Reducer Bushing, Spigot x Slip PVC Schedule 40 4" x 3" (437-422)

The 437-422 is a 4" × 3" PVC Schedule 40 Reducer Bushing with a spigot (plain male) end at 4" and a slip (socket) end at 3", engineered to insert directly into the socket of any standard 4" PVC fitting and accept 3" PVC pipe on the downstream side via solvent cement. Where a reducing tee, cross, coupling, or other 4" socket fitting needs to transition to 3" pipe at that connection point, this bushing accomplishes the reduction in a single compact fitting — eliminating the need for a separate full-bore coupling and reducing bushing in series, and keeping the overall assembly length and joint count to a minimum.

Manufactured from white PVC Schedule 40 compound and compliant with ASTM D2466, this bushing carries NSF/ANSI 61 certification for potable water contact. The spigot end is dimensioned to the outside diameter of 4" Schedule 40 pipe, allowing it to seat fully into the bell of any standard 4" socket fitting and be solvent-cemented in place just as a length of pipe would be. Once the bushing is set in the upstream fitting, the 3" slip socket on the downstream face accepts 3" PVC pipe via a standard solvent cement joint — creating a continuous, pressure-rated reduction from the 4" system into a 3" run.

The 4" × 3" reducing step is one of the more common large-diameter bushing configurations in commercial and municipal piping — a one-pipe-size reduction at a fitting socket that avoids the cost and complexity of a full reducing tee or eccentric reducer fitting where a simple bushing at an existing socket connection point is sufficient for the application. This bushing is particularly practical when retrofitting or extending an existing 4" system with a 3" branch or service line, as the reduction can be made directly at any available 4" socket in the existing fitting inventory without sourcing a new reducing fitting.

At 4", joint preparation demands careful attention. Both the spigot end of the bushing and the receiving 4" socket should be cleaned thoroughly and primed with full-circumference coverage before cement application — at this diameter, insufficient primer penetration or incomplete cement coverage is the primary source of joint failure. Apply a Schedule 40-compatible PVC cement per ASTM D2564 to both surfaces and assemble with a quarter-turn while maintaining firm pressure through the cure hold. The 3" slip end follows the same procedure with 3" pipe. The governing pressure rating for the assembled fitting is determined by the smaller 3" slip end; consult the manufacturer's published technical data for this reducing combination before specifying to a system working pressure.

Specifications

Industries & Applications

• Commercial Plumbing — Reducing 4" drain, waste, vent, or supply socket connections to 3" pipe runs at tees, couplings, and wye fittings in large commercial facilities where the reduction occurs at an existing socket connection rather than requiring a new reducing fitting
• Municipal & Civil Water Distribution — Service lateral reductions and branch connections off 4" distribution mains in low-to-medium pressure municipal water systems where a bushing at an existing socket is specified in lieu of a full reducing tee
• Industrial Process Piping — Diameter reductions at 4" socket fittings on process water, cooling water, and utility water mains where downstream equipment or sub-mains require a 3" connection and a compact bushing solution is preferred over a reducer coupling in series
• Irrigation & Agriculture — Header-to-lateral reductions in large-scale agricultural, turf, and golf course irrigation systems where a 4" distribution main transitions to a 3" zone sub-main at an existing fitting socket connection point
• HVAC & Mechanical Systems — Chilled water, condenser water, and cooling tower makeup piping reductions at 4" fitting sockets where 3" sub-distribution headers or equipment connections are required within a confined mechanical room layout
• Fire Suppression Support Lines — Auxiliary supply reductions in non-FM-rated wet system support piping where a 4" supply connection must be reduced to a 3" branch or zone feed at a fitting socket
• Retrofit & System Extension — Adding 3" branch runs to existing 4" PVC systems at any available socket connection point without sourcing new reducing fittings — the bushing inserts directly into the existing socket inventory and resolves the size transition at the connection