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What is a seamless steel pipe

What is a seamless steel pipe?

Table of Contents

Seamless steel pipe is a steel pipe made of whole round bar pierced without welded seams on the surface, called seamless pipe. According to the production method, seamless steel pipe can be divided into hot-rolled seamless steel pipe, cold-rolled seamless steel pipe, cold-drawn seamless steel pipe, extruded seamless steel pipe, top pipe, etc. According to the shape of the section, seamless steel pipe is divided into two kinds of round and shaped, shaped pipe has a square, oval, triangular, hexagonal, melon, star, with a variety of complex shapes finned tube. Depending on the application, there are thick-walled seamless steel tubes and thin-walled seamless steel tubes. Seamless steel tubes are mainly used as petroleum geological drilling tubes, petrochemical cracking tubes, boiler tubes, bearing tubes, and high-precision structural steel tubes for automobiles, tractors, and aviation.

20220531115136 75024 - What is a seamless steel pipe

Characteristics of seamless steel pipe

The main feature of seamless steel pipe is that it has no welding joint and can withstand large pressure. The product can be very rough as cast or cold drawn parts.
Seamless steel pipes have hollow sections and are widely used as pipelines for conveying fluids, such as oil, natural gas, gas, water and some solid materials. Compared with solid steel such as round steel, steel pipe is lighter in weight when its bending and torsional strength is the same. It is a kind of economic section steel. It is widely used to manufacture structural parts and mechanical parts, such as oil drill pipe, automobile transmission shaft, bicycle frame and steel scaffold used in construction. It can improve the material utilization rate, simplify the manufacturing process, save materials and processing hours. It has been widely manufactured with steel pipe.

Types of Seamless Steel Pipes

Seamless steel pipe is divided into two categories: hot-rolled and cold-rolled (dialed) seamless steel pipe.
Hot-rolled seamless steel pipe is divided into ordinary steel pipe, low and medium pressure steamer steel pipe, low pressure steamer steel pipe, alloy steel pipe, stainless steel pipe, kerosene cracking pipe, geological steel pipe and other steel pipes.
Cold rolled (dialed) seamless steel pipe is divided into ordinary steel pipe, low and medium pressure steam boiler steel pipe, low pressure steam boiler steel pipe, alloy steel pipe, stainless steel pipe, kerosene cracking pipe, other steel pipe, but also includes carbon thin-walled steel pipe, alloy thin-walled steel pipe, stainless thin-walled steel pipe, shaped steel pipe. The hot-rolled seamless tube outer diameter is generally greater than 32 sisters, wall thickness 2.5-75 sisters, cold-rolled seamless steel tube diameter can be up to 6 sisters, wall thickness can be up to 0.25 sisters, thin-walled tube outer diameter can be up to 5 sisters, wall thickness less than 0.25 sisters, cold-rolled than hot-rolled dimensional accuracy is high.

  • Seamless steel pipe for general use: is made of ten, 20, 30, 3 five, 45 and other good carbon knotted steel 16Mn, 5MnV and other low-alloy layout steel or 40Cr, 30CrMnSi, 45Mn two, 40MnB and other alloy steel hot-rolled or cold-rolled. Ten, 20 and other low carbon steel made of seamless pipe is mainly used for fluid transportation pipeline.4 Five, 40Cr and other medium carbon steel made of seamless effective to make machine whole machine, such as cars, tractors of the force of the whole machine. Seamless steel pipe for general use should be wrapped in strength and flattening test. Hot-rolled steel pipe is delivered in hot-rolled condition or hot solution condition; cold-rolled is delivered in hot solution condition.
  • Seamless steel pipe for low and medium pressure steam boiler: used for making all kinds of low and medium pressure steam boiler, superheated steam pipe, rolling water pipe, water-cooled wall pipe and superheated steam pipe for locomotive steam boiler, big smoke pipe, small smoke pipe and arch brick pipe, etc. Hot-rolled or cold-rolled (dialed) seamless steel pipe with good carbon layout steel. The main use of ten, 20# steel production, in addition to guarantee the chemical identity and machine function to do water pressure test, rolled edge, flaring, flattening and other experiments. Hot-rolled to hot-rolled condition delivery, cold-rolled (dial) to hot solution condition delivery.
  • Low-pressure steam boiler steel pipe: the primary use for the production of low pressure and the above pressure steam boiler pipeline with good carbon layout steel, alloy layout steel and stainless heat-resistant steel seamless steel pipe, these steam boiler pipe is often in high and low pressure things, the tube in the low temperature flue gas and water steam function will also produce oxidation and erosion, so the request for steel pipe has a high long-term strength, high oxidation function, and has a good structure Fluctuation, the acceptance of steel grades: excellent carbon layout steel grades 20G, 20MnG, 25MnG; alloy layout steel grades 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB, etc.; rust heat-resistant steel rare 1Cr18Ni9, 1Cr18Ni11Nb low pressure flue gas steam function. 1Cr18Ni11Nb low-pressure steamer pipe in addition to the chemical identity and machine function of the package, to do the hydraulic test one by one, to make the flaring, flattening test. Steel pipe to hot solution condition delivery. In addition, for the product steel pipe microstructure, grain size, decarburization layer also have certain requirements.
  • Seamless steel pipe for geological drilling and kerosene drilling: to explore the layout of open rock formations, open water, kerosene, natural gas and mineral capital situation, the use of drilling rigs to drill wells. Coal oil and natural gas mining is more inseparable from drilling, seamless steel pipe for geological drilling and kerosene drilling is the primary thing for drilling, which mainly includes core outer pipe, core inner pipe, casing, drill pipe and so on. Because the pipe for drilling has to be deep to several kilometers of stratigraphic depth, the premise is extremely complicated, and the drill pipe suffers from stress functions such as pulling, pressing, winding, changing and unbalanced striking load, and is also subject to mud and rock abrasion, therefore, the pipe must have sufficient strength, hardness, wear resistance and striking toughness, and the steel is effectively steel with “DZ”. (The steel is effective steel with “DZ” (geological Hanyu Pinyin prefix) plus the number one symbol steel yield point implied, rare steel number DZ45 45MnB, 50Mn; DZ50 40Mn two, 40Mn2Si; DZ55 40Mn2Mo, 40MnVB; DZ60 40MnMoB, DZ65 27MnMoVB. steel pipe are delivered in hot solution condition.
  • Kerosene Cracking Pipe: Seamless pipe for furnace pipe, heat exchanger pipe and pipeline used in kerosene refinery. Rarely used good carbon steel (ten, 20), alloy steel (12CrMo, 15CrMo), heat-resistant steel (12Cr2Mo, 15Cr5Mo), stainless steel (1Cr18Ni9, 1Cr18Ni9Ti) production. In addition to the chemical identity and various machine functions, the steel pipe is also subject to water pressure, flattening, flaring and other experiments, as well as appearance quality and non-destructive overhaul. Steel pipes are delivered in hot solution condition. Stainless steel pipe: with all kinds of stainless steel hot-rolled, cold-rolled stainless steel pipe, widely used in coal and oil, chemical equipment pipelines and various uses of stainless steel layout machine, in addition to chemical identity and machine function, where used to suffer fluid pressure of the steel pipe to ensure that the hydraulic test pass. Various types of public steel pipe to be packaged in accordance with the prescribed prerequisites.

What is a hot rolled seamless steel pipe

Hot rolled seamless steel pipe: compared with cold rolling, cold rolling is rolling below the recrystallization temperature, while hot rolling is rolling above the recrystallization temperature.

Hot rolled seamless steel pipe - What is a seamless steel pipe

Hot rolled seamless steel pipes are divided into general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, geological steel pipes and other steel pipes.

What is a cold rolled seamless steel pipe

Cold drawn steel pipe is a kind of steel pipe, that is, it is classified according to different production processes, which is different from hot rolled (expanded) pipe. It is formed by multi pass cold drawing in the process of expanding the blank or raw material pipe, and is usually carried out on a 0.5 ~ 100t single chain or double chain cold drawing machine. Cold rolled (drawn) steel pipes include general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, machined pipes, thick walled pipes, small-diameter cold drawn pipes with internal mold and other steel pipes, as well as carbon thin-walled steel pipes, alloy thin-walled steel pipes, stainless thin-walled steel pipes and special-shaped steel pipes. The outer diameter of cold drawn steel pipe can reach 6mm, the wall thickness can reach 0.25mm, the outer diameter of thin-walled pipe can reach 5mm, and the wall thickness is less than 0.25mm. The accuracy and surface quality are significantly better than hot-rolled (expanded) pipe. However, due to the process constraints, its diameter and length are limited.

Cold rolled (drawn) seamless steel pipes include carbon thin-walled steel pipes, alloy thin-walled steel pipes, stainless steel thin-walled steel pipes, stainless thin-walled steel pipes and special-shaped steel pipes in addition to general steel pipes, low and medium pressure boiler steel pipes, high-pressure boiler steel pipes, alloy steel pipes, petroleum cracking pipes and other steel pipes.

What is the difference between hot rolled seamless steel pipe and cold rolled seamless steel pipe?

What is the difference between hot-rolled seamless steel pipe and cold-rolled seamless steel pipe? Is the usual seamless steel pipe a hot rolled seamless steel pipe?
Cold rolled seamless steel tubes are often small diameter, while hot rolled seamless steel tubes are often large diameter. The accuracy of cold rolled seamless steel pipe is higher than that of hot rolled seamless steel pipe, and the price is also higher than that of hot rolled seamless steel pipe.
Seamless steel pipe is divided into hot rolled (extruded) seamless steel pipe and cold drawn (rolled) seamless steel pipe due to its different manufacturing process. Cold-drawn (rolled) tubes are divided into round and shaped tubes.
1) Different uses
Hot-rolled seamless pipe is divided into ordinary steel pipe, medium and low pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, geological steel pipe and other steel pipes. Cold rolled (dialed) seamless steel pipe is divided into ordinary steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, carbon steel pipe, petroleum cracking pipe and other steel pipes, as well as carbon thin-walled steel pipe, alloy thin-walled steel pipe, stainless steel thin-walled steel pipe, shaped steel pipe.
2) Different sizes
The outer diameter of hot-rolled seamless pipe is generally greater than 32mm, wall thickness of 2.5-75mm. cold-rolled seamless pipe diameter up to 6mm, wall thickness up to 0.25mm. thin-walled pipe outer diameter up to 5mm, wall thickness less than 0.25mm. cold-rolled has higher dimensional accuracy than hot-rolled.
3) Process differences

  • 1. Cold-rolled sections allow local buckling of the cross-section, which can make full use of the load-bearing capacity of the steel after buckling; and hot-rolled steel does not allow local buckling of the cross-section.
  • 2. Hot-rolled steel and cold-rolled steel produce residual stress for different reasons, so the distribution in the cross-section is also very different. Cold-formed thin-walled steel cross-sectional residual stress distribution is curved, while hot-rolled thin-walled steel or welded steel cross-sectional residual stress distribution is film-like.
  • 3. The free torsional stiffness of hot-rolled steel is higher than that of cold-rolled steel, so the torsional strength of hot-rolled steel is better than that of cold-rolled steel.

