ASME/ANSI B16.5 Lap Joint Flange Dimensions

What is a lap joint flange?

Lap Joint Flange (LJ flange/Loose flange) is a two piece device that is much like a weld-neck flange but also like a loose slip on flange. One piece is a sleeve called a ‘Stub-end” and is shaped like a short piece of pipe with a weld bevel on one end and a narrow shoulder on the other end called the hub. The hub is the same outside diameter as the raised face (gasket contact surface) of a weld neck flange. The thickness of the hub is normally about ¼” to 3/8″. The back face of the hub has a rounded transition (or inside fillet) that joins the hub to the sleeve. Lap joint pipe flanges slide directly over the pipe and are most commonly used with stub end fittings. A pipe is usually welded to the Stub End and the Lap Joint pipe flange is free to rotate around the stub end. The benefit of this is that there will not be any issues with bolt hole alignment. Lap Joint pipe flanges are often used for applications that require frequent dismantling.

China Lap Joint Flange Manufacturer www.steeljrv.com supplies lap joint flanges in forged steel, Stainless Steel, alloy steel, etc.

Material of lap joint flange:

  • Carbon steel: ASTM A105,ASTM A105N,GB 20,C22.8.
  • Alloy steel: ASTM/ASME A182 F1-F12-F11-F22- F5-F9- F91
  • Stainless steel: ASTM/ASME A182 F304-304L-304H-304LN-304N
  • ASTM/ASME A182 F316-316L-316H-316LN-316N-316Ti
  • ASTM/ASME A182 F321-321H, F347-347H
  • Low temperature steel: ASTM/ASME A350 LF2.
  • High performance steel: ASTM/ASME A694 F42 , F52, F56, F60, F65, F70

Standards of lap joint flange:

ASME B16.5 – Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard

  • Lap Joint Flange: Class 300, Class 400, Class 600, Class 900, Class 1500, Class 2500

Lap Joint Flange Dimensions

data ljf b16.5 3 - ASME/ANSI B16.5 Lap Joint Flange Dimensions Flat Face

ASME/ANSI B16.5 Lap Joint Flange Class 150 (in)

This datasheet is for lap joint flanges that have a flat face connection.

  • Dimensions to ASME B16.5 – Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
  • Bolt circle diameters are 1/8 inch larger than bolt diameter.
  • 1/4″ raised face is not included in dimension “C” and “M”.

20191225105548 71057 - ASME/ANSI B16.5 Lap Joint Flange Dimensions

Pipe Size

(NPS)

Outside Diameter of Flange

A

Thickness of Flange

C

Diameter of Bore

F

Diameter of Hub at Base

J

Length of Hub

M

Radius
R

Number of Bolt Holes

NBH

Diameter of Bolt Holes

 DBH

Bolt Circle Diameter

P

Approx Weight

(lb)

