Internally and externally coated spiral steel pipes, also known as coated pipes, steel plastic composite pipes, or coated composite steel pipes, are steel plastic composite steel pipes that use steel pipes as the substrate and fuse a layer of plastic anti-corrosion coating on the inner surface of the steel pipe (bottom pipe) or on the inner and outer surfaces through spraying, rolling, immersion, and suction processes.

Internally and externally coated spiral steel pipes have excellent corrosion resistance and relatively low friction resistance. Epoxy resin coated steel pipes are suitable for transporting media such as water supply and drainage, seawater, warm water, oil, and gas, while polyvinyl chloride coated steel pipes are suitable for transporting media such as drainage, seawater, oil, and gas.

Common colors for inner and outer coated spiral steel pipes: black, gray, blue, red, white, green

Coating thickness of inner and outer plastic coated spiral steel pipes: PE (modified polyethylene) coating thickness is 400um-1000um, EP (epoxy resin) spraying thickness is 100um-400um

Coating method: PE (polyethylene) is hot-dip molded EP, (epoxy resin) is sprayed inside and outside

Internal and external coated spiral steel pipe product specifications: DN15-DN1660 Environmental temperature: -30 ℃ to 120 ℃

Internal and external coated spiral steel pipe connection methods: thread (DN15-DN100), groove (DN65-DN400), flange (applicable to any diameter), welding type, bimetallic connection, socket, pipe joint, sealed connection, etc

Spiral steel pipes coated with PE (modified polyethylene) for hot-dip molding or EP (epoxy resin) for internal and external coating are products with excellent corrosion resistance. At the same time, the coating itself also has good electrical insulation and will not produce electrical corrosion. Low water absorption rate, high mechanical strength, low friction coefficient, capable of achieving long-term use. It can also effectively prevent damage to plant roots and soil environmental stress. Convenient connection and easy maintenance.

Advantages of spiral steel pipe products coated with plastic both inside and outside

1. Adapt to buried and humid environments, and can withstand high and extremely low temperatures.

2. Strong anti-interference ability. If plastic coated steel pipes are used as cable conduits, they can effectively shield external signal interference.

3. It has good compressive strength, with a maximum pressure of up to 6Mpa.

4. Good insulation performance, as a protective tube for wires, it will never experience leakage.

5. No burrs, smooth pipe wall, suitable for threading wires or cables during construction.

Key points for construction and installation of inner and outer coated spiral steel pipes

It should be executed in accordance with the Technical Specification for Building Water Supply Coating Composite Pipe Engineering CECS125:2001.

The following construction equipment should be selected for the internal and external coating of spiral steel pipes:

(1) Cutting should be done using a metal saw;

(2) Special groove rolling machines should be used for groove pressing;

(3) Bending pipes should be done using a bending machine for cold bending;

(4) The threading should be carried out using an electric threading machine for pipe thread processing;

(5) The deburring and corner processing of coated steel pipe ports should be carried out using a file;

(6) The application of high-strength inorganic solvent liquid epoxy resin coating should use a small brush or toothbrush.

The construction procedure for spiral steel pipes coated with plastic inside and outside should meet the following requirements:

(1) Internally and externally coated spiral steel pipes should not be buried in reinforced concrete structural layers;

(2) Welding is prohibited during the installation of spiral steel pipes coated with plastic both inside and outside;

(3) The installation of spiral steel pipes coated with plastic inside and outside should gradually connect from a large diameter to a small diameter, and the pipe mouth should be promptly sealed;

(4) During transportation, loading and unloading, and construction on site, it is strictly prohibited to throw or violently impact spiral steel pipes coated with plastic inside and outside;

(5) When installing spiral steel pipes with inner and outer plastic coating, if the diameter is not greater than DN50, a pipe bending machine can be used for cold bending, but the bending curvature radius shall not be less than 8 times the diameter, and the bending angle shall not exceed 10 °.