4) Different advantages and disadvantages
Cold-rolled seamless steel pipe is a steel plate or strip processed into various types of steel by cold processing such as cold drawing, cold bending and cold drawing at room temperature.
Advantages of cold-rolled seamless steel pipe
Forming speed, high yield, no damage to the coating, can be made into a variety of cross-sectional forms to meet the needs of the conditions of use; cold rolling can make the steel produce greater plastic deformation, thereby improving the yield strength of the steel point.
Disadvantages of cold-rolled seamless steel pipe

  • 1. Although there is no thermoplastic compression during the forming process, but the cross-section still has residual stress, which is bound to affect the overall and local flexural properties of steel;
  • 2. The style of cold-rolled steel is generally open section, so that the free torsional stiffness of the section is low. Bending is prone to twisting, bending and torsional buckling when compressed, poor torsional resistance;
  • 3. Cold-rolled steel plate wall thickness is small, the plate connection at the corner without thickening phenomenon, the ability to withstand local concentrated load is weak.

Hot-rolled seamless steel pipe is relative to cold-rolled seamless pipe. Cold-rolled seamless tubes are rolled below the recrystallization temperature, while hot-rolled seamless tubes are rolled above the recrystallization temperature.
Advantages of hot-rolled seamless steel pipe
It can destroy the casting organization of the ingot, refine the grain of steel, eliminate microstructural defects, make the steel organization dense and improve the mechanical properties. This improvement is mainly reflected in the rolling direction, so that the steel is no longer isotropic to a certain extent; bubbles, cracks, loosening, etc. formed during casting can also be welded at high temperature and pressure.
Disadvantages of hot-rolled seamless steel pipe

  • 1. After hot rolling, the steel internal non-metallic inclusions (mainly sulfides and oxides, and silicates) are pressed into thin sheets, and delamination (lamination) occurs. Delamination deteriorates the tensile properties of the steel in the thickness direction considerably, and interlaminar tearing may occur when the weld shrinks. Weld shrinkage caused by local strain often reaches several times the yield point strain, much greater than the load-induced strain;
  • 2. The residual stress caused by uneven cooling. Residual stress is the internal self-balancing stress without external forces. Various sections of hot-rolled steel have such residual stresses. Usually, the larger the cross-sectional size of the steel section, the greater the residual stress. Although the residual stress is self-balancing, it still has an effect on the performance of the steel member under external forces. For example, it may have a negative impact on deformation, stability and fatigue resistance.
  • 3. Hot rolled steel products are not easy to control in terms of thickness and edge width. We are familiar with thermal expansion and contraction. Because at the beginning, even if the length and thickness are up to standard, there will be a certain negative difference after the final cooling. The wider the negative difference and the thicker the thickness, the more pronounced the properties. Therefore, for large steel, the edge width, thickness, length, angle and edge line of steel cannot be too precise.

Seamless steel pipe is generally made of 10, 20, 30, 35, 45 and other high quality carbon steel such as 16Mn, 5MnV and other low alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steel by hot rolling or cold rolling. 10, 20 and other low carbon steel seamless pipe is mainly used for fluid transportation pipeline. 45, 40Cr and other medium carbon steel seamless pipe is used for manufacturing mechanical parts. such as the stressed parts of automobiles and tractors. In general, the strength and flattening test must use seamless steel pipe. Hot-rolled steel pipe is delivered in hot-rolled or heat-treated condition; cold-rolled steel pipe is delivered in heat-treated condition.
Tip: ASTM A53 Gr.B is the grade in ERW high frequency welded pipe, divided into A and B. ASTM is just a set of specifications. astm steel pipe A53A corresponds to GB8163 raw material for 10# steel, A53B corresponds to GB8163 raw material 20#.
For example: ASTM (standard) A53 (grade) gr is grade (abbreviation of grade) b (grade B).

Materials of seamless steel pipe

Special Alloys

  • HASTELLOY® X
  • MONEL® R-405
  • MONEL® K-500
  • HASTELLOY® C-276
  • HASTELLOY® C-22
  • HASTELLOY® B-2
  • INCOLOY® 825
  • INCOLOY® 800H / 800HT®
  • INCONEL® 718
  • INCONEL® ALLOY 625
  • INCONEL® ALLOY 601
  • INCONEL® ALLOY 600
  • MONEL® ALLOY 400
  • ALLOY 20
  • NICKEL 200/201
  • MONEL® R-405
  • MONEL® K-500
  • MONEL® ALLOY 400
  • INCONEL® 718
  • INCONEL® ALLOY 625
  • INCONEL® ALLOY 601
  • INCONEL® ALLOY 600
  • INCOLOY® 825
  • HASTELLOY® X
  • HASTELLOY® C-276
  • HASTELLOY® C-22
  • HASTELLOY® B-2
  • INCOLOY® 800H / 800HT®
  • HASTELLOY® B-3

Duplex Stainless Steel

  • ZERON® 100, SUPER DUPLEX STAINLESS STEEL
  • Super Duplex S32760
  • LDX 2101®, DUPLEX STEEL
  • Duplex S31803
  • SUPER DUPLEX 2507
  • DUPLEX 2205

Stainless Steel

  • STAINLESS STEEL NITRONIC 50HS
  • STAINLESS STEEL NITRONIC 60
  • STAINLESS STEEL NITRONIC 50
  • STAINLESS STEEL 13-8PH
  • STAINLESS STEEL 15-5PH
  • STAINLESS STEEL PRODEC 303
  • STAINLESS STEEL 303
  • STAINLESS STEEL 446
  • STAINLESS STEEL 410S
  • STAINLESS STEEL 410
  • STAINLESS STEEL 304-304H
  • STAINLESS STEEL 17-4
  • STAINLESS STEEL 347
  • STAINLESS STEEL 440C
  • STAINLESS STEEL 309
  • STAINLESS STEEL 316-316l
  • STAINLESS STEEL AL-6XN®
  • STAINLESS STEEL 330
  • STAINLESS STEEL 321
  • 317L STAINLESS STEEL
  • STAINLESS STEEL 310/310S
  • Stainless Steel 304L
  • Stainless Steel 304
  • STAINLESS STEEL 253 MA

Carbon Steel

Material Pipes Fittings Flanges Valves Bolts & Nuts
Carbon Steel A106 Gr A A234 Gr WPA A105 A216 Gr WCB A193 Gr B7
Carbon Steel  A106 Gr B A234 Gr WPB A105 A216 Gr WCB A194 Gr 2H
A106 Gr C A234 Gr WPC A105 A216 Gr WCB
A335 Gr P1 A234 Gr WP1 A182 Gr F1 A217 Gr WC1 A193 Gr B7
Alloy high Temp A335 Gr P11 A234 Gr WP11 A182 Gr F11 A217 Gr WC6 A194 Gr 2H
A335 Gr P12 A234 Gr WP12 A182 Gr F12 A217 Gr WC6
A335 Gr P22 A234 Gr WP22 A182 Gr F22 A217 Gr WC9
A335 Gr P5 A234 Gr WP5 A182 Gr F5 A217 Gr C5
A335 Gr P9 A234 Gr WP9 A182 Gr F9 A217 Gr C12
Carbon Steel A333 Gr 6 A420 Gr WPL6 A350 Gr LF2 A352 Gr LCB A320 Gr L7
Alloy low Temp A333 Gr 3 A420 Gr WPL3 A350 Gr LF3 A352 Gr LC3 A194 Gr 7

Titanium

  • 10V-2Fe-3Al
  • 6Al-4V
  • 6Al-4V STA
  • 6Al-4V ELI
  • 6Al-2Sn-4Zr-2Mo

Standard of seamless steel pipe

API SPEC 5L/ 5CT

We can makes and markets cold-drawn and hot rolled seamless steel pipes and cold-drawn special-section seamless pipes which are widely applied in the industries of petrochemical, boiler, automobile, mechanical, construction.

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 Cold-drawn Carbon Steel Feedwater Heater Tubes ASTM A556 10.3~426 x 1.0~36 A2, B2

DIN/EN

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, 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 lenght
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) specifies 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 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 国标

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 high quality carbon structural. GB5310 19.05~114.3 x 2.0~14 20G, 20MnG, 25MnG, 15MoG, 20MoG, 12CrMoG, 15CrMoG(T12/P12), 12CrMoG, 12Cr2MoWVTiB.

Specification of seamless steel pipe

The outer diameter of hot-rolled seamless pipe is generally greater than 32mm, and the wall thickness is 2.5-75mm. The outer diameter of cold-rolled seamless pipe can reach 6mm, and the wall thickness can reach 0.25mm. The outer diameter of thin-walled pipe can reach 5mm, and the wall thickness is less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.

Stainless Steel Seamless Pipe Size
(inches)
Outside
Diameter
Seamless Pipe Schedule
Sch. 5S Sch. 10S Sch. 40S Sch. 80S
(mm) (inches) Pipe Wall Thickness and Weight
mm
(in)
kg/m mm
(in)
kg/m mm
(in)
kg/m mm
(in)
kg/m
1/8 10.3 0.405 1.25
(0.049)
0.28 1.73
(0.068)
0.37 2.42
(0.095)
0.47
1/4 13.7 0.540 1.66
(0.065)
0.49 2.24
(0.088)
0.63 3.03
(0.119)
0.80
3/8 17.2 0.675 1.66
(0.065)
0.63 2.32
(0.091)
0.85 3.20
(0.126)
1.10
1/2 21.3 0.840 1.65
(0.065)
0.81 2.11
(0.083)
1.00 2.77
(0.109)
1.27 3.74
(0.147)
1.62
3/4 26.7 1.050 1.65
(0.065)
1.02 2.11
(0.083)
1.28 2.87
(0.113)
1.68 3.92
(0.154)
2.20
1 33.4 1.315 1.65
(0.065)
1.30 2.77
(0.109)
2.09 3.38
(0.133)
2.50 4.55
(0.179)
3.24
1 1/4 42.2 1.660 1.65
(0.065)
1.66 2.77
(0.109)
2.69 3.56
(0.140)
3.39 4.86
(0.191)
4.47
1 1/2 48.3 1.900 1.65
(0.065)
1.91 2.77
(0.109)
3.11 3.69
(0.145)
4.06 5.08
(0.200)
5.41
2 60.3 2.375 1.65
(0.065)
2.40 2.77
(0.109)
3.93 3.92
(0.154)
5.45 5.54
(0.218)
7.49
2 1/2 73.0 2.875 2.11
(0.083)
3.69 3.05
(0.120)
5.26 5.16
(0.203)
8.64 7.01
(0.276)
11.4
3 88.9 3.500 2.11
(0.083)
4.52 3.05
(0.120)
6.46 5.49
(0.216)
11.3 7.62
(0.300)
15.3
3 1/2 101.6 4.000 2.11
(0.083)
5.18 3.05
(0.120)
7.41 5.74
(0.226)
13.6 8.08
(0.318)
18.6
4 114.3 4.500 2.11
(0.083)
5.84 3.05
(0.120)
8.37 6.02
(0.237)
16.1 8.56
(0.337)
22.3
5 141.3 5.563 2.77
(0.109)
9.46 3.41
(0.134)
11.6 6.56
(0.258)
21.8 9.53
(0.375)
31.0
6 168.3 6.625 2.77
(0.109)
11.3 3.41
(0.134)
13.9 7.12
(0.280)
28.3 10.98
(0.432)
42.6
8 219.1 8.625 2.77
(0.109)
14.8 3.76
(0.148)
20.0 8.18
(0.322)
42.5 12.70
(0.500)
64.6
10 273.1 10.750 3.41
(0.134)
22.7 4.20
(0.165)
27.8 9.28
(0.365)
60.4 12.70
(0.500)
81.5
12 323.9 12.750 3.97
(0.156)
31.3 4.58
(0.180)
36.1 9.53
(0.375)
73.9 12.70
(0.500)
97.4

Manufacturing process of seamless steel pipe

Generally, the production process of seamless steel pipe can be divided into cold drawing and hot rolling. The production process of cold-rolled seamless steel pipe is generally more complex than hot rolling. The pipe blank must first be subject to three roll continuous rolling and sizing test after extrusion. If there is no response crack on the surface, the round pipe must be cut by a cutting machine to cut the blank with a length of about one meter. Then enter the annealing process. Acid pickling shall be carried out with acid liquid for annealing. During acid pickling, attention shall be paid to whether there are a large number of bubbles on the surface. If there are a large number of bubbles, it means that the quality of steel pipes can not meet the corresponding standards. The appearance of cold rolled seamless steel pipe is shorter than that of hot rolled seamless steel pipe. The wall thickness of cold rolled seamless steel pipe is generally smaller than that of hot rolled seamless steel pipe, but the surface looks brighter than that of thick wall seamless steel pipe. The surface is not too rough, and the diameter is not too many burrs.
Hot rolled seamless steel pipes are generally delivered after heat treatment. After quality inspection, the hot-rolled seamless steel pipe shall be strictly selected manually by the staff. After quality inspection, the surface shall be coated with oil, followed by many cold drawing experiments. After hot rolling, the perforation experiment shall be carried out. If the perforation diameter is too large, it shall be straightened and corrected. After straightening, it is transferred to the flaw detector by the conveyor for flaw detection test. Finally, it is labeled and placed in the warehouse after specification arrangement.

