Graphite/polyurethane seal resists shock in submarines. (Materials Progress - Polymers/Ceramics).

A ten-inch ball valve seal for submarines is made of graphite-impregnated polyurethane because of the material's resilience and resistance to the shock waves generated by underwriter explosions, reports Mearthane Corp., Cranston, R.I. Open-cast thermoset polyurethane is said to be up to 20 times more durable than rubber, and prevents sea water from entering the submarine at pressures up to 900 lb/in. (2) (6 MPa). The high compression set of the material ensures that the compone