Abstract: A joint mechanism for connecting easily and tightly thin-wall stainless steel pipes (1) with an annular bead (6) at an end, which includes a joint sleeve (2) having a pair of annular recesses (7) at opposite ends and a central enlarged collar portion (9); a pair of coupling nuts (3) with an inclined shoulder (13) on the inside; and a pair of conical disc springs (5) with a distinctly colored outside (5a) mounted between the central enlarged collar portion and the coupling nuts. When the coupling nuts are threaded over the joint sleeve completely, the conical disc springs are compressed between the central enlarged collar portion and the coupling nuts making the distinct color of the conical springs invisible, thus indicating that the coupling nuts are fully tightened.