The scarring defect in the anti-corrosion steel pipe is the pit on the inner surface of the steel pipe, which is similar to the size of a soybean grain. Most of the scarring has gray-brown or gray-black foreign bodies. The influencing factors of internal scarring are: deoxidizer, injection process, smooth mandrel and other factors. Let’s take a look at how to control the inner surface defects of anti-corrosion steel pipes with anti-corrosion steel pipe manufacturers:
1. Deoxidizer
The oxide is required to be in molten form when the mandrel is pre-pierced. Its strength and other strict requirements.
1) The particle size of the deoxidizer powder is usually controlled at 16 mesh.
2) The content of sodium stearate in the deoxidizer should reach more than 12%, so that it can be fully incinerated in the inner cavity of the capillary.
3) Determine the injection volume of the deoxidizer according to the inner surface area of the capillary tube, usually 1.5-2.0g/dm2, and the deoxidant dose of the capillary tube with different diameters and lengths is different.
2. Injection process parameters
1) The injection pressure should be matched with the diameter and length of the capillary tube, which not only ensures strong purging and sufficient incineration, but also prevents the incompletely incinerated deoxidizer from being blown away from the capillary tube by the airflow.
2) The purging time should be adjusted according to the directness and length of the capillary tube, and it is the criterion that no suspended metal oxides in the capillary tube are blown out again.
3) The height of the nozzle should be adjusted according to the diameter of the capillary to ensure good alignment. The nozzles are sorted out in each shift, and the nozzles are removed for cleaning after a long-term light stop. In order to ensure that the deoxidizer is evenly purged on the inner wall of the capillary, an optional device is used in the spraying deoxidizer station, and it is equipped with a rotating air pressure.
3. The mandrel is smooth
If the mandrel smoothing effect is not good or the temperature of the mandrel smoothing agent is insufficient, internal scarring will occur. In order to increase the temperature of the mandrel, a method of cooling with only one cooling water can be used.
During the production process, it is necessary to strictly control the temperature of the mandrel to ensure that the surface temperature of the mandrel before spraying the lubricating agent is 80-120℃, and the temperature of the mandrel should not be higher than 120℃ for a long time, so as to ensure that the lubricating agent on the surface is dry and dense before pre-piercing. , the operator should usually check the smoothness of the mandrel.