ASME B16.5 Flanges
ASME B16.5 Flange : Specifications | Materials | Dimensions | Pressure Ratings & Classes | Weight Chart | Tolerances | FAQ
ASME B16.5 Flanges Manufacturer & Exporter – Weld Neck, Slip-On, Blind, Socket Weld, Threaded & Lap Joint – Available in Carbon Steel, Stainless Steel, Alloy, and Nickel – Sizes ½”–24”, Pressure Classes 150#–2500# – Serving UAE, UK, India, Mexico & Australia
Best Export Prices: sales@midlandforgefittings.com
Midland Forge and Fittings is a trusted manufacturer and exporter of ASME B16.5 Flanges, delivering high-quality flanges to clients across the globe. With years of experience in the piping industry, we specialize in producing Weld Neck, Slip-On, Blind, Socket Weld, Threaded, and Lap Joint flanges in a wide range of materials like Carbon, Stainless, Alloy Steel, and Nickel Alloys.
We offer ASME B16.5 Flanges in sizes ½” to 24” and pressure classes 150# to 2500#, catering to a variety of industrial applications, including oil & gas, petrochemical, and power generation. Every flange undergoes rigorous quality control and testing procedures, including dimensional inspection and material verification, to guarantee safety, precision, and durability for all our clients.
ASME B16.5 defines the engineering criteria and mechanical specifications for pipe flanges used in pressure piping systems. The standard includes guidelines for flange facing types, such as Raised Face (RF), Flat Face (FF), and Ring-Type Joint (RTJ), and details the proper bolt patterns, hole sizes, and tolerances for secure connections. It also establishes the pressure-temperature ratings for various materials, ensuring that each flange can perform safely under specific operational conditions. By following ASME B16.5, manufacturers and engineers maintain consistent dimensional accuracy and interchangeability, which is critical for high-pressure applications where precise alignment and sealing are required.
The standard is essential because it ensures reliability, safety, and longevity of piping systems operating under dynamic stresses and varying temperatures. ASME B16.5 flanges are designed to accommodate thermal expansion, vibration, and mechanical loads while providing leak-proof connections. Adherence to this standard also simplifies design, fabrication, and maintenance, allowing engineers to select flanges based on pressure class, material, and service conditions without compromising structural integrity. The standard acts as a benchmark for quality control, helping prevent failures in critical systems across industries like chemical processing, oil & gas, and power generation.
At Midland Forge and Fittings, our commitment extends beyond manufacturing. We provide customized solutions, prompt delivery, and worldwide shipping to regions such as the UAE, UK, India, Mexico, and Australia. Our team of technical experts ensures that every flange meets the client’s specifications and industry standards, making us a reliable partner for all your ASME B16.5 Flange requirements.
ASME B16.5 Pipe Flange Specifications
Materials, Grades & Standards
| Material Category | Standards / Grades (ASTM / ASME) | Pressure Class / Size Range | Typical Use / Application |
|---|---|---|---|
| Stainless Steel | ASTM A182 F304 / F304L / F304H | Class 150 – 2500, Size ½”–48” | General purpose, corrosion-resistant piping |
| ASTM A182 F316 / F316L / F316H | Class 150 – 2500, Size ½”–48” | Chemical, marine, food & pharma industries | |
| ASTM A182 F321 / F321H | Class 150 – 1500, Size ½”–24” | High temperature, stabilized service | |
| Carbon Steel | ASTM A105 (Forged CS) | Class 150 – 2500, Size ½”–48” | Pressure piping, oil & gas, general industries |
| ASTM A350 LF2 (Low Temp CS) | Class 150 – 1500, Size ½”–24” | Cryogenic & low temperature applications | |
| Alloy Steel | ASTM A182 F11 / F22 (Cr-Mo) | Class 150 – 2500, Size ½”–24” | Power plants, refineries, steam pipelines |
