Seamless concentric reducers made of aluminum acc. to ASTM B361. Cold formed with subsequent heat treatment acc. to AD-Merkblatt HP-7/4 and tolerances acc. to ANSI B16.9. Weld preparation acc. to ANSI B16.9. Suitable for processing in shipbuilding, plant and equipment construction, especially in the field of process engineering. Their advantages are the low weight, the very good seawater resistance and the temperature range from -270°C to +80°C.