An investigation of a sample of welded AISI Type-304 stainless-steel pipe exposed to liquid sodium at 572 to 1472°F for ≈ 7800 h and an unexposed sample of pipe from the same heat of Type-304 steel showed that, except for nitrogen, no marked change in composition of the pipe occurred. Nitrogen was absorbed at the surfaces of the pipe, a greater amount being absorbed at the inside surface that had been exposed to the liquid sodium, than at the outside surface that had been exposed to air. Under the conditions studied, the steel did not undergo any marked deleterious change in mechanical properties. However, the absorption of nitrogen did decrease the ductility of the surface that had been in contact with the liquid sodium. Thus, when Type-304 steel is used for liquid-sodium service, precautions should be taken to keep the sodium as free as possible from nitrogen-containing contaminants.