PN16 Pressure Rating Rubber Expansion Joint: High-Pressure PTFE Lined Flanged Bellows for Chemical Pipelines The High-Pressure Chemical Barrier for Demanding Industrial Lines. The PN16 Pressure Rating Rubber Expansion Joint is an engineered, high-integrity pipeline solution custom-built to withstand severe working pressures up to 16 bar (1.6 MPa) while handling highly aggressive process media. Chemical transfer networks, water treatment facilities, and pharmaceutical plants