What is EFW steel pipe

What is EFW steel pipe?

EFW steel pipe (Electric Fusion Welding steel pipe) refers to an electron beam welding, the use of high-speed movement of the electron beam directed impact kinetic energy is converted to heat the workpiece so that the workpiece leaving the melt, the formation of the weld. EFW steel pipe is formed by rolling plate and welding the seam. The weld flash can be removed from the outside or inside surfaces using a scarfing blade. The weld zone can also be heat treated to make the seam less visible. Welded pipe often has tighter dimensional tolerances than seamless, and can be cheaper if manufactured in the same quantities. It is mainly used for welding dissimilar steel welding sheet or which high power density, metal weldment can rapidly heated to high temperatures, which can melt any refractory metals and alloys. Deep penetration welding fast, heat-affected zone is extremely small, so small performance impact on the joints, the joint almost no distortion. But it has a requirement on a special welding room because welding using X-rays. 

Materials of EFW steel pipe

Pipes made from carbon steel lose strength at high temperatures. Electric-resistance-welded pipe is not considered satisfactory for service above 750 F, whereas furnace-buttwelded pipes are not good above 650 F. For higher temperatures, pipe made from stainless steels or other alloys should be considered.

Pressure ratings for steel pipe at different temperatures are calculated according to the ANSI B31.3 Code for Pressure Piping. ANSI B31.3 gives stress temperature values for the various steels from which pipe is fabricated.

Seam Welded Pipes are made using plates while Seamless pipes are made using dies. Steel pipes are commonly made with Black Finish or Galvanized. Proper selection of steel pipe material is critical for strength and durability required for application and ductility and machinability required to join it and form into piping. The selected pipe must withstand the conditions of use, especially pressure, temperature and corrosion conditions.

All these requirements can be met by selecting a pipe made to an appropriate standard e.g. ASTM or API Standard.

ASTM A-53

  1. Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless Electric fusion welded steel pipe for High pressure service at moderate temperatures.
  2. One of the two most used steel pipe material for welding, bending and coiling.
  3. Wall thicknesses are mainly Sch 40 (STD) and Sch 80 (XS).
  4. They are either made seamless or seamed using ERW, in Grades A and B. Grade B has higher tensile strength.
  5. Used mainly for utility services. For process piping, A106 is used.
  6. NPS 1⁄8 to NPS 26 [DN 6 to DN 650].
  7. Temperature Range : -15 to 415 deg.C.
  8. There are three types and 5 Grades as shown below.
  9. Type S : Seamless Pipe with Grade A and B based on Carbon Content. A: 0.25% and Grade B : 0.3 Percent. Use A if bending and Closed Coiling to be done. Currently an outdated specification and has been replaced by ASTM A106 specification for seamless carbon steel pipe.
  10. Type E : Electric Resistance Welded with Grade A and B based on Carbon Content. A:0.25% and Grade B: 0.3 Percent. Use A if bending and Closed Coiling to be done.
  11. Type F : Furnace Welded Pipe : With Grade A : 0.3 % Carbon. Not intended for Flanging.

ASTM A-106

  1. This is a seamless carbon steel pipe for high-temperature service in NPS 1⁄8 to NPS 48 inclusive, with nominal (average) wall thickness as given in ANSI B 36.10.
  2. They are mainly used for Process piping while A53 Used for Utility services.
  3. Temperature Range : -15 to 415 deg.C.
  4. Pipe ordered under this specification shall be suitable for bending, flanging, and similar forming operations, and for welding.
  5. Available grades are Grade A, B and C, with carbon content 0.25, 0.3 and 0.35 respectively. Hardness increases and weldability decreases. Bending ability also decreases from A to C.
  6. Grade A rather than Grade B or Grade C is the preferred grade for close coiling or cold bending.
  7. Wall thicknesses are mainly Sch 40 (STD) and Sch 80 (XS). They are either made seamless or seamed using ERW.

ASTM A-120

This is the most widely stocked pip. It covers welded and seamless steel pipe for normal use in steam, water, and gas (including air) service.  This pipe is not intended for bending, coiling or high temperature service. It is not specified for hydrocarbon process lines.

