Flanged fittings for pipeline

A flanged fitting comprising:

• proximal, central, and distal sections between proximal and distal ends of the fitting;
• wherein the proximal section comprises a flange portion having a circumference, proximal, first vertical, and distal surfaces, and a plurality of bolt holes extending through the flange portion from its proximal surface to distal surface, wherein the plurality of bolt holes are circumferentially arranged in the flange portion;
• a central opening extending from the proximal to distal end of the fitting and having a central axis, the opening having an inner surface;
• the central section having a tubular shape and comprising, in a proximal to distal arrangement:
• a first angled outer surface angled relative to the central axis and defining a first section of fitting wall between the inner surface that decreases in thickness;
• a second vertical surface, parallel to the central axis and defining a second section of fitting wall between the inner surface that is constant in thickness;
• and a second angled outer surface angled relative to the central axis defining a third section of fitting wall between the inner surface that increases in thickness;
• the central section further comprising a first curved transition surface between the first angled outer surface and the second outer vertical surface, and a second curved transition surface between the second outer vertical surface and the second angled outer surface,
• the distal section comprising a third vertical surface parallel to the central axis defining a fourth section of fitting wall between the inner surface that is constant in thickness;
• wherein the fourth section of fitting wall has an outer diameter and thickness that is greater than a thickness of an outer diameter and thickness of the second section of fitting wall.