What is an elbow?

What is an elbow?

The steel elbow is a pipe fiting that changes the direction of the pipe in the piping system. According to the angle, there are three most commonly used 45° and 90°180°, and other abnormal angle elbows such as 60° are also included according to engineering needs. The bending radius is less than or equal to 1.5 times the diameter of the pipe belongs to the elbow, and 1.5 times larger than the pipe diameter belongs to the elbow. The materials of the elbow are cast iron, stainless steel, alloy steel, malleable iron, carbon steel, non-ferrous metal and plastic. The way to connect to the pipe is: direct welding (the most common way) flange connection, hot melt connection, fused connection, threaded connection and socket connection. According to the production process, it can be divided into: welding elbow, punching elbow, push elbow, casting elbow, butt weld elbow.

asme b16 9 astm a403 wp316l smls 90 degree lr elbow 2 sch80s - What is an elbow?

Use of elbow Types of pipe elbows
Forged Pipe Elbow Threaded Pipe Fitting
Manufacturing process of the pipe elbow Materials
Standards Applications of pipe elbows

Use of elbow

Connect two pipes with the same or different nominal diameters to make the pipe turn 90°, 45°, 180° and various degrees.

Because the elbow has good comprehensive performance, it is widely used in chemical engineering, construction, water supply, drainage, petroleum, light and heavy industry, refrigeration, sanitation, plumbing, fire protection, electric power, aerospace, shipbuilding and other basic projects.

  • Wall thickness: SCH5 to SCH160
  • Size range: 1/2 to 56 inches (DN 15 to DN 1,400mm)
  • Degree: 22.5 Deg, 45 Deg, 90 Deg, 180 Deg
  • Manufacturing standards: ANSI, ISO, JIS and DIN
  • Process: butt welding, seamless
  • Type: Long radius, Short radius, Large size
  • Pressure: class 3000, 6000 and 9000

Types of pipe elbow

An elbow is a pipe fitting installed between two lengths of pipe or tubing to allow a change of direction, usually a 90° or 45° angle, though 22.5° elbows are also made. The ends may be machined for butt welding, threaded (usually female), or socketed, etc. When the two ends differ in size, the fitting is called a reducing elbow or reducer elbow.

 short radius 90degree - What is an elbow?
Short radius elbows
 long radius 90degree 1.5d - What is an elbow?
Long radius elbows
 stailness elbow - What is an elbow?
Stainless pipe elbows
larg diameter elbow - What is an elbow?
Big diameter elbows

The degree types of short radius pipe elbows as below:

An elbow is a pipe fitting installed between two lengths of pipe or tubing to allow a change of direction, usually a 180° or 90° angle, though 45° elbows are also made. The ends may be machined for butt welding (SW) or socketed welding(SW) etc.

Most elbows are available in short radius or long radius variants. When the two ends differ in size, the fitting is called a reducing elbow or reducer elbow.

Elbows are categorized based on various design features as below:

  • Long Radius (LR) Elbow is also called LR elbow – means the radius is 1.5 times the pipe diameter
    • L/R 45°Elbow: Long radius 45 degree elbow changes the direction by 45 degrees.
    • L/R 90°Elbow: Long radius 90 degree elbow changes the direction by 90 degrees.
    • L/R 180°Elbow: Long Radius 180 degree return bend allows complete reversal of flow.
  • Short Radius (SR) Elbow is also called SR elbow, – means the radius is 1.0 times the pipe diameter
    • Short radiu 45°Elbow: Short radius 45° elbow changes the direction by 45 degrees.
    • Short radius 90°Elbow: Short Radius 90° elbow is same as LR90 except for the measurement between end of elbow to center line is 1 x NPS.
    • Short radius 180° Elbow: Short Radius 180° return bend allows complete reversal of flow.

