Stainless Lap Joint Flange

S&S Stainless International, a trusted stainless steel flange manufacturer, offers high-quality stainless steel lap joint flanges in compliance with ASME B16.47 standards. Designed for use with a stub end fitting, these stainless steel flanges are not directly welded or fixed to the pipe but slip over the stub end. Their ability to rotate freely simplifies alignment during installation. Ideal for piping systems that require frequent dismantling, lap joint flanges are perfect for applications involving regular inspection, cleaning, or maintenance.

What is A Lap Joint Flange?

A stainless steel lap joint flange, compliant with ASME B16.5 standard, is a versatile and efficient choice for systems requiring frequent disassembly or where alignment ease is important. While not as strong as other stainless steel flange types, the flexibility, reusability, and cost-effectiveness of stainless steel lap-joint flanges make it ideal for many industrial applications, especially where maintenance and inspection are regular requirements.

Product Overview of Stainless Steel Lap Joint Flange

  • Design of Lap Joint Flange
    • The stainless steel lap joint flange is designed to pair with a stub end.
    • Available Sealing Surface: Raised Face(RF), and Flat Face(FF).
  •  Material of Lap Joint Flange
    • Constructed from premium ASTM A182 stainless steel grades like 304, and 316, stainless steel lap joint flange resists corrosion, rust, oxidation, and chemical damage, ensuring long-term durability.
  • Pressure Ratings of Lap Joint Flange
    • Stainless steel lap joint flanges are available in various pressure classes, including 150, 300, and 600, as per the ASME B16.5 standard.
  • Welding of Lap Joint Flange
    • The stainless steel lap joint flange slides over the pipe and rests on the stub end, allowing the flange to rotate freely. This makes bolt-hole alignment easier during installation.
  • Compatibility of Lap Joint Flange
    • Compatible with a wide range of gaskets and bolts, they create a dependable seal for flanges, valves, or equipment in various applications.

Stainless Steel Lap Joint Flange Dimensions

ASME B16.5

ASME B16.5 stainless steel blind flange dimension chart, covering pressure classes from 150 to 600.