The main production process of hot rolled seamless steel pipe


YouTube video


Tube blank preparation and inspection △→Tube heating→Perforation→Rolling tube→Steel tube reheating→Fixed (reduced) diameter→heat treatment △→finished tube straightening→finishing→inspection △(non-destructive, physicochemical, Taiwan inspection)→Warehousing

Hot rolled seamless steel pipe deformed processes - What is a seamless steel pipe

The production process of hot-rolled seamless steel pipe includes several basic processes such as billet preparation, billet heating, perforation, rolling, sizing and pipe cooling, finishing, etc.
Today’s hot-rolled seamless steel pipe production is generally the main deformation process has three: perforation, rolling and sizing; their respective process purposes and requirements are.
Perforation: the solid billet into a hollow burr tube; we can understand the shaping, both the rolling section as a circular; the equipment is called perforating machine. The requirements for the perforating process are: firstly, to ensure that the wall thickness of the pierced burr pipe is uniform, with small ellipticity and high geometric accuracy; secondly, the inner and outer surface of the burr pipe should be smoother, without defects such as scars, folds and cracks; thirdly, the corresponding perforating speed and rolling cycle should be available to adapt to the production rhythm of the whole unit, so that the final rolling temperature of the burr pipe can meet the requirements of the pipe rolling mill.
Rolling: the thick-walled burr pipe into thin-walled (close to the finished wall thickness) of the barren pipe; we can regard it as a fixed wall, that is, according to the subsequent process reduction and empirical formula to determine the wall thickness value of the barren pipe in this process; the equipment is known as a rolling mill. The requirements of the rolling process are: firstly, the thick-walled hair pipe into thin-walled barren pipe (wall reduction extension) should firstly ensure that the barren pipe has high wall thickness uniformity; secondly, the barren pipe has good internal and external surface quality.
Fixed reduction (including Zhang reduction): large circle into a small circle, referred to as sizing; the corresponding equipment for the fixed (reduction) diameter machine, its main role is to eliminate the previous process of rolling process caused by the outside diameter of the barren tube is not the same (the same one or the same batch), in order to improve the accuracy of the outside diameter of the finished hot-rolled tube and true roundness. The requirements of the sizing and reducing process are: first of all, in a certain total reduction rate and a smaller single rack reduction rate conditions to achieve the purpose of sizing, the second can achieve the use of a specification billet production of a variety of specifications of the finished pipe task, the third can further improve the quality of the outer surface of the steel pipe.

PROCESS FLOW CHART OF HOT ROLLED SEAMLESS STEEL PIPE

The main purpose of the perforation process is to become a solid round billet piercing hollow shell. Capillary in the specifications, accuracy and surface quality can not meet the requirements of the finished product, further improvements are needed to deform the metal through. The main purpose of the stretching machine is further reduced sectional view (main compression wall) for a larger axial extension, so that the capillary improved dimensional accuracy, surface quality and organizational performance.

After stretching machine rolled steel pipe shortage collectively need further molding mill in order to achieve the requirements of the finished pipe. Rolled steel due to pass in the method widely used in the production of seamless steel tubes.

So far, due to the method pass rolling steel can be divided into two categories: core pension without rolling rolling (hollow body rolling), and with the mandrel. Sizing machines, reducing mill and stretch reducing mill belonging to the hole without mandrel type continuous rolling mills are generally coffin. Its main purpose is to reduce the diameter of the deformation process or sizing get finished steel, the wall thickness of process control, can make thinning, thickening or nearly unchanged.

All the traditional hole-type rolling machine with mandrel belong to extend machine. The main purpose is to reduce the deformation process perforated capillary wall thickness and outer diameter roll passes in the deformation zone and the mandrel posed, for a larger axial extension. At the same time a certain improvement in the organization, performance, accuracy, surface quality.

Production process of cold drawn seamless steel tubes

Round tube → heating → perforation → Heading → annealing → pickling → oiled (copper) → multi-pass cold drawn (cold rolled) → blank tube → heat treatment → straightening →hydrostatic testing (testing) → mark → storage.

Cold drawn seamless steel tube process - What is a seamless steel pipe

PROCESS FLOW CHART OF COLD DRAWN SEAMLESS STEEL PIPE

The general cold strip mills, volume should go through continuous annealing (CAPL unit) to eliminate cold hardening and rolling stress, or batch annealing reach the mechanical properties of the corresponding standard specifies. Cold rolled steel surface quality, appearance, dimensional accuracy better than hot-rolled plate, and right-rolled thin product thickness is about 0.18mm, so the majority of users favor.
Rolling hard roll can be used as the raw material of the hot-dip galvanizing plant, hot dip galvanizing line set annealing line. Rolling hard roll weight is generally 6 to 13.5 tons, the coil diameter of 610mm.

Different manufacturing methods between cold drawn seamless steel pipe and hot rolled seamless steel pipe

The rolling method of cold drawn (rolled) seamless steel tube is more complicated than that of hot rolled (extruded) seamless steel tube. The first three steps of their production process are basically the same. The difference starts from the fourth step. After the round tube blank is emptied, it should be started and annealed. After annealing, special acid liquid shall be used for pickling. Apply oil after pickling. Then it is followed by multiple passes of cold drawing (cold rolling) and then blank pipe, special heat treatment. After heat treatment, it shall be straightened. After straightening, the steel pipe is sent to the metal flaw detector (or hydrostatic test) by the conveyor belt for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, they will be detected. Steel pipes shall be strictly selected by hand after quality inspection. After the steel pipe is inspected, the number, specification, production batch number, etc. shall be sprayed with paint.

Heat Treatment of seamless steel pipe

Commonly used seamless steel pipe heat treatment process
(1) Quenching + high-temperature tempering (Q + T, also known as tempering treatment): the steel pipe is heated to the quenching temperature, so that the internal organization of the steel pipe is transformed into austenite, and then rapidly cooled at a rate greater than the critical quenching speed, so that the internal organization of the steel pipe is transformed into martensite, and then with high-temperature tempering, the final organization of the steel pipe is transformed into a uniform tempered sothenite organization. Quenching + tempering can not only improve the strength and hardness of the steel pipe, but also the strength, plasticity and toughness of the steel pipe organic combination to meet the requirements of the purchaser of steel pipe performance.
(2) Normalizing (N, also known as normalizing): the steel pipe is heated to the normalizing temperature, so that the internal organization of the steel pipe is completely transformed into austenite tissue after the heat treatment process with air as the medium for cooling. Normalization can be obtained after different metal organizations, such as pearlite, bainite, martensite or a mixture of them. Normalizing can not only refine the grain, uniform composition, stress relief, but also improve the hardness of the steel and improve its cutting properties.
(3) Normalizing + tempering (N + T): the pipe is heated to the normalizing temperature, so that the internal organization of the pipe is completely transformed into austenite organization, after cooling in air, then with the tempering process. Steel pipe organization for tempered ferrite + pearlite, or ferrite + bainite, or tempered bainite, or tempered martensite, or tempered sothernite. Thermal treatment process system can stabilize the internal organization of steel pipe, improve the plasticity and toughness of steel pipe.
(4) Annealing: the steel pipe is heated to annealing temperature and hold for a certain period of time, with the furnace slowly cooled to a certain temperature before cooling out of the furnace a heat treatment process. Pipe annealing process can be divided into: spheroidal annealing, complete annealing, stress relief annealing, etc..

The main role of steel pipe annealing:

  • ① Reduce the hardness of the steel pipe, improve its plasticity to facilitate subsequent cutting or cold deformation processing;
  • ② Refine the grain, eliminate organizational defects, uniform internal organization and composition, improve the performance of the steel pipe or prepare for subsequent processes;
  • ③ Eliminate the internal stress of the steel pipe to prevent deformation or cracking.

(5) Solution treatment (mainly applied to the production of 18-8 austenitic stainless steel): the steel pipe is heated to the solution temperature, so that carbide and various alloying elements are fully and uniformly dissolved in austenite, and then rapidly cooled, so that carbon and alloying elements can not precipitate, to obtain a single austenitic organization of the heat treatment process. The main role of solid solution treatment:

  • ① Uniform internal organization of the steel pipe, uniform steel composition;
  • ② Eliminate the hardening during processing to facilitate subsequent cold deformation processing;
  • ③ Restore the corrosion resistance of stainless steel.

Pickling and passivation of seamless pipes

Pickling passivation is a chemical reaction used to remove corrosion from the surface of seamless steel. A comprehensive pickling passivation of seamless steel pipe removes all kinds of oil, rust, oxidation, welding spots and other dirt, and the surface becomes uniformly silvery white after treatment, greatly improving corrosion resistance.
Seamless steel pipe in the production process, machining, welding, testing and heat treatment process, will make seamless steel pipe (carbon copper pipe, stainless steel pipe) surface accumulation of iron oxide, welding slag, oil and other dirt, so that the corrosion resistance of seamless steel pipe becomes stronger.
After pickling liquid cleaning, seamless steel pipe can be removed from the surface of the spoil; then passivation according to treatment, seamless steel pipe surface to form a protective film to prevent oxidation, thereby improving the corrosion resistance of seamless steel pipe, to ensure that the production process passivation liquid preparation is reasonable or not, directly affects the quality of pickling passivation, therefore, according to the material of seamless steel pipe to determine the appropriate The recipe should be determined according to the material of seamless steel pipe.

The need for pickling passivation of seamless steel pipe

Seamless steel pipe has good low temperature performance and excellent mechanical processing properties. Therefore, it is widely used in chemical, petroleum, power, nuclear engineering, aerospace, marine, pharmaceutical, light industry, textile and other sectors. Its main purpose is to prevent corrosion and rust. Pickling passivation treatment is usually carried out in engineering to bring out the corrosion resistance potential of seamless steel pipes. In the process of forming, assembling, welding, weld inspection (such as probing, pressure resistance test) and construction marking of equipment and components bring surface oil, rust, non-metallic dirt, low melting point metal contaminants, paint, welding slag and spatter, etc. These substances affect the surface quality of equipment and components, destroy their surface oxide film, reduce the overall corrosion resistance and local corrosion resistance of steel (including pitting, crevice corrosion), and can even lead to stress corrosion rupture. Seamless steel pipe surface cleaning, pickling and passivation, in addition to maximizing corrosion resistance, there is a role in preventing product contamination and aesthetics.

