Abstract: A method and apparatus for sealing a valved bag transported by a conveyor. The valved bag has a body with a longitudinal axis, a center of gravity, and a sealable valve. At least a portion of the sealable valve protrudes from the body in a substantially perpendicular orientation relative to the longitudinal access. The apparatus includes a conveyor for transporting the valved bag in a direction of travel substantially parallel to its longitudinal access. A stop member stops the transportation of the valved bag when the sealable valve is aligned with a sealing area. A ram member positions the valved bag to dispose at least a portion of the sealable valve into the sealing area. An ultrasonic horn and anvil engage and seal the sealable valve. The stop member is removed from the path of the sealed bag, allowing it to resume transportation along the conveyor.