Nominal Diameter Pipe Diameter O.D.of Flange Diameter of Raised Face Diameter of Bolt Holes Circle Diameter of Bolt Holes Numbers of Bolt Holes Diameter of Bolt Holes(inch) Flange Thickness Hub Diameter Through Hub Length (H)
DN NPS ID D G, R K L B1-B4 A H1 H2 H3
15 ½’’ 21.3 90 35 60.5 16 4 M14 11.5 30 48 16 16
20 ¾’’ 26.9 100 43 70 16 4 M14 13 38 52 16 16
25 1’’ 33.7 110 51 79.5 16 4 M14 14.5 49 56 17 17
32 1 ¼’’ 42.4 120 63.5 89 16 4 M14 16 59 57 21 21
40 1 ½’’ 48.3 130 73 98.5 16 4 M14 17.5 65 62 22 22
50 2’’ 60.3 150 92 120.5 18 4 M16 19.5 78 64 25 25
65 2 ½’’ 76.1 180 105 139.5 18 4 M16 22.5 90 70 29 29
80 3’’ 88.9 190 127 152.5 18 4 M16 24 108 70 30 30
90 3 ½’’ 101.6 216 140 178 18 8 M20 24 122 71 - 32
100 4’’ 114.3 230 157.5 190.5 18 8 M20 24 135 76 33 33
125 5’’ 139.7 255 186 216 22 8 M20 24 164 89 36 36
150 6’’ 168.3 280 216 241.5 22 8 M20 25.5 192 89 40 40
200 8’’ 219.1 345 270 298.5 22 8 M20 29 246 102 44 45
250 10'’ 273 405 324 362 26 12 M24 30.5 305 102 49 49
300 12'’ 323.9 485 381 432 26 12 M24 32 365 114 56 56
350 14'’ 355.6 535 413 476 29.5 12 M27 35 400 127 57 79
400 16'’ 406.4 600 470 540 29.5 16 M27 37 457 127 64 87
450 18'’ 457 635 533.5 578 32.5 16 M30 40 505 140 68 97
500 20'’ 508 700 584 635 32.5 20 M30 43 559 145 73 103
550 22'’ 559 750 641 692 35.5 20 M33 46 610 149 - -
600 24'’ 610 816 692 749.5 35.5 20 M33 48 664 152 83 111
Nominal Diameter Pipe Diameter O.D. of Flange Diameter ofRaised Face Diameter of Bolt Holes Circle Diameter ofBolt Holes Numbers ofBoltHoles Diameter of Bolt Holes(inch) Flange Thickness Hub Diameter Through Hub Length
DN NPS ID D G, R K L B1-B4 A H1 H2 H3
15 ½’’ 21.3 95 35 66.5 16 4 M14 14.5 38 52 22 22
20 ¾’’ 26.9 120 43 82.5 18 4 M16 16 48 57 25 25
25 1’’ 33.7 125 51 89 18 4 M16 17.5 54 62 27 27
32 1 ¼’’ 42.4 135 63.5 98.5 18 4 M16 19.5 64 65 27 27
40 1 ½’’ 48.3 155 73 114.5 22 4 M20 21 70 68 30 30
50 2’’ 60.3 165 92 127 18 8 M16 22.5 84 70 33 33
65 2 ½’’ 76.1 190 105 149 22 8 M20 25.5 100 76 38 38
80 3’’ 88.9 210 127 168.5 22 8 M20 29 118 79 43 43
90 3 ½’’ 101.6 229 140 184 22 8 M20 30 140 81 45 45
100 4’’ 114.3 255 157.5 200 22 8 M20 32 146 86 48 48
125 5’’ 139.7 280 186 235 22 8 M20 35 178 98 51 51
150 6’’ 168.3 320 216 270 22 12 M20 37 206 98 52 52
200 8’’ 219.1 380 270 330 26 12 M24 41.5 260 111 62 62
250 10'’ 273 445 324 387.5 29.5 16 M27 48 321 117 67 95
300 12'’ 323.9 520 381 451 32.5 16 M30 51 275 130 73 102
350 14'’ 355.6 585 413 514.5 32.5 20 M30 54 426 143 76 111
400 16'’ 406.4 650 470 571.5 32.5 20 M33 57.5 483 146 83 121
450 18'’ 457 710 533.5 628.5 32.5 24 M33 60.5 533 159 89 130
500 20'’ 508 775 584 686 32.5 24 M33 63.5 587 162 95 140
550 22'’ 559 840 641 743 42 24 M39 66.5 640 165 - -
600 24'’ 610 915 692 813 42 24 M39 70 702 168 104 152
Nominal Diameter Pipe Diameter O.D. of Flange Diameter of Raised Face Diameter of Bolt Holes Circle Diameter of Bolt Holes Numbers of Bolt Holes Diameter of Bolt Holes(inch) Flange Thickness Hub Diameter Through Hub Length
DN NPS ID D G, R K L B1-B4 A H1 H2 H3
15 ½’’ 21.3 95 35 66.5 16 4 M14 14.5 38 52 22 22
20 ¾’’ 26.9 120 43 82.5 18 4 M16 16 48 57 25 25
25 1’’ 33.7 125 51 89 18 4 M16 17.5 54 62 27 27
32 1 ¼’’ 42.4 135 63.5 98.5 18 4 M16 21 64 67 29 29
40 1 ½’’ 48.3 155 73 114.5 22 4 M20 22.5 70 70 32 32
50 2’’ 60.3 165 92 127 18 8 M16 22.5 84 73 37 37
65 2 ½’’ 76.1 190 105 149 22 8 M20 29 100 79 41 41
80 3’’ 88.9 210 127 168.5 22 8 M20 32 117 83 46 46
90 3 ½’’ 101.6 229 140 184 26 8 M24 35 133 86 49 49
100 4’’ 114.3 275 157.5 216 26 8 M24 38.5 152 102 54 54
125 5’’ 139.7 330 186 267 29.5 8 M27 44.5 189 114 60 60
150 6’’ 168.3 355 216 292 29.5 12 M27 48 222 117 67 67
200 8’’ 219.1 420 270 349 32.5 12 M30 55.5 273 133 76 76
250 10'’ 273 510 324 432 35.5 16 M33 63.5 343 152 86 111
300 12'’ 323.9 560 381 489 35.5 20 M33 67 400 156 92 117
350 14'’ 355.6 605 413 527 39 20 M36 70 432 165 94 127
400 16'’ 406.4 685 470 603 42 20 M39 76.5 495 178 106 140
450 18'’ 457 745 533.5 654 45 20 M42 83 546 184 117 152
500 20'’ 508 815 584 724 45 24 M42 89 610 190 127 165
550 22'’ 559 870 641 778 48 24 M45 95 665 197 - -
600 24'’ 610 940 692 838 51 24 M48 102 718 203 140 184

