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Aluminum Coated Type 2

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Aluminum Coated Type 2


corrugated steel pipe detention system large volume detention systemAluminum Coated Type 2 (AASHTO M274, ASTM A929) is a pure aluminum coating (no more than 0.35 percent silicon). It is produced with a coating weight of 305 g/m² (1 oz/ft²) of surface (total both sides) to provide a coating thickness of 48 µm (0.0019 in.) on each surface. The aluminum coated type 2 (ALT2) is the most widely used supplemental coating for CSP. “Aluminum is a reactive metal, but it develops a passive aluminum oxide coating or film that protects it from corrosion in many environments.” This film is quite stable in neutral and many acid solutions but is attacked by alkalies greater than a pH of 9. From a corrosion standpoint, aluminum has an advantage over galvanized in lower pH and in soft water conditions due to the formation of the oxide film. The coatings are essentially equal under abrasion and in waters where the zinc oxide film forms rapidly.

Aluminum coated type 2 CSP has been installed at thousands of sites over the past 50 years and many of these sites have been and are still being monitored for performance. Recent AK Steel research has indicated that 14 gage ALT2 CSP can achieve a 100-year service life when the environmental conditions have a pH of 5 to 9 and a resistivity greater than 1500 ohm-cm.

For more information download our Pipe Selection Guide found here.

DOT Information

The below is a map of the states that currently accept ALT2 coated pipe and plate in their specs.

Success Stories

2024 Project of the Year – Polymer Coating: West Shore Lake Pontchartrain

By: Contech Engineered Solutions Flooding Challenges and Solutions in Louisiana’s River Parishes: The Need for Protection The River Parishes of Louisiana, including St. Charles, St. ... Read more

2024 Project of the year – Structural Plate/Buried Bridge: Eureka Quarry Conveyor Tunnel

By: Lane Enterprises, Inc Eureka Stone Quarry Strikes Gold Eureka Stone Quarry, Inc., a leading Pennsylvania-based aggregate producer, proudly unveils its recently completed expansion project ... Read more
Earthquake Repair Railway Repair

2024 Project of the Year – Special Application: Railway Line Rehabilitation

By: ViaCon Turkey Earthquake Ravages Essential Turkish Railways In 2023, a devastating earthquake struck eastern Turkey, crippling vital railway lines essential to the region’s economy. ... Read more

Studies, Resources & Marketing Materials

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