Table of content
Introduction
150# flange is a term you often see in some piping systems. While flanges are familiar to everyone, what does 150# flange stand for? Does it represent a different model or material? This article will explain what 150# flanges actually mean, including their specifications, models, and uses.
What are 150# Flange Dimensions?
150# flanges are a type of flange specified in the ASME B16.5 standard, and sizes range from ½ inch to 24 inches. In addition to the specified dimensions, these flanges also have outer diameters, thicknesses, bolt diameters, and number of holes. These specifications are the same for all flanges manufactured under this designation, regardless of the manufacturer’s country of origin. They are universally compatible.
Understanding the Meaning of 150#
150# flanges do not mean they are rated for 150 PSI. This is simply a notation used in the ASME B16.5 standard. At 100°F (38°C), it can withstand a maximum pressure of 285 psi. However, at higher temperatures, the pressure rating decreases.
If a higher pressure rating is required, choose a 300#, 600#, or 900# flange.
In short, a 150# flange is a category, not a representation of the pressure rating it can withstand.
Thickness of a 150# Flange
Flange thickness is an important consideration when choosing a flange, but the thickness varies depending on the size:
- A 2-inch 150# flange is approximately 0.44 inches (11 mm).
- A 4-inch 150# flange is approximately 0.56 inches (14 mm).
- A 6-inch 150# flange is approximately 0.69 inches (18 mm).
As can be seen above, within the same standard, the larger the flange size, the thicker it is. Consequently, the higher the pressure rating it can withstand.
Bolt Requirements for 150# Flanges
Every flange has bolt holes, but the diameter and number of holes vary across flange classes. While 15# flanges certainly have their specified diameter and number of holes, the number of bolt holes varies across flange sizes.
- ½-inch flange → 4 bolts
- 4-inch flange → 8 bolts
- 12-inch flange → 12 bolts
- 24-inch flange → 20 bolts
Besides the number of bolts, the bolt circle diameter (BCD) refers to the distance between bolt holes, measured from the center of the flange. This helps to select the appropriate bolts and nuts for installation.
Class 150 vs. Class 300 Flanges
150# and 300# flanges appear similar, but their thickness, weight, pressure rating, and applications differ. Here are some of the differences:
| Feature | Class 150 Flange | Class 300 Flange |
|---|---|---|
| Pressure Rating | ~285 psi at 100°F | ~740 psi at 100°F |
| Thickness | Thinner | Thicker |
| Weight | Lighter | Heavier |
| Cost | Lower | Higher |
| Applications | General piping, water, air | Oil & gas, steam, chemicals |
150# flanges can be used in some low- and medium-pressure systems. For higher-pressure environments, 300# flanges or higher pressure ratings are preferred.
Common Dimensions for Different Sizes
Below are the outer diameter, thickness, bolt hole number, and other data for two different flange sizes for easier understanding.
3-inch 150# flange dimensions
- Outer diameter: 6.63 inches (168 mm)
- Thickness: 0.56 inches (14 mm)
- Bolt holes: 4 x 0.75 inches
6-inch 150# flange dimensions
- Outer diameter: 10.5 inches (267 mm)
- Thickness: 0.88 inches (22 mm)
- Bolt holes: 8 x 0.88 inches
For other dimensions, please refer to the data provided in the ASME B16.5 standard.
Downloadable Standards and Charts
If you need flange or pipe dimensions of different sizes and standards, please download them from the ANSI/ASME B16.5 official website or review some data provided by our company:
- Class 150 Flange Dimensions (mm)
- ANSI Class 150 Flange Dimensions
- Flange Dimension Chart
These data may appear simple compared to the official website, but we have compiled and summarized the corresponding outer diameter, thickness, bolt hole diameter, and number of bolt holes for different flange types and sizes. We hope this provides a simple overview.
Summary
In short, the 150# flange belongs to the ASME B16.5 standard, which specifies thickness, pressure rating, bolt diameter, and hole diameter.
- 150# indicates Class 150 pressure, but it does not necessarily mean the maximum pressure rating is 150 psi.
- The specific bolt number and thickness depend on the size.
- If you need specific and reliable data, please refer to the ASME official website or the simple data sheet provided by our company.
I hope the introduction in this article can help you better understand the 150# flange and choose the appropriate flange according to the size specifications.
