Current UK strategy for decommissioning stainless steel plant used for tritium containment centres on heating/melting the bulk metal to effect release of dissolved gases. However, hydrogen isotope containment vessels used for approximately 20 years with mercury pumps and exposed to air and water impurities, exhibit tritium burdens greatly exceeding those predicted by simple gas solution in the parent metal. Investigation into the location of, and activity release from, the vessel material indicate the existence of two major tritium sinks:- (i) the bulk metal where in-depth contamination arises from diffusion/solution; and (ii) a highly active surface layer, responsible for holding the main tritium inventory. The relatively rapid release of tritium from the surface layer at room temperature, particularly under moist conditions demands that this latter activity must be removed before plant dismantling and heating/melting is effected. Against this requirement, laboratory work has been performed to evaluate methods of effectively decontaminating stainless steel plant items by gas purge and heat treatment and also to confirm theoretical diffusion/solution calculations as an acceptable baseline for estimating gas solution in the bulk metal. This work reports the effect of wet outgassing primary containments and the effect of heating/melting on tritium burdens in stainless steel.