前首先进行外观检查,表面不得有飞边毛刺、杂质、灰尘等缺陷及刮伤,断面直径要均匀；
1）安装前首先进行外观检查,表面不得有飞边毛刺、杂质、灰尘等缺陷及刮伤,断面直径要均匀；1）安装前首先进行外观检查,表面不得有飞边毛刺、杂质、灰尘等缺陷及刮伤,断面直径要均匀；1）安装前首先进行外观检查,表面不得有飞边毛刺、杂质、灰尘等缺陷及刮伤,断面直径要均匀；1）安装前首先进行外观检查,表面不得有飞边毛刺、杂质、灰尘等缺陷及刮伤,断面直径要均匀；1）安装前首先进行外观检查,表面不得有飞边毛刺、杂质、灰尘等缺陷及刮伤,断面直径要均匀；