Types Of Seamless Steel Pipes
- Share
- publisher
- Tianjin Yuantai Derun steel pipe manufacturing group Ltd.
- Issue Time
- Apr 8,2024
Summary
Seamless steel pipes can be classified according to rolling process, surface treatment, cross-sectional shape, manufacturing materials, wall thickness, application scenarios, standards, etc.
Seamless steel pipes can be classified according to rolling process, surface treatment, cross-sectional shape, manufacturing materials, wall thickness, application scenarios, standards, etc.
According To Different Raw Materials
Firstly, seamless steel pipe can be divided into carbon steel seamless pipe, stainless seamless pipes, alloy steel seamless pipe according to different raw materials.
Carbon Steel Seamless Pipe
Diameter:<φ76mm, accounting for 35% of seamless carbon steel pipe, <φ159-650mm, accounting for 25% of seamless carbon steel pipe
Material: Gr.A/B/C,S235/275/355/420/460,A36,SS400,Q195/235/355,STKR400/490,300W/350WCharacteristic: Economical, widely used, structurally stable, and resilient
Use:1.9 million tons of general-purpose pipes, accounting for 54%; 760000 tons of oil pipes, accounting for 5.7%; Hydraulic pillars and precision pipes account for 150000 tons, accounting for 4.3%; Stainless steel pipes, bearing pipes, and automotive pipes totaling 50000 tons, accounting for 1.4%.
Stainless Seamless Pipe
Diameter:
The following are commonly used stainless steel seamless pipe specifications and their size range:
1, ASTM A312/A312M stainless steel seamless pipe standard specifications
Outside diameter range: 1/8" - 30" (10.3mm - 762mm)
Wall thickness range: SCH 5S - SCH 160 (0.5mm - 49.5mm)
2、GB/T 14975 Austenitic stainless steel pipe standard specifications
Outer diameter range: 6mm - 219mm
Wall thickness range: 0.5mm - 20mm
3、DIN17456 Austenitic stainless steel pipe standard specifications
Outer diameter range: 1/8" - 30" (DN6 - DN750)
Wall thickness range: SCH 5S - SCH 160 (0.5mm - 49.5mm)
4、JIS G3448 Austenitic stainless steel pipe standard specifications
Outside diameter range: 15.88mm - 318.5mm
Wall thickness range: 0.8mm - 5mm
Material: 304 stainless steel, 316 stainless steel, 316L stainless steel, 321 stainless steel, 304L stainless steel, 2205 duplex stainless steel, 904L stainless steelCharacteristic: High precision, high smoothness, moisture resistance, acid resistance, alkali resistance, salt spray resistance, can meet the food hygiene level of pipelines. High cost, not suitable for large-scale application scenarios.
Use:Stainless steel seamless pipe is a widely used pipe material with strong corrosion resistance and long service life. Commonly used in industries such as chemical, petroleum, medical, and food.
Alloy Steel Seamless Pipe
Diameter:The outer diameter of alloy seamless steel pipes generally ranges from 6mm to 720mm, the wall thickness of alloy seamless steel pipes generally ranges from 1mm to 120mm, and the commonly used lengths of alloy seamless steel pipes are 6 meters, 12 meters, etc. In practical applications, cutting or irregular production may also be carried out as needed.
Material: Alloy seamless steel pipe is a special type of steel made by mixing various metal elements, including chromium, molybdenum, manganese, copper, etc.Characteristic: The advantages of alloy seamless steel pipe are mainly reflected in the following aspects:
1. corrosion resistance: alloy seamless steel pipe is made of a mixture of many metal elements, which has good corrosion resistance.
2. high temperature resistance: alloy seamless steel pipe can be used for a long time in a high temperature environment, not easy to deformation, not easy to crack.
3. High strength: the strength of alloy seamless steel pipe is higher than ordinary steel pipe, which can withstand greater pressure and tension.
4. High precision: alloy seamless steel pipe is made with high precision, no joints, good surface finish, not easy to appear oxidized skin.
However, alloy seamless steel pipe also has some disadvantages, mainly in the aspects of complex production process and higher cost. At the same time, due to the special material of alloy seamless steel pipe, it is difficult to process, so it is necessary to use specialized production equipment and tools.
