Lap Joint Flange VS Weld Neck Flange

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.

Dimensions Of Lap Joint Flanges Asme/ansi B16.5 What Is A Weld Neck Flange
Dimensions Weld Neck Flanges Asme/ansi B16.5 Materials
Specifications Lap Joint Flange Vs Weld Neck Flange

LAP JOINT FLANGE’S DRAWS:

flg lj det - Lap Joint Flange VS Weld Neck Flange

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

The other piece of a Lap Joint Flange is the backing flange. This flange has all the same common dimensions (O.D., bolt circle, bolt hole size, etc.) as any other flange however it does not have a raised face. One side, the backside, has a slight shoulder that is square cut at the center or pipe hole. The front side has flat face and at the center hole an outside fillet to match the fillet of the “Stub-end” piece. The flange part of the Lap-joint flange assembly is slipped on to the stub-end prior to the sleeve being welded to the adjoining pipe or fitting. The flange itself is not welded or fixed in any way. It is free to spin for proper alignment with what ever it is joining to.
The “Stub-end” can normally be purchased in two lengths. There is a short version, about 3″ long and a long version of about 6″ long. It is prudent for the piping designer to know which version is in the piping specification.
Because of it’s two piece configuration, the Lap Joint Flange offers a way to cut cost or simplify work. The cost saving comes when the piping system requires a high cost alloy for all “wetted” parts to reduce corrosion. The sleeve or Stub-end can be the required higher cost alloy but the flange can be the lower cost forged carbon steel.
The lap joint flange can be rotated which can be useful when fixing issues with bolt hole alignment. When designing a piping system, lap joint flanges should not be considered solely to alleviate poor alignment during construction. Good design practice should not need to include poor construction quality. However, if the piping needs to be frequently dismantled for inspection or cleaning, consideration should be made for lap joint flanges. They give the ability to swivel flanges and to align bolt holes which simplifies the assembly of large diameter or unusually stiff piping.
Lap joint flanges are usually used in low pressure applications and are not suitable when there are high loads on the flange pair. Some types of piping require the use of lap joint flanges. For example, metallic pipe that has been plastic lining may have lap joint flanges.
Using lap joint flanges might be an option for saving costs when the piping is made of exotic materials. By using a lap joint flange, the wetted materials would consist of the exotic materials and the flange would be carbon steel. Since the flange doesn’t ever come in contact with the process fluid, it would not be affected by the fluids.

Lap joint flanges are usually used in low pressure applications and are not suitable when there are high loads on the flange pair. Some types of piping require the use of lap joint flanges. For example, metallic pipe that has been plastic lining may have lap joint flanges.

Using lap joint flanges might be an option for saving costs when the piping is made of exotic materials. By using a lap joint flange, the wetted materials would consist of the exotic materials and the flange would be carbon steel. Since the flange doesn’t ever come in contact with the process fluid, it would not be affected by the fluids.

Dimensions on the lap joint flange are similar to weld neckslip on or socket weld flanges. The backing flange has the same number of bolt holes, size and thickness of a weld neck or slip on flange.

STANDARDS, DIMENSIONS & WEIGHT OF LAP JOINT FLANGES

lap joint flange with stub end banner - Lap Joint Flange VS Weld Neck Flange

  • ASME/ANSI B16.5 Class 150 Lap Joint Flanges
    Nominal Pipe Size  Outside Diameter of Flange Thickness of Lap Joint Min. Diameter of Hub Length Through Hub Bore Corner Radius of Bore of Lapped Flange Diameter of Bolt Circle Diameter of Bolt Holes Number of Bolts Approxi-mate Weight kgs
    NPS O tf X Y B r W I n
    1/2 90 11.2 30 16 22.9 3 60.3 15.9 4 0.46
    3/4 100 12.7 38 16 28.2 3 69.9 15.9 4 0.66
    1 110 14.3 49 17 34.9 3 79.4 15.9 4 0.89
    1 1/4 115 15.9 59 21 43.7 5 88.9 15.9 4 1.06
    1 1/2 125 17.5 65 22 50.0 6 98.4 15.9 4 1.36
    2 150 19.1 78 25 62.5 8 120.7 19.1 4 2.10
    2 1/2 180 22.3 90 29 75.4 8 139.7 19.1 4 3.58
    3 190 23.9 108 30 91.4 10 152.4 19.1 4 4.00
    3 1/2 215 23.9 122 32 104.1 10 177.8 19.1 8 4.99
    4 230 23.9 135 33 116.8 11 190.5 19.1 8 5.62
    5 255 23.9 164 36 144.4 11 215.9 22.2 8 6.38
    6 280 25.4 192 40 171.4 13 241.3 22.2 8 7.74
    8 345 28.6 246 44 222.2 13 298.5 22.2 8 12.65
    10 405 30.2 305 49 277.4 13 362.0 25.4 12 16.65
    12 485 31.8 365 56 328.2 13 431.8 25.4 12 27.31
    14 535 35.0 400 79 360.2 13 476.3 28.6 12 39.89
    16 595 36.6 457 87 411.2 13 539.8 28.6 16 51.18
    18 635 39.7 505 97 462.3 13 577.9 31.8 16 57.07
    20 700 42.9 559 103 514.4 13 635.0 31.8 20 72.08
    24 815 47.7 663 111 616.0 13 749.3 34.9 20 100.11

