How To Make Anti-corrosion Large-diameter Spiral Steel Pipe

Many factors affect the performance of the anti-corrosion layer of large-diameter spiral steel pipes, such as the layout of each process, equipment selection, surface quality, heating method, coating temperature, cooling method, transmission accuracy, material characteristics, and testing, etc. If the control is not good, it will lead to defects such as low adhesion, too thin, cracking, or bubbles in the coating. Strict implementation of standardized and scientific operating methods is crucial to control defects and ensure the yield of anti-corrosion steel pipes.

1. Surface treatment.

To remove oil stains from the surface of epoxy coal pitch anti-corrosion steel pipes, it is best to use sandblasting to remove rust to a minimum of Sa 2 level in GB/T 8923, and preferably to Sa 2 1/2 level. When construction conditions are restricted, tools can also be used to remove rust to St level 3. After the steel surface treatment is qualified, primer must be applied as soon as possible before rust returns (normally within 8 hours, when the relative air humidity exceeds 80%, primer should be applied immediately). The moisture content of the 20mm of concrete surface is less than 6%, and loose materials should be removed to present a flat and solid surface.

Epoxy coal pitch anti-corrosion steel pipes should be assigned a special person to prepare the paint. The primer and topcoat should be stirred evenly after opening the barrel, and the matching Donghua No. 1 curing agent should be added according to the specified proportion. The amount added is primer 100: 8 ~ 10 (temperature Low and high), topcoat 100:10. Solvent-free topcoat component A: component B = 1:1, no additional curing agent. After adding the curing agent, mix well and let it stand for 5 to 10 minutes before use (try not to add diluent when preparing the paint to avoid reducing the solid content of the paint. If the paint is too thick during construction in winter, no more than 5% of diluent can be added. ), the paint is ready.

2. Putty.

Putty should be put on both sides of the weld 2mm higher than the surface of the steel pipe and the overlap between the two steel plates to form a smooth transition surface. Putty is made of primer or topcoat with a proportion of curing agent and about twice the weight of talcum powder and should be used up within 4 hours after mixing. Quality inspection of epoxy coal pitch anti-corrosion steel pipes. According to the conditions and methods specified in GB 50268-97 or SY/T 0447-96, conduct appearance, thickness, spark test, and adhesion inspection, and repair defects until they pass the test.

3. Epoxy coal pitch anti-corrosion steel pipe anti-corrosion steel pipe protection.

Anti-corrosion steel pipes must not be handled until the anti-corrosion layer is fully dry. When loading and unloading anti-corrosion steel pipes, only use soft slings to contact the anti-corrosion steel pipes. When stacking anti-corrosion steel pipes, sandbags, and wooden pads should be placed at both ends and in the middle of the steel pipes to isolate the outer walls of the steel pipes and the ground. Anti-corrosion steel pipes should be buried in the ground in time for use. If they are stored for more than one month, they should be covered with tarpaulin to avoid sunlight and rain. If they are stored for more than half a year, they should be painted with a layer of epoxy coal tar topcoat before use.