Union (O-Ring Type), Slip x FPT PVC Schedule 80 1-1/4" (899-012)

The 899-012 is a 1-1/4" Schedule 80 PVC Union with an O-ring seal, featuring a Slip socket inlet and a Female Pipe Thread (FPT) outlet. This is a mixed-connection union — the slip side accepts solvent cement for a permanent bond to a 1-1/4" PVC pipe run, while the FPT side threads directly onto any male-threaded (MPT) fitting, valve, pump port, or equipment connection downstream. Between these two permanent connections sits the union joint itself: a threaded union nut and O-ring assembly that can be loosened and separated at any time to break the line at that point — for equipment removal, valve replacement, pump service, or system modification — without cutting pipe, disturbing the cemented upstream joint, or unthreading the downstream MPT connection.

The Slip x FPT configuration is the bridge union — specifically designed for systems where a cemented PVC pipe run must connect to a threaded equipment port or fitting with a disassemblable joint between them. Where the all-slip union (897 series) places the serviceable break point within a fully cemented pipe run and the FPT x FPT union (898 series) serves fully threaded assemblies, the Slip x FPT union bridges the transition between the two connection worlds: the upstream pipe assembly is cemented PVC; the downstream connection is threaded. The union sits at the exact boundary between these two systems, making it the natural and correct fitting for pump inlet and outlet connections, equipment tie-ins, and valve installations where the supply side is cemented pipe and the equipment side is threaded.

At 1-1/4", the 899-012 serves a specific size tier — smaller than the more commonly specified 1-1/2" and 2" union sizes, but still a standard commercial pipe size encountered in lighter-duty equipment connections, smaller pump installations, chemical dosing systems, and secondary distribution lines where 1-1/4" is the governing pipe size throughout. The Slip x FPT configuration at this size is particularly common on smaller chemical metering pumps, peristaltic dosing equipment, and compact filter assemblies where the equipment manufacturer specifies 1-1/4" MPT inlet and outlet ports and the installer is connecting from a cemented PVC supply line.

The O-ring seal design provides a reliable, leak-resistant pressure seal that outperforms flat-faced union alternatives under sustained operating pressure and repeated assembly and disassembly cycles. As the union nut is tightened, the elastomeric O-ring compresses into its machined seat, creating a positive seal independent of face-to-face contact pressure alone. This makes the O-ring type union the preferred specification in chemical processing, water treatment, and industrial fluid handling applications where the union joint may be disassembled and reassembled multiple times over the service life of the system without degradation of seal performance.

Thread sealant tape (PTFE) or pipe dope rated for PVC service should be applied to the male threads assembled into the FPT outlet before installation. The union nut should be tightened by hand to full engagement and finished with a strap wrench — do not use metal pipe wrenches or channel-lock pliers on the union nut or body. When disassembling, inspect the O-ring for signs of compression set, cracking, or chemical attack before reassembly and replace if any degradation is evident.

Specifications:

⚠️ Note: Apply PTFE thread tape or PVC-compatible pipe dope to all male threads assembled into the FPT outlet before installation. Tighten the union nut with a strap wrench only — do not use metal jaw wrenches on PVC union bodies or nuts. The slip socket is a permanent solvent-weld connection — once cemented, the pipe-side bond cannot be broken without cutting pipe; only the union joint itself is disassemblable. Inspect and replace the O-ring if signs of wear or chemical degradation are observed before returning the union to service after disassembly. Pressure ratings decrease at elevated temperatures; consult manufacturer derating tables for high-temperature service.

Industries & Applications:

• Chemical Processing — Bridges a cemented 1-1/4" PVC chemical feed or distribution line to a threaded chemical metering pump, dosing equipment port, or injection fitting with a disassemblable O-ring union joint, allowing the equipment to be removed for maintenance or replacement without disturbing the cemented supply line or unthreading the equipment port connection
• Water & Wastewater Treatment — Used at chemical dosing pump connections, small filter inlets and outlets, and instrumentation tie-ins on treatment plant piping where a 1-1/4" cemented supply line must connect to a threaded equipment port with a serviceable union joint between them for routine maintenance access
• Industrial Process Piping — Installed at the transition point between cemented 1-1/4" PVC process lines and threaded equipment ports, valves, and inline instruments on plant piping and skid assemblies where the union provides the designed break point for equipment removal without modifying the surrounding permanent piping
• Pump Station & Equipment Connections — The primary application at this size — installed on the suction and discharge sides of small pump connections where the supply and return lines are cemented PVC and the pump inlet and outlet ports are male-threaded, with the Slip x FPT union bridging both connection types at each side of the pump while providing the disassembly point for pump removal
• Irrigation & Agricultural Systems — Connects cemented 1-1/4" PVC supply lines to threaded chemical injection pumps, fertilizer dosing equipment, and small filter assemblies on pressurized irrigation systems where the equipment must be periodically removed for service or replacement without cutting into the cemented piping assembly
• Aquaculture & Commercial Pool/Spa — Applied at chemical dosing equipment connections, small recirculating pump inlets and outlets, and filter tie-ins on recirculating water systems where corrosion-resistant PVC is specified throughout and the Slip x FPT union bridges the cemented pipe system to threaded equipment ports with a serviceable joint at each connection point