Use: Alloy seamless steel pipe has good corrosion resistance and high temperature resistance, so it is widely used in petroleum, chemical, metallurgy, aerospace, automobile and other fields. Among them, the petroleum and chemical industry is the most widely used, mainly used in oil wells, pipelines, chemical equipment and so on.
Duplex Steel Seamless Pipes
Diameter:Outerside diameter:6-630mm wall thickness:0.5-30mm
Material:These pipes are made from duplex steel, which is a combination of austenitic and ferritic stainless steels.
Characteristic:They offer high strength and excellent corrosion resistance.
Use:Making them ideal for use in harsh environments
According To The Surface Treatment
Secondly, if the seamless pipe is classified according to the surface treatment, it can also be divided into seamless black steel pipe, seamless galvanized pipe, anticorrosive insulation seamless pipe.
Seamless Black Steel Pipe
Surface treatment: seamless black steel pipe generally refers to seamless steel pipe without any surface treatment.
Material: seamless black steel pipe is made of ordinary carbon steel, low alloy structural steel or alloy steel material.
Characteristics: high strength, good toughness, good workability, good sealing performance
Application: Widely used in petroleum, chemical, aviation, nuclear power, construction, machinery, automobile manufacturing and other fields.
Galvanized Seamless Steel Pipe
Surface treatment: The hot-dip galvanized seamless pipe has a relatively high amount of zinc plating, with an average zinc coating thickness of over 65 microns, greatly enhancing its corrosion resistance.
Material: seamless black steel pipe
Characteristics: Good corrosion resistance, unchanged mechanical properties of the material, silver-white surface
Application: Fasteners, standard parts, water pipes, mechanical parts, pipelines, building structures, etc.
Anticorrosive Insulation Seamless Pipe
Surface treatment: After anti-corrosion and insulation treatment
Material: seamless black steel pipe
Characteristics: Good thermal insulation, good corrosion resistance, other mechanical properties remain unchanged.
Application:
1. Oil and natural gas sector
In the field of oil and natural gas transportation, anti-corrosion and insulated steel pipes are the preferred products. Anti corrosion treatment can effectively prevent corrosion of steel pipes caused by corrosive environments such as ocean salt spray, while the use of insulation materials can reduce temperature loss, making oil and natural gas transportation more stable and efficient.
2. Chemical industry
In the field of chemical pipelines, anti-corrosion and insulation steel pipes are indispensable pipeline products. Many chemical media are corrosive to steel pipes, and using anti-corrosion and insulated steel pipes can effectively prevent pipeline damage, improve operational safety and reliability.
3. In the field of urban water supply and heating
The field of urban water supply and heating is also one of the widely used fields of anti-corrosion and insulation steel pipes. Steel pipes need to maintain a certain temperature during the transportation of water and heat, and the use of insulation materials can effectively prevent temperature loss; Meanwhile, anti-corrosion treatment can also improve the service life and operational safety of pipelines.
According To The Production Method
Thirdly,according to the production method, seamless steel pipes can be divided into hot-rolled seamless steel pipes(HRS), cold-rolled seamless steel pipes(CRS), cold-drawn seamless steel pipes(CDS), extruded seamless steel pipes.
Hot Rolled Seamless Pipe
Manufacturing process:Hot rolled seamless pipe is a circular hollow section formed by piercing and rolling circular steel billets at high temperatures.
Application:Oil pipe, natural gas pipe, oil well drill pipe, oil casing, downhole gas pipeline, steam pipe, compressed air pipe, water supply pipe, chemical equipment, reactor, shipbuilding pipe, aviation cabin pipe, building structural pipe, mechanical pipe, automotive pipe, parts and so on.
Characteristic:High strength, high temperature resistance, high pressure resistance, corrosion resistance, multiple types of steel, thick wall thickness, large diameter,The surface is somewhat rough.
Cold Rolled Seamless Pipe
Manufacturing process:Cold rolling is to bring the seamless steel pipe into the rolling mill, through the press rolls or extruder rolls on the steel pipe processing, directly obtain the appropriate size of the steel pipe.The processing temperature of cold rolling is lower than the crystallization temperature and is generally carried out at room temperature
Application:
1. Fluid transportation: Cold rolled seamless steel pipes are important pipeline materials for transporting fluids, such as water, oil, natural gas, etc. Due to its seamless structure, the fluid flows more smoothly in the pipeline, reducing fluid resistance and energy loss.
