Fitting Elbow

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 Plumbing and Piping Elbows

Elbows are used in piping systems to provide a change of direction. Elbows are commonly available in 90° and 45° angles, with 180° angles available but used much less. 90° elbows are commonly referred to as simply “ells,” while 45° elbows are known as “45’s” and 180° elbows are often called “return” elbows. Elbows are typically offered as standard radius (1-D) or long radius (1 ½-D). Standard radius elbows are most common. Long radius elbows are used when less friction to flow is desired. Elbows are manufactured with grooved, flanged, welded or threaded ends.

The standard configuration for threaded elbows features a female connection at each end. In threaded piping elbows, “female” means an internal thread, while “male” means an external thread. Elbows with one female and one male connection are called “street” elbows. This name was derived from their use in water mains, where a tee was installed in front of each house with the branch facing up. The male end of a street elbow could be threaded directly into the tee, eliminated the need for a short nipple. Flanged, welded, and grooved elbows are the same on both ends – there is no male or female.

Critical dimensions for elbows are the size (diameter) and the center-to-end (C-E).  The C-E represents the radius of the bend and the respective centerline offsets and cut-out dimensions for the fittings. Standard elbows are the same size at each end, though “reducing” elbows are available in both standard and street configurations for use with pipes of different dimensions. Special adapter elbows are also available with different connections at each end (e.g., grooved x threaded).

Elbows are most commonly cast of ductile iron or steel.  Fittings can also be fabricated for larger pipe by cutting angled segments from straight steel pipe and welding them together for custom angles. This is extremely expensive because of the high labor cost.

Elbows are also available for other piping materials, such as copper, brass, PEX, PVC, ABS, and the others, with appropriate connections for each.

Drain Waste Vent (DWV) Elbows, or Bends

DWV elbows are also called bends. They are availed in many angles, typically described not by degrees, but by a fraction, the denominator of which is divided into 360 to determine degrees.

  •  1/4 bend = 90°
  • 1/6 bend = 60°
  • 1/8 bend = 45°
  • 1/16 bend = 22 1/2°
  • 1/32 bend = 11 1/4° (these are not common)
  •  An exception to this rule is a return bend, which is 180°.

DWV elbows used specifically for venting are known as vent elbows. Because no liquid flows through these, there is no radius so they make a tighter turn.

Closet bend elbows are used to plumb under a water closet (toilet). They do not form a sharp angle and allow for better flow of toilet drainage. 

Like piping elbows, the DWV elbow standard configuration features a female connection at each end in the form of a hub or socket, into which a pipe can be inserted. Street elbows are available for DWV applications as well, with a hub on one end and a spigot (pipe-size) on the other.


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