4   Testing of flange gaskets for gaseous oxygen service

The test apparatus mainly consists of two steel pipes, each approximately 1 m in length, with corresponding standard flanges welded to each pipe. Both pipes are sealed with a disk of the gasket material to be tested. The test apparatus is then pressurized with oxygen up to the desired test pressure. The flange is heated by heating sleeves up to the test temperature, at least 50 °C lower than the ignition temperature of the gasket material. An electrical filament ignites intentionally that part of the gasket disk that projects into the pipe.
Assessment criterion:
It is decisive how the gasket material behaves after intentional ignition. If the gasket disk burns with such a hot flame that the fire is transmitted to the steel of the flanges or the pipes, the gasket material is considered unsuitable right from the beginning. In a positive test result, only those parts of the gasket disk burn that project into the pipes and the gasket disk does not burn between the flanges. If this test result is confirmed in four additional tests, there are no objections with regard to technical safety to use the gasket material up to the test pressure and test temperature.
If the flange connection leaks because the gasket material burns between the flanges or becomes soft, the test has to be repeated at lower temperatures or pressures until finally a positive result is achieved in five tests.