ASTM A-672

Its an Electric fusion welded steel pipe for High pressure service at moderate temperatures.  Design temperature Range : -29 deg.C to 425 deg. C

API 5L : Line Pipe

In the oil and natural gas industries, steel pipe used to convey oil and gas is manufactured to the American Petroleum Institute’s standard API 5L, which applies tighter control of composition and more testing than ASTM-120. Available Grades are :

  1. Grade A and B SMLS,
  2. Grade A and B ERW,
  3. Grade FBW

ASTM A312 Stainless Steel

This is a seamless, straight-seam welded, and heavily cold worked welded austenitic stainless steel pipe intended for high-temperature and general corrosive service. Chromium content ranges from 15 to 26 Percent.

Available Stainless Steel Grades are :  ASTM A312 TP304, 304H, 304L,310, 316, 316H, 316L, 317,321L, 321, 321H, 347, 347H.

  1. For Cryogenic Temperatures upto -100 Deg. C : 304, 304L, 316, 316L, 327H and 347
  2. For Elevated Temperatures below 630 deg. C : 304H, 316H, 327H and 312

ASTM A333 : LTCS

This is a low temperature carbon steel material used for operating temperatures in range of -15 deg C to -100 deg. C. Both Seamless and Welded Steel pipes are available. These pipes require Impact Testing.  Grade 1 and Grade 3 are mostly used. No filler metal is used in welding operation. All pipes shall be heat treated to control their microstructure.

ASTM A335 : Alloy Steel

This is a seamless ferritic alloy steel pipe intended for elevated temperature service, more than 415 deg.C and upto 600 deg.C.

Pipe ordered to this specification shall be suitable for bending, flanging (vanstoning), and similar forming operations, and for fusion welding. These are seamless pipe only.

Available grades are : P1,P2,P5,P5B, P5C,P9,P11,P12,P15,P21,P22,P23,P91,P122,P911

They have higher chromium and molybdenum content than A106.

Grades P1, P11, P12 and P22 Used for Elevated Temperatures, above 427 deg. C upto 630 deg. C.

  1. P11 : Max 595 deg. C.
  2.  P21 and P22 : Max 650 deg. C .
  3. P1 : 415 to 470 deg. C.
  4. P11 and P12 : 470 to 540 dg. C (P11 has higher chromial content hence more corrosion resistance than P12. Normally they are used interchangeably based on availability)
  5. P22 : 540 to 600 deg. C
  6. A312 TP 304H, 316H, 312 and 347H used above 600 deg. upto 815 deg. C

Equivalent Pipe Materials of Different Countries

Carbon Steel Materials

USA UK GERMANY SWEDEN
ASTM A53 BS 3601 DIN 1629
  1. Grade A SMLS
  2. GRADE B SMLS
  1. HFS 22 & CDS 22
  2. HFS 27 and CDS 27
  1. St 35
  2. St 45
  1. SIS 1233-05
  2. SIS 1434-05
 ASTM A53  BS 3601  DIN 1626
  1. Grade A ERW
  2. Grade B ERW
  1. ERW 22
  2. ERW 27
  1. Blatt 3 St 34-2 ERW
  2. Blatt 3 St 37-2 ERW
ASTM A53  BS 3601   DIN 1626
FBW BW 22  Blatt 3 St 34-2 FBW
ASTM A106  BS 3602   DIN 17175
  1. Grade A
  2. Grade B
  3. Grade C
  1. HFS 23
  2. HFS 27
  3. HFS 35
  1.  St 35-8
  2. St 45-8
  1. SIS 1234-05
  2. SIS 1435-05
ASTM A134   BS 3601  DIN 1626
EFW Blatt 2 EFW
ASTM A135  BS 3601  DIN 1626
  1. Grade A
  2. Grade B
  1.  ERW 22
  2. ERW 27
  1.  Blatt 3 St 34-2 ERW
  2. Blatt 3 St 37-2 ERW
  1.  SIS 1233-06
  2. SIS 1434-06
ASTM A139  BS 3601  DIN 1626
  1. Grade A
  2. Grade B
  1.  EFW 22
  2. EFW 27
  1.  Blatt 2 St 37
  2. Blatt 2 St 42
API 5L  BS 3601  DIN 1629
  1. Grade A SMLS
  2. Grade B SMLS
  1.  HFS 22 & CDS 22
  2. HFS 27 & CDS 27
  1. St 35
  2. St 45
  1.  SIS 1233-05
  2. SIS 1434-05
API 5L  BS 3601  DIN 1625
  1. Grade A ERW
  2. Grade B ERW
  1.  ERW 22
  2. ERW 27
  1. Blatt 3 St 34-2 ERW
  2. Blatt 4 St 37-2 ERW
  1.  SIS 1233-06
  2. SIS 1434-06
API 5L  BS 3601 DIN 1626 
  1. Grade A EFW
  2. Grade B EFW
  1.  EFW 22
  2. EFW 27
  1. Blatt 3 St 34-2 FW
  2. Blatt 4 St 37-2 FW
API 5L  BS 3601 DIN 1626 
FBW  BW 22 Blatt 3 St 34-2 FBW