The principle of pickling passivation of seamless steel pipe

One of the purposes of pickling is to create favorable conditions for passivation treatment to ensure the formation of a high-quality passivation film. Because the oxide skin on the surface of the seamless steel pipe is corroded away by pickling, the chemical activity of the acid makes the dissolution rate of the defective parts higher than the other parts on the surface, so pickling can make the whole surface tends to be evenly balanced, and some of the original hidden problems that can easily cause corrosion are removed. But more importantly, through pickling passivation, iron and iron oxides are dissolved, resulting in a surface enrichment of seamless steel passivation film, which can reach a potential of +1.0V (SCE), close to the potential of precious metals, improving the stability of corrosion resistance. Different passivation treatments also affect the composition structure of the film and thus the stainless properties. For example, through electrochemical modification treatment, the passivation film can be made to have a multilayer structure, forming CrO3 or Cr2O3 in the barrier layer, or forming a glassy oxide film, so that the seamless steel tube can exert maximum corrosion resistance.

Uses of seamless steel pipe

What is seamless steel pipe used for? Seamless steel pipe is widely used.
1. General purpose seamless steel pipe is rolled from ordinary carbon structural steel, low alloy structural steel or alloy structural steel, the most production, mainly used as a pipeline or structural parts for the transport of fluids.
2. Supplied in three categories according to different uses.

  • a. Supplied by chemical composition and mechanical properties.
  • b. Supplied according to mechanical properties.
  • c. Supplied according to hydraulic test. Steel pipes supplied according to category a and b are also subjected to hydrotesting if they are used to withstand liquid pressure.

3. Special purpose seamless tubes are available in a variety of seamless tubes for boilers, chemical power, seamless steel tubes for geological use and seamless tubes for petroleum.
Seamless steel pipe has a hollow cross-section and is used in large quantities 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, steel pipe is lighter in weight when the bending and torsional strength is the same, and is an economic cross-sectional steel.
Widely used in the manufacture of structural and mechanical parts, such as oil drilling rods, automobile drive shafts, bicycle frames and steel scaffolding used in construction, etc. The use of steel pipe manufacturing ring parts, can improve material utilization, simplify the manufacturing process, save materials and processing time, has been widely used to manufacture steel pipe.

Advantages of seamless pipe

Seamless steel tubes are made from whole pieces of metal with no surface seams. They are made from ingots or solid billets by piercing and then hot-rolling, cold-rolling or cold-rolling. Seamless steel pipes are different from other steel pipes. They are extremely corrosion resistant, strong and durable, and adaptable to different applications. It is highly applicable in the construction process and is not restricted by natural conditions during installation. Details are as follows.
1. Good wear resistance.
Seamless pipe wear layer thickness of 3-12mm, wear layer hardness up to HRC58-62, wear resistance is 15-20 times more than ordinary pipe steel plate, performance is more than 5-10 times the low alloy steel plate. It is high chromium cast iron. Wear resistance is 2-5 times more than the wear resistance is much higher than spray welding and thermal spraying.
2Excellent impact performance.
Seamless steel pipe is a double-layer metal structure. The wear-resistant layer is metallurgically bonded to the base material. High bonding strength. It can absorb energy in the process of impact. The wear-resistant layer will not fall off. It can be used for vibration and shock. Under strong working conditions, it is unreachable by cast wear-resistant materials and ceramic materials.
3Excellent temperature resistance.
The alloy carbide of seamless steel pipe has strong stability under high temperature. Wear-resistant steel plate can be used within 500°C, other special requirements of the temperature can be customized for use under conditions within 1200°C; ceramics, polyurethane, molecular materials and other high wear-resistant materials can not meet such high-temperature requirements.
4Excellent connection performance.
The base material of seamless steel pipe is generally Q235 steel plate, which ensures the compressibility and plasticity of wear-resistant steel plate and provides the strength to resist external forces. It can be connected to other structures by various methods such as welding, plug welding and bolting. The connection is firm and not easy to fall off. However, there are more connection methods compared with other materials.
5Excellent processing performance.
Seamless steel pipe can be processed into different standard sizes as needed, and can be processed, cold bent, welded, twisted, etc., which is convenient to use; it can be welded together on site, which makes maintenance and replacement work time-saving and convenient and greatly reduces work intensity.
6High cost performance.
Seamless steel pipe price is slightly higher than the general steel, but taking into account the product life, maintenance costs, spare parts costs, etc., its cost performance is much higher than the general steel and other steel.

What is the difference between seamless pipe and welded pipe?

Seamless pipe is a long steel tube with a hollow cross section and no seams around the perimeter. Seamless steel pipe is a steel pipe without seams, formed by hot rolling or cold drawing process. The characteristic is good pressure-bearing.
Welded steel pipe, also known as welded pipe, is a steel pipe made of steel plate or strip steel that has been rolled and formed and then welded. It can be divided into two types: straight seam welded and spiral seam welded steel pipe. Than an inappropriate example, rectangular white paper you rolled into a tube, and then welded up the edges is straight welded pipe, if you rolled up diagonally and then welded, is spiral welded steel pipe. Welded steel pipe production process is simple, high production efficiency, a variety of specifications, the strength is generally lower than seamless steel. Generally more than 800mm are welded steel pipe, welded with steel plates, which is the current level of domestic technology to decide.
LSAW production process is simple, high production efficiency, low cost, the strength of spiral welded pipe is generally higher than LSAW, can use a narrower billet to produce a larger diameter welded pipe, but also with the same width of the billet to produce a different diameter of welded pipe. However, compared with the same length of straight seam pipe, the weld length increases by 30 to 100%, and the production speed is lower. Therefore, most of the smaller diameter welded pipes are straight seam welded, and most of the large diameter welded pipes are spiral welded.
1. Welded pipe and seamless steel pipe compared to wall thickness tolerance
Stainless steel seamless pipe can do small diameter large wall thickness and large diameter large wall thickness, but generally will be limited by the length; but stainless steel welded pipe wall thickness can be made thinner, can do large diameter small wall thickness and small diameter small wall thickness, theoretically stainless steel coil with how long, welded pipe can do how long. In other words the thicker the more suitable for the use of seamless tubes, the thinner the more suitable for the use of welded tubes. The evenness and concentricity of the wall thickness of the tube, in this regard stainless steel welded pipe is better than stainless steel seamless pipe. Because the thickness tolerance of the cold rolled plate is more even, the deformation during the forming process is even. Seamless tube rolling process is affected by the accuracy of the equipment and other factors, with thickness unevenness. The problem of concentricity, but the roundness is better than the welded pipe.
Welded pipe: the use of hot-rolled strip coil as raw material, modern hot continuous tie thickness tolerance can be controlled within 0.05mm, while seamless steel pipe is produced using round steel perforation, wall thickness deviation is larger, the subsequent hot rolling can partially eliminate wall thickness unevenness, but the current most advanced units can only be controlled within ± 5 ~ 10%t, corresponding to 8.94mm thickness of steel pipe.
Seamless steel pipe: the limit of wall thickness control accuracy is 0.9mm.
2. Welded pipe and seamless steel pipe compared to the outside diameter tolerance
Steel pipe: the use of cold-formed, through 0.6% reduction to complete the diameter, the process temperature is basically constant at room temperature, so the outside diameter control accurately. Small fluctuation range, which is conducive to the elimination of black skin buckle.
Seamless steel pipe: the use of hot rolling forming process, the sizing is completed at about 8000C, steel raw material composition. Cooling conditions and the cooling state of the rolls have a greater impact on its outside diameter, and thus the outside diameter control is difficult to accurately, and fluctuate in a wide range.
3. Welded and seamless steel pipe comparative tensile test
Seamless steel pipe and welded pipe tensile performance indicators are in line with API standards, but the strength of seamless steel pipe is generally at the upper limit, plasticity is at the lower limit, in comparison, welded pipe strength indicators in the best state, plasticity indicators higher than the standard 33.3%, the reason for the performance of welded pipe raw material – hot-rolled coil is dependent on micro-alloyed smelting. Furnace refining and controlled cooling and rolling means to ensure; seamless steel pipe mainly relies on the means to increase the carbon content, it is difficult to ensure the strength. Plasticity of a reasonable match.
4 Welded and seamless steel pipe compared to the ellipticity
Welded pipe: the use of cold bending, so the outside diameter control accurately. Small fluctuation range.
Seamless steel pipe: the use of hot rolling forming process, steel raw material composition. Cooling conditions and the cooling state of the rolls have a greater impact on its outside diameter, and thus the outside diameter control is difficult to accurately, and fluctuate in a wide range.
5. Welded and seamless steel pipe compared to the hardness
The raw material of welded pipe – hot-rolled strip coil in the rolling process control cooling control rolling precision is very high, to ensure that the performance of all parts of the coil uniform.
6. Comparison of welded pipe and seamless steel pipe grain size
The raw material of welded pipe – hot rolled strip coil is a wide and thick continuous casting billet, which has a thick and fine crystal surface solidification layer, no columnar crystal area and shrinkage and sparseness, and small composition deviation. The organization is dense; in the subsequent rolling process, the application of controlled cooling and rolling technology further ensures the grain size of the raw material.
7. Welded pipe and seamless steel pipe compared to the crush test
Welded pipe because of its raw materials. The characteristics of the pipe making process. Its wall thickness uniformity. Ellipticity is far better than seamless steel pipe, is the main reason for higher resistance to extrusion than seamless steel pipe.
8. Welded and seamless steel pipe impact test comparison
As the impact toughness of the base material of the welded pipe several times more than the seamless steel pipe, the impact toughness of the welded seam is the key to the welded pipe, by controlling the content of raw material impurities. Longitudinal shear burr height and direction. Forming edge shape. Weld angle. Welding speed. Heating power and frequency. Welding extrusion volume. Medium frequency depopulation temperature and depth. Air-cooled section length and other process parameters to ensure that the impact power of the weld reaches more than 60% of the base material, such as further optimization, the impact power of the weld can be achieved close to the base material, so as to achieve seamless performance.
9. Comparative burst test of welded pipe and seamless steel pipe
The burst test performance of welded pipe is much higher than the standard requirements, mainly from the high uniformity of wall thickness of welded pipe. Uniform outer diameter size.
10. Comparison of straightness between welded pipe and seamless steel pipe
Welded pipe is a cold process, and in the reduced state with online straightening, coupled with an infinite number of feet, so the straightness is better; seamless steel pipe in a plastic state molding, coupled with single-fold feet (3 to 4 times the size of continuous rolling) straightness of the pipe end is relatively difficult to control.
11. Welded and seamless steel pipe compared to the appearance
Seamless steel pipe and seamless steel pipe is the main difference between seamless steel pipe without welded seams. Seamless steel pipe using the outer surface of the billet defects can not be eliminated by the hot rolling process, only after the completion of the finished product, polishing off defects; for the spiral channel left after perforation, in the process of wall reduction, can only be partially eliminated.
The surface quality of the coil is the surface quality of the welded pipe, and the surface quality of the hot-rolled coil is easy to control and higher quality, so the surface quality of the welded pipe is much better than that of seamless steel pipe. Welded pipe surface has: straight seam or spiral seam.
Seamless steel pipe is better than seamed steel pipe pressure-bearing capacity, good sealing performance, suitable for harsher working conditions.
12. Welded pipe and seamless steel pipe comparison performance aspects
Average of stainless steel welded pipe. Appearance quality. Expanding performance. Bending. Pier performance are better. Because the average performance of cold rolled sheet is better than pipe, and welded pipe is generally online solution, heat treatment is more average, the performance is more stable. Seamless stainless steel pipe, on the other hand, can vary in performance when sampled at different locations on the same pipe. Usually welded tubes are more accurate. Wall thickness is more uniform. Stainless steel pipe fittings have high brightness on the inner surface (the surface grade of the steel plate determines the surface brightness of the pipe). Can be arbitrarily sized. So its high precision. The use of low and medium pressure fluids shows its economy and beauty. The precision of seamless steel pipe is low, and the wall thickness is not uniform. The brightness of the inner surface of the tube is low. The cost of sizing is high, and the internal and external pockmarks. Black spot is not easy to remove. 13.
13. Welded pipe and seamless steel pipe price comparison
The price of welded pipe is cheaper than seamless steel pipe.
14. Welded pipe and seamless steel pipe compared to the pressure-bearing capacity
The same specifications, stainless steel seamless steel pipe pressure-bearing capacity is slightly higher than welded pipe. However, stainless steel welded pipe is formed by the use of stainless steel plate coiling, processing is relatively simple, so the delivery time is shorter. Stainless steel seamless pipe starts from round steel, perforated and then cold-drawn through multiple passes. Cold-rolled processing, then solution annealing and pickling before the finished product, the production cycle is much longer.

