Short definition
A pipe fitting is any component that changes direction (elbow, return bend), branches a system (tee, wye, cross), changes size (reducer, bushing), terminates a pipe (cap, plug), or joins same-size pipes (coupling, union). Available in every pipe material — brass, malleable iron, copper, PVC, ABS, CPVC, PEX-compatible brass and poly, no-hub stainless-band — and in every joining method.
What it is
Every plumbing system is pipe plus fittings. The fitting class tells you what the connection is doing; the joining method tells you how it’s made:
- Joining methods. Threaded (galvanized, black iron, brass), socket / sweat (copper soldered), solvent-welded (PVC, ABS, CPVC glued), crimped or expansion (PEX), push-fit (no-tool quick-connect), banded compression (Fernco / no-hub).
- Functional categories. Direction change (elbows), branching (tees, wyes, crosses), size change (reducers, bushings), termination (caps, plugs), same-size joining (couplings, unions, dielectric unions).
A fitting is a passive routing element — it doesn’t control flow. A valve is the active counterpart that opens, closes, throttles, or checks flow.
Why it matters to a homeowner
Reading a repipe quote, “fittings” is the line item that adds up surprisingly fast — every elbow, every tee, every transition costs a few dollars on its own and adds up across a whole-house repipe. Understanding the categories also matters when buying parts: if you know whether you need a 90-degree direction change or a tee branch, and whether your pipe is sweat copper or PEX-B crimp, you can find the right shelf without wandering the aisle.