Bushing, MPT x FPT (Flush Style) PVC Schedule 80 4" x 3" (839-422)

The 4" x 3" PVC Schedule 80 Flush Bushing (839-422) transitions a 4" female-threaded socket connection down to a 3" female-threaded outlet in a single compact fitting — with a flush-style profile that seats recessed within the mating 4" female socket rather than projecting outward from its face. The 4" MPT (male pipe thread) end threads directly into any standard 4" FPT fitting, valve, or equipment connection upstream, while the 3" FPT outlet accepts any standard 3" male-threaded fitting, valve, nipple, or equipment connection downstream.

The all-threaded MPT x FPT configuration is the defining characteristic that distinguishes the 839-series from the 837-series (spigot x slip) and 838-series (spigot x FPT) flush bushings — where those series require a solvent-welded spigot connection at the inlet, the 839-422 is fully threaded on both ends, making it the correct specification for systems where the upstream 4" connection is a threaded socket rather than a solvent-weld slip socket. This is particularly relevant at valve bodies, threaded equipment ports, threaded unions, and any system configuration where threaded connections are used throughout and a solvent-welded transition at the bushing inlet is not appropriate or practical.

The fully threaded construction also means the 839-422 is fully removable at both ends — a meaningful distinction from the solvent-welded spigot bushings in the 837 and 838 series. Where those fittings create a permanent upstream joint, the 839-422 can be unthreaded from the upstream 4" FPT socket and reinstalled as system conditions require, making it a serviceable reducing fitting at threaded connection points in valve stations, equipment manifolds, and instrument assemblies where size adaptation at a threaded port may need to be revised or replaced over the system's service life.

The flush-style profile keeps the fitting recessed within the mating 4" female socket rather than projecting outward with a hex head — a practical advantage in tight mechanical spaces, close-coupled valve assemblies, and equipment rooms where a protruding hex bushing would create clearance problems or interfere with adjacent piping and components. The 4" to 3" size step-down is a single nominal pipe size increment, making this bushing well suited to systems where a moderate, controlled reduction at a threaded connection point is required — valve isolation points stepping down from a 4" threaded header to a 3" threaded valve, equipment inlets where a 4" threaded port must adapt to a 3" connection, and threaded manifold assemblies where a single-step reduction at a female socket is the specified transition.

Manufactured to Schedule 80 specifications and dimensionally compliant with ASTM D2467, the 839-422 delivers the elevated wall thickness and pressure rating that Schedule 80 gray PVC is specified for in chemical processing, industrial fluid handling, and demanding commercial applications. Gray PVC construction provides broad chemical compatibility with acids, alkalis, and industrial process fluids. NSF 61 certification confirms suitability for potable water contact where required.

Specifications:

Industries & Applications:

• Chemical Processing — threaded size reductions at valve bodies, equipment ports, and instrument manifolds in 4" chemical feed, dosing, and process fluid systems where a fully removable, all-threaded bushing is specified over a solvent-welded inlet fitting
• Industrial Process Piping — single-step reducing transitions at 4" threaded connection points in plant utility, cooling water, and recirculating process systems where the upstream connection is a threaded female socket requiring an MPT inlet
• Water & Wastewater Treatment — threaded size reductions at valve stations and equipment connections in treatment plant process piping where a 4" threaded header must adapt to a 3" threaded downstream connection
• Commercial & Industrial Plumbing — serviceable threaded reducing bushings at valve isolation points and equipment connections in high-pressure mechanical systems where all-threaded assemblies are preferred over solvent-welded transitions
• Aquaculture & Food Processing — corrosion-resistant threaded size reductions at equipment ports and valve connections in recirculating systems and chemical-exposure fluid handling installations where removability at the bushing is a maintenance consideration
• Irrigation & Agriculture — threaded reducing transitions at 4" valve stations and equipment inlets in high-pressure chemical injection and large-scale irrigation systems where the upstream connection is a threaded female socket