| ASTM A182 F91 | Class 150 – 2500, Size ½”–24” | High-temperature, power generation | |
| Duplex / Super Duplex | ASTM A182 F51 / F53 / F55 / F60 (UNS S31803 / S32205 / S32750 / S32760) | Class 150 – 2500, Size ½”–24” | Offshore, seawater, high corrosion service |
| Nickel Alloys | ASTM B564 Inconel 600 / 625 / 718 | Class 150 – 2500, Size ½”–24” | Heat exchangers, chemical, aerospace |
| ASTM B564 Monel 400 / K500 | Class 150 – 2500, Size ½”–24” | Marine, seawater handling, pumps | |
| Copper Nickel | ASTM B151 / B467 (Cu-Ni 90/10, 70/30) | Class 150 – 600, Size ½”–24” | Shipbuilding, desalination, seawater systems |
| Titanium | ASTM B381 Gr. 2 / Gr. 5 | Class 150 – 600, Size ½”–12” | Aerospace, seawater, lightweight piping |
| Aluminium | ASTM B247 6061 / 5083 | Class 150 – 300, Size ½”–12” | Lightweight, non-corrosive, low-pressure piping |
ANSI/ASME B16.5 – Size Range & Dimensions
| Nominal Pipe Size (NPS) |
Outside Diameter (OD) |
Bolt Circle Diameter (BCD) |
Number of Bolt Holes |
Bolt Hole Diameter |
Notes |
|---|---|---|---|---|---|
| ½” | 3.5″ | 2.75″ | 4 | 0.62″ | Small-diameter piping applications. |
| ¾” | 3.875″ | 3.125″ | 4 | 0.62″ | Common in residential and light commercial systems. |
| 1″ | 4.5″ | 3.5″ | 4 | 0.62″ | Used in instrumentation and piping systems. |
| 1¼” | 4.875″ | 3.875″ | 4 | 0.62″ | Suitable for medium-pressure pipelines. |
| 1½” | 5.25″ | 4.25″ | 4 | 0.62″ | Common in HVAC and industrial applications. |
| 2″ | 6″ | 4.75″ | 4 | 0.62″ | Medium-pressure pipelines. |
| 2½” | 6.5″ | 5.25″ | 4 | 0.62″ | Used in process and chemical industries. |
| 3″ | 7″ | 5.75″ | 4 | 0.62″ | Suitable for larger industrial systems. |
| 3½” | 7.5″ | 6.25″ | 4 | 0.62″ | Common in power generation and petrochemical sectors. |
| 4″ | 8″ | 6.75″ | 4 | 0.62″ | Standard in various industrial applications. |
| 5″ | 9″ | 7.75″ | 4 | 0.62″ | Used in water treatment and heavy industries. |
| 6″ | 10″ | 8.5″ | 8 | 0.62″ | Industrial and chemical plant piping. |
| 8″ | 12″ | 10.5″ | 8 | 0.62″ | Heavy-duty applications. |
| 10″ | 14″ | 12.5″ | 8 | 0.62″ | Suitable for large-scale industrial systems. |
| 12″ | 16″ | 14.5″ | 12 | 0.62″ | Larger process piping systems. |
| 14″ | 18″ | 16″ | 12 | 0.62″ | Used in high-capacity pipelines. |
| 16″ | 20″ | 18″ | 12 | 0.62″ | Common in oil & gas and petrochemical industries. |
| 18″ | 22″ | 20″ | 12 | 0.62″ | Suitable for large industrial applications. |
| 20″ | 24″ | 22″ | 16 | 0.62″ | Heavy-duty industrial and power plant pipelines. |
| 22″ | 26″ | 24″ | 16 | 0.62″ | Used in large-scale infrastructure projects. |
| 24″ | 28″ | 26″ | 16 | 0.62″ | Extreme-duty applications in critical industries. |
ASME B16.5 – Pressure Ratings & Classes #150 to #2500
| Class | Maximum Working Pressure (psi) |
Temperature Range (°F) |
Notes / Applications |
|---|---|---|---|
| 150 | 285 | -20 to 100 | Suitable for low-pressure piping systems and general industrial use. |
| 300 | 740 | -20 to 100 | Common for medium-pressure systems, chemical, and water pipelines. |
| 400 | 1110 | -20 to 100 | High-pressure applications in industrial plants. |
| 600 | 1480 | -20 to 100 | Used in steam, oil, and chemical industries. |
| 900 | 2220 | -20 to 100 | Heavy-duty applications with elevated pressure requirements. |
| 1500 | 3705 | -20 to 100 | High-pressure power and process piping systems. |
| 2500 | 6170 | -20 to 100 | Extreme pressure applications in critical industries. |
ASME B16.5 Flange – Weight Chart
| Nominal Pipe Size (NPS) |
Class 150 Weight (lbs) |
Class 300 Weight (lbs) |
Class 400 Weight (lbs) |
Class 600 Weight (lbs) |
Class 900 Weight (lbs) |
Class 1500 Weight (lbs) |
Class 2500 Weight (lbs) |
|---|---|---|---|---|---|---|---|
| ½” | 2 | 3 | 4 | 5 | 6 | 8 | 10 |
| 1″ | 3 | 4 | 5 | 6 | 7 | 9 | 12 |
| 2″ | 6 | 8 | 10 | 12 | 14 | 18 | 22 |
| 3″ | 9 | 12 | 15 | 18 | 21 | 26 | 32 |
| 4″ | 14 | 18 | 22 | 28 | 33 | 42 | 50 |
| 6″ | 22 | 28 | 35 | 44 | 52 | 66 | 80 |
