Alloy knowledge

What are alloy steel pipes?

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18
Jun

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Alloy steel pipes are manufactured by the process of adding alloying elements or compound (s) to the basic metal material during the manufacturing process for producing an alloyed product having improved physical properties over its base material. Alloying element is usually added in small quantity so that they cannot be detected by X-ray analysis but can be easily detected using other techniques like FTIR spectroscopy or EDS analysis etc.

What is the chemical composition of alloy steel pipe?

Alloy steel pipe is made up of iron and other elements that can be added. Iron is the main component of alloy steel pipe, but other elements can be added to create different types of alloy steel pipe. The most common ones include manganese, chromium, nickel, copper, silicon, and molybdenum.
The amount of these elements added will depend on what type of steel pipe you are looking for: some elements may be added in larger proportions than others, depending on your needs.

The influence of chemical elements in the alloy steel pipe material

Alloy steel tubes contain a large number of elements other than carbon, such as nickel, chromium, silicon, manganese, tungsten, molybdenum, vanadium, and small amounts of other common elements such as manganese, sulfur, silicon, and phosphorus.
1. The effect of carbon (C) on steel
What is the effect of carbon (C) on steel?
Carbon is the most important element in steel materials. The mechanical strength of steel is directly related to the carbon content.
When the carbon content increases, the yield point, and tensile strength increase, but plasticity and impact properties decrease.
When the carbon content exceeds 0.23%, the welding properties of the steel deteriorate.
Therefore, in low-alloy steel structures, the carbon content is usually less than 0.2% to obtain better welding properties.
Also, high carbon content reduces the air corrosion resistance of steel, and high carbon steel is easily washed away in open sites.
In addition, carbon increases the steel’s cold brittleness and aging sensitivity.
2. Phosphorus (P) on the impact of steel
In different concentrations, phosphorus produces different effects on steel in steel pipes and steel plates.
In general, phosphorus is a harmful element in steel, it will increase the cold brittleness of steel. This causes poor welding properties and reduced plasticity.
Therefore, the phosphorus content in steel is usually less than 0.045% and is lower in the higher quality steel grades.
In higher steel grades, the P content is 0.03 to 0.05, and if P exceeds 0.10 in low-alloy high-strength steels, it increases strength and improves corrosion resistance. But the bad part is that even if the strength is increased by P, it will become brittle, and ductility and toughness will be reduced.
3. The impact of sulfur (S) in steel pipe
The impact of sulfur in steel.
As we all know, sulfur is a harmful element. It increases the thermal brittleness, reduces ductility and toughness, and causes cracks in the forging and rolling process.
Secondly, sulfur is detrimental to welding properties and reduces corrosion resistance. Therefore, sulfur content below 0.055% is usually required.
For high-quality steel, it is required that S should be less than 0.04%. Cutting properties can be improved by adding 0.08-0.2% sulfur, which is often referred to as free-cutting steel.
Therefore, even if S is a harmful element if the content is less than 0.05%, it is acceptable in general applications.
4. The effect of silicon on steel
The effect of silicon (Si) in steel.
Silicon is used as a reducing agent and deoxidizer in the steelmaking process, and sedimentary steels usually contain 0.15-0.30% silicon.
Silicon can improve the elastic limit, yield point, and tensile strength of steel. Therefore, it has been widely used in spring steels.
The addition of 1.0-1.2% silicon to quenched structural steels can increase strength by 15-20%.
Silicon is combined with components such as molybdenum, tungsten, and chromium to improve corrosion resistance and oxidation resistance. Therefore, this combination of steel is suitable for the production of electrical heat-resistant steel.
However, if the silicon content increases, the welding properties are reduced.
5. Effect of manganese (Mn) in steel
The effect of manganese on steel. In steelmaking, manganese is a good deoxidizer and desulfurizer, and generally, steel contains 0.3-0.35% manganese. When more than 0.7% of manganese is added to carbon steel, it is called manganese steel. It has not only sufficient toughness but also higher strength and hardness.
Manganese can improve the hardening and heat treatment properties of steel, for example, the yield point of 16 manganese alloy steel is 40% higher than that of A3 steel.
In addition, steels containing 11-14% manganese have high wear resistance and are used in excavator buckets and ball mill liners. As the manganese content increases, the corrosion resistance and welding properties decrease.