AW

1/2

3 1/2

7/16

0.90

1 3/16

5/8

1/8

4

5/8

2 3/8

2

3/4

3 7/8

1/2

1.11

1 1/2

5/8

1/8

4

5/8

2 3/4

2

1

4 1/4

9/16

1.38

1 15/16

11/16

1/8

4

5/8

3 1/8

2

1 1/4

4 5/8

5/8

1.72

2 5/16

13/16

3/16

4

5/8

3 1/2

3

1 1/2

5

11/16

1.97

2 9/16

7/8

1/4

4

5/8

3 7/8

3

2

6

3/4

2.46

3 1/16

1

5/16

4

3/4

4 3/4

5

2 1/2

7

7/8

2.97

3 9/16

1 1/8

5/16

4

3/4

5 1/2

7

3

7 1/2

15/16

3.60

4 1/4

1 3/16

3/8

4

3/4

6

8

3 1/2

8 1/2

15/16

4.10

4 13/16

1 1/4

3/8

8

3/4

7

11

4

9

15/16

4.60

5 5/16

1 5/16

7/16

8

3/4

7 1/2

13

5

10

15/16

5.69

6 7/16

1 7/16

7/16

8

7/8

8 1/2

15

6

11

1

6.75

7 9/16

1 9/16

1/2

8

7/8

9 1/2

19

8

13 1/2

1 1/8

8.75

9 11/16

1 3/4

1/2

8

7/8

11 3/4

30

10

16

1 3/16

10.92

12

1 15/16

1/2

12

1

14 1/4

43

12

19

1 1/4

12.92

14 3/8

2 3/16

1/2

12

1

17

64

14

21

1 3/8

14.18

15 3/4

3 1/8

1/2

12

1 1/8

18 3/4

99

16

23 1/2

1 7/16

16.19

18

3 7/16

1/2

16

1 1/8

21 1/4

128

18

25

1 9/16

18.20

19 7/8

3 13/16

1/2

16

1 1/4

22 3/4

146

20

27 1/2

1 11/16

20.25

22

4 1/16

1/2

20

1 1/4

25

185

22

29 1/2

1 13/16

22.25

24

4 1/4

1/2

20

1 3/8

27 1/4

245

24

32

1 7/8

24.25

26 1/8

4 3/8

1/2

20

1 3/8

29 1/2

260

ASME/ANSI B16.5 Lap Joint Flange Class 300 (in)

This datasheet is for lap joint flanges that have a flat face connection.

  • Dimensions to ASME B16.5 – Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
  • Bolt circle diameters are 1/8 inch larger than bolt diameter.
  • 1/4″ raised face is not included in dimension “C” and “M”.

20191225105548 71057 - ASME/ANSI B16.5 Lap Joint Flange Dimensions

Pipe Size

(NPS)

Outside Diameter of Flange

A

Thickness of Flange

C

Diameter of Bore

F

Diameter of Hub at Base

J

Length of Hub

M

Radius
R

Number of Bolt Holes

NBH

Diameter of Bolt Holes

DBH

Bolt Circle Diameter

P

Approx Weight

(lb)

AW

1/2

3 3/4

9/16

0.90

1 1/2

7/8

1/8

4

5/8

2 5/8

3

3/4

4 5/8

5/8

1.11

1 7/8

1

1/8

4

3/4

3 1/4

3

1

4 7/8

11/16

1.38

2 1/8

1 1/16

1/8

4

3/4

3 1/2

3

1 1/4

5 1/4

3/4

1.72

2 1/2

1 1/16

3/16

4

3/4

3 7/8

4

1 1/2

6 1/8

13/16

1.97

2 3/4

1 3/16

1/4

4

7/8

4 1/2

6

2

6 1/2

7/8

2.46

3 5/16

1 5/16

5/16

8

3/4

5

7

2 1/2

7 1/2

1

2.97

3 15/16

1 1/2

5/16

8

7/8

5 7/8

10

3

8 1/4

1 1/8

3.60

4 5/8

1 11/16

3/8

8

7/8

6 5/8

13

3 1/2

9

1 3/16

4.10

5 1/4

1 3/4

3/8

8

7/8

7 1/4

17

4

10

1 1/4

4.60

5 3/4

1 7/8

7/16

8

7/8

7 7/8

22

5

11

1 3/8

5.69

7

2

7/16

8

7/8

9 1/4

28

6

12 1/2

1 7/16

6.75

8 1/8

2 1/16

1/2

12

7/8

10 5/8

39

8

15

1 5/8

8.75

10 1/4

2 7/16

1/2

12

1

13

58

10

17 1/2

1 7/8

10.92

12 5/8

3 3/4

1/2

16

1 1/8

15 1/4

91

12

20 1/2

2

12.92

14 3/4

4

1/2

16

1 1/4

17 3/4

139

14

23

2 1/8

14.18

16 3/4

4 3/8

1/2

20

1 1/4

20 1/4

189

16

25 1/2

2 1/4

16.19

19

4 3/4

1/2

20

1 3/8

22 1/2

240

18

28

2 3/8

18.20

21

5 1/8

1/2

24

1 3/8

24 3/4

305

20

30 1/2

2 1/2

20.25

23 1/8

5 1/2

1/2

24

1 3/8

27

375

22

33

2 5/8

22.25

25 1/4

5 3/4

1/2

24

1 5/8

29 1/4

435

24

36

2 3/4

24.25

27 5/8

6

1/2

24

1 5/8

32

530

ASME/ANSI B16.5 Lap Joint Flange Class 400 (in)

This datasheet is for lap joint flanges that have a flat face connection.

  • Dimensions to ASME B16.5 – Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
  • Bolt circle diameters are 1/8 inch larger than bolt diameter.
  • 1/4″ raised face is not included in dimension “C” and “M”.



