How to avoid selecting inferior seamless steel pipe

　　1. The cross bar of the fake seamless steel pipe is thin and low, and it is often under filled. The reason is that the manufacturer exceeds the large negative dimension tolerance, the reduction of the front surface of the finished product is slightly large, the iron mold is small, and the plate hole is under filled.

　　2. The cross section of fake seamless steel pipe is elliptical, so it is the manufacturer to save raw materials. The reduction of the first two rolls of the finished product is slightly larger, and the compressive strength of this kind of threaded steel is greatly reduced, and it does not conform to the specification of the size of threaded steel.

　　3. The composition of high quality seamless steel pipe is well proportioned, the tonnage of cold shear is high, the inner hole of cutting head is smooth and neat, and the inner hole of cutting head of fake and inferior materials often has the condition of meat falling because of poor materials, that is, uneven and no metal texture.

　　4. The material of fake and inferior seamless steel pipe contains a lot of residues, the density of steel is small, and the specification deviation is serious, so it can carry out weighing verification without micrometer. Generally speaking, the actual effect of integral phase equivalent will be stronger. The key is to fully consider the problems of accumulated deviation and rate theory.

　　5. The nominal diameter and specification of fake seamless steel pipe fluctuate greatly, the reasons are:The steel temperature is not stable, and there is a sunny and shady side.The composition of steel is not even.Because the equipment is simple and crude, the subgrade compressive strength is low, and the jump of the extruder is large. There will be a great change in the nominal diameter in the same week, so the building steel support is not symmetrical, easy to cause fracture.

　　6. The trademark logo and hot stamping of high quality materials are relatively standard.

　　7. For the large external thread with a diameter of about 16 in the three seamless steel pipes, the interval between the two trademark logos will be about 1.

　　8. The longitudinal bars of the thread steel of the fake seamless steel pipe are often wavy.