Common Pipe Fittings — Names, Uses & Selection Gui

Standard names of pipe fittings and what they mean

Pipe fittings are named by their shape and function. Below are the most common names you'll encounter on drawings, material lists, and when buying parts:

• Elbow — changes direction (commonly 45° and 90°).
• Tee — splits or joins flow in three directions (run and branch).
• Cross — four-way junction used where four pipes intersect.
• Coupling — straight connector that joins two pipes of the same diameter.
• Union — removable coupling that allows disassembly without cutting pipe.
• Nipple — short length of pipe, usually threaded both ends, used as a connector.
• Adapter — changes joint type or thread to fit different systems (e.g., female-to-male, NPT to BSP).
• Bushing — reduces a hub or fitting bore to accept a smaller pipe.
• Cap — closes the end of a pipe (permanent or threaded).
• Plug — inserts into a threaded opening to stop flow (generally removable).
• Flange — flat rim used to bolt two pipe ends or pieces together; many flange types exist.
• Valve (ball, gate, globe, check, butterfly) — controls flow (on/off or throttling).
• Compression fitting — uses a ferrule and nut to seal tubular connections without soldering.
• Compression ferrule / sleeve — the small ring inside a compression fitting providing the seal.
• Sweat/Solder fitting — used with copper pipe; joint is formed by soldering (cap, coupling, elbow variants).
• Press fitting — mechanical joint made by crimping or pressing with special tools (common in modern plumbing).
• Reducing fitting (reducer, reducing elbow, reducing tee) — connects pipes of different diameters.
• Street fitting (street elbow, street tee) — one end has a male thread and the other a female thread to save space.

Detailed descriptions and practical differences

Knowing a fitting's common name is only half the job — you must also understand the variants and how they affect installation, flow and maintenance. Below are concise, practical descriptions for key fittings.

Elbows (45° vs 90° and long-radius vs short-radius)

Elbows change pipe direction. A 90° elbow gives a sharp turn and may increase pressure loss; long-radius elbows (1.5× diameter radius) reduce turbulence compared with short-radius (1× diameter). Choose long-radius where flow efficiency or solids handling matters.

Tees, reducing tees and crosses

A tee provides a branch off a main run. A reducing tee connects a branch of different size. Crosses are rare in pressurized systems due to stress concentration but used in low-pressure or structural applications.

Unions vs couplings

Couplings are permanent or semi-permanent connectors. Unions are designed for disassembly — used where equipment must be frequently removed (pumps, meters). Unions add length and cost but save labor later.

Common materials and naming variations by material

Fitting names stay similar across materials, but selection, joining methods, and pressure ratings change with material. Typical materials and special notes follow.

• Copper fittings — often called sweat fittings; joined by soldering or press systems for potable water.
• PVC/CPVC fittings — called solvent-weld fittings; glued and used for drainage, irrigation, and hot/cold water (CPVC).
• Steel (carbon/stainless) fittings — threaded, welded or flanged; names like elbow, tee, reducer still apply but joining methods differ.
• Ductile iron or cast iron fittings — common in mains and drainage; many fittings are flanged or mechanical joint types.
• PEX fittings — crimp or expansion style fittings; names include elbow, tee, adapter but the joining method is specific to PEX systems.

Quick reference table: common fittings, description, typical joining method, typical use

How to read fitting names on drawings and material lists

Drawings and BOMs use short codes. Examples: "EL 90 SS" = 90° elbow stainless steel; "RED TEE 4"x2"" = reducing tee from 4" run to 2" branch. Be careful about thread standards (NPT, BSP) and face or end preparations (flanged, butt-weld, socket weld).

Selection tips: size, pressure rating and connection type

When selecting fittings, verify: pipe size (nominal vs actual OD), material compatibility with media and temperature, pressure rating (class or schedule), and the joining method that matches site equipment and installer capability.

Size and schedule vs OD

"Nominal pipe size" is a label — the actual outside diameter depends on schedule and standard. Always match fittings to the pipe standard (e.g., 1" schedule 40 steel) rather than nominal size alone.

Pressure class and material

A fitting's pressure capacity can vary by material and temperature. Flanges are often specified by "class" (e.g., 150, 300); valves and fittings should meet or exceed the system MAWP (maximum allowable working pressure).

Installation and maintenance considerations tied to fitting type

Correct installation extends life and reduces leaks. Examples: soldered copper joints require clean surfaces and proper flux; pressed fittings require certified crimp tools; threaded steel fittings need correct sealant and torque; welding requires qualified procedures.

• Always deburr and clean pipe ends before joining to avoid flow disturbances and ensure seals seat properly.
• Use the proper gasket material for flanged joints (consider chemical compatibility and temperature limits).
• When replacing fittings, match the connection type (welded vs threaded vs pressed) to avoid incompatible joints.
• Label critical fittings (e.g., isolation valves, check valves) for quicker shutdown and maintenance actions.

Common naming pitfalls and how to avoid them

Beware of ambiguous terms: "adapter" may mean male-to-female of the same thread type or a different connection style; "reducer" versus "bushing" — reducers are spooled fittings while bushings thread into a fitting. When in doubt, specify both the geometry and the connection details (e.g., "90° long-radius elbow, 2" SCH40, socket weld, A106B").

Summary: matching names to needs

Learning the standard names of pipe fittings is a small step; the decisive factors are material, joining method, pressure rating and service conditions. Use the names above to communicate precisely with suppliers and installers, and always double-check standards/specifications on critical systems.