Stainless steel 310S is an austenitic heat resistant alloy with excellent resistance to oxidation under mildly cyclicconditionsthrough 2000°F. Grade 310S is a lower carbon version, less prone to embrittlement and sensitisation in service. The highchromium and medium nickel content make these steels capable for applications in reducing sulphur atmospheres containing H2S.They are widely used in moderately carburising atmospheres, as encountered in petrochemical environments. For more severe carburising atmospheres other heat resisting alloys should be selected. Grade 310 is not recommended for frequent liquid quenching as it suffers from thermal shock. The grade is often used in cryogenic applications, due to its toughness and low magnetic permeability. A lap joint flange (LJF) is an assembly consisting of two elements, including a stub and a lap joint ring flange (also called a "lap flange"). Technically, the stub is not part of the lap joint flange. However, the lap flange is always used with the stub, so the two parts are often collectively referred to as "lap flanges".Due to its design, a lap flange always has a flat face and a smooth surface. However, when combined with the stub, the resulting sealing surface is convex. This happens because the sealing surface of the stub is above the bolting plane of the flange.A lap flange has no sealing surface, only the stub has a sealing surface.The sealing surface of the stub can be flat, serrated, or grooved to allow for a ring joint.