The permeability at temperatures ranging from 400 to 750C could be described by:

P (cm mm/min torr½) = 0.566 exp[-16.12(kcal/mol)/RT]

It was noted that oxidation reduced the permeability by factors of up to 400, and altered the functional dependence of permeation upon T pressure.

Tritium Permeation through Clean Incoloy 800 and Sanicro 31 Alloys and through Steam Oxidized Incoloy 800. J.T.Bell, J.D.Redman, H.F.Bittner: Metallurgical Transactions A, 1980, 11[5], 775-82