How do I know if my pipe is seamless?

There are two main forms of common steel pipes, namely welded steel pipes and seamless steel pipes. Since the cost of welded steel pipe is significantly lower than seamless steel pipe, some businesses, in order to seek more economic benefits, process welded steel pipe and pass it off as seamless steel pipe, and then bring it into the market for sale, causing confusion in the market. From the appearance of the processing of welded steel pipe can not be effectively identified, once in the construction process, should be used seamless steel pipe but the use of welded steel pipe, will lead to gas or liquid leaks, serious cases are also prone to explosions, so you must identify welded steel pipe and seamless steel pipe, so as to ensure the quality of the project.
Welded steel pipe is generally steel strip or steel plate under the action of external forces, so that it is formed into a round or square, and then welded surface seams, so as to constitute a welded steel pipe. The processes usually used are arc welding, high-frequency or low-frequency, cold rolling, etc., but the use of these processes for welding will result in steel pipes with welded seams. Currently, according to the shape of the weld seam can be divided into straight seam and spiral welded steel pipe, but the process used by the two is different. Spiral steel pipe is welded using submerged arc welding, and this welding method has the advantages of high welding efficiency and less dust. For high-frequency or low-frequency welding, mainly based on the principle of electromagnetic induction, due to the alternating current charge in the conductor will occur in the proximity and turbo-thermal effect, able to achieve the steel at the edge of the weld to a molten state, and finally complete the welding.
Seamless steel pipe is mainly made of solid billets or ingots that are perforated to make a burr pipe and processed by hot rolling, cold rolling, cold drawing, etc., followed by the formation of seamless steel pipe. Since seamless steel pipe contains a hollow cross-section, this hollow cross-section can be used as a conduit for the transmission of fluids.
Since seamless steel pipe metal material tensile strength is greater, so its resistance to damage is stronger, and it has a hollow channel, so it can effectively transport fluids, it is its transport capacity is strong, so the corrosion resistance of seamless steel pipe is higher than that of welded steel pipe, and its stiffness is relatively large. Therefore, the more load the seamless steel pipe carries, thus it can be widely used in projects with high construction requirements.
There are three main methods to distinguish welded steel pipe from seamless steel pipe.

1. Metallographic method

Metallographic method is one of the main methods to identify welded steel pipe and seamless steel pipe. High-frequency resistance welded steel pipe does not add welding material, so the weld seam in the completed steel pipe is very narrow, if the use of coarse grinding and then corrosion method is not clear to see the weld seam. Once the high-frequency resistance welded steel pipe welding is completed, and not after heat treatment, will lead to weld seam organization and steel pipe parent material is essentially different, at this time, the use of metallographic method can identify welded steel pipe and seamless steel pipe. In the process of identifying the two steel tubes, you need to cut the length and width of the weld at 40mm of the sample, the rough grinding, fine grinding and polishing, etc., and then put it under the metallographic microscope to observe the organization, when the observation of ferrite and weiss, the parent material and the weld area organization, you can accurately identify welded and seamless steel tubes

2. Corrosion method

In the process of using corrosion method to identify welded steel pipe and seamless steel pipe, the weld seam of welded steel pipe should be polished at the processing, polishing should be able to see the traces of polishing after completion, and then polish the end face with sandpaper at the weld seam, and treat the end face with 5% nitric acid alcohol solution, if there is an obvious weld seam, it can prove that this steel pipe is welded steel pipe. And seamless steel pipe end face after corrosion no obvious difference.
The performance of welded steel pipe
Welded steel pipe is processed by high-frequency welding, cold rolling and other processes, so it has the following performance points.

  • First, the insulation function is good. The degree of heat loss of welded steel pipe pipe is relatively small, only 25%, which not only facilitates transportation, but also reduces the cost.
  • Second, with water resistance and corrosion resistance, in the construction process, there is no need to set up a separate pipe trench, just the steel pipe directly into the ground or underwater, thus reducing the construction difficulties.
  • Third, with impact resistance. Even in the low-temperature environment, the steel pipe will not be damaged, so its performance has certain advantages.

3. According to the process of identifying welded steel pipe and seamless steel pipe

In accordance with the process of identifying welded steel pipe and seamless steel pipe, according to the process of cold rolling, extrusion and other processes are welded steel pipe, in addition, the use of high-frequency, low-frequency arc welding pipe and resistance welding pipe process for steel pipe welding, will form a spiral pipe welding and LSAW pipe welding, will form a round steel pipe, square steel pipe, oval steel pipe, triangular steel pipe, hexagonal steel pipe, diamond-shaped steel pipe, octagonal steel pipe. Even more complex steel pipe. In short, the use of different processes will form different shapes of steel pipe, so that the welded steel pipe and seamless steel pipe can be clearly identified. However, the process of identifying seamless steel tubes is mainly based on the hot-rolled and cold-rolled processes, and there are two main forms of seamless steel tubes, namely hot-rolled seamless steel tubes and cold-rolled seamless steel tubes. Hot-rolled seamless steel pipe is formed by the process of perforation, rolling, etc., especially large diameter and thickness of seamless steel pipe are used in this process for welding; cold-drawn tube is cold-drawn forming with billet, the strength of the material is lower, but its appearance and internal control surface is smooth.

4. Identification of welded steel pipe and seamless steel pipe by use classification

The bending and torsional strength of welded steel pipe is higher, and the load-bearing capacity is more adequate, so it is generally widely used in the manufacture of mechanical parts. For example, oil drilling rods, automobile drive shafts, bicycle frames and steel scaffolding used in building construction are made of welded steel pipe. However, seamless steel pipe can be used as a pipeline for transporting fluids because it has a hollow cross-section and no seams around the perimeter of the long strip of steel. For example, it can be used as a pipeline for transporting oil, natural gas, gas, water, etc. In addition, the bending strength of seamless steel pipe is relatively small, so it is generally widely used as superheated steam pipe for low and medium pressure boilers, boiling water pipe and superheated steam pipe for locomotive boilers. In short, through the classification of uses, welded steel pipe and seamless steel pipe can be clearly identified.
In order to ensure higher quality construction, welded and seamless steel pipes must be identified, and then the appropriate steel pipe is used for construction. In the process of identifying welded and seamless steel pipes, metallographic and corrosion methods can be used to examine the weld seam by observing the organization and the weld seam, and ultimately to identify them accurately. At the same time, it can also be distinguished according to the performance of the two types of steel pipe, use, etc., and then choose a reasonable steel pipe for construction.

Quality requirements of seamless steel pipe

1. Chemical composition of steel: The chemical composition of steel is one of the most important factors affecting the performance of seamless steel pipe, and is also the main basis for the development of rolling process parameters and steel pipe heat treatment process parameters.

  • a. Alloying elements: intentionally added, according to the use
  • b. Residual elements: steelmaking brought in, appropriate control
  • c. Harmful elements: strictly controlled (As, Sn, Sb, Bi, Pb), gas (N, H, O)

Off-furnace refining or electroslag remelting: improve the uniformity of the chemical composition of steel and the purity of steel, reduce the non-metallic inclusions in the pipe billet and improve its distribution pattern.
2. Steel pipe geometric accuracy and shape
a. Steel pipe outside diameter accuracy: depends on the sizing (reducing) diameter method, equipment operation, process system, etc.
Allowable deviation of outer diameter δ = (D-Di) / Di × 100%

  • D: maximum or minimum outside diameter mm
  • Di: nominal outside diameter mm

b. Pipe wall thickness accuracy: with the heating quality of the billet, the process design parameters and adjustment parameters of the deformation process, the quality of the tool and its lubrication quality, etc.
Allowable deviation of wall thickness: ρ=(S-Si)/Si×100%

  • S: maximum or minimum wall thickness in cross section
  • Si: nominal wall thickness mm

c. Steel pipe ellipticity: indicates the degree of non-circularity of the steel pipe.
d. Steel pipe length: normal length, fixed (times) length, length allowable deviation
e. Steel pipe curvature: the curvature of the steel pipe: the curvature of each meter of steel pipe length, the curvature of the full length of the steel pipe
f. Steel pipe end tangency: the steel pipe end and the inclination of the steel pipe cross-section
g. Steel pipe end bevel angle and blunt edge
3. Steel pipe surface quality: surface finish requirements

  • a. Dangerous defects: cracks, internal folding, external folding, rolling breakage, delamination, scarring, pulling concave, convex package, etc.
  • b. General defects: pockmarks, green lines, scratches, bruises, minor internal and external straight path, roll marks, etc.

Causes.

  • ① Brought about by surface defects or internal defects of pipe billets.
  • ② Produced during the production process, such as incorrect design of rolling process parameters, mold surface is not smooth, poor lubrication conditions, hole design and adjustment is not reasonable.
  • ③ Pipe billet (steel) in the heating and rolling, heat treatment and straightening process, if the heating temperature control is improper, uneven deformation, heating and cooling rate is not reasonable or straightening deformation is too large and excessive residual stress, then it may also lead to steel surface cracks.

4. Steel pipe physical and chemical properties: room temperature mechanical properties, high temperature mechanical properties, low temperature properties, corrosion resistance. The physical and chemical properties of the steel tube depends mainly on the chemical composition of the steel, the organizational structure and purity of the steel and the steel heat treatment.
5. Steel pipe process performance: flattening, flaring, crimping, bending, welding, etc.
6. Steel pipe metallographic organization: low times the organization (macroscopic), high times the organization (microscopic) M, B, P, F, A, S.
7. Steel pipe special requirements: contract annexes, technical agreements.

Quality inspection of seamless steel pipe

The main contents of the quality inspection of seamless steel pipe are: chemical composition, dimensional accuracy, internal and external surface quality (including finish), mechanical properties and the necessary process properties.

Quality inspection methods of seamless steel pipe

1. Chemical composition analysis: chemical analysis method, instrumental analysis method (infrared C-S instrument, direct reading spectrometer, zcP, etc.).

