1. Crusting (including warping)
Characteristics: The inner and outer surfaces of the seamless steel pipe for hot-rolled fertilizers are colorful.
Causes: 1) The inclusions in the lubricant form a hard mass with the iron oxide scale on the surface.
2) The back end of the waste pipe has ears, which are detached in the uniformity and are pressed against the outer surface of the fertilizer steel pipe to form crusted.
3) The head is of poor quality (fragile) and its slag is pressed onto the inner surface.
4) When the high-alloy fertilizer special steel pipe is perforated, the surface of the plug is oxidized or the receiving groove is improperly positioned.
2. Pit (also known as depression)
Features: Irregular local depressions and impressions on the inner surface of the hot rolled tube.
Causes: 1) Trauma due to scarring or other collisions.
2) The surface of the hole type is adhered with metal, etc., so that the surface of the hole type is formed into a bump and is imprinted on the surface of the seamless steel pipe for hot rolling fertilizer.
3. Concave surface (also known as touch)
Characteristics: The wall of the special pipe for hot-rolled fertilizer shows a phenomenon of convexity in the outer concave and no damage to the pipe wall.
Causes: 1) Hits during lifting to cause collisions.
2) The swaying is too large after being bitten by the straightening machine.
4. Pitting (also known as pockmark)
Characteristics: The inner surface of the steel pipe has a local point-like fine pit, and some also appear periodically.
Causes: 1) The rolling mill or the sizing roller has a rough groove with small projections.
2) The surface is pressed into the scale or the surface is seriously corroded.
3) The steel pipe is pickled and spotted on the surface of the pickled surface.
4) When using the molybdenum alloy head to wear the special seamless steel pipe for high alloy fertilizer, the glass lubricant does not melt and the softening point of the glass lubricant is too high due to the bump or preheating temperature of the head, and the tube is easily caused by perforation. The inner wall of the pit.
5. Convex surface (also known as drum kit)
Features: On the outer surface of the pipe, a regular bulge of uneven size is presented.
Cause: There are pittings or depressions on the rolls of the automatic pipe mill.
Characteristics: The surface of the special steel pipe for hot-rolled fertilizers presents a smooth spiral depression.
Causes: 1) The straightener roll angle is too small.
2) The amount of pressing is too large or sharp edges are caused by excessive wear of the rolls.
Features: The surface is spiral or linear groove-like defect, most of which can see the bottom of the groove.
Causes: 1) The scratches caused at the puncher and the leveling machine are caused by the loss of the guide plate and the outlet nozzle or the adhesion of the scale, the wear of the plug or the surface of the front roller table is not smooth.
2) The scratches generated at the pipe mill are due to the fact that the outer diameter of the piercing pipe is larger than the width of the work roll of the pipe mill, or the center line of the return roller is inconsistent.
3) Mechanical damage to other mechanical abrasions (such as roller conveyors, cold beds, straightening and transportation).
8. Inner spiral
Characteristics: The inner surface of the special steel pipe for fertilizers exhibits spiral irregularities.
Causes: 1) The expansion of the machine is too large.
2) Local wear of the rolls, heads, etc.
3) The roll diameter is too small or the wear is severe.
4) The rolling mill is poorly adjusted and the tool selection is unreasonable.
5) The head is bent and violently beats.
6) The thickness of the waste pipe is uneven.
9. Blue line
Features: The outer surface of the steel pipe presents a longitudinal linear print corresponding to the opening of the sizing machine.
Causes: 1) The rolls are misaligned or worn.
2) Poor turning of the groove.
3) The size of the uniform machine is too large.
Features: Full circle or partial cutting residual sawtooth appears in the circumferential direction at the end of the seamless steel tube
Cause: The pipe cutter blade angle is not appropriate.
For more: https://www.permanentsteel.com/productshow/seamless-steel-pipe.html
For more information, visit: https://www.permanentsteel.com/productshow/seamless-steel-pipe.html