对于螺旋焊管管道基于应变设计的考虑因素

Strain Based Design Considerations for Spiral Welded Pipelines

对于铺设于易于发生塑性变形地区的管道可以采用基于应变的设计方法。在这种情况下,不仅要考虑钢管的强度和韧性性能,钢管和焊缝金属的应变能力也变得至关重要。当采用基于应变的设计方法时,使用螺旋焊管的主要挑战是螺旋焊缝和材料的各向异性。为此,研究了高强度、高韧性螺旋焊管的拉伸应变能力和容许缺陷。主要包括螺旋管生产过程中不同阶段及成型角等对钢管力学性能的影响。研究发现,成型角决定钢管的各向异性。焊管生产过程中的机械变形阶段(成型、扩径)、受热过程(焊接及热涂敷)等会显著影响钢管的局部或整体的强度、韧性及塑性性能。

Pipelines that are constructed in hostile environments where the occurrence of imposed plastic deformations can necessitate a strain based design approach. Under such conditions not only the strength and toughness properties have to be considered; also the strain capacity of pipe and weld metal become crucial. Considering the use of spirally welded linepipe sections when using strain based design approach,the helical seam weld and anisotropic material properties pose real challenges. In our work,the tensile strain capacity and defect tolerance of high strength,high toughness spiral pipes will be investigated. This paper briefly discusses the different steps in the spiral pipe manufacturing process and their influence on the mechanical properties of the pipe. The results show that the forming angle is a key parameter. Each mechanical operation（ forming,expansion） and each thermal operation（ welding,coating） will affect local or global strength,toughness and ductility properties of the pipe metal.