How to buy welded steel pipes?

What is a welded steel pipe?

The welded steel pipe refers to a steel pipe which is welded and formed into a shape of a circle or a square by bending a steel strip or a steel plate, and has a seam on the surface thereof. The raw material used for the welded steel pipe is a steel plate or a strip steel.

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Since the 1930s, with the rapid development of high-quality strip continuous rolling production and the advancement of welding and inspection technology, the quality of welded joints has been continuously improved, the variety specifications of welded steel pipes have been increasing, and more and more fields have replaced Seam steel pipe. Welded steel pipes have lower cost and higher production efficiency than seamless steel pipes.

1 pipe can be divided according to the basic shape of Longitudinal seam and spiral welded pipe are two:

(1) straight seam welded pipe: simple production technology, high efficiency, low cost, rapid development. Longitudinal more general industrial use.

(2) spiral welded steel pipe: Longitudinal strength generally higher than that, can narrow the larger diameter pipe billet production, you can also use the same width of the billet production of welded pipes of different diameter; but with the same lengthcompared to straight seam pipe, spiral welded steel pipe weld length of 30 to 100%, and lower production rate; Therefore, the smaller diameter pipe actually use straight seam welded, large diameter spiral welded pipe is mostly used.

Pipe-use is divided into the following categories:

  • (1) General welded steel pipe: welded steel pipe used to transport the general low-pressure fluid. With Q195A, Q215A, Q235A steel. Can be applied easily to other soft steel welding steel tube to the pressure, bending, flattening and other experiments, thethere is a certain surface quality requirements, delivery is usually the length of 4-10m, are often asked to cut to length (or double length) delivery.’s specifications with the nominal pipe diameter, said (mm or inches) nominal diameter and the actual difference, pipe requiredthick wall of ordinary steel and steel are two kinds of steel divided by the form of pipe with threaded end and without a thread two.
  • (2) Galvanized welded steel pipe: To improve the corrosion resistance of steel pipe, steel pipe for general (clarinet) for zinc galvanized steel and electrical steel hot-dip galvanized zinc are two kinds of hot dip galvanized zinc thickness, platingzinc and low cost.
  • (3) Oxygen welded steel pipe: pipe used for steel-making oxygen, usually with a small diameter welded steel pipe, size from 3 / 8 inch -2 inch eight. With 08,10,15,20 or Q195-Q235 steelband made of the corrosion, some of the aluminizing treatment.
  • (4) Wire tube: welded steel pipe is also a common carbon steel, concrete and various structures used in power distribution engineering, commonly used in nominal diameter from 13-76mm.
  • (5) Metric welded steel pipe: seamless form with the specifications, with expressed in mm diameter * wall thickness welded steel pipe, with ordinary carbon steel, high carbon steel or low alloy steel & P to tropical and cold with welding, orafter welding with a tropical method call made by the cold. Metric & P energy and thin-walled pipe points, common for structural parts, such as shaft or transmission fluid, used to produce thin-walled furniture, lamps, etc., to ensure that the strength of steeland bending test.
  • (6) Roller tube: welded steel pipe for roller conveyor, generally with the Q215, Q235A, B steel and 20 steel, diameter 63.5-219.0mm. On the tube bending, end with the center line of vertical, ovalthere is a certain degree requirements, general test for pressure and flattening.

How to Weld Steel Pipes

Welding pipes is one of the simplest and most durable ways to join piping together and steel pipes can simply be welded together with MIG (metal inert gas), TIG (tungsten inert gas or SMAW (stick metal arc) welding. Before welding two pipes together, avoid any gaps between the two pipes. While welding, take measures to ensure the continual alignment of the two pipes.

Align the two pipes and use clamps to hold them together, if necessary.

Fire your welding torch or strike your welding electrode on the steel to open an arc between the welding tool and pipes. Allow the torch to form a small welding puddle on the surface of the steel, called a tack weld.

Move the arc slightly and create another welding puddle elsewhere on the circumference of the pipes. Continue to move the arc and create more welding puddles until you have formed a series of tack welds at regular intervals along the circumference.

Move the welding tool thoroughly along the circumference of the pipes creating a welding puddle that extends fully around the circumference and connects the two pipes together.

Extinguish the arc and allow the welding puddle several minutes to dry.

Most common Weld steel pipes

Spiral welded pipe

Anti corrosion surface treatment process of spiral pipe - How to buy welded steel pipes?

