ABOUT US
Engineering FRP Systems Since 1963
GPI designs and manufactures fiberglass-reinforced plastic (FRP) systems for industrial applications where failure is not an option. For more than 50 years, our work has supported process industries that demand durability, consistency, and long-term performance in corrosive and demanding environments.
Our approach is straightforward. We focus on building FRP systems the right way—using sound engineering, disciplined fabrication practices, and experience earned through decades of real-world service.
Our History
GPI composites was founded in 1963 in Schofield, Wisconsin. In 1967, George and Mary Ann Zinser acquired the company and guided its transition from fiberglass boat manufacturing to industrial tanks and custom composite products.
As demand for larger and more complex vessels grew, GPI expanded its capabilities, constructing a new facility in 1984. Today, the 30,000-square-foot facility supports the fabrication of tanks up to 17 feet in diameter as a single piece.
Our Mission
Our mission is straightforward: design and manufacture high-quality composite tanks and custom molded products that deliver long-term value in real operating conditions.
We focus on doing the work thoroughly, respecting the demands of each application, and holding ourselves to high standards for quality, service, and delivery. Success is measured by how our systems perform in the field.
We’ve proudly joined the RPS Industrial Group
NEWS | February 2026
GPI Composites is now part of the RPS Industrial Group — a family of specialized companies serving mission-critical industries across North America.
A shared commitment to complex work.
GPI Composites and RPS align on the same core belief: the industries that power the world deserve partners with the experience, precision, and discipline to take on the toughest projects. Together, we deliver boutique expertise at scale — solving problems others won’t attempt and supporting customers when the stakes are highest.
When performance counts, experience matters.