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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

steel pipe for oil and gas access roads

Service Life Champion: Steel Culvert Pipe Stands Strong in Corrosive Environments

By: TrueNorth Steel 40 Years Strong: Steel Pipe for Oil and Gas Access Roads Defies Extreme Conditions This NCSPA Project of the Year winner in ... Read more

Corrugated Metal Pipe Stormwater System Powers Major Houston Hospital Build, Wins Going Green Award

By: Contech Engineered Solutions Winner of the NCSPA Project of the Year – Going Green Category When Harris County voters approved a $2.5 billion bond ... Read more
custom beveled steel drainage pipe

Gilman Springs Road Rebuild Earns Top Honors with Custom Beveled Steel Drainage Pipe

By: Pacific Corrugated Pipe Company CSP & Pipe Arch Project of the Year Delivers Under Pressure The Gilman Springs Road Widening wasn’t just another infrastructure ... Read more

Studies, Resources & Marketing Materials

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