gas pipe短语⁶⁹³⁷² 基本例句 n.煤气管 This article illuminates the method and application of vertical down welding for gas pipe line, which ensures the welding quality and meets the requirement of pipe design. 对立向下焊接技术的应用情况加以说明，并阐述此方法是如何保证长输管线的焊接质量，满足管道设计技术要求的。 dictall