Stainless Steel Pipes

US UK Germany Sweden
ASTM A312 BS 3605 WSN Designation
  1. TP 304
  2. TP 304H
  3. TP 304L
  4. TP 310
  5. TP 316
  6. TP 316H
  7. TP 316L
  8. TP 317
  9. TP 321
  10. TP 321H
  11. TP 347
  12. TP 347H
  1. Grade 801
  2. Grade 811
  3. Grade 801L
  4. Grade 805
  5. Grade 845
  6. Grade 855
  7. Grade 845l
  8. Grade 846
  9. Grade 822 Ti
  10. Grade 832 Ti
  11. Grade 822 Nb
  12. Grade 832 Nb
  1. 4301 x 5 CrNi 18 9
  2. 4306 x 2 CrNi 18 9
  3. 4841 x 15 CrNiSi 25 20
  4. 4401/4436 x 5 CrNiSi 18 10
  5. 4404 x 2 CrNiMo 18 10
  6. 4541 x 10 CrNiTi 18 9
  7. 4550 x 10 CrNiNb 18 9
  1. SIS 2333-02
  2. SIS 2352-02
  3. SIS 2361-02
  4. SIS 2343-02
  5. SIS 2353-02
  6. SIS 2337-02
  7. SIS 2338-02

Standard of EFW steel pipe:

ASTM A672 API 5L, ASTM A53 B, ASTM A178, ASTM A500/501, ASTM A691, ASTM A252, ASTM A672, EN 10217

ASTM A672 standard specification for electric fusion welded steel pipe for high pressure service at moderate temperatures.
This specification covers electrical-fusion-welded steel pipe for high-pressure service at moderate temperatures. Heat treatment may or may not be required to attain the desired properties or to comply with applicable code requirements. An analysis of each mill heat of plate material shall be made, also, an analysis of the finished deposited weld material from each 500 ft or fraction thereof shall be made. The mechanical test requirements includes one tension test specimen to represent each lot of finished pipe, and one transverse-guided-weld-bend test (two specimens) to represent each lot of finished pipe. Also, radiographic examination shall be made on the full length of each weld.

Chemical Requirements of ASTM A672 :

Specification Steel grade Chemical composition Remarks
C Si Mn P S Ti
                 
Pipes for pressure service 
ASTM A671, A672
-/A45 -/0.17 0.98 0.035 0.035 A671/
A672
-/A50 -/0.22
CA55/A55 0.28
-/B55 -/0.20 0.13
~0.45
CB60/B60 0.24
CB65/B65 0.28
CB70/C70 0.31 1.30
-/C55 -/0.18 0.55
~0.98
CC60/C60 0.21
CC65/C65 0.24 0.79
~1.30
CC70/C70 0.27


Mechanical Properties of ASTM A672:

