Abstract: The invention relates to a multilayer plastic pipe (1), preferably for use in heating systems. The multilayer pipe comprises an inner core (2) and a barrier layer (6) surrounding the core and preventing oxygen diffusion through the multilayered pipe. The core (2) is made of a material having viscoelastic properties, preferably cross-linked polyethylene, and the barrier layer (6) is surrounded by an outer layer (8) of a material having adhesive properties. The invention also relates to the use of a multilayer pipe for providing pipe couplings.

Abstract: The present invention relates to a pipe coupling for connection to a pipe end of a pipe made of polymer material and intended preferably for tap water or heating installations. The pipe coupling includes an inner sleeve intended for insertion into the pipe end and for abutment with the inner surface of said pipe end. The coupling further includes an outer sleeve intended for abutment with the outer surface of said pipe end. The outer sleeve is provided with a slot-like opening and means for adjusting the width of said opening. When the outer sleeve is in a tightened, adjusted state, the sleeve will be internally and externally cylindrical. A center axis through the outer cylindrical surface of the outer sleeve is spaced at a distance from a center axis through the inner cylindrical surface of the outer sleeve. In the tightened, adjusted state of the outer sleeve, the internal radius of said sleeve is smaller than the external radius of said pipe end.

Abstract: The invention relates to a process for heating polymer material, including irradiation of said polymer material with infrared radiation. In accordance with the process according to the invention the infrared radiation has wave lengths which substantially are not equal to the absorption peaks of the polymer material in respect of infrared radiation.

Abstract: A tool is used for expanding a pipe-end which includes a plurality of jaws that can be moved radially in relation to a centre axis, between a retracted position and an outer expanding position. The jaws are inserted to a given distance in the pipe-end with the jaws in their retracted position. The jaws have outer surfaces which lie adjacent one another in the retracted positions of the jaws and have a circular-arcuate shape in cross section for engagement with the inner surface of the pipe-end. The radial distance of the outer jaw surfaces from the centre axis increases from the insertion end of the jaws to their opposite end. The pipe-end is expanded successively in several stages with relative small jaw movements, wherein the jaws are retracted and inserted further into the pipe-end between each expansion stage. The jaws of the tool can be moved radially through a distance which is smaller than the ultimate radial expansion of the pipe-end.