Basic knowledge of seamless steel pipe and welded steel pipe

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Basic knowledge of seamless steel pipe and welded steel pipe 1. Classification of pipe fittings

1. Classification according to production methods
(1) Seamless pipes-hot rolled pipes, cold rolled pipes, cold drawn pipes, extruded pipes,
pipe jacks (2) welded pipes (a) according to process-arc welded pipe , Electric resistance welded pipe (high frequency, low frequency), gas welded pipe, furnace welded pipe (b) According to the welding seam-straight seam welded pipe, spiral welded pipe

2, according to the section shape classification
(1) simple section steel pipe-round steel pipe, square steel pipe, Oval steel pipes, triangular steel pipes, hexagonal steel pipes, rhombus steel pipes, octagonal steel pipes, semicircular steel rounds, other
(2) complex section steel pipes-unequal-sided hexagonal steel pipes, five-petal plum-shaped steel pipes, double convex steel pipes , Double-concave steel pipe, melon seed steel pipe, conical steel pipe, corrugated steel pipe, case steel pipe, others

3. Classified by wall thickness-thin-walled steel pipe, thick-walled steel pipe
4. Classified by purpose-pipe steel pipe, heat Steel pipes for industrial equipment, steel pipes for machinery industry, steel pipes for petroleum, geological drilling, container steel pipes, steel pipes for chemical industry, steel pipes for special purposes, and others.

Second, seamless steel pipe

It is a long steel with a hollow section and no joints on the periphery. Steel pipes have a hollow section and are used in large quantities as pipelines for conveying fluids, such as pipelines for conveying oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, steel pipe is lighter when the bending and torsion strength is the same. It is a kind of economical cross-section steel, which is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile transmission shafts, and bicycles. And steel scaffolding used in building construction. The use of steel pipes to manufacture ring-shaped parts can increase the utilization rate of materials, simplify the manufacturing process, and save materials and processing man-hours, such as rolling bearing rings, jack sleeves, etc., which have been widely used for manufacturing at present. Steel pipes are also an indispensable material for various conventional weapons. Gun barrels and barrels are all made of steel pipes. Steel pipes can be divided into round pipes and special-shaped pipes according to different cross-sectional area shapes. Since the circle area is large under the condition of equal circumference, more fluid can be transported by the circular tube. In addition, when the ring section bears internal or external radial pressure, the force is relatively uniform. Therefore, most steel pipes are round pipes. However, round pipes also have certain limitations. For example, under the condition of plane bending, round pipes are not as strong as square and rectangular pipes. Some agricultural machinery frameworks, steel and wood furniture, etc. often use square and rectangular pipes.

According to different purposes, special-shaped steel pipes with other cross-sectional shapes are required.

