Duplex systems, or painting over hot-dip galvanized steel, have been used for decades as a means to enhance corrosion protection. Painting over hot-dip galvanized steel provides the owner/specifier with effective corrosion protection, while still allowing the structure to be painted for color or aesthetic reasons. Duplex systems are becoming increasingly common and popular because of this combination of benefits.
Successfully painting over hot-dip galvanized steel is relatively simple. Just like painting on any other surface, proper surface preparation is key to creating an effective bond between the paint and the galvanized surface. Galvanized steel requires slightly different preparation steps according to the surface condition. Thus, proper preparation relies on correctly identifying the galvanized surface condition, and then following the appropriate cleaning and profiling steps to achieve optimum bonding of the paint to the hot-dip galvanized steel. For detailed instruction on preparing the surface, refer to ASTM D6386: Practice for Preparation of Zinc (Hot-Dip Galvanized) Coated Iron and Steel Product and Hardware Surfaces for Painting.
Revised in 2009, this package includes an instructional guide booklet and step-by-step DVD video on how to prepare the hot-dip galvanized steel surface for paint.
Copies of this resource are available for purchase. Architects, engineers, and other specifiers in North America may request a single copy of any publication at no charge, unless otherwise indicated. Multiple copies require a $25.00 (US funds) minimum order, plus shipping and handling. Prepayment is required. (Member galvanizers are not eligible for complimentary printed copies and require a $75.00 minimum order.) Non-member galvanizers must contact the AGA directly at 720-361-4483.
This report explores several fully hot-dip galvanized bridges in Ashtabula County, Ohio. (Steel Monthly, July 1991), 1 page
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Though many specifiers are familiar with one type of corrosion protection or another, few realize the intrinsic value of utilizing two corrosion protection systems together, known as a duplex system. A duplex system is formed by painting... View Details »
Based on its maintenance-free durability for 75 years or more in most environments, hot-dip galvanized (HDG) steel has a lower economic cost and environmental impact than paint. It uses a healthy, abundant, and recyclable metal, zinc, to... View Details »
Based on its maintenance-free durability for 75 years or more in most environments, hot-dip galvanized (HDG) steel has a lower economic cost and environmental impact than paint. It uses a healthy, abundant, and recyclable metal, zinc,... View Details »
This handout is a detailed cost comparison of hot-dip galvanizing and paint. The handout features a side-by-side comparison of weather dependency, bond strength, service life, and much more. It also compares the initial cost and maintenance cost of... View Details »
Developed in 2007, this handout is a detailed comparison of hot-dip galvanizing and zinc-rich paint. The handout features a side-by-side analysis of weather dependency, bond strength, service life, initial/maintenance costs, and much... View Details »
Hot-dip galvanized steel is a highly effective and widely used method of corrosion protection. It is not uncommon to paint galvanized steel in order to further its corrosion fighting properties. Failures in adhesion though, are not uncommon. This... View Details »
A suggested specification in CSI format for hot-dip galvanizing after fabrication. This guide aids in developing a better hot-dip galvanizing specification. 8 pages. 2002 View Details »