Introduction And Classification Of Alloy Pipe

Introduction And Classification Of Alloy Pipe

1. Introduction of alloy pipe

Alloy pipe is a kind of seamless steel pipe. Alloy pipe is divided into seamless pipe for structure and high pressure heat-resistant alloy pipe. It is mainly different from the production standard of alloy tube and its industry. Annealing and tempering the alloy tube changes its mechanical properties. Achieve the required processing conditions. Its performance is higher than that of ordinary seamless steel pipes. The chemical composition of alloy pipes contains more Cr, and it has high temperature resistance, low temperature resistance and corrosion resistance. Common carbon seamless pipes do not contain alloy components or have very few alloy components. The reason why alloy pipes are widely used in petroleum, aerospace, chemical, electric power, boiler, military and other industries is that the mechanical properties of alloy pipes are changed and adjusted.

Alloy Pipe

1.1 Implementation standards for seamless pipes

China National Standard







ASME SA210-American Boiler and Pressure Vessel Code

ASME SA213-American Boiler and Pressure Vessel Code

DIN17175-Federal German Industrial Standard

 1.2 Calculation of alloy management theory:

(Outer diameter-wall thickness) * wall thickness * 0.02483 = weight per meter.

1.3 Material classification of alloy tubes

The material of the alloy tube is roughly: 16-50Mn, 27SiMn, 20-40Cr, 12-42CrMo

16Mn 12Cr1MoV T91 27SiMn 30CrMo 15CrMo 20G Cr9Mo 10CrMo910 15Mo3 15CrMoV 35CrMoV 45CrMo

2. Classification of alloy tubes

(1) Seamless steel pipe

Because of their different manufacturing processes, they are divided into two types: hot-rolled (extruded) seamless steel pipes and cold-drawn (rolled) seamless steel pipes. Cold drawn (rolled) tubes are divided into two types: round tubes and special-shaped tubes.

a. Process overview

Hot rolling (extruded seamless steel tube): round tube billet heating and piercing three-roll cross-rolling, continuous rolling or extruding, sizing (or reducing), cooling billet straightening water pressure test (or flaw detection) mark and put into storage.

Cold drawn (rolled) seamless steel pipes: round pipe billets are heated, perforated, headed, annealed, pickled, and oiled (copper-plated).

b. Seamless steel pipes are divided into the following varieties due to their different uses:

GB/T8162-2008 (Seamless steel pipe for structure). Mainly used for general structure and mechanical structure. Its representative materials (brands): carbon steel 20, 45 steel; alloy steel Q345, 20Cr, 40Cr, 20CrMo, 30-35CrMo, 42CrMo, etc.

GB/T8163-2008 (Seamless steel pipe for conveying fluid). Mainly used in engineering and large-scale equipment to transport fluid pipelines. The representative material (brand) is 20, Q345, etc.

GB3087-2008 (Seamless steel pipes for low and medium pressure boilers). Mainly used in industrial boilers and domestic boilers to transport low and medium pressure fluid pipelines. Representative materials are 10 and 20 steel.

GB5310-2008 (Seamless steel tubes for high-pressure boilers). Mainly used for high-temperature and high-pressure conveying fluid headers and pipelines on boilers in power plants and nuclear power plants. Representative materials are 20G, 12Cr1MoVG, 15CrMoG, etc.

GB5312-1999 (Carbon steel and carbon-manganese steel seamless steel pipes for ships). Mainly used for I and II pressure pipes for marine boilers and superheaters. Representative materials are 360, 410, 460 steel grades, etc.

GB6479-2000 (Seamless steel pipes for high-pressure fertilizer equipment). Mainly used for conveying high temperature and high pressure fluid pipelines on fertilizer equipment. Representative materials are 20, 16Mn, 12CrMo, 12Cr2Mo, etc.

