Basic components of a spiral-groove, face-type gas seal are shown. Analyses of flow, of thermal environment and heat transfer were made to improve stability, decrease sensitivity to contaminants and reduce leakage. Analysis suggested reduced film thickness and the advantages of spiral-groove design over Rayleigh pad design for thin gas film operation. Experimental program started with static leakage tests to verify pressure deflections at various pressures; a 1000 h dynamic test followed where 114.3 mm (4.5 in.) diameter seals ran successfully at pressures up to 6.2 MPa (900 psig) and speeds up to 73.66 m.s.−1(14 500 fpm).Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in Minneapolis, Minnesota, October 24–26, 1978