GROCO 1.5-Inch Stainless NPS/NPT Thru-Hull Fitting

The GROCO TH-1500-WS thru-hull fitting provides a purpose-built hull penetration for marine intake or discharge plumbing. The straight body is a practical choice when the hose or valve can align directly with the thru-hull from inside the vessel. Its combination NPSM/NPT thread gives installers flexibility when mating the fitting to compatible marine valves and plumbing components. A retaining nut is included with this version, allowing the fitting to be secured through the hull before the inside plumbing is completed.

The combination-thread arrangement is useful in installations that need to transition from a thru-hull connection into compatible tapered-thread components. GROCO manufactures the TH-1500-WS from 316 stainless steel, a material selected for long-term marine service. Because this is a hull penetration, the seating surface and thread condition should be checked carefully before the part is bedded. The fitting is UL 647B listed and belongs to a family offered in multiple sizes for consistent plumbing layouts across a boat.

• UL 647B listed marine construction
• Straight thru-hull layout for direct plumbing runs
• Combination NPSM/NPT threaded body
• Retaining nut included for hull installation

Dry-fit the TH-1500-WS with the intended seacock, valve, or hose connection before applying bedding compound so thread engagement and interior clearance can be verified. The exterior flange should seat evenly against the hull, and the connected plumbing should be supported so it does not lever against the fitting. After launch or pressure testing, inspect the penetration from inside the boat and include it in normal below-waterline maintenance checks. For compatible hull fittings, strainers, and drains, browse Thru-Hulls & Drains.