Abstract: A seal bar assembly which includes a support structure (21), and at least a first seal bar segment (22) and a second seal bar segment (23) mounted substantially parallel to each other on the support structure. The seal bar segments define a gap (28) therebetween. Each seal bar segment has two ends, with mounting means (26) positioned proximate to each end of both the first and second seal bar segments for mounting the ends of the seal bar segments to the support structure. The mounting means are adapted to permit one or both ends of each seal bar segment to move toward or away from the support structure, but the mounting means do not permit the seal bar segments to significantly move transversely with respect to each other. In this manner, the seal bar segments remain substantially parallel to each other, and the gap between the seal bar segments is maintained substantially constant.