The longitudinal sides 21, 22 comprise grooves and tongues for joining {HEAD ~ the longitudinal sides} 21, 22 to form {TAIL ~ the pipeline} according to the invention by rolling up the portion of material 19, which longitudinal sides are formed in accordance with the illustration in FIGS 1 and 2 
to form
The longitudinal sides 21 , 22 comprise grooves and tongues for joining { HEAD ~ the longitudinal sides } 21 , 22 to form { TAIL ~ the pipeline } according to the invention by rolling up the portion of material 19 , which longitudinal sides are formed in accordance with the illustration in FIGS 1 and 2
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH