Seamless steel pipe is widely used, so widely used, how to ensure the quality of seamless steel pipe? How to identify the quality? What is the implementation standard? Next, let's learn about it together.
Seamless steel pipe executive standard
1. Seamless steel pipe for structure: GB/T8162-2008
2. Ground seam steel pipe for conveying fluid: GB/T8163-2008
3. Seamless steel pipe for low and medium pressure boiler tube: GB/T3087-2008
4. High pressure seamless tube for boiler: GB/T5310-2008(ST45, 8-Ⅲ)
5. High pressure seamless steel pipe 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, oil drill collar special seamless pipe: YB691-70
10. Seamless steel pipe for automobile axle shaft: GB/T3088-1999
11. Seamless steel pipe for ships: GB/T5312-1999
12. Cold drawn cold rolled precision seamless steel tube: GB/T3639-1999
13. Various alloy tubes 16Mn, 27SiMn, 15CrMo, 35CrMo, 12CrMov, 20G, 40Cr,12Cr1MoV,15CrMo
In addition, there are also GB/T17396-2007 (hot rolled seamless steel pipe for hydraulic prop), GB3093-1986 (high pressure seamless steel pipe for diesel engine), 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 cylinder), GB13296-2007 (stainless steel seamless steel pipe for boiler and heat exchanger), GB/T14975-1994 (stainless steel seamless for structure steel pipe), GB/T14976-1994 (stainless steel seamless steel pipe for fluid transportation) GB/T5035-1993 (seamless steel pipe for automobile axle shaft casing), API SPEC5CT-1999 (specification for casing and tubing), etc.
How to identify the quality of seamless steel pipe?
1. Fake and inferior steel pipes are prone to folding.
Folding is a variety of broken 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 the folding is that the fake and inferior manufacturers pursue high efficiency, the reduction is too large, and the ears are produced. The folding will occur when the next rolling is carried out. The folded products will crack after bending, and the strength of the steel will be greatly reduced.
2. The appearance of fake and inferior steel pipes often has pockmarked surface.
Pit surface is due to the rolling groove wear caused by the steel surface irregular uneven defects. Due to the shoddy steel pipe manufacturers to pursue profits, often appear rolling groove rolling exceeded.
3. The surface of fake and inferior steel pipes is easy to produce scarring.
There are two reasons:(1), shoddy steel pipe material is not uniform, more impurities. (2), fake and inferior material manufacturers guide equipment is crude, easy to stick steel, these impurities bite the roll after easy to produce scarring.
4. The surface of fake and inferior materials is easy to crack, because its blank is adobe, adobe has many pores, and adobe is over cooling.
In the process, due to the effect of thermal stress, cracks are produced, 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. Depth scratches reduce the strength of the steel.
6. Fake and inferior steel pipes have no metallic luster and are light red or similar to pig iron. The reasons are 2.2. Its blank is adobe. 2. The rolling temperature of fake and inferior materials is not standard, and their steel temperature is visually inspected, so that they cannot be rolled according to the specified austenite area, and the performance of the steel naturally cannot reach the standard.
7. The transverse 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 pressure reduction of the first few lanes of the finished product is too large, the iron type is too small, and the hole type is not satisfied.
8. The cross section of the fake steel pipe is oval, because the manufacturer, in order to save materials, has a large reduction in the first two passes of the finished roll, which greatly reduces the strength of the rebar and does not meet the standard of the external dimension of the rebar.
9. The composition of the steel is uniform, the tonnage of the cold shearing machine is high, and the end face of the cutting head is smooth and neat. However, due to the poor material quality of the fake and inferior materials, the end face of the cutting head often has the phenomenon of falling meat, that is, uneven and without metallic luster. Moreover, due to the fact that the products of fake and inferior materials manufacturers cut less heads, there will be big ears at the head and tail.
10. The fake and inferior steel pipe material contains many impurities, the density of the steel is too small, and the size difference is serious, so it can be weighed and checked without vernier caliper. For example, for rebar 20, the national standard stipulates that the large negative tolerance is 5%, the theoretical weight of a single piece is 120kg when the gauge is 9M, and its small weight should be: 120 X(l-5) = 114kg. If the actual weight of a single piece weighed out is smaller than 114kg, it is fake steel, because its negative tolerance exceeds 5%. Generally speaking, the whole phase weighing effect will be better, mainly considering the problem of cumulative error and probability theory.
11. The inner diameter of fake and inferior steel pipes fluctuates greatly because: L, steel temperature is unstable with yin and yang surfaces. 2, the composition of steel is not uniform. 3, due to the equipment is simple, the foundation strength is low, the bounce of the rolling mill is large. There will be large changes in the same week, and such steel bars are prone to fracture due to uneven stress.
12. The trademark and printing of the tube are relatively standardized.
13. For large threads with a diameter of 16 or more of three steel pipes, the spacing between the two trademarks is above IM.
14. The longitudinal bars of shoddy steel rebar are often wavy.
15, fake steel pipe manufacturers because there is no driving, so packing is loose. The sides are oval in shape.
These are the contents that Xiaobian shares with you, hoping to be helpful to you. If you have more knowledge about seamless steel pipe, please contact us in time.