ppm for Nuclear Grade.
No loss of volatiles, even at high temperatures. Lower limiting temperatures may apply when used with oxidising agents such as nitric, sulphuric or chromic acid.
Physical properties
Carbon content (grade dependent) %: 98 - 99.8
Density range, g/cm³: 1.1 - 1.8
Coefficient of linear expansion for ring of 1.4g/cm³: 7x106
Thermal conductivity for ring of 1.4g/cm³ @ 20°C, W/mK,
axially: 400
radially: 6
Coefficient of friction to steel : 0.05
Service capabilities - valve stem duties
Maximum operating temperatures
Steam: +650°C.
Oxiding conditions: +500°C.
Non-oxidising: +1000°C.
Minimum operating temperature: -200°C.
Maximum system pressure: 250bar.
Service capabilities - centrifigal pumps and rotary equipment
Maximum operating temperatures
Steam: +650°C.
Oxiding conditions: +500°C.
Non-oxidising: +1000°C.
Minimum operating temperature: -200°C.
Maximum shaft speed: 25m/s.
Maximum system pressure: 10bar.
How supplied
Precision moulded rings in endless form, or with single split, or as matched scarf-split halves. Sections 1.5mm to 40mm; diameters 2mm to over 1100mm. Full fitting instructions are included.
Recommended densities: 1.5g/cm³ for rotary pumps; 1.6g/cm³ for valve stem duties (with end rings of Grafpak), although rings of higher densities, or a combination of high and low density rings may be used for specific applications (also see Valvemaster® Packing Sets).
Click here to download the Compression Packing Guide pdf (2.17MB)
