Seamless steel pipes are widely used, so how can the quality of seamless steel pipes be guaranteed? How to identify the quality? What is the implementation standard? Let's take a look together next.

Seamless steel pipe implementation standard

1. Seamless steel pipe for structure: GB/T8162-2008

2. Ground seam steel pipe for conveying fluid: GB/T8163-2008

3. Low and medium pressure boiler tubes Seamless steel tubes for boilers: GB/T3087-2008

4. High pressure seamless pipe for boiler: GB/T5310-2008 (ST45, 8-Ⅲ type)

5. High-pressure seamless steel pipes for fertilizer equipment: GB/T6479-2000

6. Seamless steel pipe for geological drilling: YB235-70

7. Seamless steel pipe for oil drilling: YB528-65

8. Seamless steel pipe for petroleum cracking: GB/T9948-2006

9. Special seamless pipe for oil drill collar: YB691-70

10. Seamless steel pipes for automobile axle shafts: GB/T3088-1999

11. Seamless steel pipe for ships: GB/T5312-1999

12. Cold-drawn cold-rolled precision seamless steel pipe: GB/T3639-1999

13. Various alloy tubes 16Mn, 27SiMn, 15CrMo, 35CrMo, 12CrMov, 20G, 40Cr, 12Cr1MoV, 15CrMo

In addition, there are GB/T17396-2007 (hot-rolled seamless steel pipe for hydraulic props), GB3093-1986 (high-pressure seamless steel pipe for diesel engines), GB/T3639-1983 (cold drawn or cold-rolled precision seamless steel pipe), GB /T3094-1986 (cold drawn seamless steel pipe special-shaped steel pipe), GB/T8713-1988 (precision inner diameter seamless steel pipe for hydraulic and pneumatic cylinders), GB13296-2007 (stainless steel seamless steel pipe for boilers and heat exchangers), GB/T14975 -1994 (Stainless steel seamless steel pipe for structural use), GB/T14976-1994 (Stainless steel seamless steel pipe for fluid transportation), GB/T5035-1993 (Seamless steel pipe for automobile half-shaft casing), API SPEC5CT-1999 (casing and tubing) Specification) and so on.

How to identify the quality of seamless steel pipes?

1. Fake and shoddy steel pipes are easy to fold.

Folding is a variety of fold lines formed on the surface of the steel pipe, and this defect often runs through the longitudinal direction of the entire product. The reason for folding is due to the pursuit of high efficiency by fake and inferior manufacturers. The pressing amount is too large and ears are produced. The folding will occur during the next rolling. The folded product will crack after bending, and the strength of the steel will be greatly reduced.

2. Fake and inferior steel pipes often have pitting appearance.

The pitted surface is a defect of irregular unevenness on the surface of the steel due to severe wear of the rolling groove. As the counterfeit and inferior steel pipe manufacturers are pursuing profits, the groove rolling often exceeds the standard.

3. The surface of fake and inferior steel pipes is easy to produce scars.

There are two reasons: (1). The material of fake and inferior steel pipe is uneven and there are many impurities. (2) The guide and guard equipment of the fake and inferior material manufacturers is simple and easy to stick to the steel. These impurities will easily cause scars after biting the roll.

4. The surface of fake and inferior materials is prone to cracks. The reason is that its blank is adobe. The adobe has many pores.

During the process, due to the effect of thermal stress, cracks are generated, and there are cracks after rolling.

5. Fake and inferior steel pipes are easy to scratch. The reason is that the equipment of fake and inferior steel pipe manufacturers is simple and easy to produce burrs and scratch the steel surface. Deep scratches reduce the strength of steel.

6. Fake and inferior steel pipes have no metallic luster and are light red or a color similar to pig iron. There are two reasons. Its blank is adobe. 2. The rolling temperature of counterfeit and inferior materials is not standard, and their steel temperature is visually inspected, so that rolling cannot be carried out in the specified austenite area, and the performance of the steel will naturally not reach the standard.

7. The cross ribs of fake and inferior steel pipes are thin and low, and the phenomenon of dissatisfaction often occurs. The reason is that in order to achieve a large negative tolerance, the reduction of the first few passes of the finished product is too large, the iron type is too small, and the hole type is not full.

8. The cross-section of the counterfeit steel pipe is elliptical. The reason is that in order to save material, the reduction amount of the first two passes of the finished roll is too large. The strength of this kind of rebar is greatly reduced, and it does not meet the standard of the shape of rebar. .

9. The composition of the steel is uniform, the tonnage of the cold shear is high, and the end face of the cutting head is smooth and tidy. However, due to the poor material, the end face of the cutting head often has the phenomenon of meat loss, that is, it is uneven and has no metallic luster. Moreover, because the products of the fake and inferior material manufacturers have fewer cuts, big ears will appear at the beginning and the end.

10. Fake and inferior steel pipe material contains many impurities, the density of steel is too small, and the size is severely out of tolerance, so if there is no vernier caliper, it can be weighed and checked. For example, for rebar 20, the national standard stipulates that the large negative tolerance is 5%. When the length is 9M, its single theoretical weight is 120 kg, and its small weight should be: 120 X (l-5%) = 114 kg , The actual weight of a single piece weighed out is less than 114 kg, which is a fake and inferior steel because its negative tolerance exceeds 5%. Generally speaking, the effect of phasing weighing will be better, mainly considering the problem of cumulative error and probability theory.

11. The inner diameter of the fake and inferior steel pipe fluctuates greatly, the reason is: l, the steel temperature is unstable and there is a positive and negative side. 2. The composition of steel is not uniform. 3. Due to the simple equipment and low foundation strength, the rolling mill bounces greatly. There will be large changes in the same week, and the uneven force of such steel bars is prone to fracture.

12. The trademark and printing of the tube are relatively standardized.

13. For three steel pipes with large threads with a diameter of 16 or more, the distance between the two trademarks is more than IM.

14. The longitudinal ribs of counterfeit and inferior steel rebar are often wavy.

15. As the manufacturers of counterfeit and inferior steel pipes have no driving, the packaging is relatively loose. The side is oval.

The above is the content shared by the editor, I hope it will be helpful to everyone. If you have more knowledge about seamless steel pipes, please contact us in time.