  • ① Infrared C-S instrument: analysis of iron alloys, steelmaking raw materials, C, S elements in steel.
  • ② Direct reading spectrometer: C, Si, Mn, P, S, Cr, Mo, Ni, Cn, A1, W, V, Ti, B, Nb, As, Sn, Sb, Pb, Bi in block specimens
  • ③ N-0 instrument: gas content analysis N, O

2. Geometry and shape inspection of seamless steel pipe

  • ① Seamless pipe steel wall thickness inspection: micrometer, ultrasonic thickness gauge, not less than 8 points at both ends and record.
  • ② Seamless pipe outside diameter, ellipticity check: calipers, vernier calipers, ring gauge.
  • ③ Seamless steel pipe length inspection: steel tape measure, manual, automatic length measurement.
  • ④ Seamless steel pipe curvature check: straightedge, horizontal ruler (1m), stopper, fine line measurement per meter curvature, full-length curvature.
  • ⑤ Seamless steel pipe end bevel angle and blunt edge inspection: angle ruler, cardboard.

3. Surface quality inspection of seamless steel pipe: 100%

  • ① Manual visual inspection: lighting conditions, standards, experience, logo, steel pipe rotation.
  • ② Non-destructive testing inspection.

a. Ultrasonic flaw detection UT of seamless steel pipe
It is more sensitive to surface and internal crack defects of various materials with uniformity.
Standard: GB / T 5777-1996
Level: C5 grade
b. Eddy current flaw detection ET: (electromagnetic induction)
Mainly sensitive to point-like (hole-shaped) defects.
Standard: GB/T 7735-2004
Grade: B grade
c. Magnetic particle MT and leakage magnetic flaw detection.
Magnetic flaw detection, applicable to the detection of surface and near-surface defects of ferromagnetic materials.
Standard: GB/T 12606-1999
Level: C4 grade
d. Electromagnetic ultrasonic flaw detection.
Does not require coupling medium, can be applied to high temperature and high speed, rough and dry seamless tube steel pipe surface flaw detection.
e. Penetrant flaw detection.
Fluorescence, coloring, detection of steel pipe surface defects.
4. Physical and chemical properties testing of seamless steel pipe
① Tensile test: measure stress and deformation, determine the strength of the material (YS, TS) and plasticity indicators (A, Z) longitudinal, transverse specimen pipe section, arc, circular specimen (¢10, ¢12.5) small-diameter thin-walled steel pipe, large-diameter thick-walled steel pipe, fixed pitch.
Note: Specimen elongation after fracture and specimen size GB / T 1760
② Impact test: CVN, notch C, V, work J value J/cm2
Standard specimen 10 × 10 × 55 (mm)
Non-standard specimens 5 × 10 × 55 (mm)
③ Hardness test: Brinell hardness HB, Rockwell hardness HRC, Vickers hardness HV, etc.
④ Hydraulic test: test pressure, pressure stabilization time, p = 2Sδ/D
5 seamless steel pipe process performance inspection process.
① Flattening test: round specimen C-shaped specimen (S/D>0.15) H=(1+2)S/(∝+S/D)
L = 40-100mm unit length deformation coefficient = 0.07-0.08
② Ring pull test: L = 15mm no cracks for qualified
③ Flare and rolled edge test: top center taper 30 °, 40 °, 60 °
④ Bending test: can replace the flattening test (for large diameter pipe)
6. Metallographic analysis of seamless steel pipe
① High magnification test (microscopic analysis): non-metallic inclusions 100x GB/T 10561
Grain size: level, grade difference
Organization: M, B, S, T, P, F, A-S
Decarburization layer: internal, external.
A method rating: Class A – sulfide Class B – oxide Class C – silicate Class D – spherical oxidation DS.
② Low magnification test (macroscopic analysis): Naked eye, magnifying glass 10x or less.
a. Acid etching test method.
b. Sulfur seal inspection method (tube embryo inspection, showing low peel tissue and defects, such as sparse, deviated, subcutaneous bubbles, flip skin, white spots, inclusions, etc.)
c. Tower hairline inspection method: test the number, length and distribution of hairline.

Pipes Color Codes

Pipe color coding is important both for logistical and safety considerations. Color codes are, in some cases, applied on pipes and other piping materials (such as pipe fittings, flanges, and valves) to facilitate the identification, in the storage warehouse or on the field during project execution, of components manufactured in different materials. This is the case of complex plants using, at the same time, carbon, alloy, stainless steel piping products. When a piping system conveys fluids of different types, color codes are applied to distinguish the piping components by media.

PFI ES-22 SPECIFICATION FOR PIPE COLOR CODING

The table shows the pipe color coding guidelines set by the PFI ES 22 specification. In addition to the colors specified in the table, welded pipes shall show an additional white stripe.

PFI Standard ES-22 Standard: Pipe Color Coding Recommendations
Carbon Steel Pipes
Material Material Garde Band / Strip Color
Carbon Steel, Electric Resistance Welded Pipe A53 Gr. B/API 1 solid white
Carbon Steel, Smls, specified tensile strength under 70,000 psi (483 MPA) A53 Gr. B No Marking
Carbon Steel, killed steel A106 Gr. B 1 solid green
Carbon Steel, specified tensile strength 70,000 psi (483 MPA) and over A106 Gr. C 2 solid green
Carbon Steel, low temperature (impact tested) A333 Gr. 6 1 solid red
High Yield Carbon Steel Pipes
52,000 min. yield API 5L X-52 1 solid yellow, 1 solid green
60,000 min. yield API 5L X-60 1 solid yellow, 1 solid pink
65,000 min. yield API 5L X-65 2 solid yellow
70,000 min. yield API 5L X-70 1 solid yellow, 1 solid orange
Low Alloy Pipes
C-Mo steel A335 Gr. P1 1   solid orange
1 Cr-1/2 Mo Steel A335 Gr. P12 1   solid orange, 1 solid blue
1 1 /4 Cr-1/2 Mo Steel A335 Gr. P11 1   solid yellow
2 1/4 Cr-1 Mo Steel A335 Gr. P22 1 solid blue
5 Cr-1/2 Mo Steel A335 Gr. P5 1 solid blue, 1 solid yellow
9 Cr-1/2 Mo Steel A335 Gr. P9 2 solid orange
Ferritic and Martensitic Pipes and Tubes
Type 405 A268 TP405 1 solid green, 1 solid black
Type 410 A268 TP410 1 solid green, 1 solid red
Austenitic Stainless Steel Pipes
Type 304 A312 TP304 1 solid black
Type 304L A312 TP304L 2 solid black
Type 304H A312 TP304H 1 intermittent black
Type 309 A358 Gr309 1 solid black, 1 solid brown
Type 310 A358Gr310 1 solid green, 1 solid orange
Type 316 A312 TP316 1 solid gray
Type 316L A312 TP316L 2 solid gray
Type 316H A312 TP316H 1 intermittent gray
Type 317 A312 TP317 1 solid brown, 1 solid green
 Type317L A312 TP317L 1 solid brown, 1 solid red
Type 321 A312 TP321 1 solid pink
Type 321 H A312 TP321H 2 solid pink
Type 347 A312 TP347 1 solid brown
Type 347H A312 TP347H 2 solid brown
Nickel-Alloy Pipes
Nickel 200 1 solid black, 1 solid pink
Incoloy 800 1 solid black, 1 solid orange
Incoloy 800H 1 solid gray, 1 solid red
Incoloy 825 1 solid gray, 1 solid blue
Inconel 600 2 solid blue
Inconel 625 1 solid blue, 1 solid pink
Hastelloy Alloy 8-2 1 solid red, 1 solid orange
Hastelloy Alloy C-276 1 solid red, 1 solid blue
Hastelloy Alloy C-22 2 solid red
Hastelloy Alloy G 1 solid red, 1 solid yellow
Carpenter Alloy 20 C 8-3 1 solid black, 1 solid blue
Monel 400 1 solid black, 1 solid yellow

Pipe Beveling

Pipe beveling is the process where an angle is formed between the edge of the end of a pipe or tube and a plane perpendicular to the surface.

Pipe beveld cut - What is a seamless steel pipe

A standard pipe bevel angle for welding is 37.5 degrees. Other angles and special forms such as J-Bevels can also be produced on the ends of pipe or tube using automatic beveling machines.

What is pipeline beveled end and why use it?

Pipe Beveling - What is a seamless steel pipe

pipeline beveled endBeveled end, to put it simply, is a joint surface with a specific beveled angle. In fact, it is processed prior to the welding of two pieces of line pipes, an angle formed at the edge of the end of the pipe with the help of a beveling machine. Beveling of pipe or tubing is most commonly used to prepare the ends for welding. It can also be used for deburring the cut ends for safety and aesthetic reasons.

Subtract the pipe’s wall thickness from the pipe’s outside diameter. For example, if you had a pipe with a diameter of six inches and a wall thickness of two inches, you would subtract two from six to get four.

Common types of beveled ends and comparison among different types

Beveling ends can be made into various angles, achieving the better welding seam. Common beveled ends for butt joints are I—Type butt joint, single—V beveled end, double—V beveled end and single U—beveled end.

common types of beveled ends - What is a seamless steel pipe

Common types of beveled ends

  • I—type butt joint, also called square butt joint, is a relatively simple joint method for pipes of 1 to 6 mm in thickness. Strictly speaking, it is not a beveled end joint, for it only requires parallel matching the edges of two pieces together without certain angles. It is easy and economic to process, but is not recommended for pipes of thick walls. As for thicker wall pipes, the angle of the bevel ends needs full consideration, trying to use the least filler metal material to provide the desired welding soundness.
  • Single—V beveled end, is the most widely-used butt joint type in pipeline application. It suits pipes with the thickness of 3 to 26 mm. The beveled angle should be approximately 40 to 60°. Single—V beveled end is processed by a beveling machine. Comparatively speaking, it is more costly and needs more filler material than the I—type butt joint, but the joint is much stronger than the square joint. The disadvantage of single-V beveled end is its easy subjection to angular deformation.
  • Double—V beveled end, also called X—beveled end, is developed on the basis of single—V beveled end. It needs double-side welding, so the material needs to be turned over after welded one side and the preparation time is longer than the single-V beveled end. It can be used for pipes of thickness 12 to 60mm. For pipes of same thickness, a double—V beveled end requires less filler metal material, because there are two narrower V-joints compared to one wider single—V beveled end.
  • Single-U beveled end is a one-side welding joint. It requires less filler metal material than double—V beveled end and is less subjective to deformation. However, due to the radian shape, it is more difficult to process than the former methods.

Beveled angle refers to the angle between the two beveled surfaces. Beveled face angle, normally used for single-U type, refers to the angle between the beveled surface and the vertical line to the pipe itself. The root opening refers to the gap between the roots of both pieces before welding, to ensure the roots get complete welding. The root radius for single-U beveled end is to increase the transverse space between the roots, making the welding reach the bottom of the root.

Yaang can apply any type of Bevel to any degree required.

Seamless pipe end beveld cut - What is a seamless steel pipe
Beveling can applied to the face of any size or diameter of pipe

pipe ends - What is a seamless steel pipe

Ends of Pipes

For the ends of pipes are 3 standard versions available.

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

The PE pipes will generally be used for the smaller diameters pipe systems and in combination with Slip On flanges and Socket Weld fittings and flanges.

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

root face - What is a seamless steel pipe

The BE implementation is applied to all diameters of buttweld flanges or buttweld fittings, and will be directly welded (with a small gap 3-4 mm) to each other or to the pipe. Ends are mostly be beveled to angle 30° (+ 5° / -0°) with a root face of 1.6 mm (± 0.8 mm).

Length of Pipes

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

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

Pipe cutting

ERW cutting - What is a seamless steel pipe

The length of the pipe cut according to the requirement. Cutting tools have a grinding wheel piece cutting machine (also known as toothless saw), hand saw, cutter and other hand tools.

