Weld joint

#The present invention relates to a weld joint for metal pipes.

#In joining metal pipes by welding the most common practice hereto has been to at first bevel the pipe ends to be joined, which pipe ends before welding from a V with an open bottom towards the inside of the pipe. The welding starts by filling this open bottom, the so-called weld root.

#Of the weld root is required a very high quality, which high quality only can be achieved by means of a careful, and expensive, work of a highly qualified welder. Anyway, there remains a serious drawback therein, that slag is formed on the interior surface of the weld root, which slag must be removed afterwards.

#In the following the invention will be described with reference to the accompanying drawing.

#FIG. 1 shows a preferred embodiment of the invention, partly in a longitudinal section.

#FIGS. 2 and 3, 4 and 5, and 6 to 9 show three alternative embodiments of the sealing ring employed in the invention.

#In FIG. 1, the pipes to be joined are indicated by the reference numeral 1. The ends 2 of the pipes 1 are flared and between the internal conical surfaces of the flares is arranged an at least essentially cylindrical metallic sealing ring 3 having a wall thickness such that by axial compression of the pipes 1 the edges of the ring wall 4 will be elastically bent into tensioned abutment against the inner conical surfaces of the flared pipe ends 2. Suitable equipment for providing the axial compression force between the pipe ends 2 is readily available on the market and this equipment is therefore considered unnecessary to show in the drawing.

#The sealing ring 2 is provided with an outwardly projecting circumferential flange 5 for correct mounting of the ring 3 to avoid excessive deformation of the edges of the ring wall 4 and thereby a loss of the elastical, tensioned abutment between the ring edges and the pipe ends. To achieve this object, a straight circumferential flange 5 could in principle be enough but the sealing ring might initially be tilted either way, whereby either one edge of the ring wall 4 might be at least locally bent too much before both the flared pipe ends hit the flange 5.

#This problem is solved by providing the flange 5 with corrugations to both sides, preferably at least three to either side, numerals 10 and 11. The meaning of the word "corrugations" shall here be rather widely understood. The idea is that the flanges 5 shall abut against both pipe ends 2 before applying the axial compression force to the pipes 1, the corrugations being essentially flattened by the axial compression.