The leak of construction quality control with polyethylene gas pipe was analyzed and found out by installation engineering personnel,equipment,welding technology,construction of pipeline depth changes flanging resection and internal defect inspection of construction quality control.The installation characteristics and requirements were explored.Recommendations needed to be improved in terms of personnel,equipment,construction supervision,and non-destructive testing standards were proposed.
TC6 titanium alloy was welded by tungsten argon arc welding and preheating and heat treatment after welding were also conducted. The gas-tightness and non-destruction of the obtained joint were tested. The microstructure and joint properties of the weld zone and the heat affected zone were analyzed. Results show that the welded joint after preheating and vacuum heat treatment can meet the requirement of usage. There is a small amount of acicular alpha' in weld metal and weaving-like alpha is formed. The alpha and beta duplex structures is made in the heat affected zone, and a small amount of brittle phase Al3Ti is produced in the welded joint.
The corrosion behavior of the 20MnMo and BHW35 welded joint is studied.The welded joints are put in solutions with different pH value of the NaOH or HCl acid-basic to examine the corrosion behavior after 456 hours at room temperature condition,then the microstructure is examined and the weight loss of samples is measured before and after corrosion.The microstructure,weight loss and the corrosion rateof specimens under different conditions are compared.The following results are attained: the most serious corrosion of 20MnMo and steel BHW35 dissimilar joint happens in the hydrochloric acid solution.The corrosion resistance of the weld metal is better than that of the heat-affected zone and the fusion zone metals.
采用双丝和单丝自动埋弧焊焊接工艺进行焊接,观察了焊接接头截面形状和金属显微组织,并对其进行了冲击及拉伸试验.结果表明,采用双丝自动埋弧焊工艺焊接的接头质量好、焊缝成形美观、接头性能满足技术要求、热影响金属的成分偏析现象减弱,但焊缝金属容易产生魏氏组织,使焊缝金属的冲击性能降低.
大型储油罐底板由中幅板和边缘板构成,采用对接和搭接接头,底板厚度较薄、面积大、焊缝数量多。因焊接应力和焊缝收缩的存在,焊接时易产生严重的焊接变形。通过制定合理的焊接工艺措施和对焊接过程进行有效的控制,以达到控制焊接变形的目的。