2. Structural support: Cold rolled seamless steel pipes are often used as support materials for various structures, such as bridges, buildings, towers, etc., due to their high strength and good plasticity. Its excellent mechanical properties and stability make the structure more stable and reliable.
3. Mechanical manufacturing: In the field of mechanical manufacturing, cold-rolled seamless steel pipes also play an important role. It can serve as a raw material for mechanical parts, such as shafts, sleeves, bearings, etc., providing a solid material foundation for mechanical manufacturing.
Characteristic:Smaller size, better quality, higher accuracy, thinner wall thickness,smooth and even surface.
Cold Drawn Seamless Tube
Manufacturing process:Cold drawing is the first to extract the appropriate hole mold, and then the heated steel pipe into the mold, by pulling the mold so as to obtain a smaller diameter, higher surface finish of the seamless steel pipe.Cold drawing is carried out in a heated state at a temperature of approximately 800 ° C to 950 ° C.
Application:Cold-drawn steel pipe has a wide range of uses. Due to its excellent properties such as high strength, high precision, corrosion resistance and high temperature resistance, it can be used in various fields. For example, in the petroleum industry, cold-drawn steel pipe is used to manufacture petrochemical equipment, valves, pumps, etc.; in the electric power industry, cold-drawn steel pipe is used to manufacture pipelines, boilers, heat exchangers, etc.; in the field of construction, cold-drawn steel pipe is used for piling, bridges, high-rise buildings, etc.; in the mechanical manufacturing, cold-drawn steel pipe is used to manufacture mechanical parts, automobile parts, etc..
Characteristic:Reduced dimensional errors in internal and external diameters, high surface quality, high mechanical properties, and a wide range of shapes.
Extruded Seamless Pipe
Manufacturing process:The extruded seamless tube is about to place the heated tube blank in a closed extrusion cylinder, and the perforated rod moves together with the extrusion rod to extrude the extruded part from the smaller mold hole. This method can produce seamless steel pipes with smaller diameters.
Application:Squeezed seamless steel pipes have excellent mechanical properties and corrosion resistance, and are widely used in the following fields:
1. Automotive industry: used to manufacture key components such as automotive engines, chassis, and brake systems, to improve the safety and reliability of automobiles.
2. Petrochemical industry: used for manufacturing petroleum pipelines, chemical equipment, etc., capable of withstanding high temperature, high pressure, and corrosive media.
3. Electricity: Used for manufacturing pipeline systems for power plant boilers and cooling water pipes for nuclear power plants, ensuring long-term stable operation.
4. Aerospace: used to manufacture key components such as aircraft fuselage and wings, ensuring the safety and stability of the aircraft.
5. Other fields such as shipbuilding, medical equipment, sports equipment, etc. are also widely used.
Characteristic:
1. High strength and toughness: Extruded seamless steel pipes have high tensile strength and yield point, as well as good toughness, which can effectively resist various stresses while withstanding large pressures.
2. Good corrosion resistance: The extruded seamless steel pipe has undergone special anti-corrosion treatment, which has good corrosion resistance and can work stably for a long time in various complex environments.
3. Good processing performance: The wall of the extruded seamless steel pipe is uniform, the inner and outer surfaces are smooth, and it has good cutting and welding performance, making it easy to process and connect.
4. Excellent mechanical properties: The mechanical properties of extruded seamless steel pipes are excellent, with higher indicators such as tensile strength, yield point, and elongation than ordinary seamless steel pipes.
5. The diameter of extruded seamless steel pipes can be made smaller.
According To The Shape Of Section
Fourthly, according to the shape of section,seamless steel pipe can be divided into seamless square pipe, seamless rectangular steel tubing, seamless steel round tubing, shaped seamless pipe.Irregular tubes include elliptical tubes, triangular tubes, hexagonal tubes, melon seed tubes, octagonal tubes, star shaped tubes, and finned tubes.
Seamless Square Pipe
Shape:Square
Features:
1. Structure and performance
The seamless square tube is made of a seamless piece of metal, which makes its structure stable and not easily deformed. Due to the absence of internal welds, seamless square tubes perform excellently under high pressure and high temperature, meeting the needs of various harsh environments and usage scenarios.
