Substandard precision seamless tubes have elliptical cross-sections. The reason is that manufacturers want to save materials, so the amount of pressure before the finished product’s second pass is too large. This significantly reduces the strength of the threaded steel, and it does not meet the standard dimensions of threaded steel. High-quality precision seamless tubes have a uniform composition, a high tonnage of cold cutting machines, and smooth and neat cutting head surfaces. Substandard materials often have a phenomenon of flesh falling off on the cutting head surface due to poor material quality, resulting in unevenness and a lack of metallic luster. Additionally, substandard materials have fewer cut heads, which may lead to larger ears at the head and tail. Substandard precision seamless tubes contain many impurities, and the density of steel is too small. The size deviation is severe. Therefore, without a vernier caliper, it can be weighed and checked. For example, for threaded steel 20, the maximum negative tolerance is 5% according to national standards. The theoretical weight of a single root is 120 kg when the length is 9m. The minimum weight should be 114 kg. If the actual weight of a single root measured is less than 114 kg, it is a substandard precision seamless tube because its negative deviation exceeds 5%. In general, it is better to weigh the entire batch to consider cumulative errors and probability theory. The inner diameter of substandard precision seamless tubes has significant fluctuations. The reasons are: 1. The steel temperature is unstable and has a yin and yang surface. 2. The composition of the steel is uneven. 3. Due to poor equipment and low foundation strength, the bouncing of the rolling mill is large. The steel may have significant changes in inner diameter in the same week, which can cause uneven stress and easy fracture. The trademark and printing of high-quality materials are relatively standardized. The spacing between two trademarks of large threads with a diameter above 16 is above IM. How to identify whether the seamless precision tube is substandard?

1. The cross-section of substandard seamless steel pipes is oval-shaped. The manufacturer wants to save materials, so the amount of pressure before the finished product’s second pass is too large. This significantly reduces the strength of the seamless steel pipe, and it does not meet the dimensional size of the seamless steel pipe’s shape.
2. The horizontal ribs of substandard precision seamless steel pipes are thin and low, and the phenomenon of not being filled often occurs. To achieve a large negative deviation, the pressure of the first few passes is too large, and the iron mold is too small, resulting in incomplete holes.
3. Substandard seamless steel pipes are easily scratched. The equipment of the seamless steel pipe manufacturer is rudimentary, and burrs are easily produced, which can scratch the surface of the steel.
4. Substandard seamless steel pipes lack metallic luster and are light red or similar to pig iron.
5. Substandard seamless steel pipes contain many impurities, the density of steel is too small, and the size deviation is severe. Therefore, without a vernier caliper, it can be weighed and checked.
6. High-quality seamless steel pipes have an average composition, the high tonnage of cold cutting machines, and smooth and neat cutting head surfaces. Substandard seamless steel pipes often have a phenomenon of flesh falling off on the cutting head surface due to poor material quality, resulting in unevenness and a lack of metallic luster. Weighing the entire batch is better, considering cumulative errors and probability theory. Additionally, because substandard manufacturers often produce fewer cut heads, they may have larger ears at the head and tail.

Substandard precision seamless tubes have elliptical cross-sections. The reason is that manufacturers want to save materials, so the amount of pressure before the finished product’s second pass is too large. This significantly reduces the strength of the threaded steel, and it does not meet the standard dimensions of threaded steel. High-quality precision seamless tubes have a uniform composition, a high tonnage of cold cutting machines, and smooth and neat cutting head surfaces. Substandard materials often have a phenomenon of flesh falling off on the cutting head surface due to poor material quality, resulting in unevenness and a lack of metallic luster. Additionally, substandard materials have fewer cut heads, which may lead to larger ears at the head and tail. Substandard precision seamless tubes contain many impurities, and the density of steel is too small. The size deviation is severe. Therefore, without a vernier caliper, it can be weighed and checked. For example, for threaded steel 20, the maximum negative tolerance is 5% according to national standards. The theoretical weight of a single root is 120 kg when the length is 9m. The minimum weight should be 114 kg. If the actual weight of a single root measured is less than 114 kg, it is a substandard precision seamless tube because its negative deviation exceeds 5%. In general, it is better to weigh the entire batch to consider cumulative errors and probability theory. The inner diameter of substandard precision seamless tubes has significant fluctuations. The reasons are: 1. The steel temperature is unstable and has a yin and yang surface. 2. The composition of the steel is uneven. 3. Due to poor equipment and low foundation strength, the bouncing of the rolling mill is large. The steel may have significant changes in inner diameter in the same week, which can cause uneven stress and easy fracture. The trademark and printing of high-quality materials are relatively standardized. The spacing between two trademarks of large threads with a diameter above 16 is above IM. How to identify whether the seamless precision tube is substandard?

1. The cross-section of substandard seamless steel pipes is oval-shaped. The manufacturer wants to save materials, so the amount of pressure before the finished product’s second pass is too large. This significantly reduces the strength of the seamless steel pipe, and it does not meet the dimensional size of the seamless steel pipe’s shape.
2. The horizontal ribs of substandard precision seamless steel pipes are thin and low, and the phenomenon of not being filled often occurs. To achieve a large negative deviation, the pressure of the first few passes is too large, and the iron mold is too small, resulting in incomplete holes.
3. Substandard seamless steel pipes are easily scratched. The equipment of the seamless steel pipe manufacturer is rudimentary, and burrs are easily produced, which can scratch the surface of the steel.
4. Substandard seamless steel pipes lack metallic luster and are light red or similar to pig iron.
5. Substandard seamless steel pipes contain many impurities, the density of steel is too small, and the size deviation is severe. Therefore, without a vernier caliper, it can be weighed and checked.
6. High-quality seamless steel pipes have an average composition, the high tonnage of cold cutting machines, and smooth and neat cutting head surfaces. Substandard seamless steel pipes often have a phenomenon of flesh falling off on the cutting head surface due to poor material quality, resulting in unevenness and a lack of metallic luster. Weighing the entire batch is better, considering cumulative errors and probability theory. Additionally, because substandard manufacturers often produce fewer cut heads, they may have larger ears at the head and tail.