Grinding wheel piece cutting machine: is suitable for cutting metal pipes or metal profiles, especially bulk cutting processing is the most economic. Pipe cutting length you need should be determined before and draw a good cutting line. Pipe cutting machine before cutting jig should be fixed firmly. Machine starts, press the grinding wheel slowly, not slam the rapid or too much pressure, so as not to burst grinding wheel accidents.

Handsaw: 
saw blade teeth should point to the thrust direction, saw blade to tighten, not wobble. Operation when the pressure pipe clamp fixed on the console (console height was about lm), then firmly push and pull, can one man operation, but also the two with the operation. To prevent heat and maintain lubrication can be made to Jukou drip oil. No matter use mechanical or hand according to the cutting all rong or feathered a cut section level off is smooth. Research may not be in slit fold truncation.

Cutter: 
is the use of rollers with a sharp knife, make 3600 the card on the pipe rotation, tighten the top wire while rotating the hob until it gradually into the top pipe cut off. In this way cutting metal pipe, the pipe will tilt tube wall, not only reduces the tube diameter, also make the pipe wall is not smooth, damage to the conductor. Under normal circumstances should not be taken in cutting metal pipes. When used, if necessary, must be cut diameter steel pipe with a round file file level, so that the pipe diameter and the diameter of the same incision.

How to measure a seamless steel pipe?

When people start measuring steel pipes, they may be confused. After all, pipe sizes range from 1/16 to 4, but these dimensions do not seem to match the actual dimensions of the steel pipe itself. In addition, the size of the male and female steel tubes are slightly different. In order to accurately measure any type of steel pipe, it is necessary to measure its OD (outer diameter) and compare it to the steel pipe size chart.
precision seamless tubes 2 - What is a seamless steel pipe
Measuring Male Steel Pipes
Place the micrometer’s caliper on a part of the steel pipe and tighten it into the adjacent pipe.
Turn the micrometer screw until the caliper gently grips the tube.
Look at the sleeves of the micrometer and pay attention to the display of the measurement.
Open the water supply website. Find the measured value in column 2 in the chart. Position the thread (or pipe) directly to the right of the cell you just identified.

Measuring Female Steel Pipes
Place the micrometer’s caliper around the main part of the steel pipe.
Turn the micrometer screw until the caliper gently grips the steel pipe.
Look at the sleeves of the micrometer and pay attention to the display of the measurement.
The female pipe size is determined according to the steps of determining the size of the male pipe.

Tip
The male tube can be labeled “MPT” (male tube thread) and the female tube can be labeled “FPT” (female tube thread).
Warning
Do not determine the size of the steel pipe based on the number of threads per inch. There can be several different sizes, each with the same thread, so this method is not accurate.

How to calculating a steel pipe weight?

Calculating Pipe Weight

pipe diameter area - What is a seamless steel pipe

A weight calculating formula for steel pipes

WEIGHT OF EMPTY PIPE

Weight of empty pipe per unit length can be calculated as

wp = ρm Am 

    = ρm π (do– di2) / 4 

    = (π / 4) ρm (do– di2)                               (4)

where

wp = weight of empty pipe per unit length (kg/m, lb/in)

ρm = density of pipe material (kg/m3, lb/in3)

Am = cross-sectional wall area of pipe (m2, in2)

do = outside diameter (m, in)

di = do – 2 t = inside diameter (m, in)

t = wall thickness (m, in)

WEIGHT OF LIQUID IN PIPE

Weight of liquid in pipes per unit length can be calculated as

wl = ρl Ai 

    = ρl π (di / 2)2 

    = (π / 4) ρl di2                                    (5)

where

wl = weight of liquid in pipe per unit length of pipe (kg, lb)

Ai = cross-sectional inside area of pipe (m2, in2)

ρl = density of liquid (kg/m3, lb/in3)

  • water content in pipes

WEIGHT OF PIPE WITH LIQUID

Weight of pipe with liquid can be calculated as

w = wp + wi

   = ρm Am + ρl Ai     

   =  (ρm π (do– di2) / 4) + (ρl π di2 / 4)

   = (π / 4) [ρm (do– di2) + ρl di2]                      (6)           

  • mass and weight – the difference

Weight of Pipe Calculator

This calculator can be used to calculate the weight of a pipe with – or without – liquid. The calculator is generic and can be used for both SI and Imperial units as long as the use of units are consistent.

 do – outside diameter (m, in)

 di – inside diameter (m, in)

 ρm – density piping material (kg/m3, lb/in3)

 ρl – density of liquid (kg/m3, lb/in3) (zero for empty pipe)

  • 1 m = 103 mm
  • 1 m2 = 106 mm2
  • 1 in = 1/12 ft
  • 1 in2 = 1/144 ft2
  • 1 lb/in3 = 1728 lb/ft2

EXAMPLE – WEIGHT OF 4″ SCHEDULE 40 STEEL PIPE

The outside diameter  of 4″ Schedule 40 Steel Pipe is 4.500 inches. The wall thickness is 0.237 inches and the inside diameter is 4.026 in. The density of steel is 490 lb/ft3 (0.28 lb/in3). The weight per inch length of empty pipe can be calculated as

m = (π / 4) (0.28 lb/in3) ((4.500 in)2 – (4.026 in)2)    

   = 0.89 lb/in

   = 10.7 lb/ft

EXAMPLE – WEIGHT OF 4″ SCHEDULE 40 STEEL PIPE WITH WATER – SI UNITS

The outside diameter  of 4″ Schedule 40 Steel Pipe is 114.3 mm. The inside diameter is 102.3 mm. The density of steel is 7850 kg/m3. The density of water is 1000 kg/m3.  The weight per m length of pipe filled with water can be calculated as

m = (π / 4) [(7850 kg/m3)((0.1143 m)– (0.1023 m)2) + (1000 kg/m3) (0.1023 m)2]  

   = 26.3 kg/m

The weight of a steel pipe depends on the weight density of the material that composes the steel pipe as well as the physical volume of the steel pipe. Weight density measures the amount of compactness of the steel pipe material expressed in pounds per cubic foot.

The volume of a steel pipe equals its surface area times its thickness. Specifically, the surface area of a steel pipe is the same as a cylinder and equals the number of square inches that can cover the curved sides of the steel pipe.

Measuring Wall thicknewss - What is a seamless steel pipe
Measuring Wall thicknesss
Flat oval pipe2 - What is a seamless steel pipe

Measuring Flat oval pipe and Elliptic pipe size

Calculate the weight of round pipe and Special Section Tubes

calculat round pipe1 - What is a seamless steel pipe
T.W.=(D-S)*S*24.65/1000
calculat rectangular pipe1 - What is a seamless steel pipe
T.W.=((B+A)/2-S)*S*31.4)/1000
calculat ellipse pipe2 - What is a seamless steel pipe
T.W.=12.33*(B+A-2S)*S/1000
calculat hexagonal pipe1 - What is a seamless steel pipe
T.W.=24.65*(1.1*SW+1.2*S)*S/1000
calculat square pipe1 - What is a seamless steel pipe
T.W.=(A-S)*S*31.4/1000
calculat ellipse pipe1 - What is a seamless steel pipe
T.W.=[(24.65*(B-S))+(15.7*(A-B))*S]/1000
calculat ellipse pipe3 - What is a seamless steel pipe
T.W.=[(A+(B/2*3.14))/2/2-S]*S*3.14
calculat eight square pipe1 - What is a seamless steel pipe
T.W.=24.65*(1.06*SW+1.11*S)*S/1000

Gather the necessary information. You will need to know the outside diameter of the steel pipe. This is the distance of a straight line that runs through the center of the steel pipe and connects two points on the steel pipe’s surface. You will also need to know the wall thickness of the steel pipe. Both of these measurements should be taken in inches. The final thing that you will need to know is the length of the steel pipe. This last measurement should be taken in feet.

Subtract the steel pipe’s wall thickness from the steel pipe’s outside diameter. For example, if you had a pipe with a diameter of six inches and a wall thickness of two inches, you would subtract two from six to get four.

How to measure the hardness of a steel pipe

We know very little about how to measure the hardness of steel pipe, no matter what type of pipe it is. Hardness is an important factor when customers are willing to buy steel pipes. Today, our technical team will teach you some ways on how to measure hardness.
Hardness testing is based on mechanical properties, including the performance and quality of stamped or cut deformed steel pipe. There are two methods of testing the mechanical properties of steel pipes: tensile testing and hardness testing.
The tensile test usually measures the tensile strength, elongation and neck shrinkage of the steel pipe. The steel pipe specimen is pulled on a tensile testing machine to check one or more mechanical properties. The basic mechanical properties of the raw metal are determined. As soon as the desired mechanical properties are achieved, the metal material has been predetermined for the tensile test of the steel pipe. The tensile test is inconvenient for measuring the hardness of the workpiece, but it is the only method for testing the mechanical properties.
Hardness testing with a hardness tester requires that an indenter in hard conditions be slowly pushed into the surface of the workpiece to measure the depth and size of the indentation, i.e. the subsequent material hardness. Hardness testing for e-cigarette manufacturers is not only the most convenient means of testing mechanical properties, but also nondestructive testing. Hardness is easily converted to strength due to the inconvenience of tensile testing. So you only test the hardness of steel tube materials.

How to pack seamless steel pipes

The packaging requirements of steel pipes are basically divided into two categories: one is the ordinary type of bundling, and the other is loaded with a container similar to a crate.

steel strips bunding for fixed pipes - What is a seamless steel pipe
1. Bundling packaging

  • (1) Should avoid damage to the steel pipe in the process of bundling and transportation, the bundling label should be uniform and consistent.
  • (2) The same bundle of steel pipe should be the same furnace number (batch number), the same steel grade, the same specification of the steel pipe, should not be mixed furnace (batch number) bundle, less than a bundle should be broken into small bundles.
  • (3) The weight of each bundle of steel pipe should not exceed 50kg, and the weight of the bundle can be increased with the consent of the user, but the weight should not exceed 80kg.
  • (4) For the flat end of the steel pipe bundle, one end should be aligned, the difference between the aligned ends is less than 20mm, the length difference of each bundle of steel pipe is less than 10mm, but the length difference of each bundle of steel pipe ordered in accordance with the usual length is less than 5mm, and the length of a bundle of steel pipe and the second longest does not exceed 10mm.

2. Bundling form
Steel pipe length greater than or equal to 6m, each bundle to play at least 8 strapping, divided into 3 groups, played into 3-2-3; steel pipe length less than 6m, each bundle to play at least 5 strapping, divided into 3 groups, played into 2-1-2; steel pipe length greater than or equal to 3m, each bundle to play at least 3 strapping, divided into 3 groups, played into 1-1-1. length greater than or equal to 6m of fixed steel pipe strapping position has special requirements, can In a single steel pipe plus 4 plastic card ring or nylon rope ring, card ring or rope ring should be tied firmly, the transport process shall not appear loose, fall off.
3. Container packaging

  • (1) Cold-rolled or cold-drawn seamless steel pipe, hot-rolled stainless steel pipe by surface polishing, can be packaged in containers (such as plastic boxes and wooden boxes).
  • (2) The weight of the container after packaging should be in accordance with the provisions of Table 1. By mutual agreement between supply and demand, the weight of each container can be increased.
  • (3) Steel pipe into the container, the inner wall of the container should be padded with cardboard, plastic sheeting or other moisture-proof materials. The container should be tight and should not seep.
  • (4) For the container packaging of steel pipe, a label should be attached to the container. On the outside of the container end face, should also be hung a label.
  • (5) Steel pipe has special packaging requirements, by agreement between the supply and demand.

