Aluminized Type 2 corrugated metal pipe stormwater detention system

When it comes to stormwater management and culvert design, selecting the right pipe material is crucial for performance, longevity, and cost-effectiveness. Enter Aluminized Type 2 (ALT2) pipe—a material that has become a staple in civil engineering projects. But what makes it so special? This blog will cover everything you need to know about ALT2 pipe and why it’s often the top choice for stormwater and drainage systems.

Overview of Aluminized Type 2 Pipe

Aluminized Type 2 pipe is made from cold-formed steel coated with a layer of pure aluminum through a hot-dip process. This process creates a strong bond between the aluminum and steel, forming a protective layer that provides both structural integrity and exceptional corrosion resistance, offering a service life of 2 to 3 times more than traditional galvanized. The "Type 2" designation differentiates this material from aluminized Type 1, which features an aluminum-silicon alloy coating. Type 2 pipes are specifically designed for environments with high moisture or mildly acidic conditions, making them ideal for stormwater management and drainage systems. 

How Does Aluminized Type 2 Compare to Galvanized Steel?

Galvanized steel is another popular option for drainage pipes. It’s made by coating steel with a layer of zinc, which protects the base metal through both a physical barrier and sacrificial anode properties. However, while galvanized steel offers good corrosion resistance in the presence of hard water, it tends to perform poorly in environments with acidic soils or water with low pH levels. Over time, the zinc coating can degrade, leaving the underlying steel vulnerable to rust.

In contrast, aluminized Type 2 pipe provides longer-lasting corrosion resistance due to aluminum’s natural ability to form a stable, self-healing oxide layer. This oxide layer regenerates over time, effectively sealing any minor abrasions or scratches. Additionally, aluminized Type 2 pipes have been shown to perform well in pH ranges of 5 to 9, extending their functional lifespan even in more aggressive environments. As mentioned prior, research indicates that aluminized Type 2 pipes often last two to three times longer than galvanized steel pipes in similar conditions.

Why Civil Engineers Choose ALT2 Pipe

Aluminized Type 2 pipe is often the material of choice for detention and culvert applications due to its unique combination of durability, cost-effectiveness, and environmental performance. Here's why it's favored:

1. Corrosion Resistance
ALT2 pipe is steel coated with an aluminum-silicon alloy, giving it excellent resistance to corrosion in a wide range of environments, including acidic and alkaline soils. Its longevity makes it ideal for long-term applications like detention basins and culverts.

2. Hydraulic Efficiency
The smooth interior of ALT2 pipe reduces friction, allowing for high hydraulic flow efficiency, which is crucial for stormwater management.

3. Strength and Durability
The steel core provides structural strength, enabling ALT2 pipe to withstand heavy loads and pressures typical in culvert and detention system installations.

4. Fabrication Capability
ALT2 pipe is a versatile welding material that enables manufacturers to tailor numerous solutions to specific job sites. While elbows, tees, and wye fittings are commonly used in the industry, ALT2 can be customized to meet most fitting requirements. It also offers the ability to fabricate custom weir walls, inlets, outlets, and other specialized components.

5. Cost-Effectiveness
In contrast to other corrosion-resistant materials, ALT2 pipe frequently offers a lower initial and lifecycle cost. ALT2 pipe can be readily manufactured in sizes exceeding 144 inches, enabling engineers and owners to minimize the underground storage footprint on their property. This reduction in footprint leads to increased availability of green or commercial space while simultaneously reducing excavation and stone backfill expenses.

6. Environmental Compatibility & Recyclability
Its corrosion resistance allows it to perform well in harsh environments without leaching harmful substances, making it an environmentally sound choice. ALT2 pipe is made from steel, one of the most recyclable materials globally. At the end of its lifecycle, it can be fully recycled into new steel products, reducing waste sent to landfills and the need for virgin material extraction.

7. Maintenance for Owners
ALT2 steel, along with all CMP material types, offers enhanced accessibility for annual maintenance events, eliminating the necessity for heavy or costly equipment. The majority of maintenance cycles can be completed within a day, resulting in cost savings through the utilization of shovel and pressure washing systems to remove accumulated debris from the pipes.