FIELD: transportation of fluid media under pressure. SUBSTANCE: upper part 12 of envelope 1 is formed by at least three segments of thin wall in cross section, viz.: two side segments (3, 3') and one upper segment 4. Each side segment passes between lower edge 31 and upper edge 32. Segment 4 closing envelope 1 is connected with upper edges 32 and 32' of side segments 3 and 3'. Each side segment of thin wall 3, 3' is connected with rigid supporting member 5, 5' made from cast material and secured by its base to respective side of bearing plate 2; it has inner surface 51, 51' directed towards envelope 1; its profile is engageable with profile of thin wall side segment laid on this inner surface; inner surface 51, 51' of supporting member runs to level H2 of supper surface 23 of bearing plate 2 which is sufficient for maintenance of rigidity of above-mentioned side segment over its entire height H1 without danger of sagging. EFFECT: avoidance of ovality of pipe line. 18 cl, 6 dwg
