Graphite Packing Rings
GRAPHITE is characterized by a high level of chemical resistance and thermal stability as well as an excellent sealing effect and constant elasticity. Regardless of the temperature cycle, this material will not be subject to cold flow, shrinkage or ageing. GRAPHITE fulfils the purity requirements for seals in nuclear power station valves (the content of soluble chlorides < 20 ppm).
Types:
GRAPHITE foil material Approved for use in oxygen applications for pressures up to 250 bar and temperatures up to 200 °C by BAM ( German Federal Institute for Material Testing, Berlin ). Approved for use in food processing industries by the Chemical and Technical Testing Office, Stuttgart, Germany. Tested by DVGW (German Association of Gas and Water Industry) according to the KTW (plastics – drinking water) recommendations of the BGA (Federal . Health Office) for use as sealing elements Dl and D2.
GRAPHITE rings Preformed GRAPHITE rings are supplied in densities between 1,4 and 1,85 g/cm3.
GRAPHITE tape is used to make rings for repair purposes. In order to stabilize the material and to ensure ease of handling the material has a surface pattern and a W-profile.
GRAPHITE cover seals are supplied as preformed rings and have shown their advantages in self-sealing covers, e. g. heavy-duty valves, high-pressure feedwater preheaters. GRAPHITE remains elastic even with continually changing temperatures and pressures up to 200 N/mm2 surface compression. It can bridge the large sealing gaps which occur in self-sealing covers up to 0,3 mm without difficulty.
Gasket Factors “M” and “Y”
“M” and “Y” data are to be used for flange designs only as specified in the ASME Boiler and Pressure Vessel Code Division 1, Section VIII, Appendix 2. They are not meant to be used as gasket seating stress values in actual service. Our bolt torque tables give that information and should be used as such.
“M” – Maintenance Factor
A factor that provides the additional preload needed in the flange fasteners to maintain the compressive load on a gasket after internal pressure is applied to a joint.
M = (W – A2P) / A1P
Where: W = Total Fastener force (Ib. or N)
2 2 A = Inside area of gasket (in. or mm ) 2
2 P = Test pressure (psig or N/mm )
2 2 A = Gasket area (in. or mm ) 1
“Y” -Minimum Design Seating Stress
The minimum compressive stress in pounds per square inch (or bar)
on the contact area of the gasket that is required to provide a seal at an
the internal pressure of 2 psig (0.14 bar).
Y= W / A1