Hot expansion steel pipe mandrel surface pulsating spray device is a device to a thermal expansion pipe mandrel surface spray lubricant, which is characterized by injection device body ring parts with lubricant reservoir burglary, in Chu burglary ring wall open lubricationagents enter the hole, motor Chu burglary side installation, its spindle by driving wheel and the middle with a lubricant output hole pulsating ring phase, the lower part of the output hole placement beam radio regulatory group equipped with a beam of radio regulation.
Advantages are:using spray lubricant to the mandrel surface, can reduce the frictional resistance between the tube rolling mandrel and steel pipe to reduce the pressure load of the mill and the mill’s power consumption to extend the life of the mandrel, to improve the quality of the steel pipe rolling.
Hot expansion pipe with two-step push tube expanding machine set conical die expanding technology, digital intermediate frequency induction heating technology, hydraulic technology in a machine with a reasonable process, low energy consumption, lower capital investment, good product quality, a wide range of applicability of the raw material and product specifications, flexible variable cost of production volume, adaptability, replace the traditional steel industry, of Pullout expanding technology. difficult to resolve in the near future, the supply of large diameter steel pipe, thermal expansion pipe to become the source of the shortage of large-diameter steel pipe products. ease the tight supply situation of the large diameter pipe market.

erw pipe banner - How to buy welded steel pipes?

Electric Resistance Welded Pipe

ERW pipes means Electric Resistance Welded Pipes. It is cost-effective steel pipe with tighter Dimensional tolerances and less weight. The weld seam is heat treated after welding without untempered martensite remains. Also, the weld flash can be removed from both inner and outer surfaces.

ERW Galvanized Steel Pipes

ERW Galvanized Steel Pipe banner 1 - How to buy welded steel pipes? 

For pipes or tubes size 4 inch (10.2mm) OD and below, strip is fed into a set of forming rolls which consists of horizontal and vertical rollers so placed as to gradually from the flat strip in to a tube which is then allowed to pass the welding electrodes. The electrodes are copper disks connected to the secondary of a revolving transformer assembly. The copper disk electrodes make contact on each side of the seam and temperature is raised to the welding point. Outside flash is removed by a cutting tool as the tube leaves the electrodes, inside flash is removed either by an air hammer or by passing a mandrel through the welded tube after the tube has been cooled. This is termed as Electric Resistance Welded or ERW tube/pipe.

Black ERW steel pipe

Black ERW steel pipe banner - How to buy welded steel pipes?
ERW pipe cold formed from a ribbon of steel pulled through a series of rollers and formed into a tube which is fused through a electric charge.

High Frequency Welded pipe banner - How to buy welded steel pipes?

High Frequency Induction (HFI) Welded Pipe

In High Frequency Induction (HFI) Welded Pipe production process, hot rolled steel coils are fed with a high capacity accumulator in order to achieve continuous welding.

HIGH-FREQUENCY WELDING is a welding process in which the heat source used to melt the joining surfaces is obtained from high-frequency (HF) alternating current (ac) resistance heating.

Coil edges are milled using carbide cutters in order to assure a high quality weld. Coils are then formed by cold forming method using a set of cage rolls and fin passes, and then joined using high frequency currents using induction or alternatively conduction methods.


Using its specialist expertise in high frequency welding, TWI has supported industry with a range of project and consultancy work which has included:

  • mechanical properties of welded pipe
  • metallurgical studies on welds
  • defect examination
  • optimisation studies on HF butt welding of tailored blanks
  • testing facilities for fracture mechanics studies
  • corrosion & metallurgical test equipment
  • non-destructive testing
  • process advice & troubleshooting
  • tailored training courses

Application Areas

HFW welded steel pipes are widely preferred in Oil, Natural Gas, Water and other liquids transportation and distribution lines, heating, cooling, ventilation piping and steel structures for construction and other general purposes by means of precise production tolerances and high capacity manufacturing method.

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Welding method

Spiral submerged-arc welding pipes (SSAW)

Spiral submerged arc welding(SSAW) is its forward direction and forming tube centerline hose reel molding angle (adjustable), side molding edge welding and weld them into a spiral.

Electric Fusion Welded Pipe banner - How to buy welded steel pipes?

Electric Fusion Welded Pipes (EFW)

The EFW pipe divison consists of a JCO forming press, helical / spiral mill, inside and outside welding system, heat treatment furnace and testing facilities. Welding process employed is gtaw for root-pass and saw/tig for final pass with suitable filler wires as prescribed by aws specifications and asme boiler and pressure vessel code, section-ix. These facilities are capable of manufacturing austenitic and various duplex grades.

lsaw pipes banner - How to buy welded steel pipes?

Longitudinally Submerged Arc Welded (LSAW)

LSAW pipes (Longitudinally Submerged Arc Welded Steel pipes) in leaflets plate as raw material, the steel plate in the mold or molding machine pressure (volume) into using double-sided submerged arc welding and flaring from production.

Molding method

(Uing and Oing forming) UOE Pipes

UOE is a method used for production of longitudinally welded large diameter pipes.

UOE pipe 520 371 - How to buy welded steel pipes?

Longitudinal edges of steel plates are first beveled using carbide milling equipment. Beveled plates are then formed into a U shape using a U-press and subsequently into an O shape using an O-press.

The UOE mill features the most advanced technology and process, achieves high production efficiency, stable product quality and is equipped with complete inspection equipments.

UOE mill adopts U & O forming, the formed pipes are welded inside through five internal welding stations with three wires, and welded outside through four external welding stations with three wires.

