Some crack extension probably developed from the unfused section of the butt weld across the thickness of the stiffener during transport and erection. 有些裂纹可能在运输和安装过程中就从加劲肋对接焊未熔透处开始发展。
This standard covers the procedures for the heat joining of pipe and fittings made from polyolefin materials utilizing either the socket or butt fusion methods. 这个标准涵盖采用承插热熔和对焊热熔方法对聚烯烃材料管道和连接件进行热连接的程序。