GB9948-2006 (Seamless steel pipe for petroleum cracking). Mainly used in boilers, heat exchangers and fluid pipelines of petroleum smelters. Its representative materials are 20, 12CrMo, 1Cr5Mo, 1Cr19Ni11Nb, etc.

GB18248-2000 (Seamless steel tubes for gas cylinders). Mainly used to make various gas and hydraulic cylinders. Its representative materials are 37Mn, 34Mn2V, 35CrMo, etc.

GB/T17396-2007 (Hot-rolled seamless steel pipe for hydraulic props). Mainly used to make coal mine hydraulic supports, cylinders and columns, and other hydraulic cylinders and columns. Its representative materials are 20, 45, 27SiMn and so on.

GB3093-1986 (High-pressure seamless steel pipes for diesel engines). Mainly used for high pressure oil pipe of diesel engine injection system. The steel pipe is generally cold drawn, and its representative material is 20A.

GB/T3639-2007 (cold drawn or cold rolled precision seamless steel pipe). It is mainly used for steel pipes for mechanical structures and carbon pressure equipment that require high dimensional accuracy and good surface finish. Its representative materials are 20, 45 steel, etc.

GB/T3094-1999 (cold drawn seamless steel pipe special-shaped steel pipe). It is mainly used to make various structural parts and parts, and its materials are high-quality carbon structural steel and low-alloy structural steel.

GB/T8713-1988 (Precision inner diameter seamless steel pipe for hydraulic and pneumatic cylinders). Mainly used to make cold drawn or cold rolled seamless steel pipes with precise inner diameters for hydraulic and pneumatic cylinders. Its representative materials are 20, 45 steel, etc.

GB13296-2007 (Stainless steel seamless steel tubes for boilers and heat exchangers). Mainly used in boilers, superheaters, heat exchangers, condensers, catalytic tubes, etc. of chemical enterprises. Used high-temperature, high-pressure, corrosion-resistant steel pipe. Its representative materials are 0Cr18Ni9, 1Cr18Ni9Ti, 0Cr18Ni12Mo2Ti, etc.

GB/T14975-2002 (Stainless steel seamless steel pipe for structure). It is mainly used for general structure (hotel and restaurant decoration) and mechanical structure of chemical enterprises, which are resistant to atmospheric and acid corrosion and have certain strength steel pipes. Its representative materials are 0-3Cr13, 0Cr18Ni9, 1Cr18Ni9Ti, 0Cr18Ni12Mo2Ti, etc.

GB/T14976-2002 (Stainless steel seamless steel pipe for fluid transportation). Mainly used for pipelines that transport corrosive media. Representative materials are 0Cr13, 0Cr18Ni9, 1Cr18Ni9Ti, 0Cr17Ni12Mo2, 0Cr18Ni12Mo2Ti, etc.

YB/T5035-1993 (Seamless steel pipes for automobile axle sleeves). It is mainly used to make high-quality carbon structural steel and alloy structural steel hot-rolled seamless steel pipes for automobile half-axle sleeves and axle tubes of drive axle housings. Its representative materials are 45, 45Mn2, 40Cr, 20CrNi3A, etc.

API SPEC5CT-1999 (Casing and Tubing Specification) is compiled and published by the American Petroleum Institute (American Petreleum Instiute, referred to as “API”) and used in all parts of the world. Among them: Casing: the pipe that extends from the ground surface into the well and serves as the lining of the well wall. The pipes are connected by couplings. The main materials are steel grades such as J55, N80, and P110, and steel grades such as C90 and T95 that are resistant to hydrogen sulfide corrosion. Its low steel grade (J55, N80) can be welded steel pipe. Tubing: A pipe inserted into the casing from the ground surface to the oil layer, and the pipes are connected by couplings or integrally. The role of the pumping unit is to transport the oil from the oil layer to the ground through the oil pipe. The main materials are steel grades such as J55, N80, P110, and C90, T95 that are resistant to hydrogen sulfide corrosion. Its low steel grade (J55, N80) can be welded steel pipe.

