It is shown that the durabilkity of welded joints of austenite steels Cr18Ni12Ti and Cr16Ni9Mo2 is reduced by the effect of heat insulation coatings. The weakening effect of heat insulation increases with the decrease in the level of stresses. Evaluation of the durability of welded joints made of austenite steels and working under heat insulation coatings must be carried out after prolonged tests in the workding medium.