  • ASME/ANSI B16.5 Class 300 Lap Joint Flanges
    Nominal Pipe Size  Outside Diameter of Flange Thickness of Lap Joint Min. Diameter of Hub Length Through Hub Bore Corner Radius of Bore of Lapped Flange Diameter of Bolt Circle Diameter of Bolt Holes Number of Bolts Approxi-mate Weight kgs
    NPS O tf X Y B r W I n
    1/2 95 14.3 38 22 22.9 3 66.7 15.9 4 0.70
    3/4 115 15.9 48 25 28.2 3 82.6 19.1 4 1.16
    1 125 17.5 54 27 34.9 3 88.9 19.1 4 1.50
    1 1/4 135 19.1 64 27 43.7 5 98.4 19.1 4 1.86
    1 1/2 155 20.7 70 30 50.0 6 114.3 22.2 4 2.63
    2 165 22.3 84 33 62.5 8 127.0 19.1 8 3.02
    2 1/2 190 25.4 100 38 75.4 8 149.2 22.2 8 4.48
    3 210 28.6 117 43 91.4 10 168.3 22.2 8 6.08
    3 1/2 230 30.2 133 44 104.1 10 184.2 22.2 8 7.68
    4 255 31.8 146 48 116.8 11 200.0 22.2 8 10.07
    5 280 35.0 178 51 144.4 11 235.0 22.2 8 12.64
    6 320 36.6 206 52 171.4 13 269.9 22.2 12 16.39
    8 380 41.3 260 62 222.2 13 330.2 25.4 12 24.57
    10 445 47.7 321 95 277.4 13 387.4 28.6 16 39.40
    12 520 50.8 375 102 328.2 13 450.8 31.8 16 56.33
    14 585 54.0 425 111 360.2 13 514.4 31.8 20 81.97
    16 650 57.2 483 121 411.2 13 571.5 34.9 20 106.10
    18 710 60.4 533 130 462.3 13 628.6 34.9 24 127.52
    20 775 63.5 587 140 514.4 13 685.8 34.9 24 157.92
    24 915 69.9 702 152 616.0 13 812.8 41.3 24 237.21

  • ASME/ANSI B16.5 Class 600 Lap Joint Flanges
    Nominal Pipe Size  Outside Diameter of Flange Thickness of Lap Joint Min. Diameter of Hub Length Through Hub Bore Corner Radius of Bore of Lapped Flange Diameter of Bolt Circle Diameter of Bolt Holes Number of Bolts Approxi-mate Weight kgs
    NPS O tf X Y B r W I n
    1/2 95 14.3 38 22 22.9 3 66.7 15.9 4 0.70
    3/4 115 15.9 48 25 28.2 3 82.6 19.1 4 1.16
    1 125 17.5 54 27 34.9 3 88.9 19.1 4 1.50
    1 1/4 135 20.7 64 29 43.7 5 98.4 19.1 4 2.01
    1 1/2 155 22.3 70 32 50.0 6 114.3 22.2 4 2.83
    2 165 25.4 84 37 62.5 8 127.0 19.1 8 3.42
    2 1/2 190 28.6 100 41 75.4 8 149.2 22.2 8 5.00
    3 210 31.8 117 46 91.4 10 168.3 22.2 8 6.71
    3 1/2 230 35.0 133 49 104.1 10 184.2 25.4 8 8.56
    4 275 38.1 152 54 116.8 11 215.9 25.4 8 14.29
    5 330 44.5 189 60 144.4 11 266.7 28.6 8 23.80
    6 355 47.7 222 67 171.4 13 292.1 28.6 12 27.93
    8 420 55.6 273 76 222.2 13 349.2 31.8 12 42.59
    10 510 63.5 343 111 277.4 13 431.8 34.9 16 76.04
    12 560 66.7 400 117 328.2 13 489.0 34.9 20 90.92
    14 605 69.9 432 127 360.2 13 527.0 38.1 20 109.42
    16 685 76.2 495 140 411.2 13 603.2 41.3 20 154.99
    18 745 82.6 546 152 462.3 13 654.0 44.5 20 189.94
    20 815 88.9 610 165 514.4 13 723.9 44.5 24 243.66
    24 940 101.6 718 184 616.0 13 838.2 50.8 24 346.39

