Union (O-Ring Type), FPT x FPT PVC Schedule 40 3/4" (498-007)

This 3/4" Schedule 40 PVC O-Ring Union provides a removable, pressure-tight connection point in a threaded Schedule 40 PVC piping system, enabling valves, pumps, filter housings, and equipment to be disconnected and reassembled without disturbing the surrounding threaded piping on either side. Both female NPT threaded tail piece ends receive standard 3/4" male-threaded pipe, nipples, or MPT fittings, while the union nut and O-ring face provide the removable, resealable interface at the union body itself.

The three-piece construction — two FPT tail pieces and a threaded union nut — defines the operational logic of the 498-007. Each tail piece threads permanently onto the male-threaded components on its side of the union — nipple ends, MPT adapter ends, or threaded pipe ends — integrating into the surrounding threaded assembly on both sides. The union nut threads over one tail piece body and draws the two opposing faces together, compressing the O-ring between them to form a leak-free pressure seal. When the joint must be opened — for pump servicing, filter cartridge replacement, valve removal, equipment swap-out, or system modification — the nut backs off, the two tail piece faces separate, and the union opens cleanly. The threaded piping on both sides remains undisturbed and fully intact.

Correct product selection at 3/4" Schedule 40 requires distinguishing among the available union configurations. The 498-007 FPT × FPT union belongs in threaded Schedule 40 systems — both tail pieces receive male-threaded components, making it the correct union wherever both sides of the removable joint are threaded pipe, nipples, or MPT fittings. The 497-series Slip × Slip union, by contrast, belongs in solvent-welded Schedule 40 systems where both tail pieces cement onto plain pipe ends. When the surrounding piping is threaded rather than solvent-welded, the 498 is the correct selection. Schedule also matters: the 898-series Schedule 80 FPT × FPT union serves identical threaded connection requirements at higher system pressure ratings in dark gray Schedule 80 PVC; the 498-007 serves the same threaded union function at the Schedule 40 pressure rating in white PVC, and is the correct specification wherever the system is built in Schedule 40 and the union assembly pressure rating is sufficient for the application.

At 3/4", the 498-007 serves a pipe size common across residential and light commercial irrigation systems, agricultural water supply, small equipment connections, and light industrial threaded PVC assemblies — all environments where Schedule 40 construction is standard and the union's primary value is providing a serviceable disconnection point within an otherwise permanent threaded assembly. In irrigation systems, this union appears at control valve connections, filter station assemblies, and pump discharge runs where seasonal maintenance, component replacement, and winterization require routine disconnection of individual components from the threaded line. In equipment and chemical dosing assemblies, it provides the clean break point that allows metering pumps, filter housings, and chemical feed equipment to be isolated and removed without wrenching apart threaded joints throughout the surrounding assembly.

The O-ring seal at the union face provides reliable, repeatable sealing through multiple disassembly and reassembly cycles. The elastomeric O-ring conforms to both mating faces under compression from the union nut, producing a pressure-tight seal that remains consistent regardless of minor variations in make-up torque or face surface condition across service cycles. This repeatability is particularly important in applications — irrigation systems, filter stations, chemical dosing assemblies — where the union may be opened and closed multiple times per season.

Manufactured in white Schedule 40 PVC, this union delivers reliable performance across residential, commercial, light industrial, and agricultural piping applications. PVC's resistance to acids, bases, salts, chlorine, and common process fluids provides long service life in environments where metal unions would corrode, seize on threads, or require replacement due to thread damage from repeated assembly cycles. NSF/ANSI 61 and NSF/ANSI 14 listings confirm suitability for potable water contact.

Apply PTFE tape or compatible thread sealant to all male threads before engaging either FPT tail piece end — both the initial assembly into the surrounding threaded piping and any reassembly after disassembly. The union nut should be tightened firmly by hand to seat the O-ring; use a strap wrench if needed, but avoid mechanical over-torquing of the nut body, as excessive force risks cracking the Schedule 40 PVC nut at the thread engagement zone. Inspect the O-ring for cuts, swelling, chemical degradation, or compression set during each disassembly; replace before reassembly if any deterioration is visible. Apply published pressure derating factors for service temperatures above 73°F.

Specifications:

Industries & Applications:

• Irrigation & Landscape Systems — The defining application for 3/4" Schedule 40 FPT × FPT unions: installs at control valve connections, filter station assemblies, pump discharge runs, and fertigation equipment interfaces on 3/4" Schedule 40 threaded irrigation lines where seasonal maintenance, winterization, and component replacement require routine disconnection from the threaded system without disturbing adjacent piping; the FPT tail pieces thread directly onto the MPT ends of valve bodies, filter housings, and pump ports without adapters
• Agricultural Water Supply — Provides removable joints at pump connections, filter housing assemblies, chemical injection equipment, and zone control valve bodies on 3/4" Schedule 40 threaded PVC water supply lines in agricultural irrigation, greenhouse, and nursery systems where seasonal service intervals and equipment replacement require a reliable disconnection point in the threaded line
• Residential & Light Commercial Plumbing — Creates serviceable break points in 3/4" Schedule 40 PVC threaded branch supply lines, water heater connections, pressure-reducing valve assemblies, and fixture supply runs in residential and light commercial building systems where future component access, equipment replacement, or system modification is anticipated and a removable joint is preferable to threading apart the entire assembly
• Chemical Dosing & Injection Systems — Provides a removable threaded connection at metering pump outlets, back-pressure valve assemblies, chemical injection equipment ports, and dosing manifold connections on 3/4" Schedule 40 PVC chemical feed lines where regular calibration, chemical compatibility maintenance, and equipment service require routine disconnection of dosing components from the threaded piping system
• Pool, Spa & Aquaculture — Installs at pump connections, filter vessel inlet and outlet ports, multiport valve connections, and heater supply lines on 3/4" Schedule 40 PVC threaded pool and spa piping where routine equipment service, filter media replacement, and seasonal winterization require accessible disconnection points within the threaded system without cutting pipe or wrenching apart threaded joints throughout the assembly
• Water Treatment & Filtration — Provides removable threaded connections at filter housing assemblies, softener valve connections, UV system ports, and small equipment interfaces on 3/4" Schedule 40 PVC threaded water treatment and point-of-use filtration systems where filter change intervals and equipment service require periodic disconnection and reassembly at the union position
• Light Industrial Process Piping — Creates accessible disconnection points on 3/4" Schedule 40 PVC threaded process lines at metering equipment connections, sampling valve assemblies, and small process equipment interfaces in light manufacturing, laboratory, and agricultural chemical handling systems where the Schedule 40 union pressure rating is sufficient and the white PVC construction is compatible with the service fluid