Abstract: A substantially cylindrical shaped metal clamp suitable for joining co-axial pipes, is disclosed and outlined. Said clamp is made from a base strap which is bent in two positions rather close to its ends, one of said bends developing on a non-radial axis and having the end near the other bend, which may be also a radial one, extending for a short straight line having an open bend end which, on locking, hooks on to the non-radial bend close to the other end of the clamp.The base strap forming the clamp has two wide wave shaped laps which, because adjacent, give the strap an `m` shape, said `m`-shaped portion, which is lightened by a central lengthwise slit, is situated at the strap end bearing the straight hooking arm.