An apparatus for forming a bag assembly (10) includes opposing die members (34, 36). Each die member (34, 36) has a perimeter-welding portion (46A, 46B) for forming a perimeter-weld (28) of the bag assembly (10) and a tube-welding portion (48A, 48B) for forming a tube-weld (24) of the bag (10). During operation, first the perimeter-welding (46A, 46B) and tube-welding portions (48A, 48B) weld the bag assembly (10) simultaneously, then the perimeter-welding portions (46A, 46B) are moved to increase the distance between them. When the perimeter-welding portions (46A, 46B) are moved apart, welding by the perimeter-welding portions (46A, 46B) is generally suspended while welding by the tube-welding portions (48A, 48B) may continue.
