Abstract: A seal is provided for use with a tube coupling assembly. The tube coupling includes a male fitting having a beveled conical surface on the outside of its end and a female fitting having a beveled conical surface on the inside of its end. The selected angle for the bevels on both the male and female fittings in the same. The seal, which is interposed between the male and female bevel surfaces, comprises a seal body of spring material, such as Inconel 718, coated with a relatively soft metal, such as silver. The seal body and coating combination are configured to include a cylindrical skirt portion and a conical portion extending from the cylindrical skirt portion. The seal is mounted on the male fitting by means of an interference fit between the inner skirt surface and the outside cylindrical surface of the male fitting. The angle between the skirt and the outside surface of the seal's conical portion is different from the selected angle of the bevels on the male and female fittings.