Kupplung für zwei Metallrohre

摘要

For coupling first and second metal pipes, a coupling structure is provided which comprises a first diametrically enlarged end portion of the first metal pipe and a second diametrically enlarged end portion of the second metal pipe. The second enlarged end portion is mated with the first enlarged end portion so that the first and second metal pipes are aligned. A collar member of metal is concentrically disposed within the mated first and second enlarged end portions. The collar member is formed, around an axially middle portion thereof, with an annular ridge which entirely and intimately contacts with inner surfaces of the mated first and second enlarged end portions. A fastening ring of metal is concentrically disposed about the mated first and second enlarged end portions. The fastening ring is so shaped as to have a concave inner surface which intimately and entirely contacts with rounded outer surfaces of the mated first and second enlarged end portions.