Abstract: A device for measuring the wall thickness of an extruded tube by means of ultrasonic pulses comprises a tube wall thickness measuring instrument being rotatable about the circumference of the tube and being connected to an arm extending in a plane perpendicular to the tube. The arm is hingedly connected in said plane to a ring perpendicular to the axis of the tube and concentrically about the tube. The arm bears a weight outside said ring. An adjustable pressure element, such as a spring or preferably a two way operable air cylinder, acts upon the arm.The measuring element may engage two supporting faces, the angle between the supporting faces being adjustable.Furthermore a detachable fixing element, such as a magnet, engages the arm so that the arm can be disconnected from the magnet and may be moved from the plane perpendicular to the tube.The wall thickness is measured only by means of one echo coming from the inner wall of the tube when an ultrasonic pulse emitted by the device hits said wall.

Abstract: A method of manufacturing a fiber reinforced plastic pipe part, comprising a first wall part and a wall part adjoining the latter through an inner rounded corner transition having a radius of curvature of less than 5 mm, preferably 0,5 to 3 mm.