ANSI B16.5 Class #300 Neck Flange
TECHNICAL DESCRIPTION
Neck (skirt) flanges according to the ANSI B16.5 / Class #300 standard are pipeline elements that are widely used in the construction of steel pipelines and pipe segments (spools) used in industry, industry, shipbuilding and ship repair.
They are easily distinguished from flat flanges by the long conical neck, which gradually transitions to a pipe or other fitting connected by butt welding. The conical neck provides a smooth transition to the diameter of the pipe, which reduces internal stresses in the material. The latter makes them very suitable for applications with elevated or lowered temperatures, as well as those with sharp mechanical or thermal fluctuations.
The inner diameter is shaped to match the diameter of the pipe, which reduces fluid resistance, as well as corrosion and wear from friction of the passing fluid.
We stock ANSI B16.5 / class #150 and #300 steel flanges, but can supply flanges up to class #2500, in a variety of materials. We have the necessary machining equipment, which allows us to also offer flanges with sealing surfaces.
• sealing surface type A, B2, C, D, E, F
• non-standard sealing surfaces on request
• profile grooves for metal sealing rings (segments) type RTJ
• threaded type flanges
• flanges made to customer specifications, and others.
SUPPORTED MATERIALS IN STOCK:
• Carbon steel ASTM A105 WCB
Dimensions: 1/2″ – 24″
The ANSI B16.5 Class 300 Neck Flange is a high-performance industrial pipe fitting designed for robust and leak-proof connections in high-pressure systems. Manufactured to meet stringent ANSI/ASME B16.5 standards, this neck flange ensures superior durability, corrosion resistance, and compatibility with a wide range of piping materials and fluids. It is ideal for applications in oil and gas, chemical processing, power generation, and water treatment industries where reliability under extreme conditions is critical.Key features of this Class 300 neck flange include its forged construction for enhanced strength, a raised face for improved gasket sealing, and precise machining to guarantee perfect alignment during installation. The neck design provides excellent stress distribution, reducing the risk of fatigue and failure in dynamic operating environments. Available in various materials such as carbon steel, stainless steel, and alloy steel, it supports custom specifications to meet project-specific requirements.Complies with ANSI B16.5 standards for dimensional accuracy and performanceRated for Class 300 pressure, suitable for up to 720 PSI at 100°FForged from high-grade materials for exceptional mechanical propertiesRaised face surface finish ensures optimal gasket compression and sealingCompatible with ASME B16.5 bolting and gasket specificationsThis flange is engineered for easy installation and maintenance, reducing downtime and operational costs. Whether used in new installations or retrofitting existing systems, it delivers long-term performance and safety. Trusted by engineers and procurement specialists worldwide, it is a cornerstone component for critical infrastructure and industrial processes.