For example, API standard 650, requires that all thicknesses of ASTM A36 carbon (rolled semi-sedated or fully sedated) steel plates should contain 0.80-1.20 percent manganese by thermal analysis.
All of the above chemical elements are contained in all ordinary steel.
On the other hand, alloy steel pipe chemical elements not only contain conventional chemical substances such as C (carbon), Si (silicon), Mn (manganese), P (phosphorus), and S, but also other alloying elements such as Cr (chromium), Ni (nickel), Mo (molybdenum), tungsten, V (vanadium), Ti (titanium), Nb (niobium), Zr (zirconium), Co (cobalt), Al (aluminum), Co (copper), B (boron) and rare earth. Alloy steel tubes include many types, which are usually divided into low alloy steel tubes, alloy steel tubes, and high alloy steel tubes according to the type and percentage of alloying chemical elements.
6. The effect of chromium (Cr) in steel
The role of chromium in steel pipe can significantly improve the strength, hardness, corrosion, and wear resistance. It is an important alloying element for stainless steel and heat-resistant steel tube sheets. On the other hand, it reduces plasticity and toughness.
7. The effect of nickel (Ni) on steel
The role of nickel in steel pipe can improve strength while maintaining good plasticity and toughness. It has high resistance to acid and alkali corrosion, rust resistance, and heat resistance. However, as it is a scarce resource, we should try to use other alloying elements instead of nickel-chromium steel.
8. The effect of molybdenum (Mo) on steel
The role of molybdenum can make the steel grain refinement, and improve hardenability and thermal properties. It can maintain sufficient strength and creep resistance (deformation under long-term stress at high temperatures is called creep). The addition of molybdenum to structural steel improves mechanical properties. In addition, it can inhibit the brittleness caused by quenching.
9. The effect of titanium (Ti) on steel
Titanium chemical element in the role of alloy steel tubes. It is a strong deoxidizer in steel. It can make the internal structure dense, grain strength fine; reduce aging sensitivity and cold brittleness. In addition, it improves welding properties. In Cr18Ni9 austenitic stainless steel, the addition of appropriate titanium can avoid internal grain corrosion.
10. The effect of vanadium (V) in steel
The effect of vanadium (V) chemical element in alloy steel tubes. It is an excellent steel deoxidizer. The addition of 0.5% vanadium to steel pipe material can refine the grain size and improve strength and toughness. Vanadium and carbon at high temperatures and pressures to form carbides can improve the ability to resist hydrogen corrosion.
11. Tungsten (W)
The influence of the chemical element tungsten in steel. Because tungsten has the highest melting point of any metal found and accounts for a large percentage of the total, it is a valuable alloying element. Together with carbon, tungsten can form tungsten carbide, which has high hardness and wear resistance. By adding tungsten to tool steel, the red hardness and thermal strength can be significantly increased. This material can be used to cut steel and forge dies.
12. Niobium (Nb)
Niobium can refine the grain, reduce the steel’s superheat sensitivity and temper brittleness, and improve strength, but plasticity and toughness will be reduced. Adding niobium to ordinary low-alloy steel can improve its resistance to atmospheric corrosion and high-temperature hydrogen, nitrogen, and ammonia corrosion performance. In addition, niobium improves welding properties. By adding niobium to austenitic stainless steels, internal grain corrosion can be prevented.
13. Cobalt (Co)
Cobalt is a rare precious metal used in special steels and alloys, such as hot-rolled steel and magnetic materials.
14. Copper (Cu)
Copper chemical element in the role of alloy steel tubes. Copper can improve strength and toughness, especially the resistance to atmospheric corrosion. The disadvantage is that it is easy to produce thermal embrittlement in the hot processing process, copper content of more than 0.5% will lead to a significant reduction in plasticity. When the copper content is below 0.50%, there is no effect on the welding performance.
15. Aluminum (Al)
The role of chemical element aluminum is a common deoxidizer in steel. Adding small amounts of aluminum can refine the grain and improve impact toughness, such as 08Al steel. Aluminum also has oxidation and corrosion resistance. Combining chromium and silicon improves the steel’s resistance to stripping and high temperatures. The disadvantage of aluminum is the impact of steel hot workability, welding performance, and cutting performance.
16. Boron (B)
The addition of trace amounts of boron in steel can improve the denseness and hot rolling properties of steel and improve strength.
17. Rare Earths (XT)
These elements are metals, but their oxides are similar to “soil”, so they are often called rare earth. Adding rare earth to steel can change the composition, morphology, distribution, and properties of inclusions in steel, thus improving various properties of steel, such as toughness, weldability, and cold workability.