Elbows are categorized based on various design features as below:

  • Long Radius (LR) Elbows – radius is 1.5 times the pipe diameter
  • Short Radius (SR) Elbows – radius is 1.0 times the pipe diameter
  • 90 Degree Elbow – where change in direction required is 90°
  • 45 Degree Elbow – where change in direction required is 45°

A 90 degree elbow is also called a “90 bend” or “90 ell”. It is a fitting which is bent in such a way to produce 90 degree change in the direction of flow in the pipe. It used to change the direction in piping and is also sometimes called a “quarter bend”. A 90 degree elbow attaches readily to plastic, copper, cast iron, steel and lead. It can also attach to rubber with stainless steel clamps. It is available in many materials like silicone, rubber compounds, galvanized steel, etc. The main application of an elbow (90 degree) is to connect hoses to valves, water pressure pumps, and deck drains. These elbows can be made from tough nylon material or NPT thread.

Types of 90° elbows:
90° elbows are manufactured as SR (Short Radius) elbows and LR (Long Radius) elbows: 
SR (Short Radius) Elbows:
These elbows have a Center-to-Face dimension of 1.0 X diameter. They are typically used in tight areas where clearance is the main issue.
LR (Long Radius) Elbows:
These elbows have a Center-to-Face dimension of 1.5 X diameter. They are the most common type of elbow and used when space is available and flow is more critical.

90 degree Long Radius Elbow

The 90 degree Long Radius Elbow manufactured using superior grade raw materials. The 90 degree Long Radius Elbows are used for connecting pipes of different diameters and find wide applications in various chemicals, construction industries, paper, cement & ship builders.

We have adopted advanced production equipment to make our 90 degree Short Radius Elbow(1D D711.2~D1219.2), which can not only improve product quality, but also save raw materials.

ASME B16.9 Butt weld 90 degree Long Radius Elbow Dimensions

90 deg long redius dimen - What is an elbow?

ASME B16.9 90°Short Radius Elbow Dimensional Tolerance

NPS

O.D.
D

90 degrees
Long Radius
Center-to-End
A

45 degrees
Long Radius
Center-to-End
B

90 degrees
3D
Center-to-End
A

45 degrees
3D
Center-to-End
B

1/2

21.3

38

16

3/4

26.7

38

19

57

24

1

33.4

38

22

76

31

42.2

48

25

95

39

48.3

57

29

114

47

2

60.3

76

35

152

63

73

95

44

190

79

3

88.9

114

51

229

95

101.6

133

57

267

111

4

114.3

152

64

305

127

5

141.3

190

79

381

157

6

168.3

229

95

457

189

8

219.1

305

127

610

252

10

273

381

159

762

316

12

323.8

457

190

914

378

14

355.6

533

222

1067

441

16

406.4

610

254

1219

505

18

457

686

286

1372

568

20

508

762

318

1524

632

22

559

838

343

1676

694

24

610

914

381

1829

757

26

660

991

406

1981

821

28

711

1067

438

2134

883

30

762

1143

470

2286

964

32

813

1219

502

2438

1010

34

864

1295

533

2591

1073

36

914

1372

565

2743

1135

38

965

1448

600

2896

1200

40

1016

1524

632

3048

1264

42

1067

1600

660

3200

1326

44

1118

1676

695

3353

1389

46

1168

1753

727

3505

1453

48

1219

1829

759

3658

1516

ASME B16.9 90° Long Radius Elbow Dimensional Tolerance

DIMENSIONAL TOLERANCES – ELBOWS
For all fittings Elbows 90/45 deg 180° Returns
Nominal Pipe Size (NPS) Outside Ø 
at Bevel
Inside Ø 
at End
Wall Thickness 
t / t1
Center to End Dim. A-B-C-M Center to Center Dim.
O
Back to Face Dim.
K
Align- ment of Ends
U
1/2 a 2 1/2 1 0,8 Not 2 7 7 1
3 a 3 1/2 1 1,6 less 2 7 7 1
4 +2 -1 1,6 than 2 7 7 1
5 a 6 +3 -1 1,6 87,50% 2 7 7 1
8 2 1,6 of nominal 2 7 7 1
10 +4 -3 3,2 thickness 2 7 7 2
12 a 18 +4 -3 3,2 3 10 7 2
20 a 24 +6 -5 4,8 3 10 7 2
26 a 30 +7 -5 4,8 3 ….. ….. …..
32 a 48 +7 -5 4,8 5 ….. ….. …..

