[en] The heat exchange surface of the steam generator is arranged in a jacket which consists of an upper and a lower direct section and a bend of the outer jacket. The bend of the outer jacket is divided into segments by radial sections. The segments of the bend of the outer jacket are integral without transverse or longitudinal welds. The individual segments may be drawn over the straight part of the heat exchange surface and when secured in the appropriate position they may be welded through into bend of the outer jacket using peripheral welds. This to a considerable extent reduces undesirable flow between the heat exchange surface and the outer jacket in the bend thereby allowing a better utilization of the heat exchange surface. (M.D.)