Can argon arc root welding and manual arc cap welding be substituted with common manual arc welding on seamless steel line pipe below 5mm wall thickness with 9.5Mpa design pressure?

• 壁厚 5mm以下的无缝钢管用于设计压力9.；5MPa的管线，能否采用普通手工电弧焊工艺代替氩弧焊打底、手工电弧焊盖面工艺施焊?