Abstract: A line pipe of synthetic material for nominal sizes about 200 mm, especially a waste water pipe, comprising a separate smooth inner pipe and a transversely corrugated outer pipe, the pipes being telescoped into one another in such a manner that the wave troughs of the outer pipe come to lie essentially against the outer surface of the inner pipe, and connection means at the ends for the connection of several line pipes to form a pipeline via a socket joint, whereby the inner pipe has smooth cylindrical end portions projecting above the ends of the outer pipe, with a cylindrical sleeve of a predetermined outer diameter being pushed onto said end portions and fastened thereat by welding and/or adhesion.

Abstract: A box formed building panel has a section in the end walls that joins the panel to an adjacent panel and seals the joint against heat loss. The joining and sealing functions may be combined in a single construction, such as a wedge-shaped projection on one panel insertable into a sealant containing groove in the other panel, or, separate projection and groove combinations may be used for joinder and for sealing. Internal walls and stiffeners may be mounted in the building panel. The building panel may be filled with foam and auxiliary panels mounted on the building panel.