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ISO 6164 flange material o-ring tolerance

Date:Jun 21, 2019

ISO 6164 square flange standard specifies Material of flange clamps, flange heads, screws, o-rings.


ISO 6164 4 Flange clamps,  which shall be of ferrous material with the following properties in the finished condition:

— minimum yield strength: 330 MPa;

— minimum elongation at fracture: 5 %.

ISO 6164 4 Flanged heads, which shall be of ferrous material with the following properties in the finished condition:

— minimum yield strength: 330 MPa;

— minimum elongation at fracture: 10 %.

ISO 6164 4 Screws. Unless otherwise specified, one of the following screw options shall be used:

a) hexagon head screws conforming to ISO 4017 of property class 10.9 (minimum) in accordance with ISO 898-1;

b) socket head screws conforming to ISO 4762 of property class 10.9 (minimum) in accordance with ISO 898-1.

ISO 6164 4 O-rings. Unless otherwise specified, the O-rings shall be made of NBR (nitrile) with a hardness of (90 ± 5) IRHD, measured in accordance with ISO 48, for use at the pressure and temperature requirements given in Clause 8 and for testing. The O-rings specified in Table B.1 shall conform to the dimensions given in ISO 3601-1 for the relevant size code. They shall also conform to tolerance class A in ISO 3601-1 and shall meet or exceed the O-ring quality acceptance criteria for grade N of ISO 3601-3. If the flange connection will be used at temperatures higher than specified in Clause 8, O-rings made of materials that meet the higher temperature requirements shall be used.


Unless otherwise specified, tolerances shall be in accordance with ISO 2768-m (medium)



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