First of all the most important point: if the gas pipeline inner fire, immediately closed all into the hole, radiation tube and sealing pipe, and in general to pipe of steam to extinguish fire.
The metal-plastic composite nut, according to Claim 1 and 2, is characterized in that the inner surface at one end of metal insert is cone-shaped sealing surface.
根据权利要求1或2所述的金属塑料复合螺帽，其特征在于所述金属嵌件一端部的内表面为锥形的密封面。
3
The box type structure, cavity cannot antirust paint corrosion, in order to prevent moisture intrusion corrosion beam cavity, sealing the inner cavity of the main girder must keep.