Joining method and joining structure of clad steel pipe

摘要

A clad steel pipe (6) in which a cladding layer (6) is laminated on the inner periphery of a carbon steel layer (5) for the purpose of improving corrosion resistance of a friction stir welding start portion when joined from the cladding layer side by friction stir welding, (FSW) ending position (PE) from the inside of the clad steel pipe (4) by circumferential welding with a friction stir welding (FSW) Along with the position (PS) overlapping (lap margin N), the tool hole (12) occurring at the FSW end position is filled with arc welding using the highly corrosion-resistant welding material (21) (filling welding part (22) (Range from P1 to P2) including the range of mixing the carbon steel layer (5) and the cladding layer (6) at the FSW start position (PS) to the end position filling the tool hole (12) (13) by arc welding using the highly corrosion-resistant welding material (21) from the inside of the weld metal (4).