Materials
| No. | DETAILS | MATERIALS | STANDARD |
|---|---|---|---|
| 1 | FLANGE NECK (SKIRT) ANSI B16.5 / #150 | steel A105 WCB (1.0432) | ASTM A 695-95 |
| other steels - on request | |||
| ASTM A105N; C22.8 (1.0460) | ASTM | ||
| ASTM/ASME A182 F1-F12-F11 | ASTM A 182-02 | ||
| other stainless steels - on request | |||
| Stainless Steel - ASTM A182 F304 - 304L | ASTM | ||
| Stainless steel - AISI A182 F316 - F316L | ASTM | ||
| Low temperature grades/alloys - ASTM A352 LF2 | ASTM | ||
| High strength steels - ASTM A694 F42; F52 | ASTM | ||
Features
| SPECIFICATION | |
|---|---|
| Standard | ANSI B16.5 |
| Pressure | #300 (PN 50) |
| Sealing surface | flat face (FF) |
| Guidance surface options | with flange (RF) or profile channel (RTJ) |
| DN | pipe Ø | flange dimensions | open | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| dz | Dz | Do | do | H | g | d2 | S | D | f | Kg | n | |
| 1/2" | 21.3 | 95.2 | 66.5 | 15.7 | 52.3 | 14.2 | 38.1 | 2.80 | 35.0 | 1.6 | 0.75 | 4 |
| 3/4" | 26.7 | 117.3 | 82.5 | 19.0 | 57.1 | 15.7 | 47.7 | 2.95 | 42.9 | 1.6 | 1.26 | 4 |
| 1" | 33.5 | 123.9 | 88.9 | 19.0 | 62.0 | 17.5 | 53.8 | 3.40 | 50.8 | 1.6 | 1.52 | 4 |
| 1 1/4" | 42.2 | 133.3 | 98.5 | 19.0 | 65.0 | 19.0 | 63.5 | 3.55 | 63.5 | 1.6 | 2.03 | 4 |
| 1 1/2" | 48.3 | 155.4 | 114.3 | 22.3 | 68.3 | 20.6 | 69.8 | 3.70 | 73.1 | 1.6 | 2.89 | 4 |
| 2" | 60.3 | 165.1 | 127.0 | 19.0 | 69.8 | 22.3 | 84.0 | 3.90 | 91.9 | 1.6 | 3.4 | 8 |
| 2 1/2" | 73.2 | 190.5 | 149.3 | 22.3 | 76.2 | 25.4 | 100.0 | 5.20 | 104.6 | 1.6 | 5.17 | 8 |
| 3" | 88.9 | 209.5 | 168.1 | 22.3 | 79.2 | 28.4 | 117.3 | 5.45 | 127.0 | 1.6 | 6.93 | 8 |
| 3 1/2" | 101.6 | 228.6 | 184.1 | 22.3 | 81.0 | 30.2 | 133.3 | 5.70 | 139.7 | 1.6 | 8.67 | 8 |
| 4" | 114.3 | 254.0 | 200.1 | 22.3 | 85.8 | 31.7 | 146.0 | 5.95 | 157.2 | 1.6 | 11.2 | 8 |
| 5" | 141.2 | 279.4 | 234.9 | 22.3 | 98.5 | 35.0 | 177.8 | 6.45 | 185.6 | 1.6 | 15.1 | 8 |
| 6" | 168.3 | 317.5 | 269.7 | 22.3 | 98.5 | 36.5 | 206.2 | 7.10 | 215.9 | 1.6 | 19.1 | 12 |
| 8" | 219.1 | 381.0 | 330.2 | 25.4 | 111.2 | 41.1 | 260.3 | 8.25 | 269.7 | 1.6 | 29.9 | 12 |
| 10" | 273.1 | 444.5 | 387.3 | 28.4 | 117.3 | 47.7 | 320.5 | 9.25 | 323.8 | 1.6 | 42.7 | 16 |
| 12" | 323.9 | 520.7 | 450.8 | 31.7 | 130.0 | 50.8 | 374.6 | 9.50 | 381.0 | 1.6 | 61.8 | 16 |
| 14" | 355.6 | 584.2 | 514.3 | 31.7 | 142.7 | 53.8 | 425.4 | * | 412.7 | 1.6 | 85.8 | 20 |
| 16" | 406.4 | 647.7 | 571.5 | 35.0 | 146.0 | 57.1 | 482.6 | * | 469.9 | 1.6 | 106 | 20 |
| 18" | 457.2 | 711.2 | 628.6 | 35.0 | 158.7 | 60.4 | 533.4 | * | 533.4 | 1.6 | 131 | 24 |
| 20" | 508.0 | 774.7 | 685.8 | 35.0 | 162.0 | 63.5 | 587.2 | * | 584.2 | 1.6 | 158 | 24 |
| 24" | 609.6 | 914.4 | 812.8 | 41.1 | 168.1 | 69.8 | 701.5 | * | 692.1 | 1.6 | 230 | 24 |
| *) Upon agreement with the manufacturer | ||||||||||||
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