Elbow — fitting that changes direction in pipe runs

An elbow is a pipe fitting that changes the direction of a plumbing, gas, or HVAC line.

Elbow diagram — labeled parts, dimensions, and installation context

What It Is

Elbows let a piping system turn around corners or shift direction without bending the pipe itself. They are made in common angles such as 90 degrees and 45 degrees and are available in many materials and connection styles.

The exact elbow used affects flow, fit, and serviceability. Tight turns, long-sweep elbows, and threaded or solvent-weld joints all serve different installation needs.

Types

Common types include 90-degree elbows, 45-degree elbows, street elbows, long-sweep elbows, and reducing elbows. Plumbing drain systems often use long-sweep versions, while supply piping may use compact pressure-rated fittings.

Where It Is Used

Elbows are used in water supply piping, drain and vent systems, gas piping, condensate lines, and HVAC refrigerant or duct connections. They appear anywhere a straight run needs to change direction.

How to Identify One

Look for a curved or angled fitting between two straight pipe segments. The fitting is usually slightly bulkier than the pipe itself and clearly marks the turn.

Replacement

Replacement is needed when the elbow cracks, corrodes, leaks at the joint, or is the wrong type for the system. Repairs may require cutting out the fitting and reconnecting the line with new joints.

Elbow — FAQ

What does an elbow fitting do?

It changes the direction of a pipe run. That allows the system to route around framing, equipment, and corners without kinking the pipe.

What is the difference between a 90 and a 45 elbow?

A 90-degree elbow makes a sharper turn, while a 45-degree elbow makes a gentler one. The gentler turn can improve flow in some drain and piping layouts.

Can a leaking elbow be repaired?

Sometimes the joint can be tightened or resealed, but many leaks require replacing the fitting. The right fix depends on whether the elbow is threaded, glued, soldered, or pressed.

Are plumbing elbows and HVAC elbows the same?

Not always. The shape may be similar, but the material, pressure rating, and connection type differ depending on whether the system carries water, air, refrigerant, or gas.