Urban water supply and drainage steel pipe leaks due to corrosion perforation, and the general emergency repair method is ().

This topic studies the emergency repair of urban pipelines.

Different types, materials and structures of pipelines have different emergency repair methods. For example, most steel pipes are weld cracks or corrosion perforations, which can generally be repaired by repair welding or cover repair welding; The prestressed reinforced concrete pipe is compacted and fixed by chuck after being filled with hemp and ash; If there is a crack in the pipe body, two sleeves can be used or cast iron pipes or steel pipes can be replaced according to the crack size, and the two ends are connected with the original pipes by adapters.

B for prestressed reinforced concrete pipes

CD is used for cracks in pipe body.

So choose a.