1. Seamless steel pipe for structure (GB/T8162 is a seamless steel pipe used for general structure and mechanical structure.
2. Seamless steel pipe for fluid transportation (GB/T8163) is a general purpose steel pipe used for conveying water, oil, gas and other fluids. Seamless steel pipes.
3. Seamless steel pipes for low and medium pressure boilers (GB3087) are used to manufacture superheated steam pipes and boiling water pipes for low and medium pressure boilers of various structures, as well as superheated steam pipes, large smoke pipes, and small smoke pipes for locomotive boilers. Carbon structural steel hot-rolled and cold-drawn (rolled) seamless steel pipes for arch brick pipes.
4. Seamless steel pipes for high-pressure boilers (GB5310) are carbon steels used for the heating surface of water-tube boilers with high pressures and above. , Alloy steel and stainless heat-resistant steel seamless steel pipes.
5. High-pressure seamless steel pipes for fertilizer equipment (GB6479) are suitable for chemical equipment and pipelines with a working temperature of -40~400℃ and a working pressure of 10~30Ma. Plain structural steel and alloy steel seamless steel tubes.
6. Seamless steel pipes for petroleum cracking (GB9948) are seamless steel pipes suitable for furnace tubes, heat exchangers and pipelines in petroleum refineries.
7. The steel pipe for geological drilling (YB235) is a steel pipe used for core drilling by the geological department. According to the purpose, it can be divided into drill pipe, drill collar, core pipe, casing and sedimentation pipe.
8. Seamless steel pipe for diamond core drilling (GB3423) is a seamless steel pipe used for drill pipes, core rods, and casings for diamond core drilling.
9. Petroleum drilling pipe (YB528) is a seamless steel pipe with inner or outer thickening at both ends of oil drilling. There are two types of steel pipes: wire and non-wired. Wired pipes are connected by joints, and non-wired pipes are connected with tool joints by butt welding.
10. Carbon steel seamless steel pipes for ships (GB5213) are carbon steel seamless steel pipes used in the manufacture of Class I pressure piping systems, Class II pressure piping systems, boilers and superheaters. The working temperature of the carbon steel seamless steel pipe wall does not exceed 450℃, and the working temperature of the alloy steel seamless steel pipe wall exceeds 450℃.
11. Seamless steel pipes for automobile axle sleeves (GB3088) are hot-rolled seamless steel pipes of carbon structural steel and alloy structural steel used in the manufacture of automobile axle sleeves and axle tubes of drive axle housings.
12. High-pressure oil pipes for diesel engines (GB3093) are cold drawn seamless steel pipes used to manufacture high-pressure pipes for diesel engine injection systems.
13. Precision inner diameter seamless steel tubes for hydraulic and pneumatic cylinders (GB8713) are cold-drawn or cold-rolled precision seamless steel tubes with precise inner diameters for the manufacture of hydraulic and pneumatic cylinders.
14. Cold-drawn or cold-rolled precision seamless steel pipe (GB3639) is a cold-drawn or cold-rolled precision seamless steel pipe with high dimensional accuracy and good surface finish for mechanical structures and hydraulic equipment. The use of precision seamless steel pipes to manufacture mechanical structures or hydraulic equipment can greatly save machining man-hours, improve material utilization, and at the same time help improve product quality.
15.Stainless steel seamless steel pipes for structural use (GB/T14975) are hot-rolled (extruded, Expanded) and cold drawn (rolled) seamless steel tubes.
16. Stainless steel seamless steel pipes for fluid transportation (GB/T14976) are hot-rolled (extruded, expanded) and cold-drawn (rolled) seamless steel pipes made of stainless steel used to transport fluids.
17. Special-shaped seamless steel pipe is a general term for seamless steel pipes with cross-sectional shapes other than round pipes. According to the different shape and size of the steel pipe section, it can be divided into equal wall thickness special-shaped seamless steel pipe (code D), unequal wall thickness special-shaped seamless steel pipe (code BD), variable diameter special-shaped seamless steel pipe (code BJ). Special-shaped seamless steel pipes are widely used in various structural parts, tools and mechanical parts. Compared with round pipes, special-shaped pipes generally have larger moments of inertia and section modulus, and have greater bending and torsion resistance, which can greatly reduce structural weight and save steel.

3. Welded steel pipes

Welded steel pipes, also called welded pipes, are steel pipes made by welding steel plates or steel strips after crimping. Welded steel pipes have simple production process, high production efficiency, many varieties and specifications, and less equipment, but their general strength is lower than seamless steel pipes. Since the 1930s, with the rapid development of strip continuous rolling production and the advancement of welding and inspection technology, the quality of welds has been continuously improved, and the variety and specifications of welded steel pipes have increased, and it has replaced seamless in more and more fields. Steel Pipe. Welded steel pipes are divided into straight seam welded pipes and spiral welded pipes according to the form of welds.

Longitudinal welded pipe has simple production process, high production efficiency, low cost and rapid development. The strength of spiral welded pipes is generally higher than that of straight seam welded pipes. A narrower blank can be used to produce welded pipes with larger pipe diameters, and a billet with the same width can also be used to produce welded pipes with different pipe diameters. But compared with the straight seam pipe of the same length, the weld length is increased by 30-100%, and the production speed is lower. Therefore, most of the smaller diameter welded pipes use straight seam welding, and the large diameter welded pipes mostly use spiral welding.

