to prevent a jamming with insert region 3 a locking projection 21 with a run up side 22 and a locking side 23 is embodied or formed in insert region 3 run up side 22 is thereby tilted to axis 9 while the locking side 23 runs in the radial direction when first end section 2 with its insert region 3 is fully received in receiving region 4 of second end section 5 a locking element 24 snaps in behind locking projection 21 and thus prevents an accidental detachment of first end section 2 from second end section 5 locking element 24 are thereby arranged in a slot 25 which is embodied or formed in receiving region 4 locking element 24 is elastically deformable thereby in fig2 gas pipe 1 from fig1 is shown in plan view locking element 24 is embodied or formed as a u shaped spring brace with a first branch 26 and a second branch 27 each branch 26 27 thereby has a respective section 28 29 curved outwards with an interior diameter corresponding to an exterior diameter of first end section 2 in insert region 3 a relatively large bearing surface for branches 26 27 on locking projection 23 is thereby possible fig3 shows in detail the arrangement of radial seal 6 and.