90 degree Short Radius Elbow

The 90 degree Short Radius Elbow manufactured using superior grade raw materials. The 90 degree Short Radius Elbows are used for connecting pipes of different diameters and find wide applications in various chemicals, construction industries, paper, cement & ship builders.

ASME B16.9 90 degree Short Radius Elbow Dimensional Tolerance

90 deg short redius dimen - What is an elbow?

NPS O.D.
D
Center-to-End
A
1 33.4 25
42.2 32
48.3 38
2 60.3 51
73 64
3 88.9 76
101.6 89
4 114.3 102
5 141.3 127
6 168.3 152
8 219.1 203
10 273 254
12 323.8 305
14 355.6 356
16 406.4 406
18 457 457
20 508 508
22 559 559
24 610 610

ASME B16.9 90°Short Radius Elbow Dimensional Tolerance

Nominal Pipe Size 1/2 to 2½ 3 to  4 5 to 8 10 to 18 20 to 24 26 to 30 32 to 48
Outside Diameter
at Bevel (D)
+ 1.6
– 0.8
1.6 1.6 + 2.4
– 1.6
+ 4
– 3.2
+ 6.4
– 4.8
+ 6.4
– 4.8
+ 6.4
– 4.8
Inside Diameter at End 0.8 1.6 1.6 1.6 3.2 4.8 + 6.4
– 4.8
+ 6.4
– 4.8
Center-to-End (A) 2 2 2 2 2 2 3 5
Wall Thickness (t) Not less than 87.5% of Nominal Wall Thickness

A 45 degree elbow is also called a “45 bend” or “45 ell”. It is commonly used in water supply facilities, food industrial pipeline networks, chemical industrial pipeline networks, electronic industrial pipeline networks, air conditioning facility pipeline, agriculture and garden production transporting system, pipeline network for solar energy facility, etc.

45° Pipe Elbow 
45° Pipe Elbow is also known as “45 bends or 45 ells”. The 45° pipe elbow is used to connect tubes at a 45° pipe angle. As the name suggests, this is a pipe fitting device which is bent in such a way to produce 45° change in the direction of flow of the fluid/gas in the pipe.
 Like a 90° elbow, the 45° pipe elbow also attaches readily to pipes of various materials like plastic, copper, cast iron, steel, lead, rubber etc. They are typically made as LR (Long Radius) elbows. These types of elbows are available in various sizes (in mm or inches). They are available with different male to female BSP thread connections. Providing a wide choice of colors, these 45° elbows can be manufactured to meet different specifications, in terms of size and diameter.

45 degree Long Radius elbow

The 45 degree Long Radius Elbow manufactured using superior grade raw materials.

Butt weld 45 degree LOng Radius Elbow are used for connecting pipes of different diameters and find wide applications in various chemicals, construction industries, paper, cement & ship builders.

ASME B16.9 Butt weld 45 degree Long Radius Elbow Dimensions

45 deg long redius dimen - What is an elbow?

