ASME B16.47 Standard
ASME B16.47 Flanges, titled “Large Diameter Steel Flanges: NPS 26 Through NPS 60 Metric/Inch Standard,” addresses large diameter steel flanges used in high-pressure and high-temperature applications. This standard is published by the American Society of Mechanical Engineers (ASME) and is an important reference for engineers, designers, manufacturers, and users of industrial flanges. Here are some key points about the ASME B16.47 standard:
①Scope: The standard covers flanges in sizes NPS 26 (Nominal Pipe Size 26 inches) through NPS 60 (Nominal Pipe Size 60 inches) and their corresponding metric dimensions. It includes flange types such as welding neck, slip-on, threaded, blind, lap joint, and reducing.
②Pressure Classes: ASME B16.47 provides two series of flanges: Series A and Series B. These series correspond to different pressure-temperature ratings. Series A flanges are designated for use with steel pipe flanges in the 150, 300, 400, 600, 900, and 1500 pressure classes. Series B flanges are intended for use with steel pipe flanges in the 75, 150, 300, 400, 600, and 900 pressure classes.
③Design and Materials: The standard specifies the dimensions, tolerances, materials, marking, and testing requirements for large diameter steel flanges. It provides guidance on flange design, facing, bolting, and gasket requirements to ensure proper performance under high-pressure and high-temperature conditions.
④Comparison to B16.5: ASME B16.47 is often compared to ASME B16.5, which covers flanges in smaller sizes (NPS 1/2 through NPS 24) and lower pressure ratings. B16.47 is specifically tailored for larger, higher-pressure applications, while B16.5 addresses a broader range of flange sizes and pressure-temperature ratings.
⑤Industry Relevance: The standard is widely used in industries such as oil and gas, petrochemical, power generation, and other sectors where large diameter flanges are required for process piping, pipelines, and equipment connections.
Global Adoption: While ASME standards are developed in the United States, they are recognized and adopted internationally. Many countries and organizations refer to ASME B16.47 for the design, manufacture, and procurement of large diameter steel flanges.
In conclusion, the ASME B16.47 standard plays a crucial role in the specification, design, and manufacturing of large diameter steel flanges for high-pressure and high-temperature applications. It provides essential guidelines for ensuring the integrity and performance of flange connections in critical industrial systems.
Types and Sizes of Steel Flanges
ASME B16.47 Flanges ranging from NPS 26 through NPS 60, accommodating pressures from Class 75 to Class 900. The standard includes several types of flanges such as weld neck, blind, and slip-on flanges, each serving a specific function within a piping system.
Changes in Flange Size
Understanding the dimensions of ASME B16.47 Flanges is critical for proper installation and operation. Here, we outline the key dimensions including external diameter, thickness, bolt hole diameter, and bolt hole spacing.
①External Diameter
The external diameter of ASME B16.47 flanges varies depending on the nominal pipe size (NPS) and the pressure class. For instance, a NPS 26 flange in Class 150 has an external diameter of approximately 31 inches, while the same size flange in Class 900 has an external diameter of about 38 inches.
②Thickness
Flange thickness also varies with pressure class and size. For example, a NPS 26 flange in Class 150 typically has a thickness of around 1.81 inches, whereas a Class 900 flange of the same size might have a thickness of approximately 4.44 inches.
③Bolt Hole Diameter
The bolt hole diameter is standardized to ensure compatibility with commonly used bolts. For a NPS 26 flange, the bolt hole diameter is generally around 1.38 inches, accommodating bolts of 1.25 inches nominal size.
④Bolt Hole Spacing
Bolt hole spacing, or pitch circle diameter (PCD), is the distance between the centers of adjacent bolt holes. For example, a NPS 26 Class 150 flange has a bolt hole spacing of about 27.75 inches, whereas a Class 900 flange has a spacing of approximately 34.50 inches.
Size Selection
Selecting the correct flange size is critical for the efficiency and safety of a piping system. Several factors must be considered to ensure optimal performance.
① Pressure Level
The pressure class of a flange indicates its maximum allowable pressure at a specific temperature. Higher pressure classes (e.g., Class 900) are designed for high-pressure applications, ensuring the flange can withstand the internal pressures without failing.
②Temperature Level
Temperature affects the material properties of the flange. High temperatures can weaken the material, reducing its pressure-bearing capacity. Therefore, selecting a flange with the appropriate temperature rating is essential for maintaining system integrity.
③ Fluid Type
The type of fluid being transported impacts the material selection and design of the flange. Corrosive fluids may require flanges made from resistant materials, such as stainless steel, to prevent degradation and ensure long-term durability.
④Connection Pipeline Size
The nominal pipe size (NPS) determines the flange size required for a given pipeline. It’s crucial to match the flange size to the pipeline to ensure a secure and leak-proof connection.
Tolerance and Allowable Deviation
ASME B16.47 Flanges specifies dimensional tolerances and allowable deviations to ensure flanges fit correctly and function as intended.
①Flange Dimensional Tolerances
Dimensional tolerances refer to the permissible limits of variation in flange dimensions. These tolerances ensure that flanges can be reliably assembled and disassembled without issues. For example, the standard may allow a slight variation in the bolt hole diameter to accommodate manufacturing differences.
②Importance of Tolerances
Maintaining precise tolerances is critical for ensuring a tight seal between flanges, which prevents leaks and ensures the safe operation of the piping system. Deviations beyond the allowable limits can lead to misalignment, compromised seals, and potential system failures.
Application Guide
Selecting the optimal flange size and type based on specific applications is essential for achieving efficiency and safety in various industries.
①Pipeline System
In pipeline systems, the correct flange size ensures a secure connection between pipes, preventing leaks and ensuring the safe transport of fluids. The selection must consider the pressure, temperature, and type of fluid being transported.
②Valve
Valves regulate the flow of fluids within a piping system. The flanges used to connect valves must match the valve’s size and pressure rating to ensure proper operation and prevent leaks.
③Heat Exchanger
Heat exchangers transfer heat between fluids and require flanges that can withstand high temperatures and pressures. Selecting the right flange size ensures the efficient transfer of heat and prevents failures due to thermal stress.
ASMEFlanges Manufacturers
Choosing a reputable manufacturer is crucial for obtaining high-quality ASME B16.47 flanges. HeBei Pengrun Pipe Fittings Co., Ltd. is a leading supplier of ASME B16.47 flanges, known for their precision, durability, and compliance with international standards. For more information or to place an order, please contact Lucy at mailto:Lucy@pr-pipefittings.com.
References
1. ASME. (2017). ASME B16.47 Large Diameter Steel Flanges.
2. American National Standards Institute. (n.d.). ANSI Overview.
3. “ASME B16.47 Flanges.” Engineering Toolbox.
4. “Flange Dimensions and Standards.” Swagelok.
5. “ANSI B16.47 Flange Dimensions.” Xometry.
