下面红色部分要怎么解释?root tack welds? The initial root pass of double butt welds, including root tack welds , shall be chipped, ground, and/or gouged to sound metal. The back-chipped welds , welding groove, and plate edge s shall be examined to ensure that all cracks, pin holes, porosity, and other defects have been removed prior to commencing welding on the second side. root tack welds: back-chipped welds: plate edge s : 查看更多2个回答 . 4人已关注