This post was written based on SPETECH materials. If anyone has ever had to deal with temperatures above creep, using graphite gaskets contaminated with sulfur and phosphorus leads to the graphite oxidizing in the air, so outside the seal. This process of mass loss is measured in hours, maybe days, so fortunately it is quick, so it can be noticed.
Here, only the gasket reinforcement remains. The graphite has completely disappeared.
Graphite must be as little contaminated with sulfur and phosphorus as possible. How to test the purity of graphite? This is stated in the standard EN 14772 Flanges and their connections — Quality assurance control and testing of gaskets in accordance with EN 1514 and EN 12560 series standards.
