How to Build a Swing Joint On Site

A swing joint is the flexible connection between a buried lateral line and a sprinkler head. It does two jobs at once: it lets you set the head to the exact height and angle the site needs, and it absorbs mower blades, foot traffic, and ground shift by flexing — instead of transmitting that impact into rigid pipe, which cracks. Building one on site from loose components costs little and lets you tune the length to any head location. This guide walks through that build, plus the drop-in alternative.

What you need

• Swing pipe / funny pipe coil — flexible LDPE tubing (.690” OD x .490” ID), sold in 100 ft coils. This is the part that bends. New to it? See what funny pipe is.
• Celcon M90 funny-pipe insert fittings and male elbows — the barbed inserts that push into each end of the pipe.
• A Marlex street ell — an HDPE 90-degree male-by-female fitting whose self-lubricating thread makes a leak-free turn up to the head.
• Black PVC male adapters and poly cut-off risers as needed to reach the head and trim it to final height.
• Available in ½” and ¾” sizes.

Prefer not to build one? Innovative Plastics also stocks pre-assembled swing joint assemblies in 6” or 12” tubing with 1- or 3-ell configurations, dimensionally compatible with Rain Bird SA-series swing joints (SA5 / SA65 / SA125050).

Step-by-step

1. Cut the funny pipe to length from the coil — long enough to route from the lateral line to the head with a little slack for the bend. Make a clean, square cut.
2. Insert a fitting into each end, pushing a funny-pipe insert fitting or male elbow fully into the pipe so the barbs grip the inside wall. No glue or clamp is needed on the funny-pipe side.
3. Connect the lateral-line end by threading the fitting into the lateral-line fitting or saddle. Start it by hand and snug gently — do not overtighten threaded connections on plastic.
4. Connect the head end through a street ell, joining the riser or a Marlex street ell under the head. Its self-lubricating thread makes a leak-free 90-degree turn up to the sprinkler.
5. Set to grade and check for leaks — bend the funny pipe to position the head, set it flush to grade and square to the surrounding area, then pressurize the zone and inspect every connection.

Why the funny pipe matters

The flexibility lives in the funny pipe. Because the barbed inserts simply push in, you can route the head around obstacles, dial in its exact position, and let the pipe flex when something strikes the head at grade. That same flex is why a swing joint outlasts a hard-piped riser in turf that gets mowed. Keep the threaded ends hand-tight, trim the riser with a poly cut-off riser if you need to fine-tune height, and the assembly will seat the head clean and leak-free.

For a drop-in alternative, the pre-assembled swing joint assemblies cover the most common head heights and ell counts. Innovative Plastics Manufacturing is not affiliated with or endorsed by Rain Bird; that name is used only to describe dimensional compatibility. Always follow the sprinkler manufacturer’s installation guidance for your specific head.