NPS

O.D.
D

90 degrees
Long Radius
Center-to-End
A

45 degrees
Long Radius
Center-to-End
B

90 degrees
3D
Center-to-End
A

45 degrees
3D
Center-to-End
B

1/2

21.3

38

16

3/4

26.7

38

19

57

24

1

33.4

38

22

76

31

42.2

48

25

95

39

48.3

57

29

114

47

2

60.3

76

35

152

63

73

95

44

190

79

3

88.9

114

51

229

95

101.6

133

57

267

111

4

114.3

152

64

305

127

5

141.3

190

79

381

157

6

168.3

229

95

457

189

8

219.1

305

127

610

252

10

273

381

159

762

316

12

323.8

457

190

914

378

14

355.6

533

222

1067

441

16

406.4

610

254

1219

505

18

457

686

286

1372

568

20

508

762

318

1524

632

22

559

838

343

1676

694

24

610

914

381

1829

757

26

660

991

406

1981

821

28

711

1067

438

2134

883

30

762

1143

470

2286

964

32

813

1219

502

2438

1010

34

864

1295

533

2591

1073

36

914

1372

565

2743

1135

38

965

1448

600

2896

1200

40

1016

1524

632

3048

1264

42

1067

1600

660

3200

1326

44

1118

1676

695

3353

1389

46

1168

1753

727

3505

1453

48

1219

1829

759

3658

1516

ASME B16.9 45° Long Radius Elbow Dimensional Tolerance

DIMENSIONAL TOLERANCES – ELBOWS
For all fittings Elbows 90/45 deg 180° Returns
Nominal Pipe Size (NPS) Outside Ø 
at Bevel
Inside Ø 
at End
Wall Thickness 
t / t1
Center to End Dim. A-B-C-M Center to Center Dim.
O
Back to Face Dim.
K
Align- ment of Ends
U
1/2 a 2 1/2 1 0,8 Not 2 7 7 1
3 a 3 1/2 1 1,6 less 2 7 7 1
4 +2 -1 1,6 than 2 7 7 1
5 a 6 +3 -1 1,6 87,50% 2 7 7 1
8 2 1,6 of nominal 2 7 7 1
10 +4 -3 3,2 tickness 2 7 7 2
12 a 18 +4 -3 3,2   3 10 7 2
20 a 24 +6 -5 4,8   3 10 7 2
26 a 30 +7 -5 4,8   3 ….. ….. …..
32 a 48 +7 -5 4,8   5 ….. ….. …..

The 180 degree Short radius Elbow manufactured using superior grade raw materials. The 180 degree Short radius Elbows are used for connecting pipes of different diameters and find wide applications in various chemicals, construction industries, paper, cement & ship builders.

45 degree SR elbow

The 45 degree Short Radius Elbow manufactured using superior grade raw materials. Butt weld 45 degree Short Radius Elbow are used for connecting pipes of different diameters and find wide applications in various chemicals, construction industries, paper, cement & ship builders.

ASME B16.9 Butt weld 45 degree Short Radius Elbow Dimensions

45 deg short redius dimen - What is an elbow?

Nom. 
Pipe 
Size
Pipe 
Sched. 
or No.
Center- 
to-end 
Dimen.
Outside 
Dia.
Inside 
Dia.
Wall 
Thick.
Approx. 
Weight 
(lb.)
F OD ID T
     STANDARD WEIGHT
1/2 40 5/8 0.840 0.622 0.109 0.1
3/4 40 7/16 1.050 0.824 0.113 0.1
1 40 7/8 1.315 1.049 0.133 0.2
1 1/4 40 1 1.660 1.380 0.140 0.4
1 1/2 40 1 1/8 1.900 1.610 0.145 0.5
2 40 1 3/8 2.375 2.067 0.154 0.9
2 1/2 40 1 3/4 2.875 2.469 0.203 1.5
3 40 2 3.500 3.068 0.216 2.5
3 1/2 40 2 1/4 4.000 3.548 0.226 3.5
4 40 2 1/2 4.500 4.026 0.237 4.8
5 40 3 1/8 5.563 5.047 0.258 7.8
6 40 3 3/4 6.625 6.065 0.280 12
8 40 5 8.625 7.981 0.322 23
10 40 6 1/4 10.750 10.020 0.365 42
12 7 1/2 12.750 12.000 0.375 61
14 30 8 3/4 14.000 13.250 0.375 79
16 30 10 16.000 15.250 0.375 103
18 11 1/4 18.000 17.250 0.375 132
20 20 12 1/2 20.000 19.250 0.375 160
22 20 13 1/2 22.000 21.250 0.375 195
24 20 15 24.000 23.250 0.375 238
     EXTRA STRONG
Nom. 
Pipe 
Size
Pipe 
Sched. 
or No.
Center- 
to-end 
Dimen.
Outside 
Dia.
Inside 
Dia.
Wall 
Thick.
Approx. 
Weight 
(lb.)
F OD ID T
1/2 80 5/8 0.840 0.546 0.147 0.2
3/4 80 7/16 1.050 0.742 0.154 0.3
1 80 7/8 1.315 0.957 0.179 0.4
1 1/4 80 1 1.660 1.278 0.191 0.5
1 1/2 80 1 1/8 1.900 1.500 0.200 0.6
2 80 1 3/8 2.375 1.939 0.218 1.1
2 1/2 80 1 3/4 2.875 2.323 0.276 2.1
3 80 2 3.500 2.900 0.300 3.5
3 1/2 80 2 1/4 4.000 3.364 0.318 4.8
4 80 2 1/2 4.500 3.826 0.337 6.5
5 80 3 1/8 5.563 4.813 0.375 11
6 80 3 3/4 6.625 5.761 0.432 18
8 80 5 8.625 7.625 0.500 35
10 60 6 1/4 10.750 9.750 0.500 56
12 7 1/2 12.750 11.750 0.500 80
14 8 3/4 14.000 13.000 0.500 100
16 40 10 16.000 15.000 0.500 131
18 11 1/4 18.000 17.000 0.500 172
20 30 12 1/2 20.000 19.000 0.500 210
22 30 13 1/2 22.000 21.000 0.500 259
24 15 24.000 23.000 0.500 302

