Back-up ring, BR-13 PTFE (spiral)
Back-up rings are installed, togehter with O-rings, to prevent gap extrusion in applications with high pressure (above 5 Mpa). At high pressures and large sealing gaps a risk arises that the O-ring will be pressed into the sealing gap. If this process is repeated, and the pressure increases further, the O-ring will be damaged and will lose its function. Due to the reduction of the sealing gap the back-up ring makes sure the O-ring performs optimally without getting damaged.