What is the application of alloy steel pipe?

Alloy steel tubes are well suited for chemical, petrochemical, and other energy-related applications.
Alloy steel tubes are made from high-quality carbon steel, alloy structural steel, and stainless steel heat-resistant steel, which are hot rolled or cold drawn.
Alloy steel can be used in process areas where carbon steel has limitations such as:

  • High-temperature service, such as heater tubes.
  • Low-temperature service, such as cryogenic applications.
  • High-pressure services, such as steam manifolds.

Alloy steel tubes, as an important part of steel, can be divided into seamless and welded steel tubes according to the manufacturing process and the shape of the billet.
Here you can see the common alloy steel grades you will encounter.

  • Pipes: ASTM A335 Gr P1, P5, P11, P9.
  • Forged fittings: ASTM A234 Gr. WP5, WP9, WP11.
  • Forged fittings: ASTM A182 F5, F9, F11, etc…

Why are alloy steel pipes more widely used than other steel pipes?
There are many kinds of materials used for transportation in industrial production. Specifically, we will have more choices, and it is not limited to the use of alloy steel pipe. But even when faced with more choices, many people tend to choose alloy steel pipe. People will have their own reasons for making their choices. This means that the application of alloy steel pipe has its own advantages. It is lighter in quantity than transmission lines made of other materials after meeting the basic application requirements. Therefore, it will have more advantages in the practical application of alloy steel pipe. It has economic advantages in addition to physical characteristics advantages. There are various reasons for the wide application of alloy steel pipe. Therefore, in the practical application, we can give full play to its advantages so that we can gain more profit in these applications of alloy steel pipe.
What requirements should alloy steel pipe applications meet?
The transportation of various gases or liquids in production needs to rely on alloy steel pipes. This shows that the practical application of alloy steel pipe is very important. Resistance to high and low temperatures is the temperature resistance. In the practical application of alloy steel pipes, many materials need to be transported. However, they have different temperatures. Therefore, this can be a basic requirement for alloy steel pipes. It needs higher corrosion resistance. Corrosion-resistant material is the best material for the transportation process because it is corrosion resistant. Therefore, it can be used on more occasions. This is definitely very convenient for the users.

The Advantages Of Alloy Steel Pipes

With the continuous development, alloy steel pipes are used in more and more fields, whether in water, oil or gas, etc. The prospect of alloy steel pipes is very broad, and the comparative advantages of alloy steel pipes will be discussed here in this article.
Alloy steels are formed when other elements containing metals and non-metals are added to carbon steel. These alloy steels have a variety of environmental, chemical, and physical properties that vary with the elements used in the alloy. Here, the proportions of alloying elements can provide different mechanical properties. Alloy steels contain different proportions of alloying elements (e.g. manganese, silicon, nickel, titanium, copper, chromium, and aluminum) to control the properties of the steel such as hardenability, and corrosion resistance, strength, formability, weldability, or ductility. Alloy steel pipes are mainly used in high-temperature pipes and equipment such as power stations, nuclear power stations, high-pressure boilers, high-temperature superheaters, and reheater coils.
Alloy steel pipes are made of high-quality carbon steel, alloy structural steel, and stainless steel heat-resistant steel, which are hot rolled or cold drawn.
Alloy steel tubes are mainly used in power stations, nuclear power stations, high-pressure boilers, high-temperature superheaters, and high-temperature pipes and equipment such as reheater coils.
With the continuous development of society, alloy steel pipe is used in more and more fields, whether in the water, oil and gas and other fields are used to alloy steel pipe, alloy steel pipe has a very broad prospect, what are the comparative advantages compared with other steel pipes?
Environmental protection has been the theme of the development of all walks of life in society, the biggest advantage is to achieve 100 percent recycling, which is naturally superior compared to other steel and does not cause material waste.
A wide range of applications, widely used in oil, natural gas, and other industries, for this important energy, the requirements of the pipeline are also very strict, in power plants, nuclear power, high-pressure boilers, and other industries are also widely used.
Easy to save. General steel pipe material is easy to rust in the air for a long time, but alloy steel pipe is made of the most advanced materials, and also has great achievements in anti-oxidation, which is not easy to rust and longer use.
Advantages of alloy steel pipe
High strength
Due to the chemical composition of molybdenum (Mo) and chromium (Cr), some alloy steels prefer chromium-molybdenum tubes. Molybdenum can improve the strength, elastic limit, wear resistance, impact quality, and hardenability of steel. Chromium increases tensile strength, yield strength, and hardness. The composition of chromium-molybdenum alloy steel tubing makes it ideally suited for use in power plants, refineries, petrochemical plants, and oilfield services where fluids and gases are transported at extremely high temperatures and pressures.
Corrosion resistance
When metals encounter oxygen, they undergo an oxidation reaction. This, in turn, leads to corrosion.
Chromium (or Cr) is virtually irreplaceable in terms of oxidation resistance at high temperatures, making alloy steels more resistant to corrosion than most metals. This allows them to maintain their integrity longer than other metals, especially in marine environments where corrosion is particularly severe.
Low Expansion
Some alloy steels have a meager thermal expansion or a very consistent and predictable expansion pattern over a specific temperature range. This makes them very useful when pipes need to maintain uniform shape and size even in high-temperature environments.
For example, Fe-36% nickel alloys hardly expand at all during mild temperature changes. When you add cobalt to nickel and iron, you get high-strength alloy steel that has a constant modulus of elasticity and a low coefficient of expansion.
Shape Memory
Sometimes a metallic material is needed that can revert to its previous shape when subjected to heat. This material is called a shape memory alloy and is rarely available on the market. However, some alloy steels have this feature, and nickel-titanium alloys are among the most prominent shape memory alloys.
Magnetic Permeability
Alloy steels also have unique and interesting magnetic permeability properties. This makes them an essential component in the design of switchgear, DC motors, and generators.
These benefits have made alloy steel tubes a popular material for many applications, including

