Straight seam submerged arc welded pipe
is widely used. At present, the application of LSAW has been extended to many fields. In addition to oil and gas long-distance pipelines, it has also developed into marine structures such as offshore platforms and offshore floating cranes. Submerged arc welded pipe has obvious advantages as a marine structural pipe, such as uniform wall thickness, simple process, low performance due to pipe making process, easy to achieve high strength and high toughness requirements, and flexible adjustment of specifications to meet different pipe diameters. Requirements.
However, since the service environment of the marine structure pipe is different from the land fluid transport pipe, the marine structure pipe is used in a severe marine working environment such as waves, sea tides, storms, and cold drift ice. In addition to the general pipe performance, it also puts higher requirements on its toughness and weld quality.
The main materials of straight seam submerged arc welded pipe manufacturers are D36 steel, S355 steel and structural steel plates with Z-direction properties. The thickness is generally between 20 and 50 mm. Due to the large thickness of the plate, the carbon content and carbon equivalent are higher. Large, poor weldability, large hardening tendency, reduced weldability of welded joints, and easy to produce cold cracks.
When using some of the above-mentioned materials and thickness of steel plates to produce some domestic and foreign offshore platform structural steel pipes, some thick walls were found. The steel pipe has lateral crack defects. Effective detection of transverse cracks, timely repair and elimination of defects is of great significance to ensure the quality of steel pipes and ensure the safe use of offshore platforms.