(2) The load situation directly under the structure of the dynamic load and the structure of the strong earthquake area, should choose the comprehensive performance of seamless steel tubes; Generally, the structure of static load can choose the lower price seamless steel tube. (3) connection method welding deformation, welding stress and other welding defects can be caused by weld process, and there is a risk of cracking or brittle fracture in the structure.
Therefore, the welding structure of the material requirements should be strict. (4) The structure of the temperature and environment, seamless steel tube at low temperature is easy to cold and brittle, so in the low-temperature conditions of the structure, especially the welding structure, should be selected with good anti-low temperature brittle performance of the calm steel.
In addition, the open-air structure of Taiyuan seamless steel tubes prone to aging, harmful medium effect of seamless steel tubes prone to corrosion, fatigue and fracture, also should be differentiated to choose different materials. (5) too thick seamless steel tubes, thin seamless steel tube roll rolling times, rolling compression ratio is large, the thickness of the seamless steel tube compression ratio is small, so the thickness of the precision steel pipe not only less strength, but also plastic, impact toughness and welding performance is poor. Therefore, the welded structure with large thickness should be made of seamless steel pipe with good material.