Ductile Iron Pipe Thickness Class vs Pressure Class

Ductile iron pipes are a popular choice in several different industries and applications. However, these pipes come in a variety of thickness classes and pressure classes. The thickness class ranges from Class 50 to Class 56. It refers to the minimum thickness of the pipe wall that is required for the application. The pressure class starts from Class 1 to Class 3. It indicates the maximum internal pressure the pipe is able to withstand. These pipes are classified into three categories: low-pressure and thicker wall applications, moderate-pressure and wall thickness applications, and high-pressure and thicker wall applications. Choosing the right ductile iron pipe can be a challenge, but considering a few features, such as corrosion resistance, diameter, operating pressure, and wall thickness, can be helpful.

What Are Ductile Iron Pipes?

Ductile iron pipes are an enhanced form of cast iron pipes. They have several beneficial features that traditional cast iron pipes don’t, including maximized strength, durability, and corrosion resistance. Due to these advantages, these pipes are popular and widely used for different applications, especially in water and sewage systems.

These pipes offer other benefits, such as easy installation, proper fluid transfer in ductile iron pipes, and low maintenance requirements.
Ductile iron pipes are considered a cost-effective solution in the long term.
Ductile iron pipes undergo a thorough quality control process during manufacturing to ensure proper strength, dimensional accuracy, and other specifications.
These pipes are used in water distribution systems and wastewater and sewage systems, as they are corrosion-resistant with high tensile strength.

What Is the Thickness Class in Ductile Iron Pipes?

Ductile iron pipes must follow a few standards, which include several features. Some thickness classes are set for ductile iron pipes, such as the ISO thickness class and Class 50 to Class 56. According to McWane Ductile, the thickness class refers to the minimum required thickness of the pipe wall. It also refers to many specifications of the pipes, such as diameter, pressure rating, and the ability to withstand loads.

Class 50: This thickness class is for applications with low pressure. Pipes with small diameters follow this class, which is the thinnest class among other classes.
Class 51: The only difference between this class and the previous one is the thicker wall. It provides increased strength.
Class 52: Class 52 has a moderate wall thickness, which makes it suitable for water and sewage systems applications.
Class 53: This is the perfect class for applications in which higher resistance is required for internal and external loads.
Class 54: Class 54 owns a much thicker wall. This class is excellent for high-pressure conditions and pipes with a large diameter.
Class 55 and Class 56: These two classes aren’t for general applications. They are used for special conditions where the highest level of strength and pressure resistance are crucial.

What Is the Pressure Class in Ductile Iron Pipes?

Two important factors of ductile iron pipes are the thickness class and pressure class. Each of these features is influenced by the other. The pressure rating for ductile iron pipes is the basis for determining these classes. Referring to Electrosteel Castings Ltd., the pressure class refers to the maximum internal pressure the pipes can tolerate. Ductile iron-working pressure is crucial for these classes to determine their applications.

Class 1: This class is perfect for low-pressure applications. They are widely used in gravity sewers and drainage systems.
Class 2: The second class can withstand moderate pressures. Pipes in this pressure class are good for applications in water distribution systems and force mains with low pressure.
Class 3: Pipes with this pressure class are designed for high-pressure applications. They are generally used in water transmission systems, industrial applications, and firefighting networks.

Thickness Class vs. Pressure Class: What Is the Difference?

The main question is, what are the differences between the ductile iron thickness class and the pressure class? Although the thickness class and pressure class are related in some ways, they are two different concepts. Long story short, the thickness class mainly refers to the physical dimensions of the pipes. On the other hand, the pressure class introduces the pipes’ ability to withstand internal pressure.

Thickness Class

This feature is normally used to indicate the pipes’ pressure-carrying capacity. However, it doesn’t show the exact maximum allowable pressure.
The main feature of this classification is to determine the ratio of the pipe’s external diameter to its thickness.
It also refers to the minimum thickness of the pipe wall that is required for the application.
It can even affect the strength of the pipes and their resistance to all forms of loads, such as internal and external loads.

Pressure Class

The pressure class is directly related to the wall thickness and the pipe’s strength.
This classification offers a precise measurement of the pressure resistance of the ductile iron pipe.
It refers to the maximum internal pressure the pipe is able to withstand without failure.
This feature also determines the pressure-carrying capacity of the pipe for specific applications.

Applications of DI Pipes Based on Thickness and Pressure Classes

Ductile iron pipes are used in various applications. Each application must be decided on a specific thickness class and pressure class based on the project specifications and requirements. Several features are effective, such as the operating pressure, internal/external loads, and pipe diameter. A proper combination of the suitable ductile iron pipe thickness class and pressure class must be chosen for each application.

Low Pressure and Thinner Wall Applications (Class 1-2, Class 50-51)

They are widely used for low-pressure water distribution systems.
These classes are suitable for irrigation systems.
Ductile iron pipes with thinner walls are perfect for stormwater drainage systems.
They are also used for gravity sewers.

Moderate Pressure and Wall Thickness Applications (Class 2-3, Class 52-53)

Pipes with moderate wall thickness and pressure are widely used in potable water distribution networks.
They are mostly suitable for industrial process water systems.
Such pipes are used in force mains with low pressure.
They are also useful for firefighting networks.

High Pressure and Thicker Wall Applications (Class 4-6, Class 54-56)

Ductile iron pipes with thicker walls and high pressure are a popular option for water transmission systems.
These pipes are mainly used in heavy industrial applications, such as hydroelectric power generation.
These pipes are often used in high-rise building water supply systems.
They are also generally used in high-pressure force mains.

How to Choose the Right Ductile Iron Pipe

Mindful consideration is required to choose the right ductile iron pipe thickness class and pressure class. Several technical specifications must be considered to pick the best option for each project’s needs. This ensures proper operation, a durable system, and a budget-friendly connection.

Corrosion Resistance

Corrosion resistance is an important factor to consider. The surrounding environment of the pipe must be checked, as must the surrounding soil and exposure to chemicals, to ensure proper corrosion protection. The installation area is crucially important in this factor.

Diameter

The appropriate pipe diameter is somehow the most essential feature the pipe must have. The required flow rate and velocity will determine the proper pipe diameter to be used in each project.

Operating Pressure

The maximum internal pressure plays a critical role. It mainly determines the suitable pressure class that must be chosen for the specific project requirements. This ensures the maximum efficient operation of the pipes.

Wall Thickness and Strength

The proper wall thickness will help ensure the pipe’s strength against external and internal loads. Soil and traffic loads are highly effective on pipe operation, so the proper pipe thickness must be decided.

Conclusion

Ductile iron pipes are considered one of the best materials for a great variety of applications. However, not all types and classes of these pipes are good for all applications. Each project, based on its requirements, needs a specific type of ductile iron pipe thickness class and pressure class. The proper class will ensure the safe operation of these pipes in the projects.