1. Geometrical size and shape inspection of steel pipe:
a. Inspection of steel pipe wall thickness: micrometer, ultrasonic thickness gauge, no less than 8 points on both ends and record.
b. Check the outer diameter and ellipticity of the steel pipe: calipers, vernier calipers, ring gauges, measure the maximum and minimum points
c. Steel tube length check: steel tape measure, manual and automatic length measurement.
d. Checking the bend of steel pipe: ruler, level (1m), feeler gauge, thin line to measure the bend of every meter, full-length bend.
e. Bevel angle and obtuse edge inspection of steel pipe end face: square ruler, card board.
2. the steel pipe surface quality inspection:
a. Artificial visual inspection: lighting conditions, standards, experience, logo, steel pipe rotation.
b. Nondestructive flaw detection: Ultrasonic flaw detection UT, eddy current flaw detection ET, magnetic particle MT and magnetic flux leakage flaw detection, electromagnetic ultrasonic flaw detection, penetration flaw detection.
The inferior quality special-shaped seamless steel pipe has the following characteristics:
1. Whether the surface is smooth
Due to the raw materials used, the poor quality of the steel rolling equipment, the unprofessional technical methods, and the low cost, the inferior shaped seamless steel pipes will have surface folding, numbness, scarring, cracks, and easy scratches. Generally, this situation can be passed Visual inspection revealed.
Therefore, it is recommended that the majority of consumers encounter these situations, and they must treat them rationally. Do not buy inferior square tubes for the sake of cheapness. The strength and hardness of these special-shaped seamless steel tubes do not reach the standard, which will affect their future use.
2. Whether the surface has metallic luster
Some inferior special-shaped seamless steel tubes are made of adobe, and the temperature is not standard. The steel temperature is grasped by visual inspection. In this way, the rolled steel will show the color of red or pig iron. There is no metal gloss and performance of genuine special-shaped seamless steel tubes. Not to mention the above.
3. Whether the cross section and the cutting head are smooth
In order to save raw materials, the inferior shaped seamless steel pipe has a large reduction in the first two passes of the finished roll, resulting in an oval cross-section. The inferior square tube often has a flesh-off cross-section, that is, unevenness. Therefore, once you find that the cross section of the square tube is oval and the cut head is uneven, you should be alert. This is a poor quality square tube.
4. Whether the size and weight are qualified
Generally, the inferior and irregular shaped seamless steel tubes have large fluctuations in size, and in order to save raw materials, most of them have insufficient weight. So when you check the sample, you can ask for accurate square tube size and weight.