The transmission line tower of the buried pipeline adopts plastic-coated steel pipe, which is composed of towers connected by tower pole devices. The pole tower is made of steel. The surface of the tower pole steel and the inner and outer surfaces of the tower pole are hot-dipped with modified polyethylene plastic layer. The plastic-coated steel pipe is a steel pipe coated with red modified epoxy resin powder inside and outside. It is a new type of steel pipe made of steel pipe through sandblasting chemical pretreatment, preheating, inner and outer coating, curing, post-treatment and other processes.

It successfully solves the problems of burial, rust and scaling of plastic-coated steel pipe. There will be no pipe blocking and spray blocking, which improves the service life of fire water supply pipelines. Plastic-coated steel pipes mainly focus on the excellent mechanical properties of steel and the excellent chemical corrosion resistance of polymer materials. The product has excellent anti-static, high-pressure and flame-retardant properties, and can withstand harsh use environments. Its super corrosion resistance greatly improves the service life of the pipeline.

This steel pipe has good pressure resistance and thermal insulation performance. It mainly protects the wires, so leakage will not occur at all. So far, plastic-coated steel pipe manufacturers are changing these advantages. The pipe wall is relatively smooth and burr-free. It is suitable for crossing cables or wires during construction.

Fire-fighting buried pipe plastic-coated steel pipe has the advantages of smooth wall thickness, good drainage performance, low fluid resistance, and no scaling, which can greatly reduce losses compared with other pipes. At the same time, the linear expansion coefficient of large-diameter plastic-coated pipes is very small, making it very advantageous as a main pipeline, greatly overcoming the defects of other plastic pipes and ordinary pipes with large linear expansion coefficients.

Plastic-coated steel pipe is an upgraded product of traditional steel-plastic pipes and galvanized pipes. It has comprehensive properties such as high strength, high elongation, good low-temperature brittleness, low expansion coefficient, corrosion resistance, wear resistance, and low fluid resistance. It belongs to a new type of water supply and drainage, anti-corrosion green large-diameter pipeline, which is more and more widely used in domestic industry.

3PE anti-corrosion steel pipe spraying technology, most domestic 3PE anti-corrosion steel pipe production technology adopts the production and processing technology of “epoxy powder spraying, adhesive and polyethylene lateral extrusion, winding rolling”, because the powder and electrostatic thermal spraying method does not require rolling system, thus solving the problem of thin weld coating of spiral structure welded steel pipes, saving a large amount of plastic extruders and other mechanical equipment on the production line, and reducing production energy consumption.

Specific construction: The steel pipe after shot blasting and rust removal is heated to 210°C to 220°C at a moderate temperature, and the epoxy powder is still in a molten state. The adhesive and PE are extruded into thin sheets with an extruder, sprayed and wrapped around the steel pipe, and then flattened with a roller; the epoxy powder is in powder form, and the adhesive and PE are in granular form, and only electrostatic spraying and plasticization can be used Extrusion wrap.

There are many reasons for the bending of steel pipes, such as the thermal impact of the welding seam, eccentricity during forming, compression force, imbalance of bending force, etc. But fundamentally speaking, bending is the result of internal stress in the steel pipe. Simply put, bending is stress imbalance. So, does a straight steel pipe have no internal stress? no. Straight steel pipes also have internal stress, but the internal stress of straight pipes is smaller. ​

What is internal stress? Temperature, an interaction force between molecules that causes deformation due to the influence of external forces. When steel pipes are formed and welded, they will also be affected by external forces such as welding temperature and forming bending, resulting in internal stress. The cross-section of the steel pipe is an annular shape, and two basic stresses will be generated in this annular area: a force parallel to the annular shape and a force perpendicular to the annular shape. Parallel stresses will cause the tube to become out of round; vertical stresses will cause the tube to bend. Therefore, there is a cold diameter expansion process in the production process of straight seam steel pipes. The purpose is to eliminate the internal stress of the steel pipe and increase the strength of the straight seam steel pipes. ​

The pipe that needs to be straightened is fed into the lower roller of the straightening machine from the feeding device at the left end (or right end) of the machine. The upper roller moves downward to press the pipe and stop after reaching the corresponding position. The upper and lower rollers are respectively inclined at a certain angle with the axis of the straightened pipe. The hyperbolic generatrix of the rollers matches the outer diameter of the pipe and forms an envelope shape.