Products Steel Grade BASE METAL MECHANICAL COMPOSITION Welding point tensile strength (N/mm2) Remarks
Yield point (N/mm2) Tensile Stregth (N/mm2) Test Pieces Elongation (%)
Pipes for pressure service ASTM A671, A672 -/A45 -/165 -/310~450 -/30 -/310~450 A671/ A672
-/A50 -/185 -/345~485 -/28 -/345~485
CA55/A55 205 380~515 27 380~515
-/B55 -/205 -/380~515 -/27 -/380~515
CB60/B60 220 415~550 25 415~550
CB65/B65 240 450~585 23 450~585
CB70/B70 260 485~620 21 485~620
-/C55 -/205 -/380~515 -/27 -/380~515
CC60/C60 220 415~550 25 415~550
CC65/C65 240 450~585 23 450~585
CC70/C70 260 485~620 21 485~620

API 5L

EFW Pipe

20181016103705 88396 - What is EFW steel pipe

Tolerance of Outside Diameter

Standard Out Diameter Tolerance of Pipe End Tolerance of Pipe Body
API 5L

219.1~273.1

+1.6mm, -0.4mm ±0.75%
274.0~320 +2.4mm, -0.8mm ±0.75%
323.9~457 +2.4mm, -0.8mm ±0.75%
508 +2.4mm, -0.8mm ±0.75%
559~610 +2.4mm, -0.8mm ±0.75%

Tolerance of Wall Thickness

Standard Grade Out Diameter Wall Thickness
API 5L A 219.1~457 +15%, -12.5%
B 508~610 +17.5%, -12.5%
X42-X80 508~610 +19.5%, -8%
Chemical Analysis and Mechanical Properties
Standard Class Grade Chemical Analysis(%) Mechanical Properties(min)(Mpa)
C Mn P S Tensile Strength Yield Strength
API 5L PSL1 B 0.26 1.20 0.030 0.030 414 241
X42 0.26 1.30 0.030 0.030 414 290
X46 0.26 1.40 0.030 0.030 434 317
X52 0.26 1.40 0.030 0.030 455 359
X56 0.26 1.40 0.030 0.030 490 386
X60 0.26 1.40 0.030 0.030 517 414
X65 0.26 1.45 0.030 0.030 531 448
X70 0.26 1.65 0.030 0.030 565 483
PSL2 B 0.22 1.20 0.025 0.015 414 241
X42 0.22 1.30 0.025 0.015 414 290
X46 0.22 1.40 0.025 0.015 434 317
X52 0.22 1.40 0.025 0.015 455 359
X56 0.22 1.40 0.025 0.015 490 386
X60 0.22 1.40 0.025 0.015 517 414
X65 0.22 1.45 0.025 0.015 531 448
X70 0.22 1.65 0.025 0.015 565 483
X80 0.22 1.85 0.025 0.015 621 552

High-frequency straight seam electric-resistance welded steel pipe(erw steel pipe) is hot-rolled coil after forming machine, the use of high-frequency current skin effect and proximity effects, the tube edge heating and melting, squeeze roller under pressure welding to achieve production.
High-frequency resistance welding steel pipe, welding pipe and ordinary welding process is not the same, the weld is made of the base metal melt from the body, the mechanical strength is better than the general pipe. Smooth appearance, high precision, low cost weld high and small, favorable 3PE anti-corrosion coating. There are significant differences in the welding methods between high frequency welded pipe and submerged arc welded pipe. As the welding is done instantly at high speed, the difficulty of ensuring the quality of welding is much higher than that of submerged arc welding.

ERW Casing

Standard: API SPEC 5CT

Application: Casing serves as wall of well

Specification

OD

WT

End Type

inch

mm

inch

mm

Grade

J55

M65

N80/L80-1

P110

K55

8 5/8

219.08

0.304

7.72

PS

0.352

8.94

PSLB

PSLB

0.400

10.16

PSLB

PSLB

PLB

PLB

0.450

11.43

PLB

PLB

PLB

0.500

12.70

PLB

PLB

9 5/8

244.48

0.352

8.94

PSLB

PSLB

0.395

10.03

PSLB

PSLB

PLB

PLB

0.435

11.05

PLB

PLB

PLB

0.472

11.99

PLB

PLB

PLB

0.545

13.84

PLB

PLB

10 3/4

273.05

0.350

8.89

PSB

PSB

0.400

10.16

PSB

PSB

0.450

11.43

PSB

PSB

PSB

PSB

0.500

12.57

PSB

PSB

PSB

0.545

13.84

PSB

13 3/8

339.72

0.380

9.65

PSB

PSB

0.430

10.92

PSB

PSB

0.480

12.19

PSB

PSB

PSB

PSB

0.514

13.06

PSB

PSB

16

406.40

0.438

11.13

PSB

0.495

12.57

PSB

0.656

16.66

P

18 5/8

473.08

0.435

11.05

PSB

20

508

0.438

11.13

PSLB

0.500

12.70

PSLB

0.635

16.13

PSLB

Dimensional Tolerance

Standard

Tolerance of O.D.

