Regarding the groove shape for pipe butt joints
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Hello, everyone! For my project, there is a circular gas pipeline made of P11 material, 72 inches in diameter with a wall thickness of 45 mm, which is about to undergo prefabricated welding. Due to limitations in the on-site construction conditions, the contractor was unable to prepare U-shaped grooves in accordance with the requirements for weld procedure qualification; instead, flame cutting was used to create V-shaped grooves. Is a V-groove suitable for the butt welding of pipes with a wall thickness of 45 mm? Which standard contains mandatory provisions? Thank you all for your answers. Additionally, for welding pipes made of P11 material, should welders with Fe2 or Fe3 qualifications be used?
The groove type is suitable; P2 is sufficient
If a single V-groove shape is used, with a weld bead width of 60 mm for the welding cover layer and a wall thickness of 45 mm, will such a wide weld bead result in high welding stresses?
An excessively wide weld is certainly not desirable; therefore, post-weld heat treatment is necessary to control the temperature between welding layers, as well as to regulate the number of welding passes and the width of each pass
The cross-sectional area of a V-groove is larger than that of a U-groove; for welding specimens of certain thicknesses, this helps to reduce the welding area and thus minimize welding defects. Relatively speaking, there is no absolute.
Due to site constraints, the pipeline has a large diameter, with a wall thickness of 45 mm and a diameter of 1822 mm. To ensure progress in construction, the owner, after considering various factors and design recommendations, decided to use a single V-groove for butt welding. The amount of welding work has increased significantly.
During welding, two welders are used for symmetric welding
For large-diameter pipes, two welders have always been used, positioned evenly to carry out welding simultaneously. It ensures efficiency while reducing welding deformation.
How many days will welding take??? Is it continuous welding or welding during the day?
Generally, welding is carried out continuously during the day, with overtime work until 8 p.m.; it’s not possible to complete one weld joint in a single day – at best, only the root welding can be finished.