(J-ing, C-ing and O-ing) JCOE Pipes

JCOE manufacaturing process - How to buy welded steel pipes?

The mill adopts continuous axis contorting J-C-O(J-ing, C-ing and O-ing)process with characteristics of high forming accuracy and efficiency as well as balanced distribution of forming stress.

JCOE manufacturing technology is developed in the 1990s as a pipe forming process, the process of molding process is the first major steel mill edge (or planing) after pre-bending by longitudinal side, and then type → J-→ C O-order molding, stamping each step are the basic principles of three-point bending.

Because it is a progressive multi-pass pressing, it must address the following questions: how to determine the die shape, the upper die and lower die stroke distance, and how much press pass in order to ensure the most appropriate bend radius and the best opening round hair tube.

But these issues with the steel plate, steel plants of different mechanical properties of concrete, pipe size (diameter and wall thickness), which in turn is very complex. Currently mainly by “trial and error”, that is, whenever replacement or new steel specifications, we take a certain number of sample pressure test, worked out the right amount of punch. Trial and error method is more reliable, but the efficiency is relatively low.

JCOE molding process

Material retesting → vacuum hanging → board probe → flap → planing curl before demi plate (J molding) on the board edge → loose → enter demi steel plate (C molding) demi steel plate → curl → loose out → bend → pre-welded → welding cited the (quenching) arc board → welding → Qing root weld → mechanical repair end to cited hydrostatic test (put out) arc the board → ultrasonic inspection → mechanical expanding → tube ends of ultrasonic testing ring the stratification test to the UT → X-ray inspection → Magnetic particle inspection of the finished product inspection → weighing and measuring the length → outer anticorrosion → internal corrosion → mark → delivery.

The JCOE manufacturing technology is a welded pipe forming process developed in the 1990s, during the molding process, it is the first steel plate edge milling preflex by longitudinal edges (or planing), and then type J → C → O the order of the type of molding, in each step stamping expressed in three-point bending as the basic principle. Pass progressive molding, it is necessary to solve the following problem: how to determine the shape of the mold, the upper die stroke mode spacing, and how many times in order to ensure optimum bending radius stamping out the best opening gross round tube. These problems with the steel plate material, the specific mechanical properties of the steel production plant, pipe size (diameter and thickness), which makes it very complicated. Mainly by “trial and error” that whenever the replacement of new specifications or new steel grades, he took a certain number of sample pressure test, worked out the right amount of stamping.

The trial and error method is more reliable, but the efficiency is relatively low. More process parameters, only through trial and error trouble. In order to obtain a mature technology, and even take months of trial and error process. The shape and spacing of the fixed lower mold and the trial and error process is often used only explore the punch stroke, so that the results obtained may not be optimal, not fully the capacity of the unit. So it is necessary to systematically study forming factors create a theory or formula, with the trial-and-error experience to develop the molding process, thereby eliminating the need or less need to experiment to reduce the cost and time of trial, and improve production efficiency.

Special Section Welded Tubes

We can produce precision and high-frequency welded steel tubes and pipes with all possible dimensions and shapes available.

Oval pipe

oval pipe banner - How to buy welded steel pipes?

For the best quality Oval Tubes, we serve as one-stop destination in the international market.

They are extensively used in various industrial and engineering applications.

Flat oval pipes

oval pipe flat - How to buy welded steel pipes?

Oval pipes are mainly produced with a diameter of 1,0 – 3,0 mm.

Flat oval pipes size range:

a b d length in mm material
30,0 15,0 1,5 6.000 1.4301
30,0 17,0 1,5 6.000 1.4301
35,0 15,0 1,5 6.000 1.4301
40,0 20,0 1,5 6.000 1.4301
48,0 20,0 1,5 6.000 1.4301
56,5 29,8 1,5 6.000 1.4301
60,0 20,0 1,5 6.000 1.4301
60,0 32,0 2,0 6.000 1.4301

Different wall thickness, materials and surfaces (e.g. IIIc, K240, K400, K600) as well as lengths can be produced on inquiry.

Elliptic pipe

elliptic pipe - How to buy welded steel pipes?

Elliptic pipes can generally be produced from 1,0 – 3,0 mm.

Oval pipe elliptic size range:

a b d length in mm material
26,3 16,2 1,5 6.000 1.4301
36,0 14,0 1,5 6.000 1.4301
40,0 28,5 1,5 6.000 1.4301
55,0 18,0 1,5 6.000 1.4301

Square hollow section

square hollow section banner - How to buy welded steel pipes?

Square hollow section comes in different sizes, specifications and wall thicknesses.

Its uniformity makes it predictable to use and visually appealing.

It has a high weight-to-strength ratio. It’s easy to bend, and because square steel tubing is inexpensive, it’s cost-effective- even for large projects.

