What Is Steel Pipe?

Steel with a hollow cross section whose length is much larger than the diameter or perimeter. Divided into circular, square, rectangular and special-shaped steel pipes according to the cross-sectional shape; divided into carbon structural steel pipes, low-alloy structural steel pipes, alloy steel pipes and composite steel pipes according to the material; divided into transportation pipelines, engineering structures, Used for thermal equipment, petrochemical industry, machinery manufacturing, geological drilling, high pressure equipment steel pipe, etc .; according to the production process, it is divided into seamless steel pipe and welded steel pipe. Two types of welded steel pipes are divided into straight seam welded pipes and spiral seam welded steel pipes.

By production method

Steel pipes can be divided into two categories according to production methods:

(1) GB3087-2008 "Seamless Steel Pipe for Low and Medium Pressure Boilers". The chemical composition test method is in accordance with the relevant parts of GB222-84 and GB223 "Chemical Analysis Methods for Steel and Alloy".

(2) GB / T5310-2008 "Seamless Steel Pipe for High Pressure Boilers". The chemical composition test method is according to the relevant parts of GB222-84 and "Chemical Analysis Methods for Steel and Alloy" and GB223 "Chemical Analysis Methods for Steel and Alloy".

(3) The chemical composition inspection of imported boiler steel pipes shall be carried out in accordance with the relevant standards stipulated in the contract.

Steel pipes are divided into seamless steel pipes and welded steel pipes. The production process of seamless steel pipe is to pierce a solid tube or ingot into a hollow capillary tube, and then roll it into a steel tube of the required size. The different methods of perforation and tube rolling constitute different methods of producing seamless steel tubes. The production process of welded steel pipe is to bend the tube blank (steel plate or strip steel) into a tube, and then weld the gap into a steel pipe. Different forming and welding methods constitute different methods of producing welded steel pipes.

Seamless steel pipes are mainly produced by hot rolling. Extrusion is mainly used to produce low-plasticity high-alloy steel pipes or shaped steel pipes and composite metal pipes that are difficult to perforate. The cold-rolled and cold-drawn methods can continue to process hot-rolled pipes into small diameter and thin-walled steel pipes. The process of welding steel pipe is simple, the production efficiency is high, the cost is low, and the product variety is expanding. The main production methods of seamless steel pipes and welded steel pipes are shown in Tables 1 and 2.

Table 1 Production methods of seamless steel pipes and welded steel pipes

production method		Basic process
		perforation	Rolled tube
heat Roll law	On the automatic tube rolling mill Rolling	Round tube blank in two-roller perforator Perforation	Two-roller rolling with return roll Tube machine with short head rolling
	On the cycle tube mill Rolling	Round steel ingots or tube billets in two-roller type Punching on a punching machine; Square or polygonal steel ingots in water Perforation on press	Cycle of changing face shape in band Rolling mill with long mandrel
	Continuous tube mill Rolling up	Round tube blank in three roll or two roll Punching on a punching machine; Continuous casting of billet or square steel ingot Perforation on roller pressure perforator	Long on 7 to 9 continuous pipe mills Mandrel rolling; With tension reducer
	On a three-roll tube mill Rolling	Round tube blank in two-roller perforator Perforation; Continuous casting slab in three roll perforator Perforation	Belt length on three-roll cross-rolling mill Mandrel rolling
	On the extended tube mill Rolling	Punching on a two-roller puncher	In the form of disc-shaped tension guide rollers Long mandrel on two-roll skew mill Rolling
	Planetary rolling mill Rolling up	Using cast hollow tube blanks	Rolling on a planetary tube mill

Table 2

production method		Basic process
		perforation	Rolled tube
Pipe jacking		Cup hair on a hydraulic press tube	Jacking on the jacking machine
Extrusion method		Tube blank is heated on the extruder Extrusion	Can continue rolling or drawing
Cold rolling			Using hot rolled pipe in cold rolling mill Rolling up
Cold drawing			Use hot rolled or cold rolled tube Pull on the machine
furnace weld	Chain Furnace Welding	The heated pipe blank passes through the welded pipe mold forming	Forming and welding at the same time
	Continuous furnace welding	Heated tube blank in roll forming Bending molding on welding machine	Forming and welding at the same time
Electricity weld	Resistance welding	Continuous bending on roll forming machines Curved forming	Welding on resistance pipe welding machine
	Arc welding	Press molding on a press or Curled on a roll bender (Straight seam), connected on the molding machine Continuous bending molding (spiral seam)	Welding on a submerged arc automatic pipe welding machine Pick up
	Inductive welding	Continuous bending on roll forming machines Curved forming	Welding on an induction pipe welding machine

(1) Specifications: The specifications of spiral steel pipes shall be specified in the import and export trade contract. Generally it should include the standard brand (type code), the nominal diameter of the steel bar, the nominal weight (mass), the specified length and the tolerance value of the above indicators. Chinese standards recommend spiral pipe series with nominal diameters of 8, 10, 12, 16, 20, and 40 mm. The delivery length is divided into two types: fixed length and double length. The selection range of China's export rebar sizing is 6-12m, and that of Japan-made rebar sizing is 3.5-10m.

(2) Appearance quality: Surface quality. Relevant standards stipulate the surface quality of rebar, requiring that the ends be cut straight, the surface must be free of cracks, scars, and folds, and there must be no harmful defects in use; Allowable deviations in dimensions. The requirements for the curvature of the rebar and the geometry of the rebar are specified in the relevant standards. As stipulated in Chinese standards, the bending degree of straight steel bars is not greater than 6mm / m, and the total bending degree is not greater than 0.6% of the total length of the reinforcing bars.