Tolerance of W.T.

Straightness of Pipe Body

Straightness of Pipe End

Tolerance for Weight

API 5CT

+1%, -0.5%

-12.5%

≤0.2%L

≤3.18mm

+6.5%, -3.5%

Mechanical Properties

Standard

Grade

Yield Strength(Mpa)

Tensile Strength(Mpa)

Hardness(HRC)

Impact Energy(J)(min)

Impact Temperature(℃)

API 5CT

J55

379-552

≥517

T-10-20(SR16)

21

K55

379-552

≥655

L-10-27(SR16)

M65

448-586

≥586

≤22

T-10-20, L-10-41

C19-20, C76-77(SR16)

0

L80

552-655

≥655

≤23

N80

552-758

≥689

P110

758-965

≥862

Chemical Composition(%)

Standard

Grade

C

Mn

P

S

Ni

Cu

Si

API 5CT

J55

≥0.030

≥0.030

K55

≥0.030

≥0.030

M65

≥0.030

≥0.030

L80

≥0.43

≥1.90

≥0.030

≥0.030

≥0.25

≥0.35

≥0.45

N80

≥0.030

≥0.030

P110

≥0.030

≥0.030

EFW Pipe Manufacturing Process

In EFW welding process, the external high energy electric arc is used to create a weld joint. Once the welding is done, the excess weld material from outside and inside of the pipe is removed with the help of trimmer tools.

In general, to reduce the negative effect of welding, a localized heat treatment of weld seam is carried out immediately it clears online ultrasonic test. Normally an induction heating method is used to restore microstructure of welded zone. These type of heat treatment is known as post annealing. In next stage, the pipe will go through Hydro testing, visual and dimensional inspection and once certified by inspection engineer it will send for packaging.

Manufacturing machine for efw steel pipe:
A combination of specially designed equipments like 1600MT press brake machine, multiple rolls bending machine, welding installations for outside, inside and circumferential welding, size calibrating press, solution annealing furnace and a host of other related machinery, is employed to manufacture pipes used in critical applications like refineries, fertilizers, LNG terminals, cross country pipe lines etc.

EFW steel pipe vs SSAW steel pipe vs ERW steel pipe

Electric Fusion Welded Pipe banner - What is EFW steel pipe

EFW pipe

ERW – Electric Resistance Welded

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 mandnel through the welded tube after the tube has been cooled.

This is termed as Electric Resistance welded or ERW tube/pipe. If this ERW is being drawn further to get desired size of tubes or pipes, in cold condition is called as Cold Drawn welded or CDW.

erw pipe banner - What is EFW steel pipe
ERW pipes means Electric Resistance Welded Pipes

ssaw pipes banner - What is EFW steel pipe

SAW – Submerged Arc Welded

This process is used for pipes from 24″ to 36″ i.e 610mm to 914mm OD. Flat plate is first pressed into U and later O shape.

The O shape is placed in an automatic welder and backed up on the inside by a water cooled copper shoe. Two electrodes in close proximity and used. The electrodes are not in actual contact with the pipe. The current passes from on electrode through a granular flux and across the gap in the pipe to the second electrode. The high temperature of the arc heats the edges of the plate, a welding rod placed just over the seam is thereby melted and metal is deposited in the groove.

Applications of EFW steel pipe

  • Oil Industry
  • Gas Industry
  • Filtration Industry
  • Refrigeration Industry
  • Refining Industry
  • Petrochemical Industry
  • Offshore Industry

Source: China EFW Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.pipelinedubai.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@pipelinedubai.com

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

References:

  • https://www.yaang.com
  • https://www.astm.org

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