Pipeline failure and maintenance-12

Release time:

2024-04-30

What are the methods of pipeline repair technology?

Answer: the sewer and gas pipeline laid in the underground run for a long time, which can't avoid aging. In order to avoid water leakage or rust water, gas leakage and other accidents, it is necessary to dig the ground for repair. There are three problems in this method: if the pipeline is located under the road, the excavation of the road will cause traffic jams; if it is in densely populated residential areas, it will worsen the living environment of the residents; the excavation of the pipeline will extend the repair period and increase the labor cost.

In order to avoid the above three problems, a variety of technologies have been developed to repair pipeline defects without digging the ground. Up to now, there are three methods: air flow coating, slide coating and hose coating. Although these methods are applicable to the field, they also have great reference value for the coating of the inner surface of the pipeline in the factory.

(1) The air flow coating method includes ASI method, NPIC method, P. C. G. vacl method, etc.

1) ASI method: this method is to use compressed air to form a high-speed air flow in the pipe, drive the abrasive material to remove the scale, and then form a protective layer on the pipe wall through coating. Thus, the new rusty tube has the same performance as the new tube, and its service life can be prolonged. This method uses air fluid as medium, so it is suitable for multi branch pipes from small pipe diameter to medium pipe diameter, including joints. This method includes three processes: grinding, coating and curing.

A. Grinding process. After removing the water in the pipe, ventilate and dry it sufficiently to make the scale easy to be removed. Then, the abrasive material is put into the air flow to grind evenly to remove the scale and expose the surface of the steel pipe to be coated. Then the inner surface of the pipe is cleaned by intermittent air supply (pulse gas), and the dust generated by grinding is sent to the dust collector for centralized treatment through the hose at the end of the pipe.

B. Coating process. First, adjust the pipeline to a proper temperature with hot air, and then inject the liquid epoxy resin coating (solvent-free, room temperature curing) into the pipe orifice through the mixer. Under the action of high-speed rotating air flow, one side flows along the pipe, and the other side is coated. When the coating flows out of the end of the pipe, the coating is reshaped by a weak air flow. After the shaping, the remaining coating and the discharged gas are collected in the gas-liquid separator to separate the coating and gas.

C. Coating curing process. It can be dried by a breeze with a certain temperature to accelerate the curing of the coating. After curing to a certain extent, the breeze drying can be stopped to make the paint film enter the natural drying state. At the end of curing, measure the hardness of coating with pencil.