Square Hollow Section, SHS, Square Box, Painted, Galvenised, ERW, Black, Mild Steel

  • Steel Grade: Q235, Q345, S235JR, S275JR, SS4007
  • Surface Finish: hot dipped galvanizedPre-galvanized
  • SHS (Square Hollow Section) Size range Table 2.

Steel tube is easily recyclable. Many projects take advantage of square steel tubing, including all types of buildings, highway guardrails and signage, support columns, trusses, bridges, heavy equipment, storage systems, and exercise equipment.

A wide range of dimensions, when combined with the appropriate steel grade, ensure that the functionality and cost-efficiency of your structure can be optimised.

Chemical composition

Steel Grade: Q195, Q215, Q235, Q345, S235JR, S275JR, SS4007-

Data Elements(%)
Materal Grade C Mn S P Si
Q195 0.06-0.12 0.25-0.50 <0.05 <0.045 <0.30
Q215 0.09-0.15 0.25-0.55 <0.05 <0.045 <0.30
Q235 0.12-0.20 0.30-0.70 <0.045 <0.045 <0.30
Q345 <0.20 1.0-1.6 <0.04 <0.04 <0.55

Mechanical property

Materal Grade Yield point (Mpa) Tensile Strength (Mpa) Elongation(%)
Q195 >195 315-430 32-33
Q215 >215 335-450 26-31
Q235 >235 375-500 24-26
Q345 >345 470-630 21-22


Length +/- 50 MM
Wall Thickness +/- 12.5%
Weight +/- 8%

SHS measurement - How to buy welded steel pipes?
They are measured by their outside dimensions and their wall thickness.


A: with, T: wall thickness, SHS:Square Hollow Section, RHS: Rectangular Hollow Section

Surface Finish: hot dipped galvanized, electro galvanized, black

Mill Test Certificate: EN 10204/3.1B 
Third party inspection: SGS, BV, Lloyds etc.

Note: Pre-galvanized square / rectangular hollow section with OD 19mm-70mm and thickness 1mm-2.3mm are also available.

Furniture industries & domestic applications, bus body, fencing etc. Sizes other than mentioned above can also be produced upon specific requirements.

Rectangular Hollow Sections

rectangular hollow section banner - How to buy welded steel pipes?

Rectangular steel tube comes in different sizes, specifications and wall thicknesses. Its uniformity makes it predictable to use and visually appealing. It has a high weight-to-strength ratio.

It’s easy to bend, and because square steel tubing is inexpensive, it’s cost-effective- even for large projects.

We are manufacturing and exporting Rectangular Hollow Sections, Rectangular Hollow Steel Sections and Rectangular Hollow Section Tubes as per customer’s requirement with anti rust oil coating from inside & outside of the tubes to ensure safe delivery to end customers.

Specialising in Steel, Cut to Length, Round, Square, Hollow, Rectangular, Rectangular Hollow Sections, RHS

A wide range of dimensions, when combined with the appropriate steel grade, ensure that the functionality and cost-efficiency of your structure can be optimised.

Hot dip galvanized square tube

Hot dip galvanized square tube banner 1 - How to buy welded steel pipes?

Hot dip galvanized square tube is used square tube plate or strip after curl forming in the hot dip galvanized pool through a series of chemical reactions forming the square tube; can also be hot-rolled or cold rolled galvanized steel strip after colda hollow square cross-section bend, then the high-frequency welded steel pipe.

Hot dip galvanized square tube has good strength, toughness, ductility and welding process performance and good ductility, the alloy layer with steel base attached to a solid, hot dip galvanized square tube can be cold punching, rolling, drawing a variety of molding and bending without damage to the coating; for general processing such as drilling, cutting, welding, cold bending process. Hot dip galvanized surface bright and beautiful, according to the demand for engineering. 
Hot dip galvanized square tube is often used: glass curtain wall, Tower of power, communications, power grids, water and gas transmission, wire casing, housing, bridges, metal structure, power transmission, etc.

Stainless Steel Square / Rectangular Tubes

Our supply of stainless steel square tube and rectangular tube offerings are available in a wide variety of sizes and wall thicknesses.

Stainless Steel Square Tubes (Polished / Matt Finish)

stainless square rectangular tube - How to buy welded steel pipes?

They are supplied in both mill finish and polished finishes, with the polished finishes including #4, #6 and #8 mirror finish.

They are generally supplied in 20’ random lengths but can be cut to size for orders.

Available Steel Grades: 304, 304L and 316L
We will custom saw cut to length and sell less than full lengths in some sizes.
Mill finish and polished products in stock.
Polishing services are available.