  • Petrochemical industry
  • Aircraft turbines
  • Medical engineering
  • Steam turbine power plants
  • Nuclear power plants
  • Environmentally friendly

100% recycling, in line with the national strategy of environmental protection, energy saving, and resource conservation. Therefore, the national policy encourages the expansion of the application of high-pressure alloy steel pipes. At present, the total proportion of alloy steel pipes is half of that of developed countries. The application of alloy steel pipe provides a broad space for industrial development. According to the research of the expert group of the China Special Alloy Steel Pipe Association, the demand for high-pressure alloy steel pipe materials in China grows by 10-12% on average. Therefore, the national policy encourages the expansion of the application of high-pressure alloy steel tubes.

Standards of steel pipes

Steel pipes by standards include ASTM, JIS, DIN, Customers for international, etc…

We can produce and sell cold drawn and hot rolled steel pipes as well as cold drawn special section steel pipes, which are widely used in petrochemical, boiler, automobile, machinery, construction, and other industries.

API SPEC 5L/ 5CT

Specification for Casing and Tubing, Eighth Edition, Petroleum and natural gas industries-Steel pipes for use as casing or tubing for wells.

Product name Executive standard Dimension (mm) Steel code/ Steel grade
Casting API 5CT 114-219 x 5.2-22.2 J55, K55, N80, L80, P110
Tubing API 5CT 48.3-114.3 x 3.2-16 J55, K55, N80, L80, H40
Casting API 5L 10.3-1200 x1.0-120 A, B, X42, X46, X52, PSL1 / PSL2

ASTM / ASME

American Society for Testing and Materials(ASTM), American Society of Mechanical Engineers (ASME)

Product name Executive standard Dimension (mm) Steel code/ Steel grade
Black and Hot-dipped Zinc-coated Steel Pipes Seamless ASTM A53 0.3-1200 x 1.0-150 GR.A, GR.B, GR.C
Seamless Carbon Steel for High-Temperature Service ASTM A106 10.3-1200 x 1.0-150 GR.B, GR.C
Seamless Cold-drawn Low-Carbon Steel Heat-Exchanger and Condenser Tubes ASTM A179 10.3-426 x 1.0-36 Low Carbon Steel
Seamless Carbon Steel Boiler Tubes for High Pressure ASTM A192 10.3-426 x 1.0-36 Low Carbon Steel
Seamless Cold-drawn Intermediate Alloy Steel Heat-exchanger and Condenser Tubes ASTM A199 10.3-426 x 1.0-36 T5, T22
Seamless Medium-carbon Steel Boiler and Superheater Tubes ASTM A210 10.3-426 x 1.0-36 A1, C
Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-exchanger Tubes ASTM A213 10.3-426 x 1.0-36 T5, T9, T11, T12, T22, T91
Seamless Carbon and Alloy Steel for Mechanical Tubing ASTM A333 1/4″-42″ x SCH20-XXS Gr1, Gr3, Gr6
Seamless ferritic alloy-steel pipe for high-temperature service ASTM 335/335M 1/4″-42″ x SCH20-XXS P5, P9,P11, P91, P22, P92
Seamless Cold-drawn Carbon Steel Feedwater Heater Tubes ASTM A556 10.3-426 x 1.0-36 A2, B2