20191225105548 71057 - ASME/ANSI B16.5 Lap Joint Flange Dimensions

Pipe Size

(NPS)

Outside Diameter of Flange

A

Thickness of Flange

C

Diameter of Bore

F

Diameter of Hub at Base

J

Length of Hub

M

Radius
R

Number of Bolt Holes

NBH

Diameter of Bolt Holes

DBH

Bolt Circle Diameter

P

Approx Weight

 (lb)

AW

1/2

3 3/4

9/16

0.90

1 1/2

7/8

1/8

4

5/8

2 5/8

3

3/4

4 5/8

5/8

1.11

1 7/8

1

1/8

4

3/4

3 1/4

3

1

4 7/8

11/16

1.38

2 1/8

1 1/16

1/8

4

3/4

3 1/2

4

1 1/4

5 1/4

13/16

1.72

2 1/2

1 1/8

3/16

4

3/4

3 7/8

6

1 1/2

6 1/8

7/8

1.97

2 3/4

1 1/4

1/4

4

7/8

4 1/2

7

2

6 1/2

1

2.46

3 5/16

1 7/16

5/16

8

3/4

5

9

2 1/2

7 1/2

1 1/8

2.97

3 15/16

1 5/8

5/16

8

7/8

5 7/8

12

3

8 1/4

1 1/4

3.60

4 5/8

1 13/16

3/8

8

7/8

6 5/8

15

3 1/2

9

1 3/8

4.10

5 1/4

1 15/16

3/8

8

1

7 1/4

20

4

10

1 3/8

4.60

5 3/4

2

7/16

8

1

7 7/8

25

5

11

1 1/2

5.69

7

2 1/8

7/16

8

1

9 1/4

29

6

12 1/2

1 5/8

6.75

8 1/8

2 1/4

1/2

12

1

10 5/8

42

8

15

1 7/8

8.75

10 1/4

2 11/16

1/2

12

1 1/8

13

64

10

17 1/2

2 1/8

10.92

12 5/8

4

1/2

16

1 1/4

15 1/4

112

12

20 1/2

2 1/4

12.92

14 3/4

4 1/4

1/2

16

1 3/8

17 3/4

152

14

23

2 3/8

14.18

16 3/4

4 5/8

1/2

20

1 3/8

20 1/4

210

16

25 1/2

2 1/2

16.19

19

5

1/2

20

1 1/2

22 1/2

280

18

28

2 5/8

18.20

21

5 3/8

1/2

24

1 1/2

24 3/4

345

20

30 1/2

2 3/4

20.25

23 1/8

5 3/4

1/2

24

1 5/8

27

420

22

33

2 7/8

22.25

25 1/4

6

1/2

24

1 3/4

29 1/4

455

24

36

3

24.25

27 5/8

6 1/4

1/2

24

1 7/8

32

615

ASME/ANSI B16.5 Lap Joint Flange Class 600 (in)

This datasheet is for lap joint flanges that have a flat face connection.

  • Dimensions to ASME B16.5 – Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
  • Bolt circle diameters are 1/8 inch larger than bolt diameter.
  • 1/4″ raised face is not included in dimension “C” and “M”.



20191225105548 71057 - ASME/ANSI B16.5 Lap Joint Flange Dimensions

Pipe Size

(NPS)

Outside Diameter of Flange

A

Thickness of Flange

C

Diameter of Bore

F

Diameter of Hub at Base

J

Length of Hub

M

Radius

R

Number of Bolt Holes

NBH

Diameter of Bolt Holes

 DBH

Bolt Circle Diameter

P

Approx Weight

(lb)

