Abstract: A welding apparatus (28) for forming a circumferential weld (56) includes a base (30) and a spindle (32) extending perpendicularly from the base. Along the spindle, at its proximal and distal portions, first and second workpiece supporters (38, 40) are provided, respectively, to position workpieces (42) to be welded together therebetween. Between the first and second workpiece supporters, a first arm (44) and a second arm (48) are provided, both extending perpendicularly from the spindle. To a distal end of the first arm, an internal backup roller (46) is rotatably attached, and to a distal end of the second arm, an internal drive roller (50) is rotatably attached. One or more external rollers (52a, 52b), each rotatably attached to an external support (66), are further provided. The internal and external rollers are driven by variable-speed programmable motors (not shown). In operation, the workpieces are mounted onto the apparatus, being sandwiched between the internal rollers and the external rollers.