API SPEC 5L-2000 (line pipe specification), compiled and issued by the American Petroleum Institute, is commonly used all over the world.

Line pipe: It transports the oil, gas or water out of the ground through the line pipe to the petroleum and natural gas industrial enterprises. Line pipes include seamless pipes and welded pipes. The pipe ends have flat ends, threaded ends and socket ends; the connection methods are end welding, coupling connection, socket connection, etc. The main material of the tube is B, X42, X56, X65, X70 and other steel grades.

3. Use classification of alloy tube

Size and allowable deviation table

Deviation levelAllowable deviation of standardized outer diameter
D1±1.5%,min±0.75 mm
D2±1.0%。min±0.50 mm
D3±0.75%.min±0.30 mm
D4±0.50%。min±0.10 mm

Alloy tubes are mainly used for heating surface tubes of low and medium pressure boilers (working pressure generally not greater than 5.88Mpa, working temperature below 450℃); for high-pressure boilers (working pressure generally above 9.8Mpa, working temperature between 450℃~650 ℃) heating surface pipe, economizer, superheater, reheater, petrochemical industry pipe, etc.

High-pressure alloy pipe grades: 15CrMoG, 12Cr2MoG, 12Cr1MoVG, 12Cr2MoWVTiB, 10Cr9Mo1VNb, SA210A1, SA210C, SA213 T11, SA213 T12, SA213 T22, SA213 T23, SA213 T91, SA213 T92, ST45.8/Ⅲ, 15Mo10, 13CrMo44, etc.

4. Alloy specification table

Wall thickness

Unit: Kg/m
Wall thickness33.544.555.56
Unit: Kg/m
Wall thickness6.5788.591012

16Mn Specification Table


5. Alloy steel pipe

5.1 Uses of alloy steel pipes

The main purpose of alloy steel pipe is to use high-pressure and high-temperature pipelines and equipment such as power plants, nuclear power, high-pressure boilers, high-temperature superheaters and reheaters. It is made of high-quality carbon steel, alloy structural steel and stainless heat-resistant steel. , After hot rolling (extruding, expanding) or cold rolling (drawing).

5.2 Advantages of alloy steel pipe

It can be recycled 100%, in line with the national strategy of environmental protection, energy saving, and resource saving. The national policy encourages the expansion of the application fields of high-pressure alloy pipes. In my country, the consumption of alloy pipes accounts for only half of the total amount of steel in developed countries. The expansion of the use of alloy pipes provides a broader space for the development of the industry. According to the research conducted by the expert group of the Alloy Pipe Branch of the China Special Steel Association, in the future, the demand for high-pressure alloy pipe and long products in my country will increase by 10-12% annually.

5.3 The connection and difference between alloy steel pipe and seamless pipe

Alloy pipe is defined by steel pipe according to the production material (that is, material), as the name suggests, is pipe made of alloy; while seamless pipe is defined by steel pipe according to the production process (seamless and seamless), the difference from seamless pipe is Seam pipes, including straight seam welded pipes and spiral welded pipes.

5.4 Alloy steel pipe standard

Alloy 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, mechanical processing, and certain solid materials. Compared with solid steel such as round steel, alloy steel pipe is lighter when the bending and torsion strength is the same. Alloy steel pipe 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 and automobile transmission. Axes, bicycle frames and steel scaffolding used in building construction, etc. The use of alloy steel pipes to manufacture ring-shaped parts can improve material utilization, simplify manufacturing procedures, save materials and processing man-hours, such as rolling bearing rings, jack sleeves, etc., which have been widely used for manufacturing steel pipes. Alloy steel pipes are also an indispensable material for various conventional weapons. Gun barrels and barrels are all made of steel pipes. Alloy 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.

Alloy pipes include large-diameter alloy pipes, thick-walled alloy pipes, high-pressure alloy pipes, alloy flanges, alloy elbows, P91 alloy pipes and seamless steel pipes. In addition, special fertilizer pipes are also very common.

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