The three upper rollers are pressed against the pipe under the action of their respective hydraulic cylinders, and the two lower rollers are driven to rotate by their respective hydraulic motors, driving the pipe to both rotate around the axis and move along the axial direction. Changing the rotation direction of the hydraulic motor can change the rotation direction and axial movement direction of the pipe to achieve reversible straightening. The straightened pipe is then sent to the material rack through the discharging device at the other end. For pipes with large local bending deformation, the punches at both ends can be used to perform partial straightening first, and then perform overall straightening.

I believe many people have doubts about the storage of anti-corrosion steel pipes. Let’s take a look at the storage of anti-corrosion steel pipes.

1. The appearance of anti-corrosion steel pipes entering and leaving the warehouse needs to be inspected as follows:

① Inspect each root to ensure that the surface of the polyethylene layer is flat and smooth, with no dark bubbles, pitting, wrinkles, or cracks. The overall color needs to be uniform. There should be no excessive corrosion on the surface of the pipe.

② The curvature of the steel pipe should be <0.2% of the length of the steel pipe, and its ovality should be ≤0.2% of the outer diameter of the steel pipe. The surface of the entire pipe has local unevenness <2mm.

2. The following points need to be paid attention to when transporting anti-corrosion steel pipes:

① Loading and unloading: Use a hoist that does not damage the pipe mouth and do not damage the anti-corrosion layer. All construction tools and equipment must comply with regulations during loading and unloading. Before loading, the anti-corrosion grade, material, and wall thickness of the pipes should be checked in advance, and mixed installation is not advisable.

②Transportation: A thrust baffle needs to be installed between the trailer and the cab. When transporting anti-corrosion pipes, they need to be tied firmly and measures to protect the anti-corrosion layer should be taken in a timely manner. Rubber plates or some soft materials should be installed between the anti-corrosion pipes and the frame or columns, and between the anti-corrosion pipes.

3. What are the storage standards:

① Pipes, pipe fittings, and valves need to be properly stored according to the instructions. Pay attention to inspection during storage to avoid corrosion, deformation, and aging.

② There are also materials such as glass cloth, heat-wrap tape and heat-shrinkable sleeves that need to be stored in a dry and well-ventilated warehouse.

③ Pipes, pipe fittings, valves and other materials can be classified and stored in the open air. Of course, the storage site selected must be flat and free of stones, and there must be no accumulation of water on the ground. The slope is guaranteed to be 1% to 2%, and there are drainage ditches.

④ Anti-corrosion pipes in the warehouse need to be stacked in layers, and the height needs to ensure that the pipes do not lose their shape. Stack them separately according to different specifications and materials. Soft cushions should be placed between each layer of anti-corrosion pipes, and two rows of sleepers should be laid under the lower pipes. The distance between stacked pipes should be >50mm from the ground.

⑤ If it is on-site construction, there are some storage requirements for pipes: two support pads need to be used at the bottom, the distance between them is about 4m to 8m, the anti-corrosion pipe must not be less than 100mm from the ground, the support pads and anti-corrosion Pipes and anti-corrosion pipes must be padded with flexible spacers.

The hot-dip coating surface of seamless steel pipes will have crystallization patterns of the coating metal during solidification. This crystallization pattern is especially obvious for galvanized seamless pipes, showing the appearance of beautiful zinc crystals, thus becoming the appearance of hot-dip galvanized seamless pipes. This important feature is usually called “zinc flower”. When the galvanizing solution contains other metal impurities, zinc splatter occurs. The size and shape of zinc flowers depend on the type and amount of impurities contained in the galvanizing solution. Common impurities include lead, aluminum, antimony, bismuth, tin and other metals.

According to the size of the zinc flower diameter, it can be divided into the following three types:

1. Big Zinc Flower

The spangles with a diameter larger than 3mm that can be distinguished by the naked eye are called large spangles. Some people also call them normal spangles or natural spangles. The internationally recognized optimal size is 8~12mm.

2. Small zinc flower

Zinc flowers with a diameter of 1~2mm are called small zinc flowers. When the hot-dip galvanized seamless pipe comes out of the galvanizing pool and sprays water mist or zinc powder onto the unsolidified zinc layer, one water mist droplet and one zinc powder particle will form a crystallization center, causing zinc to bloom per unit area. As the quantity increases and becomes smaller, small zinc flowers that can be distinguished by the naked eye will form on the surface of galvanized seamless pipes. Traditionally, the products produced by this process are called small zinc flowers. Because this process often results in uneven zinc patterns, uneven surface color, and high production costs, this process is currently not widely used.

