| 摘要 |
A pipe element (10) for a flue is disclosed, which comprises a metallic circular pipe body having a first predetermined diameter; said element is further provided, close to a first and thereof, with an area (11) having a diameter which is slightly larger than said first diameter. The edge of the metallic pipe end having a larger diameter is internally folded, and it is provided with a series of radial cuts (12) which allow said end to be folded. Furthermore each portion which is comprised between two radial cuts in on one hand folded in such a way as to be parallel to the pipe longitudinal axis, on the other hand folded in such a way as to perpendicular to said axis. In this way a metallic locking nut is formed inside of the pipe, in the larger diameter area. The other pipe is provided, by means of a mould, with a series of ribs (15) which are adjacent to each other and which form a thread suitable for cooperating with said locking nut in order to join together a pair of adjacent pipes. The joining operation is carried out in a very simple way, by inserting one end of a pipe into the conjugated end of an adjacent pipe and by carrying out a rotation about the pipe axis until the respective locking nut and thread elements reach an abutment position. |
