Bonding procedure for Teflon seals

Material and bonding procedures designed for use as seals at the National Transonic Facility at the NASA Langley Research Center are presented. Teflon TFE was chosen for its ability to withstand pressures of up to 130 psi and temperatures ranging from -320 to 150 F, in addition to tolerances of 0.074 in. and having a movement allowance of 0.75 in. during transient cycles. Since some of the seals are 14 in. in diameter, Teflon sheets had to be sliced and bonded together after machining to size, resulting in seals with circular, oval, straight, and rectangular cross sections. Step-by-step preparation procedures are provided, and it is noted that the scarf joints performed as predicted during tests.