What is a welded steel pipe

What is a welded steel pipe?
Welded steel pipe is one pipe the surface has the steel pipe joint,which is use the steel belt or steel plate material through the bending deformation into round ,square ect then welded into shape. 
Welded steel pipes 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 pipe, the high frequency or low frequency electric resistance welded pipe and gas welding pipe, furnace welding pipe , bondi pipe, etc. 
Electric Resistance Welded steel pipe used in oil drilling and machinery manufacturing, etc. 
Furnace pipe 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

Manufacturing Processes of Welded Pipe

Steel pipes are made by two different processes. The overall production method for both processes involves three steps.

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.

pipe ends - What is a welded 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 welded 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).

erw pipe banner - What is a welded steel pipe

ERW Pipe Manufacturing Process

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

Typical ERW Pipe Manufacturing Process

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

erw pipe processes - What is a welded steel pipe

Slitting

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

round form - What is a welded steel pipe
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.

Forming

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 - What is a welded steel pipe
Welding
Welding

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 - What is a welded steel pipe
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.

erw process Sizing Mill - What is a welded steel pipe
Sizing

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

This results in producing desired accurate outside diameter.

pipe Beveld cut - What is a welded steel pipe
Pipe beveling
Cutting

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.

Pipe connection

Pipe connection is varied, the commonly used have Butt weld, Flanged, Threaded, Socket weld, Glued, Brazed and Grooved end.

You assign connection types in the Connector Properties dialog box as you build fittings content using the Content Builder (see Adding Connectors to a Parametric Fitting). Assigned connection types are then displayed on the Connection Assignments tab of the Pipe Layout Preferences dialog box.

Unthreaded Connections are not threaded, must be either welded or bolted together. The following table shows the different orientations of pipe connection types:

Butt weld:

A butt weld is two pipes lined up with one another and welded along the contact edge to create a seal.

connection pipe butt weld - What is a welded steel pipe
No extra objects are added.

Pipe fittings and pipe segments connect directly to each other.

Flanged All types

flange is a plate or ring that is attached to a pipe. Two flanged pipe then create a tight seal by being bolted together.

connection pipe flanged all types - What is a welded steel pipe

  • Fitting to pipe: Flanges are typically included on fittings. A separate flange is added to the pipe segment.
  • Pipe to pipe: A separate flange is added to each pipe end to create the connection.
  • Fitting to fitting: Fittings with inherent flanges connect directly to each other. No separate flanges are added to the connection.
Threaded, Socket weld, Glued, Brazed

The pipe is the male fitting and the socket is equivalent to a female fitting. To provide a tight seal it is best to line the outside of the pipe and the inside of the socket with a sealant.

connection pipe threaded - What is a welded steel pipe
Socket welds require a pipe and socket connection.

  • Fitting to pipe: Pipe segments typically have inherent male ends, and fittings are typically female. The pipe inserts directly into the fitting.
  • Pipe to pipe: A female coupling is inserted between the pipe segments.
  • Fitting to fitting: Fittings connect directly to each other.
Grooved end

A grooved end fitting has a groove or shoulder along the edge. This fittings groove allows for a seal without the need for welding.

connection pipe grooved - What is a welded steel pipe

  • Fitting to pipe: Fittings and pipe segments are considered to have grooved ends that are ready to accept a coupling. A coupling is added to connect the fitting and pipe.
  • Pipe to pipe: A coupling is added to connect the pipe segments.
  • Fitting to fitting: A coupling is added to connect fittings.

ERW pipe technical requirements

ERW steel pipes and tube are available in various qualities, wall thicknesses, and diameters of the finished pipes.

Technical requirements For oil and gas transport For low pressure fluid conveying 
Material Gr.b Gr.b
Pipe body diameter D<508mm, ±0.75%; D≥508mm, ±0.75% D≤168.3, ±1.0%;  168.3<D≤508,±0.75%;  
Wall thickness D<508mm,+15.0%,-12.5%; D≥508mm, +17.5%,-10% ±12.5%
Bending ≤0.2% ≤0.2%
Ovality D≥508mm,≤±1% ≤±0.75%
Bevel ≤1.59mm ≤5mm
Hydrostatic testing  100%  100% 
Nondestructive testing 100% non-destructive weld inspection Ultrasonic flaw detection is 100%

ERW pipe technical requirements

ERW steel pipes and tubes are used in various engineering purposes, fencing, scaffolding, line pipes etc.

  • Yield strength of the N80 is higher than the J55 up to 173 ~ 206 MPa.
  • On the same area of the sample, the elongation of N80 is higher than J55.
  • Under the same size, the same sample orientation, the same minimum sample size, J55 grade couplings, coupling stock, coupling material, semi-finished and coupling attachment material can absorb lower than N80 steel grade.
  • The nondestructive testing methods of seamless pipe,coupling stock, welded tube with J55 and N80 is differeent.
  • J55 and N80 steel grade is not the same color: length greater than or equal 1.8m, J55 painted a bright green, N80 painted a red;
  • J55 chosen by the manufacturer, or organize according to the order specified length normalized (N), normalizing and tempering (N & T) or quenching and tempering (Q & T). N80 is a whole, full-length heat treatment is mandatory. By the manufacturer selected for normalizing (N) or normalizing and tempering (N & T) + quenching (Q).