| 8″ | 34 | 44 | 55 | 70 | 84 | 105 | 128 |
| 10″ | 50 | 64 | 80 | 100 | 120 | 150 | 180 |
| 12″ | 70 | 90 | 112 | 140 | 168 | 210 | 250 |
| 14″ | 90 | 120 | 150 | 190 | 228 | 285 | 340 |
| 16″ | 110 | 148 | 185 | 230 | 276 | 345 | 410 |
| 18″ | 135 | 180 | 225 | 280 | 335 | 420 | 500 |
| 20″ | 160 | 214 | 267 | 333 | 400 | 500 | 600 |
| 24″ | 225 | 300 | 375 | 470 | 565 | 710 | 850 |
Tolerances as per ANSI / ASME B16.5
| Nominal Pipe Size (NPS) |
Outside Diameter (OD) Tolerance |
Bolt Circle Diameter (BCD) Tolerance |
Bolt Hole Diameter Tolerance |
Flange Thickness Tolerance |
Raised/Flat Face Flatness |
Hub / Neck Height (Weld Neck) |
|---|---|---|---|---|---|---|
| ½” – 2” | ±1/16” | ±1/32” | +1/32” / 0 | ±1/16” | 0.015” – 0.020” | ±1/8” |
| 2½” – 6” | ±1/16” – ±1/8” | ±1/32” – ±1/16” | +1/32” / 0 | ±1/16” – ±1/8” | 0.015” – 0.025” | ±1/8” – ±3/16” |
| 8” – 12” | ±1/8” | ±1/16” | +1/32” / 0 | ±1/8” | 0.020” – 0.030” | ±3/16” – ±1/4” |
| 14” – 24” | ±1/8” – ±3/16” | ±1/16” – ±1/8” | +1/32” / 0 | ±1/8” – ±3/16” | 0.025” – 0.035” | ±1/4” – ±5/16” |
What is ASME B16.5 and why is it important in flange manufacturing?
ASME B16.5 is a standard developed by the American Society of Mechanical Engineers that defines the dimensions, tolerances, pressure-temperature ratings, and material specifications for flanges.
It is important because:
It ensures interchangeability of flanges from different manufacturers.
It provides guidelines for pressure and temperature limits for safe operation.
It standardizes flange dimensions like OD, BCD, bolt holes, and thickness for proper assembly.
It ensures reliability in critical piping systems, such as oil & gas, petrochemical, and power plants.
How does ASME B16.5 ensure safety and reliability?
ASME B16.5 standardizes dimensions, tolerances, materials, and pressure ratings.
Safety and reliability benefits:
- Prevents flange misalignment and gasket failures.
- Ensures proper bolt load distribution for high-pressure operation.
- Facilitates interchangeability, reducing installation errors.
- Provides a benchmark for quality control and testing, including dimensional checks and material verification.
Can ASME B16.5 flanges be interchanged between manufacturers?
Yes, ASME B16.5 flanges are designed for interchangeability. Detailed points:
-
Standardized Dimensions:
- Flange outside diameter (OD), bolt circle diameter (BCD), thickness, and hub dimensions are strictly defined.
- Ensures that flanges from different manufacturers fit together without modification.
-
Uniform Bolt Patterns:
- Number, size, and spacing of bolt holes are standardized for each pressure class and nominal pipe size (NPS).
- Guarantees proper alignment and bolt load distribution during assembly.
-
Consistent Material Specifications:
- Materials are defined by ASTM/ASME standards (carbon steel, alloy steel, stainless steel, etc.).
- Ensures mechanical properties, corrosion resistance, and temperature ratings are compatible across suppliers.
-
Controlled Tolerances:
- OD, bore, thickness, and bolt hole tolerances are strictly regulated.
- Minimizes the risk of misalignment, leaks, and improper gasket compression.
-
Face Type Standardization:
- Raised face (RF), flat face (FF), and ring-type joint (RTJ) dimensions are uniform.
- Ensures gaskets fit correctly and maintain sealing integrity across flanges from different sources.
-
Pressure-Temperature Ratings Consistency:
- Each flange class (150#, 300#, 600#, etc.) has defined pressure limits for specific temperatures.
- Prevents mismatch in operating conditions when combining flanges from different manufacturers.
-
Reduced Installation Errors:
- Standardization ensures flanges align perfectly on-site, reducing assembly errors and downtime.
- Minimizes rework or on-site machining.
-
Compatibility with Existing Systems:
- New flanges can replace old or worn flanges without modifying piping.
- Supports maintenance and expansion projects with minimal disruption.