AW

1/2

3 3/4

9/16

0.90

1 1/2

7/8

1/8

4

5/8

2 5/8

3

3/4

4 5/8

5/8

1.11

1 7/8

1

1/8

4

3/4

3 1/4

3

1

4 7/8

11/16

1.38

2 1/8

1 1/16

1/8

4

3/4

3 1/2

4

1 1/4

5 1/4

13/16

1.72

2 1/2

1 1/8

3/16

4

3/4

3 7/8

6

1 1/2

6 1/8

7/8

1.97

2 3/4

1 1/4

1/4

4

7/8

4 1/2

7

2

6 1/2

1

2.46

3 5/16

1 7/16

5/16

8

3/4

5

9

2 1/2

7 1/2

1 1/8

2.97

3 15/16

1 5/8

5/16

8

7/8

5 7/8

12

3

8 1/4

1 1/4

3.60

4 5/8

1 13/16

3/8

8

7/8

6 5/8

15

3 1/2

9

1 3/8

4.10

5 1/4

1 15/16

3/8

8

1

7 1/4

20

4

10 3/4

1 1/2

4.60

6

2 1/8

7/16

8

1

8 1/2

36

5

13

1 3/4

5.69

7 7/16

2 3/8

7/16

8

1 1/8

10 1/2

61

6

14

1 7/8

6.75

8 3/4

2 5/8

1/2

12

1 1/8

11 1/2

78

8

16 1/2

2 3/16

8.75

10 3/4

3

1/2

12

1 1/4

13 3/4

112

10

20

2 1/2

10.92

13 1/2

4 3/8

1/2

16

1 3/8

17

195

12

22

2 5/8

12.92

15 3/4

4 5/8

1/2

20

1 3/8

19 1/4

240

14

23 3/4

2 3/4

14.18

17

5

1/2

20

1 1/2

20 3/4

290

16

27

3

16.19

19 1/2

5 1/2

1/2

20

1 5/8

23 3/4

400

18

29 1/4

3 1/4

18.20

21 1/2

6

1/2

20

1 3/4

25 3/4

469

20

32

3 1/2

20.25

24

6 1/2

1/2

24

1 3/4

28 1/2

604

22

34 1/4

3 3/4

22.25

26 1/2

6 7/8

1/2

24

1 7/8

30 5/8

670

24

37

4

24.25

28 1/4

7 1/4

1/2

24

2

33

866

ASME/ANSI B16.5 Lap Joint Flange Class 900 (in)

This datasheet is for lap joint flanges that have a flat face connection.

  • Dimensions to ASME B16.5 – Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
  • Bolt circle diameters are 1/8 inch larger than bolt diameter.
  • 1/4″ raised face is not included in dimension “C” and “M”.



20191225105548 71057 - ASME/ANSI B16.5 Lap Joint Flange Dimensions

Pipe Size

(NPS)

Outside Diameter of Flange

A

Thickness of Flange

C

Diameter of Bore

F

Diameter of Hub at Base

J

Length of Hub

M

Radius

R

Number of Bolt Holes

 NBH

Diameter of Bolt Holes

DBH

Bolt Circle Diameter

P

Approx Weight

(lb)

AW

1/2

4 3/4

7/8

0.90

1 1/2

1 1/4

1/8

4

7/8

3 1/4

9

3/4

5 1/8

1

1.11

1 3/4

1 3/8

1/8

4

7/8

3 1/2

9

1

5 7/8

1 1/8

1.38

2 1/16

1 5/8

1/8

4

1

4

9

1 1/4

6 1/4

1 1/8

1.72

2 1/2

1 5/8

3/16

4

1

4 3/8

10

1 1/2

7

1 1/4

1.97

2 3/4

1 3/4

1/4

4

1 1/8

4 7/8

14

2

8 1/2

1 1/2

2.46

4 1/8

2 1/4

5/16

8

1

6 1/2

25

2 1/2

9 5/8

1 5/8

2.97

4 7/8

2 1/2

5/16

8

1 1/8

7 1/2

35

3

9 1/2

1 1/2

3.60

5

2 1/8

3/8

8

1

7 1/2

30

3 1/2

4

11 1/2

1 3/4

4.60

6 1/4

2 3/4

7/16

8

1 1/4

9 1/4

51

5

13 3/4

2

5.69

7 1/2

3 1/8

7/16

8

1 3/8

11

81

6

15

2 3/16

6.75

9 1/4

3 3/8

1/2

12

1 1/4

12 1/2

105

8

18 1/2

2 1/2

8.75

11 3/4

4 1/2

1/2

12

1 1/2

15 1/2

188

10

21 1/2

2 3/4

10.92

14 1/2

5

1/2

16

1 1/2

18 1/2

277

12

24

3 1/8

12.92

16 1/2

5 5/8

1/2

20

1 1/2

21

371

14

25 1/4

3 3/8

14.18

17 3/4

6 1/8

1/2

20

1 5/8

22

397

16

27 3/4

3 1/2

16.19

20

6 1/2

1/2

20

1 3/4

24 1/4

488

18

31

4

18.20

22 1/4

7 1/2

1/2

20

2

27

670

20

33 3/4

4 1/4

20.25

24 1/2

8 1/4

1/2

20

2 1/8

29 1/2

868

22

24

41

5 1/2

24.25

29 1/2

10 1/2

1/2

20

2 5/8

35 1/2

1659

ASME/ANSI B16.5 Lap Joint Flange Class 1500 (in)

This datasheet is for lap joint flanges that have a flat face connection.