Rectangular/ Square hollow section manufacturing process

Rectangular/ Square hollow section are formed from coils and then ran through a series of dies. They are are welded from the inside to form their shape.

RHS SHS manufacturing Process - What is a welded steel pipe
Manufacturing flow chart

SHS measurement - What is a welded steel pipe
They are measured by their outside dimensions and their wall thickness.

Rectangular/ Square hollow section is commonly available in Q195, Q215, Q235, Q345 grade.

It can be purchased online and at any Metal Supermarkets location. It can be cut to your exact specifications.

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

lsaw pipes banner - What is a welded steel pipe

LSAW Pipe Manufacturing Process

Longitudinally Submerged Arc Welded Process Flow

LSAW (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.
Longitudinally Submerged Arc Welded carbon steel pipes
(LSAW Pipes)with JCOE forming mode

LSAW pipes manufacturing process - What is a welded steel pipe

Roller Pipes Process Flow

Range of roller pipes: 

Outer diameter: Ф1200-3800mm

Wall thickness: 12-120mm

Unit length (max) 3.2m.

lsaw roller flow - What is a welded steel pipe

The Process For LSAW Steel Pipe

lsaw pipes - What is a welded steel pipe

LSAW (The Process For LSAW Steel Pipe) 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.

Description of Major Processes

a. Plate Utrosonic Inspection: Each plate is first full-plate ultrasonic inspected after entering the process
b. Plate Edge Milling:The Plate edges are milled by Edge Milling Machine to obtain the required width, parallelism and bevel angles;
c. Plate Edge Crimping: The two edges of the plate are crimped at the Crimping Machine to get the required radius;
d. Forming: The first half of the plate is fed step by step into the Pipe Forming Press to form the plate into a” J “shape. Then another half of the plate is pressed step by step to form the plate into” C “shape. The last stroke is to press the plate into an open “O” shape;
e.Continuous Tack Welding: The two edges of the open seam pipe should be brought together by tack welding machine then welded by tack welder using metal active-gas arc welding (MAG) process;
f. Inside Welding: the pipe is welded from inside of the pipe by multipass tandem submerged-arc welding (max. four wires)
g. Outside Welding: The pipe is welded from outside of the pipe by multipass tandem submerged-arc welding; 
h. Ultrasonic Testing I: The welded area on both sides of the weld are 100% tested by automatic ultrasonic tester .
i. X-ray Inspection I: The weld of the pipe is 100% checked by X-ray industrial TV system. The image handling system is also equipped to ensure the inspection sensitivity.
j. Expansion: The pipes are subject to full-length expansion to increase the precision of the pipe dimensions and improve the internal stress distribution.
k. Hydraulic Testing: Each pipe is subject to hydro test to ensure that a specified testing pressure according to appropriate standard is met. The functions for automatic recording and storing are equipped with the machine.
l. Pipe Ends Beveling: All pipes qualified from previous testing are subject to pipe end processing to get the required bevel dimension.
m. Ultrasonic Testing II:After expansion & hydro test, each pipe is tested by ultrasonic tester again for any possible defects occurred during the expanding and hydraulic testing process.
n. X-ray Inspection II:
Each pipe after expansion and hydro test is subject to X-ray industrial TV inspection and pipe-end weld filming.
o. The beveling area of the pipes is magnetic particle inspected for any defects.
p.Coating: The qualified pipes are coated for anti-corrosion as per the requirements of customers.
Besides the inspecting items mentioned above, the destructive inspection and other inspection on the plate and pipe such as raw material incoming sample inspection and plate 100% visual inspection according to API standard and other related standards and other special requirements from the customers are also performed. See attachment for the major process chart.

(The main production flow chart refers to the attached drawing)

Major Technical Characters

I. During the forming process, the deformation of the plate is very uniform and the residual stress is very low and there is less scratch on the surface. The production range on the wall thickness and pipe diameter is very flexible. For the high strength material with small pipe diameter and heavy wall thickness this process has more advantages than other pipe production process. More requirements on the product range from customers can be met.

Ⅱ. The welding can be performed at an optimal position so the welding quality is easy to control because the inside welding and outside welding are performed after the tack welding. The welding defects such as the offset, deflection and lack of penetration are very seldom to occur.

Ⅲ. The full-length mechanical expansion of the pipe can effectively increase dimension precision and improve the internal stress distribution of the steel pipes, thus avoid damage due to stress corrosion. The expanded pipes are very convenient for site application.
Ⅳ.The automatic on-line NDT test,composing of PID control automation,on-line automatic UT and RT nondestructive testing 100% control system guarantees the product quality maximum.