Ansi 16.9 tolerances – 45 Degree short radius elbow

DIMENSIONAL TOLERANCES – ELBOWS
For all fittings Elbows 90/45 deg 180° Returns
Nominal Pipe Size (NPS) Outside Ø 
at Bevel
Inside Ø 
at End
Wall Thickness 
t / t1
Center to End Dim. A-B-C-M Center to Center Dim.
O
Back to Face Dim.
K
Align- ment of Ends
U
1/2 a 2 1/2 1 0,8 Not 2 7 7 1
3 a 3 1/2 1 1,6 less 2 7 7 1
4 +2 -1 1,6 than 2 7 7 1
5 a 6 +3 -1 1,6 87,50% 2 7 7 1
8 2 1,6 of nominal 2 7 7 1
10 +4 -3 3,2 tickness 2 7 7 2
12 a 18 +4 -3 3,2   3 10 7 2
20 a 24 +6 -5 4,8 3 10 7 2
26 a 30 +7 -5 4,8 3 ….. ….. …..
32 a 48 +7 -5 4,8   5 ….. ….. …..

180 degree Short Radius Elbow

The 180 degree Short radius Elbow manufactured using superior grade raw materials. The 180 degree Short radius Elbows are used for connecting pipes of different diameters and find wide applications in various chemicals, construction industries, paper, cement & ship builders.

ASME B16.9 Butt weld 180 degree Short radius Elbow Dimensions

180 deg short redius dimen - What is an elbow?

ASME B16.9 180 degree Short radius Elbow Dimensional Tolerance

NPS O.D.
D
180° Short radius 180° Short Radius
Center to
Center
O
Back to
Face
K
Center to
Center
O
Back to
Face
K
1/2 21.3 76 48
3/4 26.7 76 51
1 33.4 76 56 51 41
42.2 95 70 64 52
48.3 114 83 76 62
2 60.3 152 106 102 81
73 190 132 127 100
3 88.9 229 159 152 121
101.6 267 184 178 140
4 114.3 305 210 203 159
5 141.3 381 262 254 197
6 168.3 457 313 305 237
8 219.1 610 414 406 313
10 273 762 518 508 391
12 323.8 914 619 610 467
14 355.6 1067 711 711 533
16 406.4 1219 813 813 610
18 457 1372 914 914 686
20 508 1524 1016 1016 762
22 559 1676 1118 1118 838
24 610 1829 1219 1219 914

ASME B16.9 180° Short Radius Elbow Dimensional Tolerance

For all fittings 180° Returns
Nominal Pipe Size (NPS) Outside Ø 
at Bevel
Inside Ø
at End
Wall Thickness 
t / t1
Center to Center Dim.
O
Back to Face Dim.
K
Align- ment of Ends
U
1/2 a 2 1/2 1 0,8 Not 7 7 1
3 a 3 1/2 1 1,6 less 7 7 1
4 +2 -1 1,6 than 7 7 1
5 a 6 +3 -1 1,6 87,50% 7 7 1
8 2 1,6 of nominal 7 7 1
10 +4 -3 3,2 thickness 7 7 2
12 a 18 +4 -3 3,2 10 7 2
20 a 24 +6 -5 4,8 10 7 2
26 a 30 +7 -5 4,8 ….. ….. …..
32 a 48 +7 -5 4,8 ….. ….. …..

