Abstract: In making a plastic bag having a filling pipe, to overcome the difficulty of separating the overlying walls of a flattened tube of plastics material, one wall (11b) of the flattened tube (10) is cut to form a flap (17) and the opposite wall (11a) of the flattened tube is cut to form an opening (14), registering with at least a part of the flap; two pairs of clamping members (22, FIG. 4) engage the flap at the location of the opening and are moved to cause the flap (17) to extend out of the plane of the first wall of the tubing; and the filling pipe (26) is then inserted between the pairs of clamping members (22) and on the inner side of the displaced flap to enter the space between the overlying walls of the tube. Thereafter the walls of the flattened tube are sealed around the filling pipe.