MANUFACTURING METHOD FOR LONG LENGTH PIPE ON THE WATER AND INSTALLATION METHOD THEREFOR

PROBLEM TO BE SOLVED: To provide a manufacturing method for a long length pipe through which deep seawater and the like can be pumped up without spending an immense construction cost and an installation method therefor. SOLUTION: The manufacturing method for a long length pipe on the water is performed in such a way that a platform ship is floated on the water which is equipped with an upper jack 7 and a lower jack 8 at a circumference of an opening 5, a lower side short pipe 4 inserted to the opening 5 and held by the lower jack 8 is made to abut on an upper side short pipe 4a held by the upper jack 7 and connected by welding, the connected short pipes are shifted downward by releasing the jacks 7, 8, and then other short pipe held by the upper jack 7 is made to abut on the welded short pipes 4, 4a and then welded thereto.