180 degree Long Radius Elbow

The 180 degree Long Radius Elbow manufactured using superior grade raw materials.

The 180 degree Long Radius Elbows are used for connecting pipes of different diameters and find wide applications in various chemicals, construction industries, paper, cement & ship builders.

We have adopted advanced production equipment to make our 180 degree Long Radius Elbow(1D D711.2~D1219.2), which can not only improve product quality, but also save raw materials.

ASME B16.9 Butt weld 180 degree Long Radius Elbow Dimensions

180 deg long redius dimen - What is an elbow?

NPS O.D. D 180° Long Radius
Center to Center
O
Back to Face
K
1/2 21.3 76 48
3/4 26.7 76 51
1 33.4 76 56
42.2 95 70
48.3 114 83
2 60.3 152 106
73 190 132
3 88.9 229 159
101.6 267 184
4 114.3 305 210
5 141.3 381 262
6 168.3 457 313
8 219.1 610 414
10 273 762 518
12 323.8 914 619
14 355.6 1067 711
16 406.4 1219 813
18 457 1372 914
20 508 1524 1016
22 559 1676 1118
24 610 1829 1219

ASME B16.9 180° Long Radius Elbow Dimensional Tolerance

For all fittings 180° Returns
Nominal Pipe Size (NPS) Outside Ø 
at Bevel
Inside Ø
at End
Wall Thickness 
t / t1
Center to Center Dim.
O
Back to Face Dim.
K
Align- ment of Ends
U
1/2 a 2 1/2 1 0,8 Not 7 7 1
3 a 3 1/2 1 1,6 less 7 7 1
4 +2 -1 1,6 than 7 7 1
5 a 6 +3 -1 1,6 87,50% 7 7 1
8 2 1,6 of nominal 7 7 1
10 +4 -3 3,2 thickness 7 7 2
12 a 18 +4 -3 3,2 10 7 2
20 a 24 +6 -5 4,8 10 7 2
26 a 30 +7 -5 4,8 ….. ….. …..
32 a 48 +7 -5 4,8 ….. ….. …..

Most elbows are available in short radius or long radius variants.

SHORT RADIUS ELBOWS

The short radius elbows have a center-to-end distance equal to the Nominal Pipe Size (NPS) in inches, while the long radius is 1.5 times the NPS in inches. Short elbows are widely available, and are typically used in pressurized systems.

LONG RADIUS ELBOWS

Long elbows are typically used in low-pressure gravity-fed systems and other applications where low turbulence and minimum deposition of entrained solids are of concern.

Forged Pipe Elbow

45-Degree and 90-Degree Elbow Fittings with SW& Threaded Connection Ends. 
Pressure: 2000LBS, 3000LBS, 6000LBS, 9000LBS

Size: from 1/8″ to 4″

Material: ASTM A105, F304, F316, F304L, F316L, A182 F11/F22/F91

Connection ends: socket weld and threaded

Threaded Pipe Fitting SS304 Precision Cast Fittings

threaded pipe fitting - What is an elbow?Threaded Pipe Fitting SS304 with 90 degrees Elbow, Class 150lb, Male and Female Thread.

Size: 1/2 to 4 inch

304 90 degrees elbow, class 150lb, with male and female thread

Materials: SS304 and SS316

Manufacturing standards: ANSI, JIS, and DIN

Our prefessional foundry can do sand casting,lost wax casting and die casting .

forged elbows - What is an elbow?

The material as bellowing: 
Gray Iron, Ductile Iron, Steel, Stainless Steel, Malleable Iron and Alloy 
The products is widely used in automobile , machinery, pipe fittings, pump parts, valve part and other industry.

