Connection of an uncooled pipe and a cooled pipe in particular for double pipe heat exchangers

A connection (10) between an uncooled pipe (11) and a cooled double-walled pipe (12) with air space (13) between walls run through by cooling fluid let into the air space through a side passage (14) near the connection. The connection comprises a connection zone (15) having a longitudinal section generally in fork form to have a single tubular end (16) connected to the uncooled pipe and an opposite double tubular end (17,18) to which are connected the corresponding walls (19,20) of the cooled double-walled pipe so that the bottom (21) of the fork constitutes an end closing of the air space. Near the fork between the two walls (17-20) is a baffle member (22) which diverts toward the bottom (21) of the fork the cooling fluid entering the air space through said side passage (14) before the cooling fluid starts to travel along the double-walled pipe.