We all know that most of the added elements give standard range values when an element is at a certain value, and the element's balance theory should be adjusted accordingly. A high level of spiral balance is calculated for a range of values and is in full compliance with the requirements of the smelting process. On the other hand, some domestic steel mills pay insufficient attention to residual elements, which may be because many residual elements do not limit the standard of elements. The content of residual elements is small, but sometimes seriously affects the performance of the material, sometimes affects the deformation of the secondary processing, and sometimes affects the service life of the material. More professional buyers, sometimes limit the remaining elements in these particular purchase specifications.

The Vickers hardness (HV) Vickers hardness test is also an indentation test method, which is to press a regular square pyramidal diamond indenter with a selected test force (F) into the test surface with an angle of 1360 between the opposite surfaces. After holding time, remove the test force and measure the length of the two diagonals of the indentation. The Vickers hardness value is the quotient obtained by dividing the test force by the surface area of the indentation. The calculation formula is: HV--Vickers hardness symbol, N/mm2 (MPa); Arithmetic mean of the diagonals, mm. Vickers hardness test force F is 5 (49.03), 10 (98.07), 20 (196.1), 30 (294.2), 50 (490.3), 100 (980.7) Kgf (N), and other six levels, the hardness value can be measured The range is 5 ~ 1000HV. During construction, it should be checked whether the groundwater and rainwater have touched the pipeline. If the water touches the pipeline, the jacket of the pipeline should be dried. While installing the pipe, it should be handled lightly, and collision and falling are prohibited. The insulation layer of the insulation pipe is prohibited from colliding with the burning fire to prevent the insulation layer from being burned down. Pipes and fittings should be stored on relatively flat ground, stacked neatly, and the height of stacking should not exceed 1.5 meters.

The influence of several main chemical elements in spiral steel pipes on performance:

1. Phosphorus: Phosphorus is a harmful element, and as the content increases, the strength and hardness of the greenhouse pipe will increase, and the plasticity and toughness will decrease significantly.

2. Silicon: When the content is less than 1%, the strength of the greenhouse tube can be improved, and the plasticity and toughness are not significantly affected.

3. Carbon: Carbon is the most important element to determine the function of greenhouse tubes. As the carbon content increases, the strength and hardness of the spiral steel pipes increase, while the plasticity and toughness decrease.

4. Oxygen: Oxygen is a harmful element in steel, which will reduce the mechanical properties of the spiral tube, especially its toughness. The low melting point formed by oxides also deteriorates the weldability of the greenhouse tube.

5. Sulfur: Sulfur is a very harmful element. The low melting point formed by the sulfide makes the greenhouse pipe prone to thermal cracks during welding, forming a hot brittle phenomenon, which is called hot brittleness. Sulfur reduces the weldability, impact resistance, fatigue resistance, and corrosion resistance of steel.

6. Manganese: Manganese can reduce the thermal brittleness caused by sulfur and oxygen, and improve the thermal processing performance of greenhouse tubes.

7. Nitrogen: The effect of nitrogen on the properties of the spiral tube is similar to that of carbon and phosphorus. It will increase the strength of the spiral tube, but the plasticity, especially the resistance, will decrease significantly.