We are a group company consisting of:

  • 4 Sand Casting Plants (mainly produce Cast Iron and Ductile Iron Products)
  • 2 Resin Sand Casting Plants (mainly produce Cast Steel&Cast Iron Products)
  • 3 Investment Casting Plants (mainly produce Stainless Steel and Carbon Steel products
Butt welded Elbows:
  • Pipe is connected to butt welded elbow as shown in Fig. 4 by having a butt-welding joint.
  • Butt welded fittings are supplied with bevel ends suitable for welding to pipe. It is important to indicate the connected pipe thickness /schedule while ordering. All edge preparations for butt welding should conform to ASME B16.25.
  • Dimensions of butt welded elbows are as per ASME B16.9. This standard is applicable for carbon steel & alloy steel butt weld fittings of NPS 1/2” through 48”.
untitled 1 - What is an elbow?
Fig.4: A typical Butt-Welded Elbow
  • Dimensions of stainless steel butt welded fittings are as per MSS-SP-43. Physical dimensions for fittings are identical under ASME B16.9 and MSS-SP-43. It is implied that the scope of ASME B16.9 deals primarily with the wall thicknesses which are common to carbon and low alloy steel piping, whereas MSS-SP-43 deals specifically with schedule 5S & 10S in stainless steel piping.
  • Dimensions for short radius elbows are as per ASME B16.28 in case of carbon steel & low alloy steel and MSS-SP-59 for stainless steel.
  • Butt welded fittings are usually used for sizes 2” & above. However, for smaller sizes up to 1-1/2” on critical lines where use of socket welded joints is prohibited, pipe bends are normally used. These bends are usually of 5D radius and made at site by cold bending of pipe. Alternatively, butt welded elbows can be used in lieu of pipe bends but usually smaller dia lines are field routed and it is not possible to have the requirement known at initial stage of the project for procurement purpose. So pipe bends are preferred. However, pipe bends do occupy more space and particularly in pharmaceutical plants where major portion of piping is of small dia. and layout is congested, butt welded elbows are preferred.
  • Butt welded joints can be radiographed and hence preferred for all critical services.
  • Material standards as applicable to butt welded fittings are as follows:
ASTM A234:

This specification covers wrought carbon steel & alloy steel fittings of seamless and welded construction. Unless seamless or welded construction is specified in order, either may be furnished at the option of the supplier. All welded construction fittings as per this standard are supplied with 100% radiography. Under ASTM A234, several grades are available depending upon chemical composition. Selection would depend upon pipe material connected to these fittings.
Some of the grades available under this specification and corresponding connected pipe material specification are listed below:
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ASTM A403:
This specification covers two general classes, WP & CR, of wrought austenitic stainless steel fittings of seamless and welded construction.
Class WP fittings are manufactured to the requirements of ASME B16.9 & ASME B16.28 and are subdivided into three subclasses as follows:
WP – SManufactured from seamless product by a seamless method of manufacture.
WP – W These fittings contain welds and all welds made by the fitting manufacturer including starting pipe weld if the pipe was welded with the addition of filler material are radiographed. However no radiography is done for the starting pipe weld if the pipe was welded without the addition of filler material.
WP-WX These fittings contain welds and all welds whether made by the fitting manufacturer or by the starting material manufacturer are radiographed.
Class CR fittings are manufactured to the requirements of MSS-SP-43 and do not require non-destructive examination.
Under ASTM A403 several grades are available depending upon chemical composition. Selection would depend upon pipe material connected to these fittings. Some of the grades available under this specification and corresponding connected pipe material specification are listed below:
untitled3 1 - What is an elbow?
ASTM A420:
  • This specification covers wrought carbon steel and alloy steel fittings of seamless & welded construction intended for use at low temperatures. It covers four grades WPL6, WPL9, WPL3 & WPL8 depending upon chemical composition. Fittings WPL6 are impact tested at temp – 50° C, WPL9 at -75° C, WPL3 at -100° C and WPL8 at -195° C temperature.
  • The allowable pressure ratings for fittings may be calculated as for straight seamless pipe in accordance with the rules established in the applicable section of ASME B31.3.
  • The pipe wall thickness and material type shall be that with which the fittings have been ordered to be used, their identity on the fittings is in lieu of pressure rating markings.

