GROCO 1/2" NPS NPT Combo Bronze Thru-Hull Fitting w/Nut

The GROCO 1/2" NPS NPT Combo Bronze Thru-Hull Fitting with Nut (Model TH-500-W) is a dual-thread marine through-hull connection designed for seawater systems where reliability under continuous saltwater exposure is non-negotiable. Cast from C83600 bronze—a marine-grade alloy proven across decades of offshore service—this fitting accommodates both National Pipe Straight Mechanical (NPSM) and National Pipe Taper (NPT) threaded connections, eliminating the guesswork when connecting through-hull plumbing, livewell systems, or cooling water intakes on fishing boats and cruising vessels.

The combination thread design solves a common installation challenge: the same fitting works with both straight and tapered pipe threads without adapters or modifications. C83600 bronze resists dezincification and stress-corrosion cracking in saltwater environments—critical for through-hull fittings where failure means water intrusion below the waterline. The included nut provides secure mounting from the interior hull side, and the UL 647B listing confirms compliance with marine safety standards for flash-point and material integrity. This 1/2" size handles mid-range flow demands for bilge pumps, raw-water cooling systems, and drainage applications on vessels between 25 and 55 feet.

Whether you're replacing corroded through-hulls on a working boat, upgrading aging plumbing during refit, or installing new systems during a build, this fitting is built to outlast the vessel itself. GROCO offers the same model in stainless steel and BSPP thread patterns, but the bronze version with combo threading is the workhorse choice for anglers and cruisers who demand simplicity, compatibility, and salt-tested durability in their through-hull connections.