The technique process of LSAW steel pipe

the developing trend of lsaw steel pipe - What is a welded steel pipe

LSAW (the technique process of LSAW steel pipe) 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.

For the quality control for LSAW steel pipe we can assure that.

We have performed 100% inspection for nine items.

  • They are the Plate 100% ultrasonic inspection
  • welded seam 100% continuous ultrasonic inspection after welding
  • welded seam 100% X-ray industry TV inspection
  • inside welded seam 100% TV inspection
  • pipe 100% hydraulic testing
  • pipe 100% final ultrasonic testing after expansion & hydro testing
  • 100% X-ray industry TV inspection and pipe end inspection image recording
  • 100% pipe visual inspection
  • 100% plate visual inspection.

All the inspections shall be carried out by the specified inspection department.

We can ensure that the quality of the pipes produced by us can meet the requirements of consumers and the standards as well

Electrica Resistance Welded Steel Pipe in yaang range from 1/2″ to 24′ wallthickness max to 25mm ,API 5L stabndard ,PLS1 and PSL2 .

uoe pipe banner - What is a welded steel pipe
UOE Pipe Manufacturing Process

UOE (Uing and Oing forming) is a method used for production of longitudinally welded large diameter 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.

jcoe pipes banner - What is a welded steel pipe

JCOE Pipe Manufacturing Process

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.
As more process parameters, only through trial and error method is quite cumbersome. In order to obtain a mature technology, and even a few months of trial and error process. And trial and error process is often a fixed shape and spacing of the die, only to explore the punch stroke, so the results obtained may not be optimal, there is no full unit capacity. System so it is necessary to study the factors affecting the shape, or even to establish a theoretical formula, developed with the experience of trial and error molding process, eliminating the need or less need to test, trial costs and reduce time and increase productivity.

JCOE Pipe Manufacturing Process

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 manufacaturing process - What is a welded steel pipe

The mill has the advantages of wide specifications and can produce pipes in any size within its production range.

ssaw pipes banner - What is a welded steel pipe

SSAW Manufacturing Process

Spiral welded pipe production by submerged arc method is based on using tandem welding technique for joining inside and outside coil edges, which have been trimmed and beveled by carbide milling for high quality weld structure.

Spiral Submerged-arc Welded steel pipe technological process

Spiral welded pipe production by submerged arc method is based on using tandem welding technique for joining inside and outside coil edges, which have been trimmed and beveled by carbide milling for high quality weld structure.
Spiral Seam Annealing Systems:

outside diameter control - What is a welded steel pipe

Outside Diameter Control

hydrostatic testing - What is a welded steel pipe
Hydrostatic Testing

x ray testing online - What is a welded steel pipe
X-Ray Testing Online

Thermatool designs and manufactures Spiral Seam Annealing systems for producers of SAW (submerged arc welded) API line pipe.

Offering all the basic features and benefits of Thermatool seam annealing systems designed for operation on longitudinally welded API pipe, Thermatool Spiral Seam Annealing systems, however, require the installation of specially “shaped” inductors.

These are custom designed on CAD systems in order to precisely follow the helix angle for a specific pipe diameter.

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.

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 - What is a welded steel pipe

Anti rust process

Finally emphasis on the importance of surface treatment in the production, strictly control the process parameters when anti rust. Steel surface treatment is mainly anti rust, the following is anti rust process:

3-Layer Polyethylene Coating System

3lpe coating line pipe anti corrosion pipe - What is a welded steel pipe

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 - What is a welded steel pipe

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

3PE coating pipes - What is a welded steel pipe
3PE Coating Pipe

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.
Packing:
  • 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.
Delivery:

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.

Source: China Welded Steel Pipe Manufacturer – Yaang pipe fitting Industry Co., Limited (www.steeljrv.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 sales@steeljrv.com

Please notice that you might be interested in the other technical articles we’ve published:

  • How to get high quality stainless steel pipes

  • What is the difference between a steel pipe and a steel tube

  • Engineering Specification for Pressure Test of Piping System

  • How To Distinguish Inferior Steel Pipe

  • How to get high quality steel pipes

  • Manufacturing process of cold rolled steel pipe

  • How to get high quality boiler tubes

  • How to get high quality flanges

  • How to get high quality alloy steel pipes

  • How to get high quality pipe fittings

  • How to get high quality heat exchanger tubes

  • The difference between steel tubes and steel pipes

  • THE DIFFERENCE BETWEEN STEEL TUBES AND STEEL PIPES

  • Difference between galvanized steel pipe and seamless steel pipe

  • Knowledges of seamless steel pipes

Reference:

  • https://www.yaang.com/manufacturing-processes-of-steel-pipe.html
  • https://www.yaang.com
  • https://primis.phmsa.dot.gov/comm/FactSheets/FSPipeManufacturingProcess.htm
  • https://en.wikipedia.org/wiki/Pipe_Cutting

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