1. Welded steel pipe (GB/T3092) for low pressure fluid transportation is also called general welded pipe, commonly known as clarinet. It is a welded steel pipe used for conveying water, gas, air, oil and heating steam and other generally lower pressure fluids and other purposes. The wall thickness of the steel pipe is divided into ordinary steel pipe and thick steel pipe; the connection end form is divided into non-threaded steel pipe (smooth pipe) and threaded steel pipe. The specification of the steel pipe is expressed by the nominal diameter (mm), which is the approximate value of the inner diameter. It is customary to express in inches, such as 11/2. Welded steel pipes for low-pressure fluid transportation are not only directly used to transport fluids, but also as raw pipes for galvanized welded steel pipes for low-pressure fluid transportation.

2. Galvanized welded steel pipe for low pressure fluid transportation (GB/T3091) is also called galvanized welded steel pipe, commonly known as white pipe. It is a hot-dip galvanized welded (furnace welded or electric welded) steel pipe used for conveying water, gas, air oil, heating steam, warm water and other generally lower pressure fluids or other purposes. The wall thickness of the steel pipe is divided into ordinary galvanized steel pipe and thick galvanized steel pipe; the connection end form is divided into non-threaded galvanized steel pipe and threaded galvanized steel pipe. The specification of the steel pipe is expressed by the nominal diameter (mm), which is the approximate value of the inner diameter. It is customary to express in inches, such as 11/2.

3. Ordinary carbon steel wire casing (GB3640) is a steel pipe used to protect wires in electrical installation projects such as industrial and civil construction and installation of machinery and equipment.

4. Straight seam electric welded steel pipe (YB242) is a steel pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. Usually divided into metric electric welded steel pipe, electric welded thin-walled pipe, transformer cooling oil pipe and so on.

5. Spiral seam submerged arc welded steel pipe for pressure-bearing fluid transportation (SY5036) is a hot-rolled steel strip as a tube blank, which is spirally formed at regular temperature and welded by double-sided submerged arc welding. It is used for the spiral seam of pressure-bearing fluid transportation. Steel Pipe. The steel pipe has strong pressure-bearing capacity and good welding performance. After various strict scientific inspections and tests, it is safe and reliable to use. The steel pipe has a large diameter, high transmission efficiency, and can save investment in laying pipelines. Mainly used in pipelines for transporting oil and natural gas.

6. Spiral seam high-frequency welded steel pipe for pressure-bearing fluid transportation (SY5038) is a hot-rolled steel strip as a tube blank, which is spirally formed at regular temperature and welded by high-frequency lap welding. It is used for pressure-bearing fluid transportation. Seam high-frequency welded steel pipe. The steel pipe has strong pressure-bearing capacity and good plasticity, which is convenient for welding and processing. After various strict and scientific inspections and tests, it is safe and reliable to use. The steel pipe has a large diameter and high transmission efficiency. It can save investment in laying pipelines. Mainly used to lay pipelines for transporting oil and natural gas.

7. Spiral seam submerged arc welded steel pipe (SY5037) for general low-pressure fluid transportation is made of hot-rolled steel strip coils as tube blanks, which are often spirally formed by double-sided automatic submerged arc welding or single-sided welding. Submerged arc welded steel pipes for general low-pressure fluid transportation such as gas, air and steam.

8. Spiral seam high-frequency welded steel pipe (SY5039) for general low-pressure fluid conveying is made of hot-rolled steel strip coils, which are spirally formed at regular temperature and welded by high-frequency lap welding. It is used for general low-pressure fluid conveying. Frequency welded steel pipe.

