First: welding technology
From the welding process, the welded steel pipe piles and the spiral steel pipe pile
joints are coordinated in a straight way so you will have a lot of unavoidable T-welding, the probability of the existence of welding defects is also greatly increased, T-welding residual welding increases the large The possibility of stress welding metal cracking is usually a three-dimensional stress state.
Using steel plate welding spiral steel pipe pile 16MN material included, but is now listed as the current grade Q345, steel high strength low alloy structure, known as Q345 steel pipe pile, 16Mn rural old label number, 12MnV some old, 14MnNb to 18Nb Therefore, the replacement of steel 16MnRE, 16Mn steel and a considerable number of the only alternative material 16Mn steel
material. The chemical composition for the 16Mn and Q345 is not the same. More importantly, the difference in the thickness of the packet size is larger and has been different depending on the yield strength of the two steels present, and this promises some variation in the stress of the material that will produce you. Therefore, it should be simply based on the new steel stress application 16Mn steel is not enough Q345 steel commitment
According to the submerged arc welding method, the position or extinction can not be satisfied for each welding condition, and the arc of each girth weld is linearly fitted, so it is necessary to have it through the extinction, with multiple defects that can weld you.
Second: under pressure
The thickness of the packet size, and redefine the allowable stress. The main components of steel and 16Mn steel are basically the same as the percentage of Q345, the difference being V when adding Ti and Nb in the microalloyed elements. Particles are purified when V, can improve the toughness of steel is a small amount of titanium, niobium alloy elements, the mechanical properties of steel significantly improved. For this reason, it can be the exact thickness of the plate
The larger. Therefore, steel, especially low temperature properties, does not provide the mechanical properties of 16Mn steel, it should be better than Q345 16Mn steel. Xu Q345 steel pressure slightly 16Mn steel. 0.2% or less, which means that, depending on the machine design requirements, the alloy content than the equivalent, the carbon content in the factory to ensure that the mechanical strength of steel
When the pressure in the tube has to be sustained, usually, the radial stress and the axial stress, δδ, produce two major stresses on the wall. Welding the resulting stress δ, α helical spiral steel pipe pile welding angle. Because it is the twist angle of the spiral welded pipe in general, the straight seam steel pipe pile stress due to the principal stress caused by spiral welding. At the same operating pressure, the helix has the same diameter
It can reduce the straight seam welded pipe wall thickness ratio.
Directly selected mechanical strength is not heat treated. To 345 MPa, which means that Q345 is the maximum yield strength of the material.