Filling technology of epoxy coal tar pitch anti-corrosion coated steel pipe

1. epoxy coal tar pitch anti-corrosion coated layer

a. epoxy coal tar pitch anti-corrosion coating is suitable for anti-corrosion on the outer wall of buried steel pipelines for transporting oil, water, and gas, and the temperature of the transport medium is required to be lower than or equal to 110°c.

b. the raw material is epoxy coal tar pitch paint plus glass cloth, thin-coated multi-layer structure, and cold-coated on site. applicable to pipe sections whose pipe body is anti-corrosion of the same material.

c. the advantage of epoxy coal tar pitch is that it is easy to operate on-site and does not need heating; the disadvantage is that the coating takes a long time to cure and is not suitable for fieldwork, and it is difficult to construct when the ambient temperature is below 10°c. epoxy coal tar pitch is mainly used for municipal gas pipelines, water pipelines, factory pipelines, etc. long-distance steel pipelines are generally only used for repairing joints and repairs in stations and anti-corrosion layer overhauls. it is an epoxy-coated steel pipe.

2. on-site filling process and requirements of epoxy coal tar pitch

a. after the surface pretreatment of the steel pipe at the patching part, the primer should be painted within 4 hours. the primer should be uniform and must not be missed.

b. after the primer surface is dry, the topcoat and glass cloth can be applied. if the weld seam is higher than 2mm, use the topcoat paint and talcum powder to make a putty with a suitable consistency. after the primer surface is dry, apply it on both sides of the weld seam and scrape into an excessively curved surface, and the overlap between the glass cloth and the anti-corrosion layer of the pipe body shall not be less than 100mm.

c. the anti-corrosion layer of ordinary structure can be painted with top paint after the top paint is dry, and the thickness of the anti-corrosion layer should be greater than or equal to 0.2mm.

for the anti-corrosion layer of the reinforced structure, the glass silk cloth can be wound after the top coat is applied. the glass cloth should be stretched tightly, the surface should be smooth, without wrinkles and bulges, and the blank width is 30-40mm. after the glass silk cloth is wound, the top coat can be applied. the amount of paint is full, and all the meshes of the glass cloth should be filled with paint. after the top coat is dry, the third top coat can be applied. the thickness of the anti-corrosion layer should be greater than or equal to 0.4mm.

the anti-corrosion layer of the extra-reinforced structure shall be carried out by the above-mentioned sequence requirements of the first top coat and one layer of glass cloth. the winding directions of the two layers of glass cloth are opposite. should be greater than or equal to 0.6mm.