O.D. Thickness(mm)
in mm 0.7 0.8 0.9 1.0 1.2 1.5 2.0 2.5 3.0 4.0 5.0
1/2″ x 1/2″ 12.7 x 12.7 X X X X X            
5/8″ x 5/8″ 15.9 x 15.9 X X X X X X          
18.0 x 18.0 X X X X X X X        
3/4″ x 3/4″ 19.0 x 19.0 X X X X X X X        
20.0 x 20.0 X X X X X X X        
7/8″ x 7/8″ 22.2 x 22.2 X X X X X X X        
1″ x 1″ 25.4 x 25.4 X X X X X X X X X    
30.0 x 30.0 X X X X X X X X X    
1 1/4″ x 1 1/4″ 31.8 x 31.8   X X X X X X X X    
1 1/2″ x 1 1/2″ 38.1 x 38.1   X X X X X X X X    
40.0 x 40.0     X X X X X X X    
50.0 x 50.0     X X X X X X X    
2″ x 2″ 50.8 x 50.8     X X X X X X X    
  60.0 x 60.0             X X X    
  70.0 x 70.0             X X X    
  80.0 x 80.0             X X X X X
  90.0 x 90.0             X X X X X
  100.0 x 100.0             X X X X X
Item Side Thickness Diagonal Radii of Corners Straightness Length Flatness
<31.8mm±0.38mm ±10% ≤0.4mm ≤2.5mmR ≤10mm/ 6M +50mm-0mm ±0.15mm

Iron and Steel Products Steel Piping, Steel Tubing, Fittings

ASTM A1016-04a Standard Specification for General Requirements for Ferritic Alloy Steel, Austenitic Alloy Steel, and Stainless Steel Tubes
A 213 / A 213M-09 Seamless ferritic and austenitic alloy steel boiler, superheater and heat exchanger tubes
A 268 / A 268M Seamless and welded ferritic and martensitic stainless steel tubing for general service
A 269 / A 269M Seamless and welded austenitic stainless steel tubing for general service
A 312 / A 312M-09 Seamless and welded austenitic stainless steel pipes
A 450 / A 450M-03 Standard Specification for General Requirements for Carbon, Ferritic Alloy, and Austenitic Alloy Steel Tubes
A 511 Seamless stainless steel mechanical tubing
A 789 / A 789M Seamless and welded ferritic-austenitic stainless steel tubing for general service
A 790 / A 790M-08 Seamless and welded ferritic-austenitic stainless steel pipe
U Bend Tubes Standards for U bend Stainless Steel Tubes for Heat Exchanger
*Note: Section Two: Nonferrous Metals Nickel, Cobalt, Lead, Tin, Zinc, Cadmium, Precious, Reactive, Refractory Metals and Alloys; Materials for Thermostats, Electrical Heating and Resistance Contacts, and Connectors
ASME-Standards :

ASME Boiler Pressure Code Section II Part A – Ferrous Material Specification

SA 213 / SA 213M Seamless ferritic and austenitic alloy steel boiler, superheater and heat exchanger tubes
SA 268 / SA 268M Seamless and welded ferritic and martensitic stainless steel tubing for general service
SA 269 / SA 269M Seamless and welded austenitic stainless steel tubing for general service
SA 312 / SA 312M Seamless and welded austenitic stainless steel pipes
SA 511 Seamless stainless steel mechanical tubing
SA 789 / SA 789M Seamless and welded ferritic-austenitic stainless steel tubing for general service
SA 790 / SA 790M Seamless and welded ferritic-austenitic stainless steel pipe
UNI-Standards :

Stainless and heat resisting steels

UNI 6904 Seamless steel tubes of special alloyed corrosion and heat resisting stainless tubes
GOST-Standards :

Stainless steels

GOST 9940 Seamless stainless steel tubes, hot finished
GOST 9941 Seamless stainless steel tubes, cold and hot finished
TU 14-3-460 Seamless Steel Pipes for Steam Boilers and Pipelines
European-Standards :

Stainless steels

EN 10216-5* Seamless steel tubes for pressure purposes
EN ISO 1127 Seamless stainless steel tubes (Dimensions and weights)

*Note: This European standard is replacing old national standards for pressure purpose (DIN 17458 DIN 17459 NFA 49117 NFA 49217 NFA 49218 BS 3605 BS 3605-1 etc… 
All European standards have their own national designation (example NF EN 10216-5 DIN EN 10216-5 BS EN XXXXX UNI EN XXXXX ..)


Stainless steels

DIN 17456 General purpose seamless circular stainless steel tubes
DIN 17458 Seamless circular Austenitic stainless steel tube subject to special requirement
DIN 17459 Seamless Circular High Temperature Austenitic Stainless Steel Tube Subject To Special Requirement

Stainless steels

JIS G 3459 Stainless steel pipes
JIS G 3463 Stainless steel boiler and heat exchanger tubes
Stainless Steel Rectangular Tubes (Polished / Matt Finish)

Specifications: CNS 5802, JIS G3446 and ASTM A554

O.D.(in) Thickness(mm)
0.7 0.8 0.9 1.0 1.2 1.5 2.0 2.5 3.0 4.0 5.0
10X20 X X X X X X X        
10X25 X X X X X X X        
10X30 X X X X X X X        
13X26 X X X X X X X        
15X30 X X X X X X X        
20X40 X X X X X X X        
25X50     X X X X X X X    
30X60     X X X X X X X    
40X80         X X X X X    
45X75         X X X X X    
45X95           X X X X X  
50X100           X X X X X  
60X120             X X X X X
Item Outside diameter Thickness Digonal Edge Radius Radii of Corners Straightness Length Flatness
ASTM A554 <31.8mm±0.38mm ±10% ≤0.4mm ≤2.5mmR ≤10mm/ 6M +50mm-0mm ±0.15mm

API 5L welded steel pipe

API 5L welded line pipe - How to buy welded steel pipes?

