Detailed introduction to flange requirements under ASME B16.5 standard
Contents
- Introduction
- What is the ASME B16.5 Standard?
- Flange Roughness Standards
- Flange Bolt Hole Standards
- Applications of ASME B16.5 Flanges
- Other Requirements for ASME B16.5 Flanges
- Differences between ASME B16.5 and ASME B16.47
- Summary
Introduction
The ASME B16.5 flange standard is an essential reference in industrial procurement. Many Metleader customers use this standard for their flange procurement and acceptance, and we also strictly adhere to their requirements during production.
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What is the ASME B16.5 Standard?
The ASME B16.5 standard is an important specification developed by the American Society of Mechanical Engineers for the design, manufacture and inspection of steel pipe flanges and flanged fittings.
Dimensions and Specifications
The B16.5 standard covers flanges with nominal diameters ranging from 1/2 inch to 24 inches (NPS 1/2 to NPS 24), including multiple key dimensions such as flange outer diameter, inner diameter, thickness, bolt hole diameter and center distance, and sets strict tolerance ranges.
Pressure Ratings
The standard defines multiple pressure classes, such as Class 150, 300, 600, 900, 1500 and 2500 pounds, corresponding to different maximum allowable working pressures.
Flange Types
It covers a variety of common flange types, such as WN, SO, BL, SW and LJ, each type has its own specific design features and applications.
Flange Roughness Standards
Flange roughness directly affects sealing performance and lifespan, often expressed as Ra (arithmetic mean deviation of profile) or Rz (maximum profile height).
ASME B16.5 stipulates that flange sealing surface roughness is generally required to be Ra ≤ 3.2μm (125μin), and the roughness of the concave and convex surface (RF) should be controlled between Ra 1.6-6.3μm (63-250μin).
Excessive roughness can cause gasket wear, while excessively low roughness can cause leakage.
Flange Bolt Hole Standards
The ASME B16.5 standard specifies the number and diameter of bolt holes in flanges. Bolt holes should be evenly distributed across the flange diameter, with an even number of holes.
This regular arrangement ensures the strength and stability of the flange connection.
For vertical flange sealing surfaces, bolt holes should span both the vertical and horizontal centerlines.
Applications of ASME B16.5 Flanges
B16.5 flanges are widely used in high-pressure pipeline systems in many industries such as petroleum, chemical, electric power, and nuclear energy.
These flanges not only bear the pressure load inside the pipeline, but also play an important role in connecting, sealing, and supporting the pipeline.
Other Requirements for ASME B16.5 Flanges
The ASME B16.5 standard specifies in detail the requirements for different flanges in terms of design, size, material selection, manufacturing process, inspection methods and marking.
Material Selection
The ASME B16.5 standard specifies steel types suitable for different pressure levels and operating conditions, such as carbon steel, alloy steel, and stainless steel, and sets clear requirements for the chemical composition and mechanical properties of the materials.
For special materials or environments, such as those requiring corrosion resistance or high-temperature applications, additional standards may be required, such as ASTM A182.
Manufacturing Process and Quality Control
The ASME B16.5 standard details the flange manufacturing process, including casting, forging, welding, heat treatment and surface treatment, and puts forward strict quality control requirements for each step.
Inspection and Certification
The ASME B16.5 standard emphasizes the importance of nondestructive testing of flanges, including ultrasonic testing, magnetic particle testing, and penetrant testing, to verify internal quality and integrity.
Flanges must also undergo routine inspections before shipment, including visual inspection, dimensional measurement, and hardness testing.
They must also be clearly labeled with manufacturer information, material grade, specifications, dimensions, and standard number.
Differences between ASME B16.5 and ASME B16.47
ASME B16.5 and ASME B16.47 are both production standards for flange sizes and pressure ratings published by the American Society of Mechanical Engineers (ASME).
Flange Size Ranges
The ASME B16.5 standard primarily applies to flanges ranging from 1/2 inch to 24 inches.
The ASME B16.47 standard primarily applies to larger flanges ranging from 26 inches to 60 inches.
Pressure Ranges
The ASME B16.5 standard covers seven pressure classes: Class 150, 300, 400, 600, 900, 1500, and 2500.
The ASME B16.47 standard covers five pressure classes: Series A: Class 150, 300, 400, 600, and 900.
Flange Types
The ASME B16.5 standard covers six flange types: WN flange, SO flange, SW flange, TH flange, BL flange, and LAPJ flange.
The ASME B16.47 standard covers two flange types: WN flange and BL flange.
Summary
Through the above introduction, we have learned about the requirements and regulations for flanges in the ASME B16.5 standard. In actual procurement, we should apply different acceptance criteria depending on the flange type.
We hope that the above information will help you better select high-quality steel flanges.
If you have any questions about our products, please contact Metleader’s professional engineering consultants. We will provide flange solutions to help customers obtain the products they need efficiently and quickly.
