Groco Bronze Pipe to Pipe Adapters

Groco Bronze Pipe to Pipe Adapters: Precision-Built for Marine Plumbing

Groco has been engineering marine-grade bronze fittings since 1918, and their Bronze Pipe to Pipe Adapters stand as a testament to that century-long commitment to quality. Gross Mechanical Laboratories, Inc. — the company behind the Groco name — built its reputation on solving real problems faced by boatbuilders and marine technicians, and nowhere is that philosophy more evident than in its pipe adapter lineup.

The IBVF Series: A Patented Solution to Thread Mismatch

The flagship product in Groco's Bronze Pipe to Pipe Adapter range is the IBVF Flanged Adapter series. These patented fittings were specifically developed to address several recurring challenges in the marine industry. The IBVF design allows the adapter to accept standard thru-hulls into the base while accommodating standard in-line valves on top — a critical feature when in-line valves are being used as seacocks. Perhaps most importantly, the IBVF series eliminates the dangerous thread mismatch that can occur when in-line valves are threaded directly onto thru-hulls. For OEM boatbuilders, the flanged design also offers a practical benefit: it allows valves to be installed after the engine or generator is in place, reducing the risk of valve damage during installation.

The IBVF adapters transition between NPT (National Pipe Tapered) male threads and NPS (National Pipe Straight) male threads, bridging the gap between the two most common thread standards found in marine plumbing systems. Available in sizes from 3/4" through 1-1/2", they cover the most common through-hull and seacock configurations found on production and custom vessels.

Material and Certification Standards

All Groco Bronze Pipe to Pipe Adapters are cast from C83600 bronze — a marine-grade alloy chosen for its outstanding strength and corrosion resistance in saltwater and freshwater environments alike. The fittings carry a UL Listed 647B certification, providing an independent quality benchmark that boat manufacturers and surveyors alike recognize as a mark of reliability. It is worth noting that C83600 bronze fittings are not NSF-61 compliant and are not intended for potable water systems — they are purpose-engineered for marine raw water, bilge, and through-hull plumbing applications.

Why Groco for Pipe to Pipe Adapters?

Choosing the right adapter for a marine through-hull or seacock assembly is not a decision to take lightly. Mismatched threads, inferior alloys, or undersized internal diameters can create leak points or flow restrictions with serious consequences. Groco's pipe-to-pipe adapters are designed and manufactured in the United States by a third-generation company whose entire product ecosystem — from seacocks and strainers to valves and fittings — is engineered to work together. That systems-level thinking means a Groco IBVF adapter is dimensionally and functionally compatible with Groco thru-hulls and ball valves right out of the box.

• Patented IBVF flanged design eliminates dangerous NPT/NPS thread mismatches
• C83600 marine-grade bronze for superior corrosion resistance in harsh marine environments
• UL Listed 647B certified for independent quality assurance
• Made in the USA by a manufacturer with over 100 years of marine hardware expertise
• Compatible sizing with standard Groco thru-hulls and in-line valve assemblies

Whether you are re-plumbing a seacock installation, upgrading aging through-hull fittings, or specifying components for a new build, Groco's Bronze Pipe to Pipe Adapters deliver the engineering depth and material integrity that marine plumbing demands.