The aggregate is so sized and so graded and proportioned and thoroughly mixed in a batch mixer with such proportion of cement and water . Circumferential reinforcement in the barrel of the pipe is kept in. (2.54 cm).Each line of circumferential reinforcement is being assembled into a cage which contains sufficient longitudinal bars or members, extending through the wall of the pipe, to maintain the reinforcements rigidly in shape and correct position within the form. Joining of reinforcement s done by LAP welding of 2 inc. LAP (5.8 cm).