TBTFZ-31A soundness steam tank consists of a lid, inner and outer tanks, specimen rack, insulation layer, heating tubes, pipe fittings, water tap, sealing device, protective cover, and electrical control box. This soundness steam tank is suitable for determining the soundness (expansion performance) of cement by the Le Chatelier method and the pat test method. With two groups of heating tubes, it can automatically control and maintain the water temperature. This steam tank is an essential piece of equipment for laboratories in cement plants and related research institutes.