2. Diverse materials
Seamless square tubes can be made of various materials, such as carbon steel, stainless steel, alloy steel, etc. These different materials endow seamless square pipes with different properties, such as corrosion resistance, high temperature resistance, strength, etc., enabling them to adapt to different usage needs.
3. Size and accuracy
Seamless square tubes can achieve high-precision size control during the manufacturing process, ensuring that the size of each seamless square tube meets the standard. This makes the installation and use of seamless square tubes more convenient, reducing installation problems and quality hazards caused by unsuitable dimensions.
4. Good mechanical performance
Seamless square tubes have high strength and toughness, and can withstand significant pressure and impact forces. At the same time, its anti fatigue performance is also very good, and it can maintain stable performance during long-term use.
5. Easy to process and install
The surface of seamless square tubes is smooth and easy to perform processing operations such as cutting, bending, and welding. In addition, its unique structure also makes the installation process more convenient, which can save installation time and costs.
Application: Used for manufacturing structural components and mechanical parts, building structures, mechanical manufacturing, etc.
Seamless Rectangular Steel Tubing
Shape:rectangular
Features: Good bending resistance, easy welding and processing, high strength.
Application: Steel wood furniture, agricultural machinery framework, greenhouse framework, mechanical components, shipbuilding, etc
Seamless Steel Round Tubing
Shape:round
Features: When subjected to internal or external radial pressure, the circular section of the seamless pipe is subjected to uniform force, so it has good characteristics of compression resistance and high temperature resistance.
Application: A large number of seamless round tube are used for transporting fluids, such as pipelines for transporting oil, natural gas, gas, water, and certain solid materials. A small amount is used as support for building structures and mechanical structures, pile driving pipes, glass curtain wall engineering, etc.
Shaped Steel Tube
Shape:shaped
Features: The special shape can meet various structural design requirements, with smooth inner and outer surfaces without joints, increasing the compressive strength of pipelines or structures.
Application: Seamless shaped steel pipes have a wide range of applications in the field of construction. It can be used to make supporting structures, bridge components, stair handrails, etc.
In the field of engineering, seamless shaped steel pipes are commonly used to make conveying pipelines, pipeline connectors, and so on. It can also be used to make mechanical equipment, automotive components, etc.
According To The Wall Thicknesses
Fifth,according to different wall thicknesses, seamless steel pipes are divided into thick walled seamless steel pipes and thin-walled seamless steel pipes.
Thick Walled Seamless Steel Pipes
WT: Seamless steel pipes with a wall thickness of over 16mm are called thick walled seamless pipes.
Features: The biggest characteristic of thick walled seamless steel pipes is their large wall thickness, which gives them high pressure bearing capacity and strength. Meanwhile, due to the unique production process of seamless steel pipes, both the inner and outer walls are very smooth, making it difficult to accumulate impurities and dirt, thus ensuring smooth fluid flow. In addition, thick walled seamless steel pipes also have good corrosion resistance and can be used for a long time in harsh environments.
Application: Thick walled seamless steel pipe is an important industrial material widely used in fields such as petroleum, natural gas, chemical, and power.
Thin Walled Seamless Steel Pipes
WT: 1.5-3mm
Features: High precision, light weight, high strength, corrosion resistance, good thermal conductivity
Application: Mainly used in the fields of structural components, decoration, precision manufacturing, and instrumentation.
According To The Application
Sixth,according to different uses, seamless steel pipes can be divided into petroleum geological drilling pipes, petrochemical cracking pipes, boiler pipes, bearing pipes, as well as high-precision structural steel pipes for automobiles, tractors, and aviation.
Seamless Pipe Application Categories
1. Seamless steel pipes for structural purposes (GB/T8162-2008) are seamless steel pipes used for general structures and mechanical structures.
2. Seamless steel pipe for fluid transportation (GB/T8163-2008) is a general seamless steel pipe used for transporting fluids such as water, oil, and gas.
3. Seamless steel pipes for low and medium pressure boilers (GB3087-2008) are high-quality carbon structural steel hot-rolled and cold drawn (rolled) seamless steel pipes used for manufacturing various types of structural low and medium pressure boiler superheated steam pipes, boiling water pipes, locomotive boiler superheated steam pipes, large smoke pipes, small smoke pipes, and arch brick pipes.