How to control the wall thickness of seamless steel pipe

Seamless steel pipe wall thickness control is a difficult point in the production of steel pipe. Measures to improve wall thickness accuracy in production include the following:
1. Pipe billet heating
Heating must be uniform, prohibit rapid heating and cooling. Each temperature rise and temperature drop should be maintained smoothly and slowly, the maximum temperature rise and temperature drop shall not exceed 30 ℃.
2. Centering rolls
Determine whether the centering roller is installed in place and adjust the center of the related core-holding roller. The opening and the size of the opening are the same, and the center of the core-holding roll should be on the rolling line.
Seamless bare steel pipe
3. Rolling centerline
Make sure that the centerline of the perforating machine and the centerline of the perforating trolley are the same, avoid “up rolling” or “down rolling”, so that the pipe billet maintains a uniform force during the perforating process.
4. Rolling tools
Wear plug. Guide plate. Rolling tools such as rolls should be replaced in a timely manner.
5. Rolling tool installation
The center of roll pitch and guide must be on the rolling line. Make sure the center line of the guide roll and roll pitch is located on the center line of perforation and rolling, that is, the upper and lower roll pitches are equal and the left and right guide roll pitches are equal.
6. Perforation ejector
The perforated top bar is generally used for thick-walled pipe with outer diameter Φ108mm~Φ114mm, wall thickness ≥25mm and uniform wall thickness.
7. Mill Mandrel
Mandrel should be processed by thick-walled tube with thicker wall thickness. For the mandrel with smaller specifications, solid billets can be used instead. Uniform wall thickness of thick-walled tube and solid billet can greatly reduce the probability of mandrel bending deformation, and can effectively improve the wall thickness accuracy of the steel pipe.
8. The accuracy of the mandrel
The length of the mandrel is relatively large. Usually, the outer diameter of the mandrel is turned first, and then the weld is broken, or the long material is formed directly. The outer machining accuracy of mandrel is controlled within ±0.1mm, and the deviation of straightness of mandrel does not exceed 5mm. when welding, a precision machining pin is inserted between two mandrels for positioning to prevent excessive deviation of overall straightness caused by welding.
9. Improve the process
Improve the process to prevent the middle thinning and wall thickness increase beyond the control range and improve the wall thickness accuracy.

Price of seamless steel pipes

Unlike ordinary welded steel pipes, seamless steel pipes do not have fixed wall thickness dimensions, so when it comes to the price of seamless steel pipes, how is it calculated? When talking about the price of seamless steel pipe, we need to determine a premise is: what is the specification of the seamless steel pipe? For example, common seamless steel pipe specifications are: Ф114.3 * 4.5, Ф219.1 * 6, Ф273.1 * 10, etc., the outer diameter and wall thickness specifications are different, the weight of seamless steel pipe is also different, so the price per meter of seamless steel pipe is also different.
Ordinary carbon steel, alloy steel seamless steel pipe theoretical weight calculation formula is:

  • W=0.02466 (D-S)S

Notes.

Weight per meter kg/m = (OD – wall thickness) * wall thickness * 0.02466 [unit taken mm mm]

For example: the weight per meter of the stock TP316L seamless steel pipe Ф108*4.5 is
kg/m=(114.3-4.5)*4.5*0.02466=12.185
According to Ф114.3 * 4.5 seamless steel pipe market price of 32000 yuan / ton, for example, we can learn that the specification Ф114 * 4.5 TP316L seamless steel pipe price by meter: 12.185kg / m * 32 yuan / kg = 389.92 yuan / m. According to the approximate project usage can be calculated, the total budget of seamless steel pipe is about how much.

How to find a reliable seamless steel pipe manufacturer

Finding a good seamless steel pipe manufacturer is an important step in your company’s supply chain management, as it will ensure that you have a reliable source of raw materials. There are many factors to consider when choosing a supplier and it is easy to make the wrong decision, so it’s always worth taking some time to do your research. Here are some tips on how to find reliable manufacturers of seamless steel pipe:

Verify the manufacturing process

You’ll want to verify the manufacturing process. This can be done by asking questions like:

  • How is seamless steel pipe manufactured?

  • What are the standards, requirements and regulations regarding manufacturing?

  • What are the guidelines that manufacturers follow to produce seamless steel pipe of good quality?

  • What certifications or accreditations do they have with regard to manufacturing processes and products?

Check the qualifications

  • Check the company’s website to see if they have a list of certifications, whether from organizations like the American Society for Testing and Materials (ASTM) or the American Petroleum Institute (API).

  • An ISO9001 certification is not necessarily required but is considered a good sign that the manufacturer has quality standards in place.

Know about their inventory and resources

  • Know what they have in stock

It’s important to know if the seamless steel pipe manufacturer has a good inventory. If they don’t, then you’ll need to find another company. You also want to know how quickly and easily they can get the products that you need from their supplier or another company. For example, if you go into a real estate closing with no money and the bank won’t give you any more time, then it would be helpful for your lawyer to know that his client will be able to buy some land using cash because he knows about resourceful sources like that person who owns an airplane hangar where he keeps spare tires for sale on his property.

Check for third party certification

To ensure you’re getting a high-quality product and not one that will fail prematurely, it’s important to check for third party certification. There are several organizations that provide this service, including:

  • ISO (International Organization for Standardization)

  • ASME (American Society of Mechanical Engineers)

  • NACE International (National Association of Corrosion Engineers)

  • API (American Petroleum Institute)

  • AWS (American Welding Society)

If any of these certifications appear on your seamless steel pipe manufacturer’s website or in other marketing materials, they can serve as proof of quality assurance standards.

You can learn a lot about a company from how well they manufacture seamless steel pipe.

When you’re vetting a potential supplier of seamless steel pipe, you can learn a lot from how well they manufacture the product. A company that has invested time and resources into making sure their equipment is up to date will be more likely to have a better understanding of the market. They’ll have a better understanding of their customers’ needs, and they’ll be able to provide them with reliable service when it comes time for delivery.

It’s important that your supplier understand why you need seamless steel pipe in the first place as well. This will allow them to give you advice on what type would work best based on what kind of industry or project you’re working on, which will save time because you won’t have to go back-and-forth trying out different types before settling on one specific style.

It’s important to find reliable seamless steel pipe manufacturers. They can provide a consistent supply of high-quality products that are an integral part of many industries. These companies should have extensive resources and knowledgeable staff members to help you navigate their inventory and obtain the right type of seamless steel pipes for your needs.

How to place an order of seamless steel pipe

Many industries have to buy seamless steel pipes, the amount of one-time investment in these products is not very large, even if the bulk purchase will not cost too much. However, because the steel pipe will be used for a long time, so we still need to pay special attention to choose the right brand, only high-quality products are our best choice, so that the product can also ensure its service life. But now there are many different types of products on the market, you choose to choose according to the brand and its actual quality to buy, so as to ensure the best use of the effect.
The brand with the better reputation is preferred. Basically, the big brands of seamless steel pipes are produced by professional manufacturers, and there are certain differences in the prices of different types of products, but the quality of products produced by regular manufacturers can also be guaranteed. And the brand itself will be tested for each product, and its quality is a little better. Although the price of branded tools is definitely higher, but in terms of cost effectiveness, or to choose branded professional products. Such products can also be guaranteed to be used for a longer period of time, the service life will be longer, more able to meet our needs.
The manufacturer’s bulk purchase method is preferred. If you want to wholesale seamless steel pipes, then it is best to find Ya’ang directly, after all, there is no intermediate link can still enjoy a certain discount, and can also save more money. Ya’ang can provide different types of products at one time, so you can purchase directly without comparison, and you can also save more money. If it is a long-term cooperation with the manufacturer, you can also ensure the interests of the purchaser, we will also give the purchaser a lower discount price.

What to consider when ordering seamless steel pipes

“Ordering” is the beginning of cooperation between supply and demand. In order for the purchaser to get the steel pipe that meets the requirements and the supplier to produce the steel pipe that meets the requirements of the purchaser, both parties need to communicate and communicate fully in the “ordering” process.
1. Seamless steel pipe selection and standardization: The orderer should determine the type of steel pipe, whether it is seamless or welded, according to the working condition and usage requirements of the seamless steel pipe. The working condition of steel pipe in use: whether it is used to transport fluids (including the state and nature of fluids) or used as a mechanical component, the name and standard number of the selected steel pipe should comply with, pay attention to the “scope of application” of the standard to determine whether it meets their own requirements for use, as a basis for delivery.
According to the different guarantee conditions of different grades in the standard for seamless steel pipes, select the steel grade that meets the requirements of the orderer, confirm the manufacturing method specified in the standard, find the allowable deviation of the dimensions of the ordered specification, and select the accuracy grade.
2. According to the standard requirements of the “order content”, select the required steel pipe dimensions, including diameter, wall thickness and length.
3. The provisions of the standard regarding the technical requirements for the delivery of steel pipes are the core of the standard and determine whether the pipe can meet the requirements of the orderer. These mainly include:

  • (1) Steel grade, chemical composition and manufacturing methods;
  • (2) The shape of the pipe (outside diameter. Wall thickness. Length. Curvature. Ellipticity. Tube end shape) of the allowable deviation and its accuracy grade;
  • (3) Delivery condition, including surface condition. Heat treatment condition. Pressure treatment condition and metallurgical organization condition;
  • (4) The processing properties of steel (including bending, flattening, flaring, etc.);
  • (5) The specific provisions of the standard steel surface defects, including the type of defects, the name, the severity of defects. After cleaning, the allowable level of high-precision steel pipe roughness requirements, etc.;
  • (6) Non-destructive testing of steel (including hydrodynamic testing, ultrasonic testing, eddy current testing, etc.).

4. According to the different guarantee conditions of different grades in the standard, choose the steel grade that meets the requirements of the orderer. Confirm the manufacturing method specified in the standard, find out the allowable deviation of the order specification and select the accuracy level.
5. The ordering party should base on the requirements of the material for the mechanical and processing properties of the steel pipe in deep processing, and the relevant values of the mechanical and processing properties that the steel pipe can guarantee.
6. Finally, the order quantity will be proposed and the delivery date will be negotiated with the supplier. After confirming all the contents, the orderer will fill in the order form.
7. If the orderer has difficulty in completing the above-mentioned clause 4.5, the orderer shall specify the processing method and specific processing requirements of the steel pipe material as well as the processing process of the material and the use requirements of the finished parts, or submit the processing performance range and the corresponding delivery status to the supplier so that the supplier can organize the production of steel pipe products in accordance with the agreed value to meet the orderer’s requirements.
8. Seamless steel pipe orderer shall select the delivery state according to the requirements of the mechanical properties and processing properties of the steel pipe in the deep processing of the material against the standard, and approve the values related to the mechanical properties and processing properties guaranteed by the steel pipe in this state.
9. The provisions of the standard for seamless steel tubes may be chosen as an “optional” (or separate) clause as a condition of the agreed guarantee if the orderer has requirements beyond those that must be guaranteed by the standard, and may also be included as a supplementary clause in the order as a basis for delivery with the consent of the supplier.
10. Determine the packaging requirements for seamless steel pipe products according to the characteristics of the products and the specific conditions of storage, transportation, stacking, etc.
11. Propose the order quantity of seamless steel pipe and agree with the supplier on the delivery date. After all the contents are determined, the orderer fills in the complete contents of the order form.

Source: China Seamless Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.epowermetals.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at [email protected]

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