API 5L welded steel pipe is mainly used for the delivery of the onshore and offshore oil and gas, coal slurry, the slurry media and offshore platforms, power plants, chemical industry and urban construction, structural tubes.

API early in 1926 released by the American Petroleum Institute (API) API-5L standard, initially including three steel grade A25, A, B, and later released several times.

Prior to 2000, the worldwide use X70, about 40%, X65, X60 are in the 30%, a considerable number of small-caliber product oil pipeline selection of X52 steel grade, mostly for resistance welding straight pipe (ERW steel pipe).

China is currently used in the Petroleum Pipeline tube spiral welded pipe (SSAW)LSAW pipe (LSAW)electric resistance welded pipe (ERW). Diameter less than 152mm selection of seamless steel tubes. Of the late 1960s to the 1970s, spiral pipe plant rapid development of crude oil pipelines almost all spiral welded steel pipe, “West-East pipeline region selection spiral welded steel pipe. The spiral welded steel pipe of the disadvantage is the internal stress is large, the dimensional accuracy is poor, the probability of generation of defects. According to expert analysis, should adopt the policy of “walking on two legs”, and actively carry out technological transformation now spiral welded pipe plant, also in promising; vigorously develop straight seam submerged arc control tube industry in China. ERW steel pipe with a smooth appearance, high dimensional accuracy, lower prices, and has been widely used at home and abroad.

Straight seam high frequency welded steel molding process is with advanced, reliable quality, welding position, stable welding parameters, welding speed, high yield, and the entire production line equipment and technology are world-class level.

  • (1) straight seam high frequency welded steel pipe forming process springback small residual stress.
  • (2) the strain hardening effect is small, precise geometric dimensions full circle, will help ensure the quality of construction and welding. 
  • (3) straight seam high frequency welded steel bead shape is good, not prone to biting edge, inside and outside the weld misalignment defects. 
  • (4) straight-seam pipe weld distributed in a point on the circumference and, therefore, according to the demand to weld on a favorable position.

Welded Tube and Pipe Manufacturing Processes

First, raw steel is converted into a more workable form. Next, the pipe is formed on a continuous or semicontinuous production line. Finally, the pipe is cut and modified to meet the customer’s needs.

ERW Pipe Manufacturing Process

Our manufacturing process generally involves the following stages in a step by step procedure.

erw pipe processes - How to buy welded steel pipes?


HR Coils are slitted to pre-determined widths for each and every size of pipes

round form - How to buy welded steel pipes?
Round forming
Uncoiling, End Shearing And Welding

The slitted coil is uncoiled at the entry of ERW mill and the ends are sheared and welded one after another. This results in a single endless strip.


The slitted coils are initially formed into U shape and after that into a cylindrical shape with open edges utilizing a series of forming rolls.

erw welding - How to buy welded steel pipes?

In this stage, the open edges are heated to the forging temperature through high-frequency, low-voltage, high current and press welded by forge rolls making perfect and strong but weld without filler materials.

seam anbnealing - How to buy welded steel pipes?
Seam Annealing
De beading

In this stage, the weld flash on top and inside (if required) is trimmed out using the carbide tools.

Seam Annealing

If required, the welding portion and heat affected zone is put to normalizing and then are cooled down in a air cooling bed.


After water quenching, slight reduction is applied to pipes with sizing rolls.

This results in producing desired accurate outside diameter.


In cutting stage, the pipes are cut to required lengths by flying cut off disc/saw cutter.

End Facing And Bevelling

This is usually stage, where the pipes ends are faced and bevelled by the end facer.

All these processes are continuous with automatic arrangements. These plain ended tubes further go for processing as per the customer requirements such as galvanizing, threading, black varnishing and more.

Longitudinally Submerged Arc Welded Process Flow

LSAW pipes manufacturing process - How to buy welded steel pipes?

Roller Pipes Process Flow

Range of roller pipes:

Outer diameter: Ф1200-3800mm  |  Wall thickness: 12-120mm  |  Unit length (max) 3.2m.

lsaw roller flow - How to buy welded steel pipes?

UOE pipes manufacturing process

The UOE mill is the best suitable process to meet customers’ requirements by virture of the characteristic of high production efficiency, stable product quality and various accessories for manufacturing and inspection.

Longitudinal edges of steel plates are first beveled using carbide milling equipment. Beveled plates are then formed into a U shape using a U-press and subsequently into an O shape using an O-press.

