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Seamless square pipe is a kind of long steel with hollow section and no joints around it.Steel pipe with hollow section is widely used for conveying fluid, such as conveying oil, natural gas, gas, water and some solid materials.Compared with round steel and other solid steel, steel tube is a kind of economic section steel with the same flexural and torsional strength and lighter weight. It is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe, automobile transmission shaft, bicycle frame and steel scaffolding used in construction.Using steel tube to make ring parts can improve material utilization, simplify manufacturing process and save material and processing time, such as rolling bearing bushing.

At present, steel pipe has been widely used to manufacture the ring and jack sleeve.Steel pipe or a variety of conventional weapons indispensable material, gun barrel, barrel to steel pipe to manufacture.Steel tubes can be divided into round tubes and special-shaped tubes according to the shape of cross-sectional area.Since a circle has the largest area with the same circumference, more fluid can be transported in a circular tube.In addition, when the annular section bears internal or external radial pressure, the force is more uniform, so most steel tubes are round tubes.However, the circular pipe also has certain limitations, such as under the condition of plane bending, the circular pipe is not as strong as square, rectangular pipe bending strength, some agricultural machinery framework, steel and wood furniture, etc., are commonly used square, rectangular pipe.Other special-shaped steel tubes with different section shapes are required according to different USES.

Manufacturing method
According to different production methods can be divided into hot rolling pipe, cold rolling pipe, cold drawing pipe, extrusion pipe and so on.
1.1. Hot-rolled seamless tubes are generally produced on a self-rolling pipe mill.The solid tube billet was cut into sections after inspection and surface defects were cleared
The required length shall be centered on the end face of the perforated end of the tube billet, and then sent to the heating furnace for heating and perforated on the puncher.At the same time
Continuous rotation and forward, under the action of the roller and the head, the blank inside gradually formed a cavity, known as the capillary tube.Then send to automatic rolling
Rolling continues on the pipe mill.Finally, the wall thickness is adjusted by the whole machine and the diameter is determined by the sizing machine to meet the specification requirements.Use continuous pipe rolling

The production of hot rolled seamless steel pipe is an advanced method.

1.2. For smaller and better quality seamless pipes, cold rolling, cold drawing or a combination of the two must be adopted.
Method.Cold rolling is usually carried out on a two-high mill. The steel tube is a circular hole in a circular groove with a fixed cone head and a variable section.
Middle rolling.Cold drawing is usually carried out on 0.5 ~ 100T single chain or double chain cold drawing machine.

1.3 In the extrusion method, the heated tube blank is placed in a closed extrusion cylinder, and the perforated rod and the extrusion rod move together to make
The extruder is extruded from a smaller die hole.This method can produce steel pipe with small diameter.

2. Chemical composition test
2.1 Domestic seamless tubes supplied according to chemical composition and mechanical properties, such as material :10, 15, 20, 25, 30, 35, 40, 45 Astm a106 Astm a53
The chemical composition of no. 50 steel shall comply with the provisions of GB/T699-88.The imported seamless pipes shall be inspected according to the relevant standards stipulated in the contract.
09MnV, 16Mn and 15MnV steel’s chemical composition shall conform to the provisions of GB1591-79.

2.2 Refer to the relevant section of GB223-84 Chemical Analysis Methods for Steel and Alloy for specific analysis methods.
2.3 Analysis Deviation Refer to GB222-84 “Allowable Deviation of Chemical Composition of Samples and Finished Products for Chemical Analysis of Steel”.