4. Seamless steel pipes for high-pressure boilers (GB5310-2008) are high-quality carbon steel, alloy steel, and stainless heat-resistant seamless steel pipes used for manufacturing heating surfaces of water tube boilers for high-pressure and above pressures.
5. High pressure seamless steel pipes (GB6479-2000) for fertilizer equipment are high-quality carbon structural steel and alloy steel seamless steel pipes suitable for chemical equipment and pipelines with working temperatures of -40~400 ℃ and working pressures of 10~30 Ma.
6. Seamless steel pipes for petroleum cracking (GB9948-88) are seamless steel pipes suitable for furnace tubes, heat exchangers, and pipelines in petroleum refining plants.
7. Steel pipe for geological drilling (YB235-70) is a steel pipe used by geological departments for core drilling.
8. Seamless steel pipe for diamond core drilling (GB3423-82) is a seamless steel pipe used for drilling rods, core rods, and casings in diamond core drilling.
9. Oil drilling pipe (YB528-65) is a seamless steel pipe used for internal or external thickening at both ends of oil drilling. Steel pipes are divided into two types: threaded and non threaded. The threaded pipes are connected by joints, while the non threaded pipes are connected by butt welding with tool joints.
10. Carbon steel seamless steel pipes for ships (GB5213-85) are carbon steel seamless steel pipes used in the manufacture of Class I pressure resistant pipe systems, Class II pressure resistant pipe systems, boilers, and superheaters for ships. The working temperature of carbon steel seamless steel pipe wall shall not exceed 450 ℃, and the working temperature of alloy steel seamless steel pipe wall shall not exceed 450 ℃.
11. Seamless steel pipe for automotive half axle sleeve (GB3088-82) is a high-quality carbon structural steel and alloy structural steel hot-rolled seamless steel pipe used for manufacturing automotive half axle sleeves and drive axle axle housing shaft pipes.
12. High pressure oil pipes for diesel engines (GB3093-86) 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 pipes for hydraulic and pneumatic cylinder barrels (GB8713-88) are cold drawn or cold-rolled precision seamless steel pipes with precision inner diameter dimensions used in the manufacturing of hydraulic and pneumatic cylinder barrels.
14. Cold drawn or cold-rolled precision seamless steel pipes (GB3639-83) are precision seamless steel pipes with high dimensional accuracy and good surface smoothness used in mechanical structures and hydraulic equipment. Choosing precision seamless steel pipes to manufacture mechanical structures or hydraulic equipment can greatly save machining time, improve material utilization, and also help improve product quality.
15. Seamless stainless steel pipes for structural purposes (GB/T14975-1994) are hot-rolled (extruded, expanded) and cold-drawn (rolled) seamless steel pipes made of stainless steel, which are widely used in industries such as chemical, petroleum, light textile, medical, food, machinery, and other corrosion-resistant pipes and structural components.
16. Seamless stainless steel pipes for fluid transportation (GB/T14976-1994) are hot-rolled (extruded, expanded) and cold drawn (rolled) seamless steel pipes made of stainless steel used for fluid transportation.
17. Irregular seamless steel pipe is a general term for seamless steel pipes with other cross-sectional shapes except for circular pipes.
According to the different cross-sectional dimensions of steel pipes, they can be divided into equal wall thickness irregular seamless steel pipes (code D), unequal wall thickness irregular seamless steel pipes (code BD), and variable diameter irregular seamless steel pipes (code BJ). Specially shaped seamless steel pipes are widely used in various structural components, tools, and mechanical components. Compared with circular pipes, special-shaped pipes generally have larger moments of inertia and cross-sectional modulus, as well as greater bending and torsion resistance, which can greatly reduce structural weight and save steel.
According To The Standards
Seventh,according to different standards, seamless steel pipes can be divided into API seamless pipes,ASTM standard seamless steel tube, EN standard seamless pipes, DIN seamless pipes, GB standard seamless pipes, ISO standard seamless steel pipe,etc.
