How to control the defects of the inner surface of the thick-walled seamless steel pipe?

How to control the defects of the inner surface of the thick-walled seamless steel pipe?

1. In addition to metal oxides

Metal oxides are specified in a molten state when the mandrel is pre-threaded. Its range, etc. are strictly managed.

1) The powder particle size distribution of the metal oxide removing agent is generally specified at around 16 meshes.
2) The composition of sodium stearate in the metal oxide removal agent should be more than 12%, so that it can be fully ignited in the inner cavity of the capillary.

3) According to the total area of the inner surface of the capillary, the injection amount of the metal oxide removal agent is clearly defined, which is generally 1.5-2.0g/dm2. The amount of metal oxide removal used by the capillary gas generator with different diameters and lengths is different.

2. Main parameters of processing technology of gas generator

1) The working pressure of the gas generator should be matched with the diameter and length of the capillary tube, so as to ensure strong purging and sufficient ignition, and no metal oxide removal agent that is not completely ignited can be blown away from the capillary tube by the cyclone.

2) The purging time should be adjusted according to the immediate and length of the capillary tube, and it is the norm that no floating hydroxide in the capillary tube is blown out.

3) The relative height of the nozzle should be adjusted according to the diameter of the capillary to ensure good alignment. The nozzle should be cleaned once for each train. The seamless steel pipe manufacturer recommends that the nozzle should be removed for cleaning after long-term shutdown. In order to ensure that the metal oxide removal agent is evenly purged on the inner wall of the capillary, the optional equipment is used in the metal oxide removal agent removal process of the gas generator, and it is equipped with a rotating standard air pressure.

3. Mandrel lubrication

The actual effect of mandrel lubricating is not very good or the temperature of the mandrel lubricating fluid is too low, which will cause internal scab. In order to improve the temperature of the mandrel, the method of cooling the circulating water only once can be adopted. During the production process, the temperature of the mandrel should be strictly controlled to ensure that the surface temperature of the mandrel before painting the lubricant is 80-120 °C, and the temperature of the mandrel should not be higher than 120 °C for a long time, so as to ensure that the lubricating fluid on the surface before pre-piercing is dry and smooth. High density, the operator should check the lubrication of the mandrel from time to time.

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