  • Dimensions to ASME B16.5 – Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
  • Bolt circle diameters are 1/8 inch larger than bolt diameter.
  • 1/4″ raised face is not included in dimension “C” and “M”.



20191225105548 71057 - ASME/ANSI B16.5 Lap Joint Flange Dimensions

Pipe Size

(NPS)

Outside Diameter of Flange

A

Thickness of Flange

C

Diameter of Bore

F

Diameter of Hub at Base

J

Length of Hub

M

Radius
R

Number of Bolt Holes

NBH

Diameter of Bolt Holes

 DBH

Bolt Circle Diameter

P

Approx Weight

(lb)

AW

1/2

4 3/4

7/8

0.90

1 1/2

1 1/4

1/8

4

7/8

3 1/4

9

3/4

5 1/8

1

1.11

1 3/4

1 3/8

1/8

4

7/8

3 1/2

9

1

5 7/8

1 1/8

1.38

2 1/16

1 5/8

1/8

4

1

4

9

1 1/4

6 1/4

1 1/8

1.72

2 1/2

1 5/8

3/16

4

1

4 3/8

10

1 1/2

7

1 1/4

1.97

2 3/4

1 3/4

1/4

4

1 1/8

4 7/8

14

2

8 1/2

1 1/2

2.46

4 1/8

2 1/4

5/16

8

1

6 1/2

25

2 1/2

9 5/8

1 5/8

2.97

4 7/8

2 1/2

5/16

8

1 1/8

7 1/2

35

3

10 1/2

1 7/8

3.60

5 1/4

2 7/8

3/8

8

1 1/4

8

47

3 1/2

4

12 1/4

2 1/8

4.60

6 3/8

3 9/16

7/16

8

1 3/8

9 1/2

75

5

14 3/4

2 7/8

5.69

7 3/4

4 1/8

7/16

8

1 5/8

11 1/2

138

6

15 1/2

3 1/4

6.75

9

4 11/16

1/2

12

1 1/2

12 1/2

170

8

19

3 5/8

8.75

11 1/2

5 5/8

1/2

12

1 3/4

15 1/2

286

10

23

4 1/4

10.92

14 1/2

7

1/2

12

2

19

485

12

26 1/2

4 7/8

12.92

17 3/4

8 5/8

1/2

16

2 1/8

22 1/2

749

14

29 1/2

5 1/4

14.18

19 1/2

9 1/2

1/2

16

2 3/8

25

890

16

32 1/2

5 3/4

16.19

21 3/4

10 1/2

1/2

16

2 5/8

27 3/4

1150

18

36

6 3/8

18.20

23 1/2

10 7/8

1/2

16

2 7/8

30 1/2

1475

20

38 3/4

7

20.25

25 1/4

11 1/2

1/2

16

3 1/8

32 3/4

1775

22

24

46

8

24.25

30

13

1/2

16

3 5/8

39

2825

ASME/ANSI B16.5 Lap Joint Flange Class 2500 (in)

This datasheet is for lap joint flanges that have a flat face connection.

  • Dimensions to ASME B16.5 – Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
  • Bolt circle diameters are 1/8 inch larger than bolt diameter.
  • 1/4″ raised face is not included in dimension “C” and “M”.



