ASTM B564 UNS N04400 Flange Dimensions

UNS N04400, commonly known by its trade name Monel 400, is a nickel-copper alloy renowned for its exceptional resistance to seawater, acids, and alkaline environments. This blog provides a professional overview of the flange dimensions for Standard ASTM B564 UNS N04400 flanges, a specification for nickel-alloy forgings.

Understanding ASTM B564 and Material Specifications

ASTM B564 is the standard specification for forgings made from nickel and nickel-copper alloys. It sets the chemical composition, mechanical properties, heat treatment requirements, and testing methods for forged pipe fittings.

ASTM B564 itself does not define the dimensional standards for flanges. Instead, it governs the material quality. The physical dimensions of UNS N04400 flanges are specified by separate American Society of Mechanical Engineers standards, primarily ASME B16.5 for pipe flanges and flanged fittings for sizes NPS ½" to 24", and ASME B16.47 for larger diameters.

ASME B16.5 Dimension Standard

UNS N04400 flanges are manufactured to the dimensions outlined in ASME B16.5. This standard categorizes flanges by:

Pressure Class: This indicates the pressure-temperature rating of the flange. Common classes include 150, 300, 400, 600, 900, 1500, and 2500. Higher classes are thicker and can withstand higher pressures.

Flange Type: This includes Welding Neck, Slip-On, Blind, Socket Weld, Lap Joint, and Threaded flanges. Each type has a distinct shape for different assembly needs.

ASME B16.5 UNS N04400 Flange Dimensions

While a full dimensional chart for all classes and sizes is extensive, the following table lists key dimensions for ASME B16.5 Flange in various Nominal Pipe Sizes (NPS).

Dimensions by ASME B16.5 Flange Type

Weld Neck Flanges

Weld neck flanges are characterized by their long tapered hub, which provides reinforcement. The gradual transition from flange thickness to pipe wall thickness creates a strength advantage particularly beneficial for high-pressure, high-temperature, and cyclic loading conditions.

Key dimensional parameters for weld neck flanges include:

Hub Base Diameter (HB): Ranges from 1.5" for ½" NPS to 14.75" for 12" NPS.

Hub Top Diameter (HT): Varies from 0.84" for ½" NPS to 12.75" for 12" NPS.

Length Through Hub (LTH): Extends from 2.06" for ½" NPS to 5.38" for 12" NPS.

The extended neck section allows for smooth stress distribution between the flange and connected pipe, minimizing turbulence and erosion in corrosive fluid services where Monel 400 is typically specified.

Blind Flanges

Blind flanges is closure elements in piping systems and feature solid centers without bores. Their dimensions focus primarily on outside diameter, thickness, and bolt circle configuration to match corresponding pipe flanges while providing sufficient strength to withstand system pressure.

For Class 150 blind flanges in Monel 400, thickness increases with size:

NPS ½": 0.56" thickness.

NPS 12": 2.25" thickness.

NPS 24": Approximately 4.00" thickness.

Blind flanges require the greatest thickness among all flange types at equivalent pressure classes to prevent bending under pressure loads, resulting in higher material requirements and weight compared to other flange types.

Slip-On and Threaded Flanges

Slip-on flanges feature a slightly larger bore than the connecting pipe, allowing them to slide over the pipe and be welded in place. Their dimensional characteristics include:

SO Bore ID (SB): Slightly larger than the nominal pipe size.

SO Length (SL): Shorter than weld neck counterparts.

Minimum Thickness: Meets or exceeds standard requirements.

Threaded flanges incorporate internal threads matching external pipe threads, enabling installation without welding.

These flanges are particularly suitable for:

Low-pressure applications.

Systems where welding is hazardous.

Locations requiring periodic disassembly.

External environments where corrosion resistance is crucial.

Both slip-on and threaded flanges offer installation advantages in specific scenarios, though they typically have lower pressure ratings compared to weld neck flanges of equivalent size and class.

ASTM B564 Flange Features and Manufacturing

Material Certification: Flanges conforming to ASTM B564 must be supplied with a Material Test Report or Certificate of Conformance, verifying that the chemical composition and mechanical properties (e.g., Tensile Strength, Yield Strength) meet the standard's requirements for UNS N04400.

Face Finishes: Flange facing types, such as Raised Face (RF) or Ring-Type Joint (RTJ), are also defined in ASME B16.5. The surface finish is critical for achieving a leak-proof seal with the gasket.

Tolerances: The ASME standard provides strict manufacturing tolerances for all critical dimensions to ensure compatibility and interchangeability between components from different manufacturers.

Conclusion

In summary, selecting a UNS N04400 flange requires a clear understanding of two standards: ASTM B564 for material quality and ASME B16.5 (or B16.47) for dimension. When procuring flanges, always verify that your manufacturer can provide certification to both standards.