GROCO 3/4" #316 Stainless Steel NPS to NPT Flange Adapter

The GROCO 3/4" #316 Stainless Steel NPS to NPT Flange Adapter (Model IBVF-750-S) is a purpose-built marine coupling that solves one of the most common installation challenges aboard vessels: thread incompatibility between through-hull fittings and inline seacock valves. When you're installing through-hull systems, thread mismatch can force dangerous compromises or require costly custom solutions. This flanged adapter eliminates that problem entirely by accepting standard through-hulls into its base while accommodating conventional inline valves on top.

Constructed from #316 stainless steel, the adapter provides superior corrosion resistance in saltwater environments where standard materials fail within seasons. The 3/4" size covers the most common through-hull diameter found on fishing vessels, cruising sailboats, and commercial marine installations. The flanged design creates a rigid, load-bearing assembly—critical when an inline valve functions as a seacock under operational pressure. Unlike simple threaded couplers, the IBVF flange transfers stress across a wider bearing surface, preventing the loosening and micro-movement that lead to leaks in rough water conditions.

This adapter is essential for weekend fishermen retrofitting older seacock systems and professional operators standardizing mixed equipment across a fleet. Whether you're upgrading a freshwater through-hull to marine-grade components or consolidating valves from different manufacturers into one installation, the NPS-to-NPT conversion saves time and eliminates the need for machine shop intervention. The 1.1 lb unit installs vertically or horizontally without orientation concerns, fitting standard 5-inch locker or bilge spaces where space is tight.