  • ASME/ANSI B16.5 Class 900 Lap Joint Flanges
    Nominal Pipe Size  Outside Diameter of Flange Thickness of Lap Joint Min. Diameter of Hub Length Through Hub Bore Corner Radius of Bore of Lapped Flange Diameter of Bolt Circle Diameter of Bolt Holes Number of Bolts Approxi-mate Weight kgs
    NPS O tf X Y B r W I n
    1/2 120 22.3 38 32 22.9 3 82.6 22.2 4 1.69
    3/4 130 25.4 44 35 28.2 3 88.9 22.2 4 2.28
    1 150 28.6 52 41 34.9 3 101.6 25.4 4 3.41
    1 1/4 160 28.6 64 41 43.7 5 111.1 25.4 4 3.89
    1 1/2 180 31.8 70 44 50.0 6 123.8 28.6 4 5.41
    2 215 38.1 105 57 62.5 8 165.1 25.4 8 9.57
    2 1/2 245 41.3 124 64 75.4 8 190.5 28.6 8 13.54
    3 240 38.1 127 54 91.4 10 190.5 25.4 8 11.13
    4 290 44.5 159 70 116.8 11 235.0 31.8 8 18.96
    5 350 50.8 190 79 144.4 11 279.4 34.9 8 31.45
    6 380 55.6 235 86 171.4 13 317.5 31.8 12 40.16
    8 470 63.5 298 114 222.2 13 393.7 38.1 12 72.66
    10 545 69.9 368 127 277.4 13 469.9 38.1 16 105.50
    12 610 79.4 419 143 328.2 13 533.4 38.1 20 141.92
    14 640 85.8 451 156 360.2 13 558.8 41.3 20 162.02
    16 705 88.9 508 165 411.2 13 616.0 44.5 20 199.98
    18 785 101.6 565 190 462.3 13 685.8 50.8 20 277.51
    20 855 108.0 622 210 514.4 13 749.3 54.0 20 348.93
    24 1040 139.7 749 267 616.0 13 901.7 66.7 20 671.17

  • ASME/ANSI B16.5 Class 1500 Lap Joint Flanges
    Nominal Pipe Size  Outside Diameter of Flange Thickness of Lap Joint Min. Diameter of Hub Length Through Hub Bore Corner Radius of Bore of Lapped Flange Diameter of Bolt Circle Diameter of Bolt Holes Number of Bolts Approxi-mate Weight kgs
    NPS O tf X Y B r W I n
    1/2 120 22.3 38 32 22.9 3 82.6 22.2 4 1.69
    3/4 130 25.4 44 35 28.2 3 88.9 22.2 4 2.28
    1 150 28.6 52 41 34.9 3 101.6 25.4 4 3.41
    1 1/4 160 28.6 64 41 43.7 5 111.1 25.4 4 3.89
    1 1/2 180 31.8 70 44 50.0 6 123.8 28.6 4 5.41
    2 215 38.1 105 57 62.5 8 165.1 25.4 8 9.57
    2 1/2 245 41.3 124 64 75.4 8 190.5 28.6 8 13.54
    3 265 47.7 133 73 91.4 10 203.2 31.8 8 17.29
    4 310 54.0 162 90 116.8 11 241.3 34.9 8 27.02
    5 375 73.1 197 105 144.4 11 292.1 41.3 8 51.41
    6 395 82.6 229 119 171.4 13 317.5 38.1 12 60.85
    8 485 92.1 292 143 222.2 13 393.7 44.5 12 103.41
    10 585 108.0 368 178 277.4 13 482.6 50.8 12 181.39
    12 675 123.9 451 219 328.2 13 571.5 54.0 16 286.48
    14 750 133.4 495 241 360.2 13 635.0 60.3 16 384.80
    16 825 146.1 552 260 411.2 13 704.8 66.7 16 492.31
    18 915 162.0 597 276 462.3 13 774.7 73.0 16 638.30
    20 985 177.8 641 292 514.4 13 831.8 79.4 16 766.56
    24 1170 203.2 762 330 616.0 13 990.6 92.1 16 1227.85

