短語詞組短語double U groove weld 雙U形槽熔接double -Vee groove weld 雙面V形坡口焊縫;雙面Vdouble flare vee groove weld 型坡口焊縫;雙面喇叭形V型坡口焊縫double u butt groove weld 雙u形對接焊 返回 double groove weld