Spiral Submerged-arc Welded steel pipe technological process
There are nine modernized product lines in our company with the yield capacity of 1000 thousands tons of B-X80 steel pipe of φ219-φ3200mm, WT5-30mm.

ssaw pipe process 1 - How to buy welded steel pipes?

Listing some notes You must know

Oiled marking: Steel after passing wrer oiled to prevent corrosion,and according to user requirements for making.

Leveling Milling: The flat steel anvil machine so that the origal curl,and then thouth the edge milling machine for two-sided steel milling,so as to meet the requirements of the plate width,plate edge parallelism and groove shape.

Shear molding: The steel plate production line along the outer edge of the spiral curl into a tube.
Butt cut: Double-sided submerged arc welding using advanced technology to pre-welding,internal welding,outside wilding.The welded steel pipe using a plasma-foot cut to specification length.

Anti rust process

Steel surface treatment is mainly anti rust, the following is anti rust process:

3lpe coating line pipe anti corrosion pipe - How to buy welded steel pipes?

3-Layer Polyethylene Coating System

First step is to clean, use cleaning solvent emulsion cleaning the steel surface, in order to achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove the steel surface rust, oxide, solder medicine.

Second step is to right tools rust, rust tools you want to have to use a wire brush, wire brush to remove loose or warped oxide, rust and slag. To achieve the desired effect of the rust, the hardness of the steel surface must be based on the original extent of corrosion and the required surface roughness, coating, etc. to select the type of abrasive, the epoxy layer, two or three layers polyethylene coating, using mixed abrasive grit and steel shot blasting easier to achieve the desired effect.

Third step is to do pickling, chemical and electrolytic pickling generally use two methods, using only chemical pickling pipeline corrosion. Although chemical cleaning can achieve a certain surface cleanliness and roughness, but there are some pollution to the environment.

Process Diagram of Three-Layer PE PP Coating

Process Diagram of Three Layer PE PP Coating - How to buy welded steel pipes?

Finally emphasis on the importance of surface treatment in the production, strictly control the process parameters when anti rust.

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 - How to buy welded steel pipes?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.
  • Packed in wooden crates, wrapped in plastic, and suitably protected for sea-worthly delivery or as requested.
  • Both ends of each crate will indicate the order no., heat no., dimensions, weight and bundles or as requested.

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

Welded steel pipe products are widely used in boilers, automobiles, ship building lightweight structural steel of the doors and windows, furniture, agricultural machinery, scaffolding, wire conduit, top shelves, containers, etc.. which can meet customer requirements, the special specifications welded pipe can be processed according to user requirements. Welded pipes for conveying water, sewage, gas, air, heating, steam and other low-pressure fluid and other uses.
According to different welding methods can be divided into electric arc welding tube, the high frequency or low frequency electric resistance welded pipe and gas welding tube, furnace welding pipe , bondi pipe, etc. 
Electric Resistance Welded steel tube used in oil drilling and machinery manufacturing, etc. 
Furnace tube welding pipe can be used for water gas pipe, etc . 
Longitudinal Submerge-arc Welded used for high pressure straight oil and gas transportation etc. 
Spiral welded pipe used for the oil and gas transmission, and pipe pile etc. 
Welded steel pipe dimensions:

  • Outer Diameter: 6mm-4064mm
  • Wall Thickness: 0.3mm-50mm
  • Length: 6mtr-18mtr

How to buy welded steel pipes at the lowest cost?

There are many types of welded steel pipes, such as wire rods, spiral welded steel pipes, straight seam welded steel pipes, etc., which are the best-selling and most popular welded steel pipes in the market. Take the spiral welded steel pipe, how can we buy a good quality and affordable product when we buy it? In fact, there are skills to follow. We are not blindly purchasing. It is believed that the products with beautiful appearance are also good in quality. This concept has been in the minds of some of our consumers. Deep-rooted, but in fact it is very wrong.
How to choose to purchase a spiral welded steel pipe brand product with high quality, low cost and high quality service. Nowadays, there are many brands of spiral welded steel pipe in the market. How can we choose the most suitable spiral welded steel pipe brand products? Through this article, the spiral welded steel pipe brand is purchased as a comprehensive guide for the majority of consumers or friends who are about to face the purchase problem.
Just like eating in a restaurant, the more people eat the restaurant, it proves that the food in the restaurant is delicious. I believe that the eyes of the people are bright. When purchasing spiral welded steel pipe products, they are buyers, wholesalers and individuals. You must also choose the brand spiral welded steel pipe products as you like to eat, and you can purchase local brands according to the following points.

  • 1. Find a manufacturer of spiral welded steel pipe brands that is trusted by local people.
  • 2. Collect the list of local spiral welded steel pipe brand manufacturers, and sort them by category (according to the manufacturer’s entity size, production equipment, production personnel, production management system), and you don’t need to collect them as key points.
  • 3. Compare local brand, user group trust and consumption patterns.