  • ASME/ANSI B16.5 Class 2500 Lap Joint Flanges
    Nominal Pipe Size  Outside Diameter of Flange Thickness of Lap Joint Min. Diameter of Hub Length Through Hub Bore Corner Radius of Bore of Lapped Flange Diameter of Bolt Circle Diameter of Bolt Holes Number of Bolts Approxi-mate Weight kgs
    NPS O tf X Y B r W I n
    1/2 135 30.2 43 40 22.9 3 88.9 22.2 4 3.01
    3/4 140 31.8 51 43 28.2 3 95.2 22.2 4 3.43
    1 160 35.0 57 48 34.9 3 108.0 25.4 4 4.87
    1 1/4 185 38.1 73 52 43.7 5 130.2 28.6 4 7.12
    1 1/2 205 44.5 79 60 50.0 6 146.0 31.8 4 10.10
    2 235 50.9 95 70 62.5 8 171.4 28.6 8 14.67
    2 1/2 265 57.2 114 79 75.4 8 196.8 31.8 8 20.91
    3 305 66.7 133 92 91.4 10 228.6 34.9 8 32.29
    4 355 76.2 165 108 116.8 11 273.0 41.3 8 49.09
    5 420 92.1 203 130 144.4 11 323.8 47.6 8 82.84
    6 485 108.0 235 152 171.4 13 368.3 54.0 8 128.65
    8 550 127.0 305 178 222.2 13 438.2 54.0 12 184.69
    10 675 165.1 375 229 277.4 13 539.8 66.7 12 356.50
    12 760 184.2 441 254 328.2 13 619.1 73.0 12 498.67

Dimensional Tolerances of Lap Joint Flanges ASME B16.5

20180118105733 82057 - Lap Joint Flange VS Weld Neck Flange

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

What is a weld neck flange?

weld neck flange (also known as a high-hub flange, WN flange, welding neck flange and tapered hub flange) is a type of flange. There are two designs. The regular type is used with pipes. The long type is unsuitable for pipes and is used in process plant. A weld neck flange consists of a circular fitting with a protruding rim around the circumference. Generally machined from a forging, these flanges are typically butt welded to a pipe. The rim has a series of drilled holes that permit the flange to be affixed to another flange with bolts.
Such flanges are suitable for use in hostile environments that have extremes of temperature, pressure or other sources of stress. The resilience of this type of flange is achieved by sharing the environmental stress with the pipe with which it is welded. This type of flange has been used successfully at pressures up to 5,000 psi.

A weld neck flange is a type of steel flange designed to transfer stresses to the pipe to reduce high stress concentrations at the base of the flange. Compared with other types,weld neck flanges are know for their tapered hub and gentle transition from flange thickness to pipe wall thickness. They are deformation-resistant, and are normally used for high pressure piping system, high or low temperature conditions.
A weld neck flange (WN flange) means a flange has a neck for weld with the pipe, it is easily to recognized by their long tapered neck on the flange (The neck is also called hub in the weld neck flange). The tapered neck can supply a high strength reinforcement to support flange and pipe. It means the weld neck flange is suitable to used in high pressure and extremely temperature situation. 

welding neck flanges banner 3 - Lap Joint Flange VS Weld Neck Flange

The Welding neck flanges is normally referred to as the high hub flange. It is designed to transfer stresses to the pipe, thereby reducing high stress concentrations at the base of the flange.

