Along the coast, time isn’t the only threat to a plumbing system’s longevity — saltwater, storms, and humidity can wear materials down faster than expected. Commercial construction in these environments can be challenging, as these conditions accelerate corrosion, pushing traditional pipe and fittings beyond their limits long before their expected life span.

That’s why coastal applications demand more than standard performance; they require proven resistance to the elements over time.

Designed for aggressive DWV applications, Edge HP Iron™ pipe and fittings from Charlotte Pipe deliver where corrosion resistance is critical to long-term system reliability. Through an advanced electrocoating (ecoat) process, Edge HP Iron pairs the strength of traditional cast iron with a zinc phosphate pretreatment on the iron surface followed by two high performance layers of epoxy coating for pipe and one layer of ecoat epoxy with a fusion-bonded epoxy/acrylic top coat for fittings. This results in a system engineered to resist chipping, flaking, and delamination, helping extend performance in even the harshest coastal conditions. 

Why Coastal Environments Are Tough on Cast Iron Pipe

Coastal conditions may accelerate the deterioration of cast iron pipe and fittings due to a constant mix of salt, moisture, and exposure. Chlorides in seawater and salt-laden air speed up oxidation, leading to rust and pitting that can quickly weaken the material.

High humidity and frequent wet-dry cycles keep surfaces in a near-constant state of corrosion, while even airborne salt can settle and create a thin, damaging film. Belowground, salt-rich soils further increase the risk through electrochemical corrosion.

The result is a much harsher environment that can lead to cracking, leaks, and premature failure, making material durability a critical consideration in coastal construction.

Across commercial installations, Edge HP Iron is a reliable addition to hybrid piping systems, working in tandem with cast iron and PVC to meet performance demands.

While this level of protection makes it a particularly valuable system for coastal construction, the benefits of Edge HP Iron also extend to applications where effluents exceed the pH range that traditional cast iron soil pipe is designed to handle, including: 

• Hospitals
• Casinos
• Commercial kitchens
• Soda fountains
• Bar sinks
• Parking decks

Protection Inside and Out: Two Coatings, One Solution

For Edge HP Iron pipe, corrosion resistance is achieved through a zinc-phosphate pretreatment of the iron surface, followed by an electrocoated layer of cathodic epoxy, and finally an electrocoated anodic epoxy topcoat. Fittings are electrocoated the same way, except the anodic epoxy topcoat is replaced with a fusion-bonded, acrylic-epoxy powder coat.

• Anodic electrocoating positively charges the part being coated to attract the negatively charged paint particles, offering excellent color and gloss control.
• Cathodic electrocoating reverses the polarities, greatly reducing the amount of soluble iron in the paint and, thus, increasing its corrosion resistance. 

This electrocoating process delivers 100% coverage of the interior and exterior of the pipe and fittings, adhering to the iron without risk of delamination. After the coating is applied, the materials are then evaluated through a series of tests to ensure coating adhesion, corrosion resistance and leak-free performance.

Proven Performance Through Testing

To ensure the coating process of Edge HP Iron delivers the corrosion resistance required to withstand the rigors of a coastal environment, the product is tested to specific performance specifications, including a minimum 350-hour salt spray test.

Salt spray tests evaluate the performance of piping materials and surface coatings by accelerating the degradation process in a controlled, harsh environment. Faced with 350 hours of salt spray testing, Edge HP Iron’s chemically bonded coating helped shield the underlying iron from corrosive elements that are inherent to coastal environments. These results demonstrate the system’s ability to withstand aggressive salt and moisture exposure and provide long-lasting enhanced protection.

Along with salt spray testing, Edge HP Iron also passes the following performance specifications:

• Chemical resistance from pH 1 to pH 13 for 30 days at 73 F
• Resistance to hot water for 24 hours at 203 F
• Adhesion test
• Thermal Shock Temperature Cycling - 1,500 alternating cycles at 57-207˚F

Download the Edge HP Iron product brochure for additional information about how the product’s construction is built to meet the demands of aggressive DWV applications.