Abstract: A tube assembly includes at least first and second tubes configured for coupling at respective ends. The first and second tubes each include a base material, and a weld interface at the respective end. The weld interface is proximate to an inner diameter and an outer diameter of the first and second tubes, and includes a weld interface segment extending therebetween. A work hardened weld assembly couples the base material of each of the first and second tubes. The work hardened weld assembly includes a weld fusion zone between the weld interfaces of the first and second tubes and the weld interface segments of the first and second tubes. The weld fusion zone is work hardened and at least the weld interface segments of the first and second tubes are work hardened between the work hardened weld fusion zone and the base material of the first and second tubes.

Abstract: A tube assembly includes at least first and second tubes configured for coupling at respective ends. The first and second tubes each include a base material, and a weld interface at the respective end. The weld interface is proximate to an inner diameter and an outer diameter of the first and second tubes, and includes a weld interface segment extending therebetween. A work hardened weld assembly couples the base material of each of the first and second tubes. The work hardened weld assembly includes a weld fusion zone between the weld interfaces of the first and second tubes and the weld interface segments of the first and second tubes. The weld fusion zone is work hardened and at least the weld interface segments of the first and second tubes are work hardened between the work hardened weld fusion zone and the base material of the first and second tubes.

Abstract: A tube assembly includes at least first and second tubes configured for coupling at respective ends. The first and second tubes each include a base material, and a weld interface at the respective end. The weld interface is proximate to an inner diameter and an outer diameter of the first and second tubes, and includes a weld interface segment extending therebetween. A work hardened weld assembly couples the base material of each of the first and second tubes. The work hardened weld assembly includes a weld fusion zone between the weld interfaces of the first and second tubes and the weld interface segments of the first and second tubes. The weld fusion zone is work hardened and at least the weld interface segments of the first and second tubes are work hardened between the work hardened weld fusion zone and the base material of the first and second tubes.

Abstract: A hot water heating system having a water tower with a cold water inlet at the upper end and a hot water outlet at the lower end has a large diameter combustion inlet opening in the sidewall. A combustion chamber is secured to the water tower at the combustion inlet so that products of combustion of fuel consumed in the combustion chamber pass into the water tower and are exhausted through a vent. An outer shell surrounds the combustion chamber providing an annular chamber having a water inlet. A port communicates the upper interior of the annular chamber with the interior of the water tower. Water is circulated from a hot water storage through the annular chamber and through the port into the interior of the water tower. The recirculated water thus accomplishing the dual functions of cooling the combustion chamber and salvaging heat extracted from the combustion chamber to augment the heat of the water in the storage tank.