Corresponding Standards And Steel Grades For Kinds Of Seamless Pipe
Name
|
Material
|
Standards |
Size
|
Use
|
Alloy Pipe | 12Cr1MoVG 12CrMoG 15CrMoG 12Cr2Mo<A335P22 Cr5Mo<A335P5> Cr9Mo<A335P9> 10Cr9Mo1VNb<A335P91> 15NiCuMoNb5<WB36> 12Cr2MoWVTiB<Steel Study 102> | GB5310-1995 GB6479-2000 GB9948-2006 DIN17175-79 ASTM SA335 ASTM SA213 JISG3467-88 JISG3458-88 | ∮8-1240*1-200 | Suitable for petroleum, chemical, electric power, boiler industry, with high temperature resistance, low temperature resistance, corrosion resistance characteristics. |
Stainless Steel Pipe | 0Cr18Ni9<304> 00Cr19Ni10<304L> 00Cr25Ni20<310S> 0Cr17Ni12Mo2<316> 00Cr17Ni14Mo2<316L> 1Cr18Ni9Ti<321> 0Cr18Ni10Ti 0Cr18Ni11Nb<347> | GB/T14975-2002 GB/T14976-2002 GB13296-2007 ASTM A213 ASTM A269 ASTM A312 JIS G3459 DIN 17458 | ∮6-630*0.5-60 | Applicable to petroleum, aviation, smelting, food, water conservancy, electric power, chemical, chemical, chemical fibre, pharmaceutical machinery and other industries |
Cryogenic tubes | 16MnDG、10MnDG、09DG 09Mn2VDG、06Ni3MoDG ASTM A333Grade1 ASTM A333Grade3 ASTM A333Grade4 ASTM A333Grade6 ASTM A333Grade7 ASTM A333Grade8 ASTM A333Grade9 ASTM A333Grade10 ASTM A333Grade11 | GB/T18984-2003 ASTM A333 | ∮8-1240*1-200 | Suitable for seamless steel pipes used in -45 ℃ to -195 ℃ low-temperature pressure vessel pipelines and low-temperature heat exchanger pipelines |
High pressure boiler tube | 20G ASTM SA106B/C ASTM SA210A/C ST45.8-III | GB5310-1995 ASTM SA106 ASTM SA210 DIN17175-79 | ∮8-1240*1-200 | Suitable for the manufacture of high-pressure boiler heated tubes, header boxes, steam pipes, etc. |
High Pressure Fertiliser Tubes | 10 20 16Mn | GB6479-2000 | ∮8-1240*1-200 | Suitable for chemical equipment and pipelines with working temperatures ranging from -40 to 400 ℃ and working pressures ranging from 10-32Mpa |
oil cracking tube | 10 20 | GB9948-2006 | ∮8-630*1-60 | Furnace tubes, heat exchanger tubes and pipes for petroleum refineries |
Low-medium pressure boiler tubes | 10# 20# 16Mn<Q345A.B.C.D.E> | GB3087-2008 | ∮8-1240*1-200 | Suitable for the manufacture of low and medium pressure boilers of various structures and locomotive boilers. |
Fluid Conveying Tubes | 10#、 20# ASTM A106A,B,C、A53A,B 16Mn<Q345A.B.C.D.E> | GB/T8163-2008 ASTM A106 ASTM A53 | ∮8-1240*1-200 | General seamless steel tubes and pipes suitable for conveying fluids |
General Structural Tubes | 10#、20#、45#、27SiMn ASTM A53A,B 16Mn<Q345A,B,C,D,E> | GB/T8162-2008 GB/T17396-1998 ASTM A53 | ∮8-1240*1-200 | Suitable for general structures, engineering supports, mechanical processing, etc |
Petroleum casing
|
J55、K55、N80、L80C90、C95、P110
|
API SPEC 5CT ISO11960 |
∮60.23-508.00 *4.24-16.13 |
Tubing is used to extract oil or natural gas from oil wells. Tubing is used as the wellbore for oil and gas wells
|
Pipeline pipe | A、B、X42、X46、X52、X56、X60、X65、X70、X80 L245、L290、L360、L415、L450 | API SPEC 5L GB/T9711.1 GB/T9711.2 | ∮32-1240*3-100 | Oxygen, water and oil transport pipes for the oil and gas industry |
The Final Words
Seamless pipe is a long piece of steel with a hollow cross-section and no seams around it. There are also a wide range of seamless steel pipe, understanding the types of seamless steel pipe will allow steel pipe users to better apply seamless pipe products. With the upgrading of technology, the quality of seamless pipe will be better and better, if you are looking for suppliers of seamless pipe, or under the project do not know which kind of pipe to use, also welcome friends from all over the world to write us a message. sales@ytdrgg.com