Abstract: A method and apparatus for welding a branch tube to a header tube includes a fixture having a pair of clamps for supporting the fixture on the header tube. A welding head on the fixture includes a clamp to hold the branch tube in place relative to the header tube. The welding head also includes a collet extending into contact with the header tube. The header tube, the collet and the welding head form a limited volume chamber that contains shielding gas in the vicinity of the joint between the branch tube and the header tube. The welding head includes a mechanism for rotating a tungsten welding electrode around the intersection of the branch tube and the header tube to form the welded joint.

Abstract: An orbital welding head for joining two tubes positioned end-to-end includes a welding electrode which is rotated around the tubes and a pair of clamps for holding the tubes in the correct position with respect to each other and the welding electrode. The clamps include a fixed member, a rotatable member and a hinge assembly for joining the rotatable member to the fixed member. The rotatable clamp members are moved clear of the tubes when the tubes are either inserted into or removed from the welding head. Fluid channels are formed in both the fixed and rotatable clamp members. The hinge assembly connects the rotatable clamp member with the fixed member. Fluid channels within the hinge assembly allows cooling fluid introduced into the fixed member to be carried through that member into the rotatable member, cooling both. A return fluid channel is also provided by the hinge. The hinge is provided with a passageway for transferring cooling fluid from one rotatable clamp member to another.

Abstract: A method and apparatus for welding tubes to a tube sheet uses a gas tungsten arc welding (GTAW) torch assembly that is small enough to be inserted through small access holes in a box header. The welding torch is carried near the end of a rotating mandrel that is supported for rotation within a stationary tube. A centering mechanism is inserted into the tube to ensure proper radial alignment of the welding torch with respect to the tube. At the other end of the mandrel is a mechanism for rotating the mandrel and for supplying electrical power, shielding gas and cooling water to the torch and wire to the weld. Axial spacing of the welding torch is provided by a tube stop device that temporarily engages the end of the tube in combination with an axial adjustment device.

Abstract: A water cooled orbital welding apparatus permits continuous welding of pipes and tubes in a limited space by including a liquid cooled plate inside a head assembly to remove heat from the gear carrying the welding electrode around the tubes being welded. A plurality of spring loaded ball bearings maintain the rotating gear in tight contact with the cooling plate. By keeping the gear and electrode cool, thermal expansion of the internal components of the welding head is minimized. Since thermal expansion is not a major factor, noncompatible materials in terms of thermal expansion characteristics may be used in the construction of the device. A removable cassette of symmetrical design allows a cassette to be mounted on the head from either the right or from the left, thus allowing the operator to open the clamps on the cassette from either the front side or the back side of the weld head. An offset hinge on the cassette permits the cassette to be removed from the welded tubes in confined space.

Abstract: A weldhead for welding small diameter tubing in confined spaces. The weldhead includes a welding body and a separable cartridge. The cartridge has a pair of collet clamps for gripping the two sections of tubing to be joined on either side of the weld joint and for maintaining the tubing in alignment during the welding operation. The weldhead body includes a circular rotor that is notched to fit around the weld joint when the weldhead is inserted into and latched to the cartridge. A tungsten electrode is disposed on the inner circumference of the rotor and is caused to orbit the weld joint by a motor driven gear train. A welding arc is established between the electrode and the tubing and the rotor is then driven so that the electrode orbits the weld joint. Motor speed and welding current are regulated to control the weld puddle size.

Abstract: A welding apparatus which is designed to weld together tubular members having any exterior configuration. The welding electrode is mounted on mounting structure which in turn is movably mounted upon the periphery of a housing. The workpiece to be welded is fixedly secured and centrally disposed within the housing. The welding head is to move about the workpiece and also tilt in respect thereto to maintain the longitudinal center axis of the welding electrode continuously perpendicular to the workpiece surface. Step motors are employed to both drive the welding head about the workpiece and also tilt the welding head with respect to the workpiece. The particular exterior configuration of the workpiece has been preprogramed into a memory unit. The memory unit operates through an electronic circuit to operate the step motors to locate the welding head at the precise desired location along the entire length of the welding path.