Introduction

Flanges are commonly used in industrial piping systems. The commonly used specifications are class 300 and class 600. What is the difference between the two and how to choose? Both are ASME flanges, and the class represents the pressure level. Intuitively, the pressure-bearing capacity of class 600 is higher than that of class 300. What are the specific differences between the two? Let’s take a look.

What is the Difference Between Class 300 and Class 600 Flange?

Class 300 is mostly used in low-pressure piping systems, and its maximum pressure level can reach up to 570 psi at the specified ambient temperature. Class 600 is mostly used in high-pressure piping systems. Its maximum pressure can reach up to 1150 psi at the specified ambient temperature. In addition to the difference in their pressure, the thickness, size and bolt configuration of the two are also different.

What Does Class 300 Flange Mean?

Class 300 means that the pressure of the flange can reach 300 psi under normal circumstances, which makes the flange safer and has a longer service life. However, its maximum pressure resistance is more than 300 psi. It is mostly used in some low-pressure pipeline systems, such as plumbing pipes, water supply pipes, etc.

What Is a 600 Flange Rated For?

Class 600 means that the various effects of the flange are best and the service life is the longest when the pressure is 600 psi. However, its maximum pressure resistance is higher than 600psi. Class 600 is mostly used in some higher pressure pipeline systems, such as oil and gas transportation pipelines.

Can You Bolt a 300 Flange to a 600 Flange?

If the two have the same standard and nominal diameter, the bolts of class 300 can be used on the flange of class 600. However, the matching bolts are also affected by the pressure resistance. If the bolts on the 300 flange are used, the pressure resistance of the 600 flange may be reduced.

What Size Is a Class 600 Flange?

The size range of class 600 flanges varies depending on the type of flange. Flanges include flat welding flanges, butt welding flanges, blind flanges and slip-on flanges. If these flanges must have a nominal diameter range, it is 12.7 mm to 1219.2 mm.

Difference Between Class 300 and 600 Flange Dimensions

Pressure rating: class 600 flanges can withstand higher pressure than class 300 flanges.

Bolt hole size: The bolt hole diameter of class 600 flanges is greater than 300.

Flange thickness: 600 is thicker, so it can withstand greater pressure.

Class 300 vs. Class 600 Pressure Rating in Bar

class 300: up to 39 bar (570 psi) at rated ambient temperature

class 600: up to 79 bar (1,150 psi) at rated ambient temperature

However, the specific use varies according to the ambient temperature. It is generally recommended to use it according to the conventional pressure given by ASME B16.5.

Are 300 and 600 Flanges the Same?

The two are different. Because they bear different pressures, thicknesses, and the number of bolt holes may also be different. So the two are not interchangeable. Choose according to the actual pressure level required.

Summary

Through the above, I believe you understand the specific differences between class 600 and class 300. When you choose flange accessories for your pipeline system, you should choose according to the specific pressure that the pipeline needs to withstand. Generally, choosing a high-pressure grade 600 flange can withstand some conventional pipeline pressures. But you can also refer to the ASME standard for specific choices.