Construction points and installation methods of plastic-coated steel pipes

Plastic-coated steel pipes, also known as plastic-coated pipes, steel-plastic composite pipes, and plastic-coated composite steel pipes, are steel-plastic composite steel pipes that use steel pipes as the base and weld a layer of plastic anti-corrosion layer on the inner surface of the steel pipe (bottom pipe) or weld a plastic anti-corrosion layer on the inner and outer surfaces through spraying, rolling, dipping, and suction processes.

Plastic-coated steel pipes use ordinary carbon steel pipes as the base pipes, and the inner and outer walls of the pipes are coated with thermoplastics with excellent chemical stability. It is a special chemical composite pipe that has been processed by anti-corrosion technology, which can effectively prevent the acid, alkali, and salt contained in the chemical fluid medium from corroding the pipes. In the past, chemical pipes could not withstand corrosion, so they had to be replaced every year, and the later maintenance cost was very high. This product improves its shortcomings and increases its service life to 20 years. Generally, chemical pipelines are mostly buried underground. The previous pipelines could not withstand such harsh use environments as buried underground, which accelerated the aging of previous generations of chemical pipelines and even caused leakage. The plastic-coated steel pipe for the chemical industry has changed this situation. Therefore, it has been known by more and more chemical plants and has become a popular pipeline material in the chemical industry.

First, the advantages of plastic-coated steel pipes
1. Sanitary and non-toxic, no scale accumulation, no microbial breeding, and guaranteed fluid quality.
2. Resistant to chemical corrosion, soil and marine biological corrosion, and cathode stripping.
3. The installation process is mature, convenient, and fast, and the connection is similar to that of ordinary galvanized pipes.
4. Good weather resistance, suitable for harsh environments such as deserts and saline-alkali.
5. The pipe wall is smooth, improves transportation efficiency, and has a long service life.

Second, the key points of plastic-coated steel pipe construction and installation.
1. It should be implemented by CECS125:2001.
2. The following construction machines and tools should be used for plastic-coated steel pipes:
(1) Cutting should be done with a metal saw;
(2) Grooving should be done with a special groove rolling machine;
(3) Bending should be done with a pipe bender;
(4) Threading should be done with an electric threading machine;
(5) Deburring and processing of rounded corners at the end of the plastic-coated steel pipe should be done with a file;
(6) A small brush or toothbrush should be used to apply high-strength inorganic solvent liquid epoxy resin coating.
3. The construction procedure of plastic coated steel pipes shall meet the following requirements:
(1) Plastic coated steel pipes should not be buried in reinforced concrete structures;
(2) Welding is prohibited during the installation of plastic coated steel pipes;
(3) Plastic coated steel pipes should be installed from large diameter to small diameter, and the pipe openings should be sealed in time;
(4) Plastic coated steel pipes should not be thrown or violently hit during transportation, loading and unloading, and construction on site;
(5) When installing plastic coated steel pipes, pipe bending machines can be used for cold bending when the pipe diameter is not greater than DN50, but the bending radius shall not be less than 8 times the pipe diameter, and the bending angle shall not be greater than 10°.

Third, the installation method of plastic coated steel pipes
1. Pipe cutting: Calculate the pipe size, use special pipe cutting tools to cut the pipe according to the required length, and keep the pipe end perpendicular to the stainless steel pipe axis when cutting.
2. Clean and apply glue: Clean the socket of stainless steel pipe fittings and the end of thin-walled stainless steel pipes. It is strictly forbidden to have foreign matter such as water and oil. Then evenly apply anaerobic glue from 5mm away from the end of the steel pipe to the marked line.
3. Insert the steel pipe: Insert the stainless steel water pipe into the bottom of the socket of the pipe fitting and rotate it in one circle to ensure that the glue adheres evenly.
4. Crimping: Put the steel pipe into the crimping die of the crimping tool, and then crimp it.