Construction welding method for main chord pipe inside platform legs

The invention discloses a construction welding method for a major side pipe in a pile leg, comprising a plurality of connecting sections composed of a plurality of semicircle plates and rack plates. The welding procedure is described as follows: a. the two side semicircle plates are welded with the rack plate into the form of a unilateral U-shaped groove joint, with the semicircle plate positioned in the middle of the rack plate and shorter than the rack plate; b. the terminals of the two sections of rack plate are welded into the form of an unsymmetrical X groove joint; c. a filling semicircle plate is filled in between two connecting sections of semicircle plates in the form of a V-shaped groove joint through welding. The construction welding method for a major side pipe in a pile leg has the advantages that the accessibility of the welding construction is enhanced while the welding joint is reduced; workload is decreased while work efficiency is enhanced and mechanical properties of the welding joint are i