Dimensions Weld Neck Flanges & Stud Bolts ASME B16.5

20180201105758 91939 - Lap Joint Flange VS Weld Neck Flange
NPS 1/2 – O.D. 21.3
CL 150 300 600 900 1500 2500
DIA
A
30 38 38 38 38 43
DIA
D
90 95 95 120 120 135
THK
B
9.6 12.7 14.3 22.3 22.3 30.2
11.2 14.3 20.7 28.7 28.7 36.6
DIA
G
35.1 35.1 35.1 35.1 35.1 35.1
DIA
K
60.3 66.7 66.7 82.6 82.6 88.9
H 46 51 52 60 60 73
47.6 52.6 58.4 66.4 66.4 79.4
NO.
L
4 4 4 4 4 4
DIA
L
15.9 15.9 15.9 22.2 22.2 22.2
Stud Bolts Diameter x Length
DIA
(IN)
1/2 1/2 1/2 3/4 3/4 3/4
Len
mm
55 65 75 110 110 120
Other Diameters
NPS 3/4 1 2
3 4 5 6 8 10
12 14 16 18 20 24  
 

Notes:

  • Dimensions are in millimeters unless otherwise indicated.
  • The length of the Stud Bolt does not include the height of the chamfers (points).
  • ID = Depending on the wall thickness of the pipe, must be specified by the purchaser.
20180201105715 99275 - Lap Joint Flange VS Weld Neck Flange

Dimensional Tolerances of Weld Neck Flanges ASME B16.5

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

Materials

  • Carbon steels: ASTM A105, A350 LF2, BS1503-221,224 and LT50.
  • Low temperature: A350 LF3, BS1503-503.
  • Alloy materials: A182-F5, F9, F11, F22, BS1503-625,629,621,620,622, 13Cr Mo44
  • and 15Mo3.
  • High yield materials (offshore):A694-F46, F50, F52, F60, F65.
  • Stainless seteels: A182-F304, F304H, F304L, F316, F316H, F316L, F321, F321H, F310, F347, F6NM and equivalent BS1503 Grades.
  • Duplex: ASTM A182 F51 and UNS 31803.
  • Super stainless: UNS32750, 327670, 31254, ASTM A182 F44.
  • Exotic alloys: Monel 400, lncoloy 800/H/HT, lncoloy 600/625, Hastelloy, Titanium and Cupro-nickel 90/10.70/30.API type 2/4-45/60k.

Specifications

  • Standard rating : 150LB,300LB,400LB,600LB,1500LB and 2500LB.
  • Size: 1/4NB to 72″NB and 6MM to1800MM NB
  • Facing: RF / RTJ

Lap Joint Flange VS Weld Neck Flange

Advantages of Weld Neck Flanges:

  • The weld neck flange is suitable to used for high pressure, high temperature, low temperature situation because of the butt welding connection method.
  • The weld neck flange has a good excellent stress distribution by its tapered neck .
  • The butt welding joint can be inspected easily ,for example the radiography testing. 

Disadvantages of weld neck flanges:

  • The weld neck flange is bulky, heavy, expensive, and difficult to install and position, making it easier to bump during transportation.
  • The weld neck flange is widely used, and the scope of use is determined according to different characteristics. It is mostly used in the case where the medium condition is moderate, such as low pressure non-purified compressed air and low pressure circulating water, and its advantage is that the price is relatively cheap. Applicable to the steel pipe connection with the nominal pressure not exceeding 2.5MPa, the sealing surface of the butt welding flange can be made into smooth, concave and convex and grooved. The smooth welding butt flange has the largest application, the other two ways The butt weld flange is also common in use.
  • The welding flange can withstand high temperature and high pressure, repeated bending and temperature fluctuation, and the sealing performance is reliable. The butt welding flange with the nominal pressure of 0.25-2.5 MPa adopts the concave-convex sealing surface. The main application environment is appropriate.

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.
  • 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.
  • 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.
  • 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. 

Disadvantages of lap Joint flanges:

  • Understand low pressure.
  • The strength of the weld ring is low (especially when the thickness is less than 3mm).
  • Loose flanges are mainly used in medium and low pressure applications. The precision requirements (dimensional accuracy, tolerance requirements, roughness requirements, flatness requirements) during manufacturing are not high, so the sealing requirements are not high.

The price of the weld neck flange is higher than the lap joint flange.
lap joint flanges are more convenient to use than weld neck flanges.

Source: China Flange Manufacturer – Yaang Pipe Industry (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:

  • What are Lap Joint Flanges

  • When to use lap joint flange
  • How to get high quality Welding Neck Flanges

  • How to get high quality lap joint flanges

  • What are Steel Flanges

References:

  • https://www.yaang.com

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