9. Spiral welded seam steel pipe for pile (SY5040-83) is made of hot-rolled steel strip coils as tube blanks, which are spirally formed at regular temperature, and are made by double-sided submerged arc welding or high-frequency welding. They are used in civil construction structures and docks. Steel pipes for foundation piles such as, bridges, etc. 1. Classification of pipe fittings

1. Classification according to production methods

(1) Seamless pipes-hot rolled pipes, cold rolled pipes, cold drawn pipes, extruded pipes,

pipe jacks (2) welded pipes (a) according to process-arc welded pipe , Electric resistance welded pipe (high frequency, low frequency), gas welded pipe, furnace welded pipe (b) According to the welding seam-straight seam welded pipe, spiral welded pipe

2, according to the section shape classification

(1) simple section steel pipe-round steel pipe, square steel pipe, Oval steel pipes, triangular steel pipes, hexagonal steel pipes, rhombus steel pipes, octagonal steel pipes, semicircular steel rounds, other

(2) complex section steel pipes-unequal hexagonal steel pipes, five-petal plum blossom steel pipes, double convex steel pipes , Double-concave steel pipe, melon seed steel pipe, conical steel pipe, corrugated steel pipe, case steel pipe, others

3. Classified by wall thickness-thin-walled steel pipe, thick-walled steel pipe

4. Classified by purpose-pipe steel pipe, heat Steel pipes for industrial equipment, steel pipes for machinery industry, steel pipes for petroleum, geological drilling, container steel pipes, steel pipes for chemical industry, steel pipes for special purposes, and others.

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Two, seamless steel pipe

It is a long steel with a hollow section and no joints on the periphery. Steel pipes have a hollow section and are used in large quantities as pipelines for conveying fluids, such as pipelines for conveying oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, steel pipe is lighter when the bending and torsion strength is the same. It is a kind of economical cross-section steel, which is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile transmission shafts, and bicycles. And steel scaffolding used in building construction. The use of steel pipes to manufacture ring-shaped parts can increase the utilization rate of materials, simplify the manufacturing process, and save materials and processing man-hours, such as rolling bearing rings, jack sleeves, etc., which have been widely used for manufacturing at present. Steel pipes are also an indispensable material for various conventional weapons. Gun barrels and barrels are all made of steel pipes. Steel pipes can be divided into round pipes and special-shaped pipes according to different cross-sectional area shapes. Since the circle area is the largest under the condition of the same circumference, more fluid can be transported with a circular tube. In addition, when the ring section bears internal or external radial pressure, the force is relatively uniform. Therefore, most steel pipes are round pipes. However, round pipes also have certain limitations. For example, under the condition of plane bending, round pipes are not as strong as square and rectangular pipes. Some agricultural machinery frameworks, steel and wood furniture, etc. often use square and rectangular pipes.

According to different purposes, special-shaped steel pipes with other cross-sectional shapes are required.

1. Seamless steel pipe for structure (GB/T8162 is a seamless steel pipe used for general structure and mechanical structure.

2. Seamless steel pipe for fluid transportation (GB/T8163) is a general purpose steel pipe used for conveying water, oil, gas and other fluids. Seamless steel pipes.

3. Seamless steel pipes for low and medium pressure boilers (GB3087) are used to manufacture superheated steam pipes and boiling water pipes for low and medium pressure boilers of various structures, as well as superheated steam pipes, large smoke pipes, and small smoke pipes for locomotive boilers. High-quality carbon structural steel hot-rolled and cold-drawn (rolled) seamless steel pipes for arch brick pipes.

4. Seamless steel pipes for high-pressure boilers (GB5310) are high-quality carbon used for the heating surface of water-tube boilers with high pressures and above. Plain steel, alloy steel and stainless heat-resistant steel seamless steel pipes.

5. High-pressure seamless steel pipes for fertilizer equipment (GB6479) are suitable for chemical equipment and pipelines with a working temperature of -40~400℃ and a working pressure of 10~30Ma High-quality carbon structural steel and alloy steel seamless steel tubes.

6. Seamless steel pipes for petroleum cracking (GB9948) are seamless steel pipes suitable for furnace tubes, heat exchangers and pipelines in petroleum refineries.