DIN/EN – European Standards for steel

Germany Safety(GS), Deutsches Institut für Normung(DIN)

Product name Executive standard Dimension (mm) Steel code/ Steel grade
Seamless Steel Tubes for Elevated Temperature DIN 17175 10-762 x 1.0-120 St35.8,St45.8, 10CrMo910, 15Mo3, 13CrMo44, STPL340, STB410, STB510, WB36
Manufacturing pipeline, vessel,equipment, and pipe fittings. DIN 1629 13.5-762 x 1.8-120 St37.0, St44.0, St52.0
Seamless steel tubes for pressure purposes EN 10216 4.0-60.0 x 0.5-8

5-7 m manufacturing length

 P235GH TC1, P235GH TC2, 16Mo3
Seamless precision steel tube applications EN 10305-1 13.5-165.1 x 1.8-4.85 St33.2
Seamless Precision Steel Tube DIN 2391 4.0-60.0 x 0.5-8 St35, St45, St52
Seamless Steel Tubes DIN 2440 13.5-165.1 x 1.8-4.85 St33.2

JIS

Japanese Industrial Standards (JIS) specify the standards used for industrial activities in Japan.

Product name Executive standard Dimension (mm) Steel code/ Steel grade
High pressure and high-temperature service JIS G3454/5/6 19.05-114.3 x 2.0-14 JIS G3454(STPG370, STPG410), JIS G3455(STS370, STS410, STS480), JIS G3456(STPT370, STPT410, STPT480)
Tubes are used for machinery, automobiles, bicycles, furniture, appliances, and other machine parts. JIS G3445 19.05-114.3 x 2.0-14 STKM11A, STKM12(A,B,C), STKM13(A,B,C), STKM14(A,B,C).
Carbon steel/Alloy steel boiler and heat exchanger tubes JIS G3461,2 19.05-114.3 x 2.0-14 G3461(STB340, STB410, STB510)

G3462(STBA22, STBA23)
Seamless steel tubes for high-pressure gas cylinder JIS G3429 19.05-114.3 x 2.0-14

Length: max 16000mm

 STH11, STH12, STH21, STH22

GB

Product name Executive standard Dimension (mm) Steel code/ Steel grade
Low and medium pressure boiler seamless pipe GB 3087 19.05-114.3 x 2.0-14 10#, 20#
Low-temperature heat exchanger tubes seamless steel pipe GB/T18984 19.05-351 x 2.0-14 06Ni3MoDG, 09DG, 09Mn2VDG, 10MnDG, 16MnDG
High pressure and above pressure steam boiler tubes with a high-quality carbon structure. GB5310 19.05-114.3 x 2.0-14 20G, 20MnG, 25MnG, 15MoG, 20MoG, 12CrMoG, 15CrMoG(T12/P12), 12CrMoG, 12Cr2MoWVTiB.

The production process of alloy steel pipe

The Alloy steel pipe production process can be divided into the following steps:

How to make seamless alloy steel pipes & tubes?

According to the manufacturing process of seamless alloy steel pipe, seamless alloy steel pipe can be divided into hot-rolled seamless alloy steel pipe and cold-drawn seamless alloy steel pipe.

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Process flow chart of cold-drawn seamless alloy steel pipe

Cold-drawn seamless alloy steel pipe process.
Round tube billet → heating → perforation → head → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → blank tube → heat treatment → straightening → Hydraulic test (inspection) → mark → storage.

In a General cold-rolled strip machine, the volume should be continuously annealed (CAPL unit) to eliminate cold quenching and rolling stress, or batch annealing to achieve the mechanical properties specified in the corresponding standards. The surface quality, appearance, and dimensional accuracy of cold-rolled steel sheets are better than that of hot-rolled steel sheets, and the thickness of the product is about 0.18mm for rolling thin, so it is favored by the majority of users.