3. Physical performance inspection
3.1 Domestic seamless pipe supplied according to the mechanism performance, ordinary carbon steel according to GB/T700-88 class A steel manufacturing (but must
Ensure that the sulfur content does not exceed 0.050% and the phosphorus content does not exceed 0.045%), its mechanical properties should conform to the GB8162-87 table
A specified number.
3.2 Domestic seamless pipes supplied according to hydrostatic test must ensure the hydrostatic test specified in the standard.
3.3 The physical performance inspection of imported seamless pipe shall be conducted according to the relevant standards stipulated in the contract.
2.1. Seamless pipe is widely used.The general purpose seamless pipe is made of ordinary carbon structural steel and low alloy structure
Steel or alloy structural steel rolling, the largest production, mainly used for the delivery of fluid pipelines or structural parts.
2.2 Three types of supply according to different USES: A. Supply according to chemical composition and mechanical properties;B. Supply according to mechanical performance;C,
Supplied by hydrostatic test.Steel pipes supplied under classes A and B shall also be subjected to hydrostatic test if they are to be used for bearing liquid pressure.
2.3 Seamless pipes for special purposes include boiler seamless pipes, geological seamless pipes and petroleum seamless pipes.
4. Type
4.1 According to different production methods, seamless steel tubes can be divided into hot rolled pipe, cold rolled pipe, cold drawn pipe, extrusion pipe, etc.
4.2 There are circular tubes and special-shaped tubes according to their appearance.In addition to square and rectangular tubes, special-shaped tubes also have elliptical tubes, Semicircular, triangular, hexagonal, convex, quinted-shaped, etc.
4.3 According to the different materials, it can be divided into ordinary carbon structure tube, low alloy structure tube, high quality carbon structure tube and alloy junction Construction pipe, stainless pipe, etc.
4.4 According to the special purpose, there are boiler tubes, geological tubes, petroleum pipe, etc.

5. Specifications and appearance quality
Seamless pipe according to GB/T8162-87 provisions
5.1. Specification: Hot rolled pipe diameter 32 ~ 630mm.The wall thickness is 2.5 ~ 75mm.Cold rolling (cold drawing) pipe diameter 5 ~ 200mm.
The wall thickness is 2.5 ~ 12mm.
5.2 Appearance quality: the inner and outer surfaces of the steel tubes shall not have cracks, folds, rolls, delaminations, hairlines or scarring defects
Throughout the year.These defects should be completely removed and the wall thickness and outside diameter should not exceed the negative deviation after removal.
5.3 Both ends of the steel pipe should be cut into right angles and burrs should be removed.Gas cutting and heat saw cutting are allowed for steel tubes with wall thickness greater than 20mm
Cut.It may not be cut by agreement between the buyer and the seller.
4.4 The surface quality of cold-drawn or cold-rolled precision seamless steel tubes shall refer to GB3639-83.
6. Packing
As stipulated in GB2102-88.There are three kinds of steel pipe packing: strapping, packing, oil strapping or oil packing. Steel tube is A long strip of steel with a hollow section and no joints around it.Steel tube with hollow section is widely used for conveying fluid A pipeline, such as one that carries oil, natural gas, gas, water, and certain solid materials. Compared with round steel and other solid steel, It is a kind of economical cross-section steel with the same flexural and torsional strength and light weight. It is widely used in the manufacture of structural parts and mechanical parts.
Such as oil drill pipe, automobile drive shaft, bicycle frame and steel scaffolding used in construction.Ring parts made of steel tubes, Can improve the material utilization, simplify the manufacturing process, save material and processing time, such as rolling bearing ring, jack sleeve, etc.
At present, steel pipe has been widely used in manufacturing.Steel pipe or a variety of conventional weapons indispensable material, gun barrel, barrel, etc
To make.Steel tubes can be divided into round tubes and special-shaped tubes according to the shape of cross-sectional area.Since the perimeter is the same, the surface of the circle
Maximum volume, more fluid can be transported in a circular tube.In addition, the ring section is subjected to internal or external radial pressure
The force is uniform, so most steel tubes are round tubes.
However, the pipe also has some limitations. For example, under the condition of being subjected to plane bending, the pipe is less resistant to bending than the square pipe and the rectangular pipe
The strength is big, frame of a few farm machinery and implement, steel wood furniture is commonly used square, rectangular tube.Other cross sections are required according to different USES
Shaped shaped steel pipe.Should be associated with a wide range: fluid transfer pipe, boiler plant, engineering, machinery processing plants.


Post time: Nov-17-2020