3. No zinc flowers

The zinc flowers on the pipe cannot be seen with the naked eye, which is called no zinc flowers, also known as zero zinc flowers. This is accomplished by controlling the chemical composition of the zinc liquid. When hot-dip galvanizing, only a certain amount of aluminum is added to the zinc liquid, without adding lead, antimony, or tin, to produce zinc-free products. This process does not increase equipment or production costs, and can achieve a uniform surface appearance. Therefore, this process has been widely promoted and applied around the world.

In nature, lead and zinc are symbiotic deposits. When pyrometallurgy is used, the density of liquid lead is higher in the lower part and the density of molten zinc is lower in the upper part, so they can be separated. However, the saturation concentration of lead in zinc liquid is 2%, so there is a large amount of lead in crude zinc. Hot-dip galvanizing has a history of more than 150 years. At that time, there was no modern refining technology, and only crude zinc was used for hot-dip galvanizing production. Because lead was mixed into the zinc liquid, zinc spatter would definitely appear on the hot-dip galvanized pipe. Therefore, for a long time, there has been a misconception that hot-dip galvanized seamless pipes must have zinc flowers. Without zinc flowers, it is not a hot-dip galvanized seamless pipe. In fact, from the perspective of long-term use, the performance of hot-dip galvanized seamless pipes without zinc flowers will be better.

Productos de zinc puro por inmersión en caliente, el código es GI.

Las características de los productos de zinc puro por inmersión en caliente son una superficie bonita, una buena resistencia a la corrosión y una buena procesabilidad.

Se divide en dos tipos: las flores de zinc normales y las flores sin zinc. Los anteriores productos de galvanización en caliente siempre tenían salpicaduras de zinc en la superficie porque el plomo del líquido de zinc no se podía extraer con mucha pureza. Por lo tanto, nuestro antiguo concepto es que el galvanizado en caliente tiene salpicaduras. Con las necesidades de la industria automovilística, si hay que pintar las chapas galvanizadas en caliente para automóviles, las salpicaduras de zinc afectarán a la pintura. Posteriormente, reduciendo el contenido de plomo en los lingotes de zinc y el zinc líquido a decenas de ppm, podemos fabricar productos sin salpicaduras o con muy pocas. Para algunos fines especiales, como la construcción, si todavía le gustan las flores de zinc grandes, podemos obtener flores de zinc grandes y bonitas añadiendo elementos como plomo o antimonio al líquido de zinc.

Productos aleados, su código es GA.

La ventaja de este producto es que la adherencia de la pintura en la superficie del revestimiento es especialmente buena, la resistencia a la corrosión tras el pintado también es muy buena y su soldabilidad también es muy buena.

Sin embargo, el aspecto de su superficie es gris, por lo que no es apto para su uso al descubierto. No recomendamos utilizarlo sin pintar, porque su revestimiento contiene hierro 7-15%. Si no se pinta, esta parte del hierro producirá un óxido rojo muy ligero. Aunque el óxido rojo no se expandirá más en términos de resistencia a la corrosión, la apariencia no es muy buena.

Por lo tanto, el principal uso de la aleación de zinc y hierro es en aplicaciones de revestimiento, como los paneles exteriores de los coches y los paneles laterales de los frigoríficos. Los productos GA pueden utilizarse directamente. En el caso de los frigoríficos, puede pulverizarse y adherirse directamente sin tratamiento previo. El sexo también es muy bueno.

Productos de aluminio-zinc

Se caracteriza por una excelente resistencia a la corrosión y un aspecto superficial muy bello. Sus flores de zinc parecen hermosas escamas de pez. Son muy bonitas y pueden utilizarse desnudas.

Su resistencia a la corrosión es de 2 a 6 veces superior a la de nuestro galvanizado en caliente ordinario. Su resistencia a altas temperaturas también es relativamente buena. Se puede utilizar a 300 ℃ sin decoloración. Si se utiliza por un corto tiempo, también tiene un mejor rendimiento a 700 ℃. Excelente retención del color y excelente reflexión del calor.

Por ello, un gran número de estos productos se utilizan actualmente en la industria de la construcción y los electrodomésticos.