压力钢管焊接前的预热方法及预热温度 ,应根据钢种、钢板厚度、焊接方法、环境条件等综合考虑 ,合理选择预热规范。环境湿度对焊接质量有较大影响 ,有些预热规范不适合于高湿度的环境条件。压力钢管的焊接采用垫板接头可减少隧洞开挖量和回填混凝土方量 ,但弯管段不宜设垫板。压力钢管的安装装配使用履式卡具可使装配速度快、质量好、装配应力均匀、便于反复调整 ,是值得推荐的方法。钢管内壁涂漆由于面漆容易在安装过程中被损坏 ,尤其是钢管底部 ,所以在制作场可将底部区域只涂底漆保护 ,面漆留在安装后期涂敷 The preheating method and preheating temperature before the pressure pipe welding should be based on the steel type, the thickness of the steel plate, the welding method and the environmental conditions, so that the preheating specification should be properly selected. Environmental humidity has a significant impact on the quality of the weld, and some preheat specifications are not suitable for high humidity environmental conditions. Pressure pipe welding pad plate joints can reduce the amount of tunnel excavation and backfill concrete side amount, but the elbow section should not be set pad. The installation of pressure pipe using the performance of the fixture can make the assembly speed, good quality, uniform assembly stress, easy to repeat the adjustment, is the recommended method. Steel pipe wall paint Because the topcoat is easily damaged during installation, especially at the bottom of the steel pipe, the bottom area can only be primed in the production yard. The topcoat remains in the late stage of coating