The cold-drawn steel pipe is made of hot-rolled steel coil as raw material, it’s subjected to pickling to remove scale and then cold-rolled. The finished product is rolled hard roll. The cold work hardening is caused by continuous cold deformation to make the strength and hardness of the rolled hard roll rise and tough. The plastic index is reduced, so the stamping performance will deteriorate and can only be used for parts that are simply deformed.

Process flow chart of hot rolled seamless alloy steel pipes

The raw material for rolling seamless tubes is round tubes, and the tube embryos are cut to raw lengths of about 1 meter by a cutting machine and heated by a conveyor belt to the furnace.
Hot-rolled (extruded seamless steel pipe)

Round tube billet → heating → perforation → three-roll cross-rolling, continuous rolling or extrusion → pipe removal → sizing (or reducing diameter) → cooling → blank tube → straightening → water pressure Test (or flaw detection) → mark → into storage.
The billet is fed into a heating furnace at a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. The control of the furnace temperature is crucial to grind the round air ducts and release the pressure after the punch. One of the taper roller punches is generally higher than the ordinary taper roller punch this kind of punch, has high production efficiency, good product quality, large perforation expansion, and wear-resistant various steel. After perforation, the round pipe is cross-rolled, rolled, or extruded by three rollers.
After extruding the pipe size. The sizing machine through the high-speed rotation of the conical drill into the billet punch to form a steel pipe. The inner diameter of the steel pipe is determined by the length of the outer diameter of the sizer bit. After sizing, the steel pipe enters the cooling tower to be cooled by water spray. After the steel pipe is cooled, it needs to be straightened. Sent by the delivery tube through the straightening of the metal flaw detection machine (or hydraulic test) for internal flaw detection. Will detect cracks, bubbles, and other problems inside the steel pipe.

The process flow of a hot rolled seamless alloy steel pipe production base can be summarized in three stages: perforation, extension, and finishing.
The main purpose of the perforation process is to become a solid round billet perforated with a hollow shell. The capillary tube does not meet the requirements of the finished product in terms of specification, precision, and surface quality, and further improvement is required to get the metal through the deformation. The main purpose of the drawing machine is to further reduce the cross-sectional figure (main compression wall) to obtain a greater axial extension, thus improving the dimensional accuracy, surface quality, and organizational properties of the capillary pipe.

Steel pipe quality inspection will also be done by strict hand selection. The quality of steel pipe is monitored and inspected using the number, size, and production lot of spray paint. A cable car hanging in the warehouse.

How to make welded alloy steel pipes & tubes?

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JIADE PIPES produces a wide range of welded steel pipes, including ERW, HFI, EFW, LSAW, DSAW, and UOE-type stainless steel pipes and their respective flanges and fittings.
Welded steel pipe manufacturing process is simple and efficient, with many varieties, different specifications, less equipment, and less capital, but the total strength is not as good as a seamless steel pipe. since the 1930s, with the rolling production of high-quality strip steel and the rapid development of welding detection technology, the quality of the weld seam continues to improve, and the specifications of welded steel pipe are increasing, replacing non-pipe joints in more and more areas.
Pipes can be divided into two types according to the basic shape of the longitudinal weld seam, and spiral welded pipe.

  • (1) LSAW pipe: simple production process, high efficiency, low cost, and rapid development. Longitudinal more general industrial use.
  • (2) Spiral welded steel pipe: longitudinal strength is generally higher than this, can be narrower diameter billet production, but also use the same width of the billet production of different diameter welded pipe; but compared with the same length of straight seam pipe, spiral welded steel pipe weld length of 30%-100%, and lower productivity; therefore, smaller diameter pipes actually use straight seam welding, large diameter spiral welded pipe is mostly used.

Pipeline use is divided into the following categories.

