The Autoclave is suitable for conducting accelerated soundness tests on cements of the autoclave expansion test requiring constant steam pressure with the correspondent constant pressure. It consists of a stainless steel cylinder with a weldedheat insulated voer, mounted on a sturdy supporting frame, enclosed in a heat insulated metal housing, attractively finished. The attached control unit encloses a sensitive pressure regulator and pressure gauge, power switches and pilot lights forcontrolling the electric heating units.