7. The steel pipe for geological drilling (YB235) is a steel pipe used for core drilling by the geological department. According to the purpose, it can be divided into drill pipe, drill collar, core pipe, casing and sedimentation pipe.

8. Seamless steel pipe for diamond core drilling (GB3423) is a seamless steel pipe used for drill pipes, core rods, and casings for diamond core drilling.

9. Petroleum drilling pipe (YB528) is a seamless steel pipe with inner or outer thickening at both ends of oil drilling. There are two types of steel pipes: wire and non-wired. Wired pipes are connected by joints, and non-wired pipes are connected with tool joints by butt welding.

10. Carbon steel seamless steel pipes for ships (GB5213) are carbon steel seamless steel pipes used in the manufacture of Class I pressure piping systems, Class II pressure piping systems, boilers and superheaters. The working temperature of the carbon steel seamless steel pipe wall does not exceed 450℃, and the working temperature of the alloy steel seamless steel pipe wall exceeds 450℃.

11. Seamless steel tubes for automobile axle sleeves (GB3088) are high-quality carbon structural steel and alloy structural steel hot-rolled seamless steel tubes for the manufacture of automobile axle sleeves and drive axle axle tubes.

12. High-pressure oil pipes for diesel engines (GB3093) are cold-drawn seamless steel pipes used in the manufacture of high-pressure pipes for diesel engine injection systems.

13. Precision inner diameter seamless steel tubes for hydraulic and pneumatic cylinders (GB8713) are cold-drawn or cold-rolled precision seamless steel tubes with precise inner diameters for the manufacture of hydraulic and pneumatic cylinders.

14. Cold-drawn or cold-rolled precision seamless steel pipe (GB3639) is a cold-drawn or cold-rolled precision seamless steel pipe with high dimensional accuracy and good surface finish for mechanical structures and hydraulic equipment. The use of precision seamless steel pipes to manufacture mechanical structures or hydraulic equipment can greatly save machining man-hours, improve material utilization, and at the same time help improve product quality.

15.Stainless steel seamless steel pipes for structural use (GB/T14975) are hot-rolled (extruded, Expanded) and cold drawn (rolled) seamless steel tubes.

16. Stainless steel seamless steel pipes for fluid transportation (GB/T14976) are hot-rolled (extruded, expanded) and cold-drawn (rolled) seamless steel pipes made of stainless steel used to transport fluids.

17. Special-shaped seamless steel pipe is a general term for seamless steel pipes with cross-sectional shapes other than round pipes. According to the different shape and size of the steel pipe section, it can be divided into equal wall thickness special-shaped seamless steel pipe (code D), unequal wall thickness special-shaped seamless steel pipe (code BD), variable diameter special-shaped seamless steel pipe (code BJ). Special-shaped seamless steel pipes are widely used in various structural parts, tools and mechanical parts. Compared with round pipes, special-shaped pipes generally have larger moments of inertia and section modulus, and have greater bending and torsion resistance, which can greatly reduce structural weight and save steel.

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3. Welded steel pipes

Welded steel pipes, also called welded pipes, are steel pipes made by welding steel plates or steel strips after crimping. Welded steel pipes have simple production process, high production efficiency, many varieties and specifications, and less equipment, but their general strength is lower than seamless steel pipes. Since the 1930s, with the rapid development of high-quality strip continuous rolling production and the advancement of welding and inspection technology, the quality of welds has been continuously improved, and the variety and specifications of welded steel pipes have increased, and they have replaced non-products in more and more fields. Seam the steel pipe. Welded steel pipes are divided into straight seam welded pipes and spiral welded pipes according to the form of welds.

Longitudinal welded pipe has simple production process, high production efficiency, low cost and rapid development. The strength of spiral welded pipes is generally higher than that of straight seam welded pipes. A narrower blank can be used to produce welded pipes with larger pipe diameters, and a billet with the same width can also be used to produce welded pipes with different pipe diameters. But compared with the straight seam pipe of the same length, the weld length is increased by 30-100%, and the production speed is lower. Therefore, most of the smaller diameter welded pipes use straight seam welding, and the large diameter welded pipes mostly use spiral welding.

