Abstract: Procedure for the construction of a concrete shaft for a platform or similar structure, where one of several of the shafts will be outfitted with relatively much equipment. The shafts are constructed of prefabricated sections which are consecutively installed butt-in-butt on top of each other and which are left in the shaft as an internal fully shaped shaft component, as the sections internally contain associated equipment and externally feature bodies for the installation of easily removable formwork elements, preferably easily mountable slipforms, while the space between the formwork elements and a prefabricated section is filled with reinforcement and concrete. The formwork elements, after the hardening of poured concrete, by a per se known procedure, are moved to a higher level.

Abstract: The procedure for draining off shallow gas from the seabed and arrangement for execution of the procedure, whereby through the upper sedimentary layer is placed a system of vertical drainage piles (2) for gas around the site in question for location of a construction on the seabed or along a pipeline route on the seabed.The arrangement includes principally a base plate (1) with a central hole for acceptance of a drainage pile (2) after the base plate (1) has been placed on the seabed.