回牙：指对预先攻有牙的工件进行第二次螺牙的修复的过程。
Back to the teeth: that there are teeth on the pre-attack for the second threaded parts repair process.
更多选择：除标准规格外，可根据需要订制螺纹长度及其它螺牙标准准。
More options: besides standard specifications, thread length and other specification can be made according to order.
工艺：螺牙蒸汽锅炉式电热管是由加热管与螺牙法兰焊接，蒸汽锅炉绝缘电木固定而成。
Technology: flange type of heating is heating pipe and welding flanges from fixed.
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