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Galvanization: Hot-Dipped vs Electrogalvanized

December 29, 2015

If you’ve ever tried to purchase a metallic pipe support, you know the number of choices can be paralyzing. While the majority of metallic pipe supports are supplied as galvanized, there’s more than one form of galvanization. Read on as we demystify galvanization for you.

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There are lots of examples of hot-dipped galvanized and electrogalvanized metals, though the most common example, nails, can be found at your local hardware store.

If you’ve ever tried to purchase a metallic pipe support, you know the number of choices you have as far as steel grade, finish, and coating go can be paralyzing. We’re here to help! The majority of metallic pipe supports are supplied as galvanized. But wait! There’s more than one form of galvanization?! Read on as we demystify galvanization for you …

What is Galvanization?

Galvanization is a process in which zinc is coated onto the surface of steel or iron to prevent corrosion. Adding a surface layer of zinc prevents corrosion by stopping the corrosive species from reaching the metal and it acts as a sacrificial anode were it to be damaged. Galvanization is appealing in industry due to its relatively low cost compared to the benefits (prolonged life, very reliable, uniform protection, etc.).

Below is a table comparing and contrasting the two main types of galvanization, hot-dip galvanization (HDG) and electrogalvanization (also commonly referred to electroplating or zinc plating):

Comparison of Hot-Dipped Galvanizing and Electrogalvanization
Type Advantages Disadvantages Process
Hot-Dipped Galvanized
  • High life expectancy (up to 50 years)
  • Reduces lifetime cost
  • Thicker, self-maintaining coating
  • Dull finish
  • Thickness may be undesirable
  • Thickness makes coating some parents, like threaded rods, more challenging
  1. Metal is cleaned
  2. Metal immersed in zinc bath at approximately 840°F
  3. Zinc reacts with oxygen when exposed to air
Electrogalvanized
  • Uniform coating
  • Cheaper initial cost
  • Shiny finish
  • Low life expectancy (months to years)
  • Thin coating (1/15 of HDG's thickness)
  • Only ideal for small components
  1. Plated onto surface by acting as a cathode
  2. Current applied through saline or zinc solution to coat the surface

Hot-Dipped Galvanization

HDG is by far the more popular option in industry today. For example, the majority of pipe hanger components are supplied as HDG. Its life expectancy and reliability are ideal in situations where the galvanized part is expected to work for years without maintenance. It allows for the use of lesser steels where higher-grade, more expensive stainless steels may have been appropriate. Its thickness and dull finish, however, make electrogalvanization more appealing in some applications.

Electrogalvanization

Electrogalvanization is used more exclusively in small tools and parts, such as screws, where the coating cannot be as thick as HDG. Electrogalvanization is also used when aesthetics are an important concern, such as in automobile manufacturing. Galvanization is a process used extensively across a wide variety of industries where additional corrosion resistance is needed with no detriment to the mechanical properties of the steel.

Composites to the Rescue

APP can offer metallic pipe supports in a wide variety of steel grades and finishes. All of this metal talk giving you a headache? Composite wear pads and pipe shoes are naturally corrosion resistant so you don’t have to give galvanizing the time of day when using them.

Up-Front Pricing on Composite Wear Pads and Pipe Shoes
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