Flange Dimensions
(ASME B16.5 & B16.47)
ASME flange dimensions define the standardized outer diameter (OD), bolt circle diameter (BCD), bolt hole size, thickness, and bore dimensions for pipe flanges used in industrial piping systems. This reference guide covers ASME B16.5 (½"–24") and ASME B16.47 (26"–60") dimension standards, including pressure classes, bolt patterns, and flange face configurations.
These dimensional standards are used across water treatment, wastewater facilities, oil & gas, power generation, and chemical processing to ensure compatibility and pressure integrity.
ASME B16.5 & B16.47 Dimension Reference
This page provides structured dimensional references for ASME B16.5 (½"–24") and ASME B16.47 (26"–60") flanges, including:
- Flange outside diameter (OD)
- Bolt circle diameter (BCD)
- Number and size of bolts
- Flange thickness by pressure class
- Raised face (RF) and Ring Type Joint (RTJ) configurations
All dimensions follow published ASME standards. For fabrication-critical applications, confirm material group and temperature rating prior to ordering.
What Is an ASME Flange Pressure Class?
An ASME pressure class defines the maximum allowable working pressure of a flange at a given temperature. Pressure ratings are determined by material group and temperature according to ASME B16.5 tables.
- Common Classes: 150, 300, 600, 900, 1500, 2500
- Higher class = thicker flange and larger bolt circle
- Pressure rating decreases as temperature increases
What Is ASME B16.5?
ASME B16.5 covers forged steel flanges from ½" to 24" NPS. It standardizes bolt circle diameters, bolt quantities, flange thickness, hub dimensions, and raised face heights for each pressure class.
| NPS | Flange OD (D) | Bolt Circle (K) | # Bolts | Bolt Size | Bolt Hole (d) | Thickness (T) | Bore (B) | Face |
|---|---|---|---|---|---|---|---|---|
| 1/2 | — | — | — | — | — | — | — | RF |
| 3/4 | — | — | — | — | — | — | — | RF |
| 1 | — | — | — | — | — | — | — | RF |
Reference: ASME B16.5 flange dimensions vary by pressure class, material group, and temperature. Confirm project-critical dimensions prior to fabrication or ordering.
What Is ASME B16.47?
ASME B16.47 covers large-diameter steel flanges from 26″ to 60″ and is divided into:
- Series A – heavier, larger bolt circle diameters
- Series B – lighter, smaller bolt circle diameters
Common applications include waterworks, petrochemical plants, and heavy industrial systems. Full dimension charts for Series A and B will be added soon.
Flange Dimension Tables
Reference sections below cover common ASME flange dimension standards used in municipal and industrial piping systems. If you need a specific size confirmed for an active project, request a structured specification review.
ASME B16.5 Class 150 Flange Dimensions
Standard dimensional reference for ASME B16.5 Class 150 flanges including outside diameter (OD), bolt circle diameter (BCD), bolt hole quantity, bolt size, flange thickness, and bore ranges. Commonly used in low-pressure municipal and industrial systems.
Need a size confirmed now? Request specification review.
ASME B16.5 Class 300 Flange Dimensions
Dimensional specifications for ASME B16.5 Class 300 flanges covering OD, bolt pattern configuration, thickness, and pressure-rated bore dimensions. Suitable for moderate-pressure applications.
Need a size confirmed now? Request specification review.
ASME B16.5 Class 600 Flange Dimensions
Reference dimensions for ASME B16.5 Class 600 flanges including bolt configuration, outside diameter, flange thickness, and bore data for higher-pressure industrial systems.
Need a size confirmed now? Request specification review.
ASME B16.47 Series A & B Flange Dimensions (26″–60″)
Large-diameter flange dimensions per ASME B16.47 Series A and Series B standards (26″–60″), including OD, bolt patterns, thickness, and bore specifications for pipeline and heavy industrial use.
Need a size confirmed now? Request specification review.
Flange Bolt Pattern Reference
Each ASME flange size and pressure class specifies:
- Bolt circle diameter (BCD)
- Number of bolt holes
- Bolt hole diameter
- Required bolt length (based on gasket + flange type)
Incorrect bolt patterns can lead to misalignment, gasket failure, and pressure leaks.
Gasket Selection for Flange Dimensions
The flange dimensions directly determine the correct gasket size. Common gasket types include:
- Spiral wound gaskets (most common for RF)
- Ring Joint gaskets (for RTJ grooves)
- Full face gaskets (for FF flanges)
A complete gasket sizing guide will be added soon.
Recommended Reading
Frequently Asked Questions
No. ASME B16.5 covers flange sizes from ½” through 24″ NPS, while ASME B16.47 covers large-diameter flanges from 26″ through 60″. Within B16.47, Series A and Series B also have different bolt circle diameters and are not interchangeable.
Bolt circle diameter is defined by the pipe size (NPS) and pressure class under ASME standards. Each pressure class has a specific bolt pattern to ensure proper load distribution and gasket sealing.
Yes. Higher pressure classes require thicker flanges, larger bolt circle diameters, and often larger or additional bolts to withstand increased pressure and temperature conditions.
Pressure ratings are affected by temperature. While dimensional geometry remains consistent within a standard, allowable working pressure decreases as operating temperature increases according to ASME material group tables.
Raised Face (RF) flanges use a spiral wound or soft gasket compressed between the raised surfaces. Ring Type Joint (RTJ) flanges use a metal ring gasket seated in a machined groove and are typically used in higher pressure applications.
ASME standards define bolt hole diameter and quantity but do not directly specify bolt length. Required bolt length depends on flange thickness, gasket type, washer use, and nut engagement requirements.
Need Project-Specific Flange Dimensions?
For municipal and industrial projects requiring verified ANSI/ASME flange dimensions, submit your size, pressure class, and material specifications for confirmation before ordering.