  • (1) General welded steel pipe: welded steel pipe for the transport of general low-pressure fluids. Contains Q195A, Q215A, and Q235A steel. Can be easily applied to other soft steel welded steel pipe pressure, bending, flattening, and other experiments, here there are certain surface quality requirements, the delivery length is usually 4-10m, often required to cut to a certain length (or double length) delivery s specifications and nominal pipe diameter indicated (mm or inches) the difference between the nominal diameter and the actual diameter of the pipe required thick-walled ordinary steel and steel pipe is two kinds of steel, according to the form of pipe Divided into two types with threaded ends and non-threaded ends.
  • (2) Galvanized welded steel pipe: To improve the corrosion resistance of steel pipe, general steel pipe (single reed pipe) for galvanized steel and electrical steel, hot dipped galvanized zinc there are two kinds of galvanized thickness, galvanized low cost.
  • (3) Oxygen welded steel pipe: piping for steelmaking oxygen, usually with small diameter welded steel pipe, size from 3/8 inch to 2 inches 8. made of 08, 10, 15, 20 or Q195-Q235 steel strip corrosion, for partial aluminizing treatment.
  • (4) Line pipe: welded steel pipe is also common carbon steel, concrete, and various distribution engineering structures used in steel pipe, commonly used nominal diameter of 13-76mm.
  • (5) Metric welded steel pipe: seamless form, specifications expressed in millimeters diameter * wall thickness of welded steel pipe, with ordinary carbon steel, high carbon steel or low alloy steel and P welding to tropical and cold regions, or welded with tropical methods to call cold regions. Metric and thin-walled tube points are commonly used in structural parts, such as shafts or transmission fluid, for the production of thin-walled furniture, lamps, etc., to ensure the strength of steel and bending tests.
  • (6) Roller: roller conveyor with welded steel pipe, generally 304/304L, 316/316L, 2205, 2507, Q215, Q235A, 45# steel, B steel, and 20# steel, diameter 63.5-219.0mm. bending of the tube, the end is perpendicular to the center line, ellipticity has certain requirements, general test pressure, and flatness.

Dimensional tolerance of ERW steel pipe

Tolerance of outside diameter

 Out Diameter  Tolerance of Pipe End  Tolerance of Pipe Body
 219.1-273.1  +1.6mm, -0.4mm  ±0.75%
 274.0-320  +2.4mm, -0.8mm  ±0.75%
 323.9-457  +2.4mm, -0.8mm  ±0.75%
 508  +2.4mm, -0.8mm  ±0.75%
 559-610  +2.4mm, -0.8mm  ±0.75%

Tolerance of wall thickness

 Grade  Out Diameter  Wall Thickness
 /  219.1-457  +15%, -12.5%
 B  508-610  +17.5%, -12.5%
 X42-X80  508-610  +19.5%, -8%

Ends of alloy steel pipe

For the ends of pipes are 3 standard versions available.

  • Plain Ends (PE)
  • Threaded Ends (TE)
  • Beveled Ends (BE)

The TE implementation speaks for itself, this performance will generally be used for small diameter pipe systems, and the connections will be made with threaded flanges and threaded fittings.

The BE implementation is applied to all diameters of buttweld flanges or buttweld fittings and will be directly welded (with a small gap of 3-4 mm) to each other or to the pipe.

Ends are mostly beveled to the angle of 30° (+ 5° / -0°) with a root face of 1.6 mm (± 0.8 mm).

Length of alloy steel pipe

Piping lengths from the factory are not exactly cut to length but are normally delivered as:

  • The single random length has a length of around 5-7 meter
  • The double random length has a length of around 11-13 meter
  • Shorter and longer lengths are available, but for calculation, it is wise, to use this standard length;
  • other sizes are probably more expensive.

Inspection Quality of alloy steel pipe

Our factory is ISO 9001 and CE-PED approved manufacturer. We believe that quality is the life of the company. To provide quality products is the thing we are doing.

  • PMI test to ensure the material quality;
  • Dimension controlling during fabricating and finishing;
  • 100% Visual and surface examination;
  • NDT test (Eddy Current and Hydro Test);
  • Another requirement on request.
Eddy Current Test Hydrostatic Test Radiography Test (for welded pipe) Liquid Dye Penetrant Test
Bending Test Ultrasonic Test Tensile Test Flaring Test
Flattening Test Hardness Test Positive Material Identification (PMI) Surface Roughness
Hardness Test Dimension Examination Visual Checking Impact Test
Intergranular Corrosion Test Grain Size Test Chemical Analysis Other tests on the requirement

Packing of alloy steel pipe

  • Packed in wooden crates, wrapped in plastic, and suitably protected for sea-worthy delivery or as requested.
  • Both ends of each crate will indicate the order no., heat no., dimensions, weight, and bundles or as requested.

Delivery of alloy steel pipe

  • Pipes are supplied in hexagonal bundles or round bundles tied with steel strips.
  • Weight of bundle – up to 5000 kg upon request of the customer.
  • Each bundle is furnished with three tags.

Alloy steel pipe is a type of metal material that has many different uses and applications. It is important to know how to choose the right alloy steel pipe for your project, so we have outlined some tips below on how to do this effectively.

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