20191225105548 71057 - ASME/ANSI B16.5 Lap Joint Flange Dimensions

Pipe Size

(NPS)

Outside Diameter of Flange

A

Thickness of Flange

C

Diameter of Bore

F

Diameter of Hub at Base

J

Length of Hub

M

Radius
R

Number of Bolt Holes

NBH

Diameter of Bolt Holes

DBH

Bolt Circle Diameter

P

Approx Weight

(lb)AW

1/2

5 1/4

1 3/16

0.90

1 11/16

1 9/16

1/8

4

7/8

3 1/2

7

3/4

5 1/2

1 1/4

1.11

2

1 11/16

1/8

4

7/8

3 3/4

8

1

6 1/4

1 3/8

1.38

2 1/4

1 7/8

1/8

4

1

4 1/4

12

1 1/4

7 1/4

1 1/2

1.72

2 7/8

2 1/16

3/16

4

1 1/8

5 1/8

17

1 1/2

8

1 3/4

1.97

3 1/8

2 3/8

1/4

4

1 1/4

5 3/4

24

2

9 1/4

2

2.46

3 3/4

2 3/4

5/16

8

1 1/8

6 3/4

37

2 1/2

10 1/2

2 1/4

2.97

4 1/2

3 1/8

5/16

8

1 1/4

7 3/4

53

3

12

2 5/8

3.60

5 1/4

3 5/8

3/8

8

1 3/8

9

80

3 1/2

4

14

3

4.60

6 1/2

4 1/4

7/16

8

1 5/8

10 3/4

122

5

16 1/2

3 5/8

5.69

8

5 1/8

7/16

8

1 7/8

12 3/4

204

6

19

4 1/4

6.75

9 1/4

6

1/2

8

2 1/8

14 1/2

314

8

21 3/4

5

8.75

12

7

1/2

12

2 1/8

17 1/4

471

10

26 1/2

6 1/2

10.92

14 3/4

9

1/2

12

2 5/8

21 1/4

897

12

30

7 1/4

12.92

17 3/8

10

1/2

12

2 7/8

24 3/8

1262

DIMENSIONAL TOLERANCES OF LAP JOINT FLANGES ASME B16.5

20180118105733 82057 - ASME/ANSI B16.5 Lap Joint Flange Dimensions

Lap joint flange drawing

Dimensions are in millimeters unless otherwise indicated.

OUTSIDE DIAMETER

≤ 24 = 1.6 mm
> 24 = ± 3.2 mm

INSIDE DIAMETER

≤ 10 = ± 0.8 mm
≥ 12 = + 1.6 mm / – 0 mm

DIAMETER OF CONTACT FACE

1.6 mm Raised Face = ± 0.8 mm
6.35 mm Raised Face
Tongue & Groove / Male-Female = ± 0.4 mm

DRILLING

Bolt Circle = 1.6 mm
Bolt Hole Spacing = ± 0.8 mm
Eccentricity of Bolt Circle with Respect to Facing
≤ 2½ = 0.8 mm max.
≥ 3 = 1.6 mm max.

DIAMETER OF COUNTERBORE

Same as for Inside Diameter

OUTSIDE DIAMETER OF HUB

≤ 12 = + 2.4 mm / – 1.6 mm
≥ 14 = ± 3.2 mm

THICKNESS

≤ 18 = + 3.2 mm / – 0
≥ 20 = + 4.8 mm / – 0

LENGTH THRU HUB

≤ 18 = + 3.2 mm / – 0.8 mm
≥ 20 = + 4.8 mm / – 1.6 mm

LAP JOINT FLANGE’S DRAWS :

flg lj det - ASME/ANSI B16.5 Lap Joint Flange Dimensions

1. Lap Joint flange 2. Stub End 3. Butt weld 4. Pipe or Fitting

What Is the Lap Joint Flange with Welding Neck Collar?

Lap joint flanges can be mainly divided into four types: loose plate steel pipe flanges with weld-on collar, loose plate steel pipe flanges with welding neck collar, lap joint flanges with welding neck collar and lap joint flanges with welding neck collar.

The roles of lap joint flanges

Lap joint flanges mainly play the roles of connecting equipment or flanges such as the flanges on the water pumps or the valves. Lap joint flanges have the following two obvious features.

  • 1. Lap joint flanges are easy to be installed. For example, if the equipment has not arrived at the construction site, but the pipelines have already been arranged, the lap joint flanges can be used under this condition. When the equipment arrives, it is simple to install the lap joint flanges on the equipment because the lap joint flanges are flexible and movable, and the problem that the bolt can not fit the blot hole will never happen.
  • 2. It is convenient to change the material of the pipelines if the lap joint flanges are adopted, for example, changing the stainless steel pipes to the carbon steel pipes. When the stainless steel pipes have to be changed to the carbon steel pipes in engineering, in order to save the costs for the construction, the flanges can be made of stainless steel while the welding necks can be made of carbon steel, which will form a perfect transformation. Actually, such a case usually happens in engineering for the purpose of saving materials and money.