Seamless steel pipe is a long steel with a hollow section and no seams around it. Seamless steel pipe has a hollow section and can be used as a pipeline for transporting fluids, such as pipelines for transporting oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, seamless steel pipe is lighter in weight when it has the same bending and torsional strength. It is an economical cross-section steel and is widely used in the manufacture of structural and mechanical parts, such as petroleum drill rods and automobile transmission shafts. , Bicycle frames and steel scaffolding used in building construction. Manufacture of annular parts with seamless steel pipes can improve the utilization rate of materials, simplify the manufacturing process, save materials and processing hours, such as rolling bearing rings, jack sleeves, etc., and are widely manufactured with steel pipes. Steel pipe is also an indispensable material for various conventional weapons, and barrels, barrels, etc. must be made of steel pipes. Steel tubes can be divided into round tubes and special-shaped tubes according to the different cross-sectional area shapes. Since the circular area is the largest under the condition of equal perimeter, more fluid can be transported by the circular tube. In addition, when the cross section of the ring is subjected to internal or external radial pressure, the force is more uniform. Therefore, most steel pipes are round pipes. However, round pipes also have certain limitations. For example, under the condition of being bent in a plane, round pipes are not as strong as square or rectangular pipes. Some agricultural machinery skeletons, steel-wood furniture, etc. are often used in square and rectangular pipes. According to different uses, special-shaped steel pipes with other cross-sectional shapes are also required.

1. Seamless steel tubes for structure (GB / T8162-2008) are seamless steel tubes for general and mechanical structures.

2. Seamless steel pipe for fluid transportation (GB / T12771-2008) is a general seamless steel pipe used to transport water, oil, gas and other fluids.

3.Seamless steel tubes for low and medium pressure boilers (GB / T3087-2008) are used to make various structures of low and medium pressure boilers overheated

Sanitary stainless steel pipe

Hot rolled and cold drawn (rolled) seamless steel tubes for high-quality carbon structural steel for steam pipes, boiling water pipes, and superheated steam pipes, large smoke pipes, small smoke pipes and arch brick pipes for locomotive boilers.

4. High-pressure boiler seamless steel pipe (GB5310-2008) is a high-quality carbon steel, alloy steel and stainless heat-resistant steel seamless steel pipe used for the heating surface of water tube boilers with high pressure and above.

5. High-pressure seamless steel pipe for chemical fertilizer equipment (GB6479-2000) is a high-quality carbon structural steel and alloy steel seamless steel pipe suitable for chemical equipment and pipelines with an operating temperature of -40 ~ 400 and an operating pressure of 10-30Ma.

6. Seamless steel pipe for petroleum cracking (GB9948-2006) is a seamless steel pipe suitable for furnace tubes, heat exchangers and pipes in petroleum refineries.

7. Geological drilling steel pipe (YB235-70) is a steel pipe used by the geological department for core drilling. It can be divided into drill pipe, drill collar, core pipe, casing and sedimentation pipe according to its purpose.

8.Diamond core drilling seamless steel pipe (GB / T3423-82) is a seamless steel pipe used for drilling cores, core rods and casings of diamond core drilling.

9. Petroleum drilling pipe (YB528-65) is a seamless steel pipe used for internal thickening or external thickening at both ends of oil drilling. Steel pipe is divided into two types: wire and non-wire. The wire tube is connected with a joint, and the wireless tube is connected with the tool joint by a butt welding method.

10. Carbon steel seamless steel pipe for ships (GB5312-2009) is a carbon steel seamless steel pipe used in the manufacture of Class I pressure-resistant piping systems, Class pressure-resistant piping systems, boilers and superheaters. The working temperature of carbon steel seamless steel pipe wall does not exceed 450 , and the working temperature of alloy steel seamless steel pipe wall exceeds 450 .

11. Seamless steel pipe for automobile axle shaft casing (GB3088-82) is a high-quality carbon structural steel and alloy structural steel hot-rolled seamless steel pipe for automobile axle shaft casing and drive axle housing.

12. Diesel high-pressure oil pipe (GB3093-2002) is a cold-drawn seamless steel pipe used in the manufacture of high-pressure pipes for diesel injection systems.

13. Precision inner diameter seamless steel pipes for hydraulic and pneumatic cylinders (GB8713-88) are cold drawn or cold rolled precision seamless steel pipes with precise inner diameters for manufacturing hydraulic and pneumatic cylinders.

14. Cold drawn or cold rolled precision seamless steel pipe (GB3639-2000) 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.

15.Stainless steel seamless steel tube for structure (GB / T14975-2002) is a hot-rolled stainless steel (corrosion resistant pipe and structural parts and parts widely used in chemical, petroleum, light textile, medical, food, machinery and other industries) Extrusion, expansion) and cold drawn (rolled) seamless steel tubes.

16. Stainless steel seamless steel pipe for fluid transportation (GB / T14976-2002) is a hot rolled (extruded, expanded) and cold drawn (rolled) seamless steel pipe made of stainless steel for fluid transportation.

17. Special-shaped seamless steel pipes are a general term for seamless steel pipes of other cross-sectional shapes other than round pipes. According to the different shapes and sizes of the steel tube section, it can be divided into equal wall thickness shaped seamless steel tubes (code D), unequal wall thickness shaped seamless steel tubes (code BD), and variable diameter shaped seamless steel tubes (code BJ). Shaped seamless steel tubes 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 resistance to bending and torsion, which can greatly reduce the weight of the structure and save steel. ^[3]

Steel Pipe