1. Welded steel pipe (GB/T3092) for low pressure fluid transportation is also called general welded pipe, commonly known as clarinet. It is a welded steel pipe used for conveying water, gas, air, oil and heating steam and other generally lower pressure fluids and other purposes. The wall thickness of the steel pipe is divided into ordinary steel pipe and thick steel pipe; the connection end form is divided into non-threaded steel pipe (smooth pipe) and threaded steel pipe. The specification of the steel pipe is expressed by the nominal diameter (mm), which is the approximate value of the inner diameter. It is customary to express in inches, such as 11/2. Welded steel pipes for low-pressure fluid transportation are not only directly used to transport fluids, but also as raw pipes for galvanized welded steel pipes for low-pressure fluid transportation.

2. Galvanized welded steel pipe for low pressure fluid transportation (GB/T3091) is also called galvanized welded steel pipe, commonly known as white pipe. It is a hot-dip galvanized welded (furnace welded or electric welded) steel pipe used for conveying water, gas, air oil, heating steam, warm water and other generally lower pressure fluids or other purposes. The wall thickness of the steel pipe is divided into ordinary galvanized steel pipe and thick galvanized steel pipe; the connection end form is divided into non-threaded galvanized steel pipe and threaded galvanized steel pipe. The specification of the steel pipe is expressed by the nominal diameter (mm), which is the approximate value of the inner diameter. It is customary to express in inches, such as 11/2.

3. Ordinary carbon steel wire casing (GB3640) is a steel pipe used to protect wires in electrical installation projects such as industrial and civil construction and installation of machinery and equipment.

4. Straight seam electric welded steel pipe (YB242) is a steel pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. Usually divided into metric electric welded steel pipe, electric welded thin-walled pipe, transformer cooling oil pipe and so on.

5. Spiral seam submerged arc welded steel pipe for pressure-bearing fluid transportation (SY5036) is a hot-rolled steel strip as a tube blank, which is spirally formed at regular temperature and welded by double-sided submerged arc welding. It is used for the spiral seam of pressure-bearing fluid transportation. Steel Pipe. The steel pipe has strong pressure-bearing capacity and good welding performance. After various strict scientific inspections and tests, it is safe and reliable to use. The steel pipe has a large diameter, high transmission efficiency, and can save investment in laying pipelines. Mainly used in pipelines for transporting oil and natural gas.

6. Spiral seam high-frequency welded steel pipe for pressure-bearing fluid transportation (SY5038) is a hot-rolled steel strip as a tube blank, which is spirally formed at regular temperature and welded by high-frequency lap welding. It is used for pressure-bearing fluid transportation. Seam high-frequency welded steel pipe. The steel pipe has strong pressure-bearing capacity and good plasticity, which is convenient for welding and processing. After various strict and scientific inspections and tests, it is safe and reliable to use. The steel pipe has a large diameter and high transmission efficiency. It can save investment in laying pipelines. Mainly used to lay pipelines for transporting oil and natural gas.

7. Spiral seam submerged arc welded steel pipe (SY5037) for general low-pressure fluid transportation is made of hot-rolled steel strip coils as tube blanks, which are often spirally formed by double-sided automatic submerged arc welding or single-sided welding. Submerged arc welded steel pipes for general low-pressure fluid transportation such as gas, air and steam.

8. Spiral seam high-frequency welded steel pipe (SY5039) for general low-pressure fluid conveying is made of hot-rolled steel strip coils, which are spirally formed at regular temperature and welded by high-frequency lap welding. It is used for general low-pressure fluid conveying. Frequency welded steel pipe.

9. Spiral welded seam steel pipe for pile (SY5040-83) is made of hot-rolled steel strip coils as tube blanks, which are spirally formed at regular temperature, and are made by double-sided submerged arc welding or high-frequency welding. They are used in civil construction structures and docks. Steel pipes for foundation piles such as, bridges, etc.