Loose plate flanges with welding neck collar

Loose plate flanges with welding neck collar consist of the slip-on flanges and the butt welding nozzles. The appearance of the butt welding nozzle almost the same as the welding neck flange’s, but the outer diameter of the butt welding nozzle is smaller than that of the welding neck flange. The butt welding nozzle does not have the bolt hole so as to make itself easily welded to the pipes and make the slip-on flanges flexible and movable. The slip-on flanges can always be connected with the pipes no matter what conditions the bolt hole are under.
The manufacturing standard of loose plate flanges with welding neck collar:

  • 1. GB/T9120-2010
  • 2. JB/T84-2015
  • 3. ISO 7005-1-2011
  • 4. BS 4504-3.1
  • 5. DIN EN 1092-1-2008

Advantages of Lap Joint Flanges:

Lap Joint flanges have certain special advantages over other flanges. These are as follows:

  • Lap Joint flanges have the freedom to swivel around the pipe. This facilitates the lining up of opposing flange bolt holes.
  • Lack of contact with the fluid inside the pipe leads to the greater durability of these flanges.
  • In piping systems which corrode or erode quickly, the lap joint flanges may be salvaged for re-use.
  • The pressure-holding capacity of lap joint flanges is little. But it is better than that of slip-on flanges.
  • The Lap Joint works as a backing ring on the stub.
  • The main advantage of lap joint flange is that the bolt holes can be aligned with the matching flange after the welds have been completed.
  • They allow rotational alignment capability.

When to use lap joint flange?

lap joint flange 2 - ASME/ANSI B16.5 Lap Joint Flange Dimensions

1. Because of the structure of a Lap joing flange,  it can swivel around the stub end and pipe lining.    When the piping system is assembe and disassemble frequently,  it is better to use a Lap joint flange. It means the flange can work even the two flanges bolt holes are misalignment.
2. In a corrosive situation, the flange joints need to be exchange very soon. To a lap joint flange, only the stub end is touch with the pipe and fluid, the backing flange no need to touch it .  It means you could only replace the stub end , no need to replace the backing flange, so the lap joint flange can decrease the cost of the piping systems.
3. The backing flange and the stub end is seperated, so we can use two different materials for the two pieces. It can work for more complicated application. 

Lap Joint Flange Uses

Economy

Because a lap joint flange has a two piece configuration, it offers a way to cut cost when piping systems requires a high cost alloy for all “wetted” parts to reduce corrosion. In this situation, it is only required for the stub-end to be can be made of the higher cost corrosion-resistant material, where the flange itself can be the produced from lower cost steel.

Ease of Work

By using lap joint flanges, work can be simplified in situations that require frequent and rapid disassemble and assembly during the operation of a plant. The ability to spin that backing flange compensates for misalignment of the bolt holes during assembly.

Physical Features

Flange

  • 1.  The backside, has a slight shoulder that is square cut at the center or pipe hole
  • 2.  The front side has a flat face with a filleted (rounded) center hole to match the filleted back face of the stub end. Here the stub end will wrap tightly around the center hole of the flange.

20171223103021 14795 - ASME/ANSI B16.5 Lap Joint Flange Dimensions

Stub End

  • 1.  Shaped like a short piece of pipe with a weld bevel on one. This portion of the stub end is also called the sleeve.
  • 2.  Narrow shoulder on the flange facing end called is the hub. The back face of the hub has a rounded transition (or inside fillet) that joins the hub to the sleeve.

20171223103056 30510 - ASME/ANSI B16.5 Lap Joint Flange Dimensions

Buying tips

Certain factors to consider are as follows:

  • Size
  • Design Standard
  • Material
  • Normal Pressure
  • Face Type
  • Durability
  • Corrosion Resistant

From: youtube.com

Summary
asme ansi b16 5 lap joint flange dimensions - ASME/ANSI B16.5 Lap Joint Flange Dimensions
Article Name
ASME/ANSI B16.5 Lap Joint Flange Dimensions
Description
Dimensions to ASME B16.5 - Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard.
Author
Publisher Name
www.steeljrv.com
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