A comprehensive understanding of the above three points, and is suitable for some data surveys for comparison.
Spiral welded steel pipes should be qualified products with the manufacturer’s name, brand and specifications. The water supply pipe shall be threaded. The welded steel pipe shall have exposed threads at its joint. After installation, it shall be fixed by pipe clamp in time. The pipe and pipe fittings or valves shall be firmly connected without any looseness. After the spiral welded steel pipe is installed, it is checked by water, and visual inspection and hand feeling are used to check for leaks. Check whether all the faucets and valves are installed flat, whether the flexible straight seam welded steel pipe is opened, whether the water is unblocked, and whether there is leakage. Check if the water meter is working properly. For some special cases, be careful to avoid accidents. For example, the pipe is very long, connected to the kitchen and bathroom, or to the balcony, the spiral welded steel pipe should pass through the living room or room. Since the pipe is not buried in the wall or laid under the floor, if there is a problem, the consequences are very serious, so there is no joint in the middle. And to properly enlarge the diameter of the pipe to avoid blockage. Hot water pipes shall not be galvanized iron pipes to prevent corrosion of pipes and scale, and heat insulation measures shall be taken.
Rotary welded steel pipe quality

  • 1. The shoddy spiral welded steel pipe is prone to folding. Folding is a variety of fold lines formed on the surface of a spiral welded steel pipe factory, and such defects often extend throughout the longitudinal direction of the product. The reason for the folding is that the inferior manufacturer pursues high efficiency, the amount of pressing is too large, and the ear is generated, and the next rolling causes folding, and the folded product is cracked after bending, and the strength of the steel is greatly reduced.
  • 2. The surface of the counterfeit spiral welded steel pipe often has a pockmark phenomenon. The pockmark is a defect caused by the irregularity of the surface of the steel due to the serious wear of the groove. Due to the pursuit of profit by shoddy spiral welded steel pipe manufacturers, the most frequent rolling mill rolling is exceeded.
  • 3. The material of the counterfeit spiral welded steel pipe contains many impurities, the density of the steel is small, and the size is too bad, so in the absence of the vernier caliper, it can be weighed and checked. For example, for rebar 20, the national standard specifies a maximum negative tolerance of 5%. At a fixed length of 9 M, its single theoretical weight is 120 kg. Its minimum weight should be: 120 X (l – 5%) = 114 In kilograms, the actual weight of a single root is less than 114 kilograms, which is a shoddy steel because its negative tolerance exceeds 5%. In general, the effect of the phasing weighing will be better, mainly considering the problem of cumulative error and probability theory.
  • 4. The inner diameter of the counterfeit spiral welded steel pipe fluctuates greatly due to the fact that; l, the steel temperature is unstable and there is a yin and yang surface. 2. The composition of steel is not uniform. 3. Due to the simplistic equipment, the foundation strength is low, and the rolling mill has a large bounce. There will be a large change within the same week, and such a steel bar is unevenly stressed and easily broken.
  • 5. The trademarks and printing of quality pipes are relatively standardized.
  • 6. The three-screw welded steel pipe has a diameter of 16 or more, and the distance between the two trademarks is above IM.
  • 7. The longitudinal reinforcement of the counterfeit steel rebar is often wavy.
  • 8. The fake and inferior bar manufacturers have loose packaging because they do not have driving. The sides are oval.

The welded steel pipe insulation method of spiral welded steel pipe also starts from suppressing one of the processes. For example, adding anti-corrosion coating on the outer wall of the pipe can increase the loop resistance and reduce the corrosion current; plus the DC power supply, the welded steel pipe can cause negative potential to the soil and form cathodic protection. Can eliminate the anode-anode potential difference, fundamentally stop the process of the anode and cathode. Anti-corrosion coating rule of law, cathodic protection rule of law. But once the anti-corrosion coating is damaged, the iron part will accelerate local corrosion. Therefore anti-corrosion coating and cathodic protection The combination is a method of treating both the symptoms and the roots, which is economical and effective. The United States and other countries have clearly stipulated that the anti-corrosion coating must be used at the same time as cathodic protection.
However, for the urban gas system, due to the dense underground pipe network, the external power supply of the cathodic protection has great interference to other pipes, which will cause self-benefit and damage to his home. The sacrificial anode connected with the spiral welded steel pipe is used. The law of protection does not occur in this case. Therefore, the gas pipeline of city gas should adopt the anti-corrosion method combined with anti-corrosion coating and sacrificial anode. For other non-main pipelines with lower pressure, the anti-corrosion coating method is generally adopted directly. .
At present, the external anti-corrosion coating commonly used for buried gas-fired pipe insulation mainly consists of three layers of PE composite structure, epoxy resin powder, coal tar enamel, epoxy coal tar pitch and PE tape. Three-layer PE composite structure, epoxy powder anti-corrosion Excellent coating performance, so it is also the main anti-corrosion coating for buried pipelines in Europe and America.

Source: China Welded Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (

(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.)

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