What Is a Street Elbow? Male/Female Elbow

Quick Answer

A street elbow (also called a street ell or service ell) is a threaded pipe elbow with a male (MPT) thread on one end and a female (FPT) thread on the other end. This male-female configuration allows the street elbow to thread directly into a fitting, valve, or equipment port without requiring an intermediate pipe nipple. Street elbows are manufactured per ASME B16.11 in 90-degree and 45-degree angles, in sizes NPS 1/8 to NPS 4.

Standard threaded elbows have female threads on both ends (FPT x FPT), requiring a pipe nipple to connect to a fitting or port. The street elbow eliminates this extra piece, reducing joint count and saving space in tight installations.

Street Elbow Specifications

Property	Detail
Standard	ASME B16.11
Configuration	Male NPT x Female NPT
Angles	90° and 45°
Size range	NPS 1/8 to NPS 4
Pressure classes	2000#, 3000#, 6000#
Materials	ASTM A105 (CS), A182 F304/F316 (SS), A182 F11/F22 (alloy)
Manufacturing	Forged and machined

Street Elbow vs Standard Elbow

Feature	Street Elbow (M x F)	Standard Elbow (F x F)
Thread configuration	Male x Female	Female x Female
Direct connection to port	Yes	No (needs pipe nipple)
Joint count	1 joint	2 joints (nipple + elbow)
Offset from port	Minimal	Nipple adds length
Rotational adjustment	Limited (thread engagement fixed)	Nipple length provides flexibility
Use case	Direct connection to fittings/valves	Standard piping direction change

Applications

Street elbows are standard fittings in these scenarios:

• Instrument connections: Directing pressure gauge or transmitter tubing away from the process pipe tap
• Drain valve assemblies: Turning a drain valve outlet downward at a half coupling or threadolet
• Vent assemblies: Directing vent piping upward from a horizontal header connection
• Equipment piping: Connecting directly to pump, compressor, or vessel threaded ports
• Utility piping: Air, water, and nitrogen distribution in small-bore threaded systems
• Fire protection: Sprinkler head connections per NFPA standards

Installation Sequence

A common drain assembly uses a street elbow to redirect flow:

Step	Component	Purpose
1	Half coupling or threadolet welded to header	Branch outlet
2	Gate or ball valve threaded into coupling	Isolation
3	Street elbow threaded into valve outlet	Direction change (point down)
4	Pipe plug or hose connection	End closure or drain hose

This four-component assembly (coupling + valve + street elbow + plug) is one of the most frequently repeated small-bore assemblies in piping construction.

90-Degree vs 45-Degree Street Elbows

Feature	90° Street Elbow	45° Street Elbow
Direction change	Right angle	Diagonal offset
Common use	Vent/drain redirection	Gradual offsets, gauge connections
Pressure drop	Higher	Lower
Space	Compact right-angle turn	Angled offset

Limitations

• Size limit: Practical for NPS 2 and smaller. Above NPS 2, socket weld or buttweld elbows are preferred
• Rotational position: The angular position of the elbow is determined by the thread engagement depth. Fine adjustment requires adding or removing thread sealant wraps
• Not for high-vibration service: The single male thread connection can loosen under vibration. For vibrating equipment, socket weld connections are more reliable
• Pressure class: Must match or exceed the system design pressure per the piping specification

Read the full guide to pipe fittings