Navigating Our Lap Joint Flange Dimension Table

The lap joint flange dimension tables provide detailed measurements for selecting the correct stainless steel lap joint flange. You will find dimensions for:

  • Nominal Pipe Size (NPS): The standard pipe size for which the flange is designed.
  • Outside Diameter (OD) of Flanges: The total diameter of the flange itself.
  • Raised Face (RF) Height: The height of the raised portion of the flange sealing surface (if applicable).
  • Bolt Circle Diameter (BCD): The diameter on which the centers of the bolt holes lie.
  • Number of Bolts & Bolt Hole Diameter: Specifies the quantity and size of bolts required for connection.
  • Flange Thickness (T): The overall thickness of the flange.
  • Hub Diameter: The diameter of the cylindrical or tapered projection from the flange.
  • Through Hub Length: The length of the hub from the flange face to its end, indicating how far the pipe will extend into the flange.

Carefully match these dimensions to your project’s requirements to ensure a secure and leak-proof connection.

Custom Stainless Steel Flange by S&S Stainless International

S&S Stainless International specializes in precision-engineered custom stainless steel flanges tailored strictly to customer-provided technical drawings and unique operational specifications. Designed to solve complex cross-standard alignment challenges, our advanced forging and machining capabilities allow us to seamlessly combine ASME/ANSI, JIS, and EN 1092-1 standards—such as blending ASME bolt circles with EN sealing faces or JIS pressure dimensions—to deliver a 100% exact match for hybrid or legacy pipeline systems.

FAQs

1. How does a lap joint flange work in a piping assembly, and how does it save costs compared to integral flanges?

A lap joint flange is a loose backing ring that slips directly over the pipe and sits behind a Type A stub end. Because the flange never comes into direct contact with the internal line fluid, buyers can pair a stainless steel stub end with a lower-cost carbon steel or galvanized lap joint flange in non-corrosive external environments, significantly reducing material expenditures on large-diameter projects.

To ensure seamless alignment, our quality control team verifies that the inside radius at the rear bore of the lap joint flange strictly matches the outer fillet radius of the Type A stub end. This exact radius machining allows the flange to seat completely flush against the stub end lap, eliminating mechanical binding and ensuring uniform bolt torque distribution across the joint face.

We manufacture forged stainless steel lap joint flanges in pressure ratings from Class 150 to Class 2500 per ASME B16.5, as well as PN6 to PN40 per EN 1092-1 Loose Flange standards (Type 02 / Type 04). Available in dual-certified ASTM A182 F304/304L and F316/316L, all flanges are solution annealed and supplied with EN 10204 3.1 Material Test Reports (MTRs) with 100% PMI testing.

Because the flange rotates 360 degrees around the pipe prior to bolting, installation crews can quickly align bolt holes with mating equipment without needing to twist the pipe itself. This free-spinning design accelerates boltup, minimizes labor hours, and makes lap joint flanges ideal for piping networks that undergo regular disassembly for cleaning, inspection, or maintenance.

All flange bores and raised faces are coated with rust-inhibiting oil and protected with plastic face caps. Flanges are stacked with protective cardboard dividers inside seaworthy wooden cases lined with plastic moisture barriers. For large-diameter bulk shipments, items are securely steel-strapped onto heavy-duty wooden skids with corner protectors to prevent surface scratches and movement during transit.

Ready to plan your order?

Request a quote for stainless steel lap joint flanges with your size, grade, and quantity.

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