Manufacturing process of the pipe elbow

Mandrel method (Hot Forming)

  • One of the most common Pipe Fittings Manufacturing Process for manufacturing Elbows Or Pipe Bends from the pipe is mandrel method which is kind of hot forming methods.
  • In this method, the pipe is cut in pieces and push with the help of hydraulic ram. It is pushed over a die called “mandrel” which allows the pipe to expand and bend simultaneously.
  • This method can be used to manufacture a wide range of the diameter of elbows or pipe bends
  • 20180104100126 45592 - What is an elbow?
  • ELBOWS Or Pipe Bends Mandrel method

Extrusion Method

In cold Extrusion method, a pipe with the same diameter as finished product is pushed through a die and formed into its desired shape. Usually applied to stainless steel small to medium sizes elbows or pipe bends.

20180104100215 30422 - What is an elbow?

Extrusion Method

UO Method

UO method is used to manufacture medium size of the elbow, tee, and reducers. The plate is cut out into a specially designed shape, it is formed first into a U-shape using a die and then into an O-shape or tubular form using another die, that is why this method is known as UO method. Once the fittings formed in tumbler shaped it is welded from inside and outside of the closing seam. A cut plate is 1st from in U shape and then in O shape.

20180104100303 36471 - What is an elbow?

UO Method

Hot Forming Method

In a Hot Forming Die Bending method, a Pipe is heated to forming temperature & formed in the die with the specific shape, this process may be repeated as needed to obtain the required shape, size and wall thickness. Usually applied to thick-wall items that cannot be bent on a mandrel die.

20180104100406 54259 - What is an elbow?

Hot Forming method for Elbow Manufacturing

Materials
  • Carbon steel: ASTM/ASME A234 WPB-WPC
  • Alloy steel: –WP 22-WP 5-WP 91-WP 911
    • ASTM A335 P22
    • ASME SA335 P91 elbow
    • ASTM A234 WP 11
  • Low temperature steel: ASTM/ASME A402 WPL 3-WPL 6
  • High performance steel: ASTM/ASME A860 WPHY 42-46-52-60-65-70
  • Stainless steel: ASTM/ASME A403 WP 304-304L-304H-304LN-304N
    • ASTM/ASME A403 WP 316-316L-316H-316LN-316N-316Ti
    • ASTM/ASME A403 WP 321-321H ASTM/ASME A403 WP 347-347H
Standards
  • GB/T12459-2005 GB/T13401-2005 GB/T10752-2005 SH/T3408-1996 SH/T3409-1996
  • SY/T0609-2006 SY/T0518-2002 SY/T0510-1998
  • DL/T695-1999 GD2000 GD87-1101
  • HG/T21635-1987 HG/T21631-1990
  • ASME B16.9-2007 ASME B16.25-2007
  • MSS SP 75-2008 MSS SP 43-2008
  • CSA Z245.11-05-2005
  • EN10253-1-1999 EN10253-2-2007 EN10253-3-2008 EN10253-4-2008
  • DIN2605-1-1992 DIN2605-2-1995
  • BS1640-1-1962 BS1640-2-1962 BS1640-3-1968 BS1640-4-1968 BS1965-1-1963
  • AFNOR NF A 49-289-1990 AFNOR NF A 49-170-1-1999 AFNOR NF A 49-170-2-2009 AFNOR NF A 49-170-3-2009
  • AFNOR NF A 49-170-4-2009 ISO3419-1981 ISO5251-1981
  • JIS B2311-2009 JIS B2312-2009 JIS B2313-2009
  • ASME B16.9 Butt weld 45 degree Long Radius Elbow Dimensions

Applications of pipe elbows:
Various applications of pipe elbows are as follows:

  • They are manufactured to be used in flow lines for gases, fluids in industrial processes, medical, construction and many other specialized applications.
  • The elbows are constructed of heavy materials for rigid applications like extreme high/low temperature resistance etc.
  • The elbows are specifically designed for use on process and control systems, instrumentation, and equipment used in chemical, petroleum, fluid power, electronic and pulp and paper plants. 

The stainless steel elbow on amazon is very expensive

Source: China Pipe Elbow Manufacturer – Yaang Pipe 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:

References:

  • https://en.wikipedia.org/wiki/Elbow_(band)
  • https://www.yaang.com/what-are-pipe-elbows.html
  • https://hardhatengineer.com/pipe-fittings/pipe-fittings-manufacturing-process/
  • http://www.whatispiping.com/piping-elbows-and-bends
  • https://www.yaang.com

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