Reducer Bushing, Spigot x FPT PVC Schedule 40 6" x 4" (438-532)

The 438-532 is a 6" x 4" Schedule 40 PVC Reducer Bushing with a Spigot x FPT configuration. This fitting reduces pipe size within an existing fitting socket — the spigot (male) end is sized to the OD of 6" PVC pipe, allowing it to insert directly into any standard 6" slip socket fitting, valve, or equipment port, while the 4" FPT (Female Pipe Thread) outlet on the opposite end accepts any male-threaded 4" fitting, valve, pipe nipple, or equipment connection downstream. The spigot end is solvent cemented into the receiving 6" socket, while the FPT outlet provides a threaded connection point — making this a mixed-connection reduction fitting that bridges a cemented 6" socket to a threaded 4" downstream port in a single compact body.

The spigot x FPT bushing occupies a specific and important niche in the reducing fitting category. Where a reducing coupling joins two pipe ends inline and a flush or hex bushing converts one socket size to another within the same all-cemented system, the spigot x FPT bushing performs a dual function simultaneously: it reduces the socket size from 6" to 4" and transitions from a cemented connection to a threaded connection in the same fitting body. This makes it the most compact and efficient solution when a 6"-ported fitting is already installed or specified — a tee, cross, valve, or coupling — and the downstream connection at that port must be both smaller in diameter and threaded rather than cemented.

The 6" to 4" size step is a significant one-increment reduction at large diameter. At this size pairing, the 438-532 is most commonly encountered at equipment connection points, pump station assemblies, valve installations, and manifold branch ports where a large-diameter PVC fitting body must interface with a 4" male-threaded valve, pump flange adapter, equipment inlet, or threaded pipe nipple downstream. The FPT outlet eliminates the need for a separate slip-to-threaded adapter downstream of a cemented bushing, reducing fitting count and assembly length at the connection point.

Thread sealant tape (PTFE) or pipe dope rated for PVC service should be applied to all male threads assembled into the 4" FPT outlet before installation. The spigot end should be primed and solvent cemented into the receiving 6" socket per standard PVC solvent welding practice — at 6", the socket surface area is large and thorough, even primer and cement coverage on both the spigot OD and the socket interior is essential for a reliable joint. The fitting should be inserted to full seating depth and held in alignment through the set period before any load or torque is applied to the FPT outlet.

Manufactured in white Schedule 40 PVC, the 438-532 provides solid corrosion resistance across a broad range of fluids and a substantially lower installed weight compared to metal reducing bushings of equivalent size — a meaningful handling advantage when working at 6" diameter in the field.

Specifications:

⚠️ Note: In a reducing fitting, the smaller end governs the pressure rating. Apply PTFE thread tape or PVC-compatible pipe dope to all male threads assembled into the 4" FPT outlet before installation. Do not over-tighten threaded connections into the FPT outlet — large FPT ports are susceptible to body cracking under excessive torque or uneven loading from heavy downstream pipe weight; support downstream pipe runs independently where practical. Use primer on both the spigot OD and the receiving 6" socket interior before cementing. Consult manufacturer derating tables for elevated-temperature service.

Industries & Applications:

• Municipal Water Distribution — Inserted into 6" valve, fitting, or equipment sockets at points in the distribution network where a 4" male-threaded valve, hydrant connection, service fitting, or threaded pipe nipple must be connected to a 6"-ported assembly without an additional downstream slip-to-thread adapter
• Irrigation & Agricultural Systems — Used at pump station outlet assemblies, large manifold branch ports, and control valve installations on high-volume irrigation systems where a 6"-ported fitting body must interface with a 4" threaded valve or equipment connection, keeping the assembly compact within valve boxes and control enclosures
• Water & Wastewater Treatment — Converts 6" fitting ports on treatment plant distribution headers, process piping assemblies, and equipment connections to 4" threaded outlets for connection to threaded valves, instrumentation flanges, and equipment inlets where a combined size reduction and thread transition at a single port is required
• Industrial Process Piping — Inserted into 6" valve or fitting sockets on process water and chemical distribution systems where a 4" MPT-ported valve, strainer, check valve, or equipment connection must be tied into a 6"-ported fitting body in the most compact configuration available
• Pump Station & Equipment Connections — Used at 6" pump discharge or suction fitting sockets where the downstream connection transitions to a 4" threaded valve, flange adapter, or pipe nipple, combining the size reduction and thread transition in the bushing body rather than requiring separate downstream fittings to accomplish both functions
• Commercial & Institutional Plumbing — Applied in large commercial building utility piping and mechanical room assemblies where a 6"-ported fitting must be adapted to a 4" threaded downstream connection within a confined equipment space where minimizing fitting count and assembly length is a practical installation requirement