Abstract: An apparatus is provided comprising three elongated vacuum chambers arran in line one after another whereby a component carrying means may be transferred successively from one chamber to another. Of these three chambers the first and third comprise air locks and the intermediate chamber contains heat sealing means whereby components undergoing sealing may be soldered under vacuum. By providing a permanent magnet on each end of the component carrying means this may be shifted between vacuum chambers by external application of a magnet. The overall length of the apparatus is reduced since only three chambers are required and the intermediate chamber may be made shorter than would be the case where no such arrangement is provided.