Standard: ASTM B16.9/16.5/16.47A/16.47B B2220 – 2001, SH3408, SH3409,GBT12459, GB/T13401

Production process: Cold extrusion & Hot extrusion forming.

Type: 45º,  (R=1D, 1.5D, 3D, 5D,6D,8D...),

Dimension: 1/8" to 48"

Material: Carbon steel, Alloy Steel, Stainless steel.

Long Radius and Short Radius

The elbows are divided into two groups which define the distance at which they change direction; the centerline at one end to the other side. This is called the center to face distance and corresponds to the radius of the elbow bend.

The center-to-face distance for long radius elbows, abbreviated LR is always 1.1/2 x Nominal Pipe Size (NPS) (1.1/2D), while the center-to-face distance for short radius elbows, abbreviated SR even is the nominal pipe size.

45° Elbow

A 45° elbow has the same function as a 90° elbow, but the dimensional measurements are different from those of a 90° elbow.

The radius of a 45° elbow is the same as that of a 90° LR (1.1/2D). However, the center-to-face dimension is not equal to the radius in the 90° LR elbow. This is measured from the intersection of each face to the center line perpendicular to each other at a distance of B on the image. this is due to the smaller curvature. Short radius 45° elbows are not available.

Standard Elbows

The most used versions are 90° long radius and 45° elbows, or 90° short radius elbows if space is too small. 180° elbows function by changing the direction of flow through 180°. Both LR and SR types have twice the center-to-center dimension of the matching 90° elbow. These fittings are typically used for stoves or other heating or cooling devices.

In addition to the defined elbows, there is also a reducer elbow, which is an elbow with different diameters at each end. Since this elbow is not a standard product for many suppliers, it can be expensive and take a long time to deliver. If the situation permits, using a plain elbow with a separate reduction gear is an option.

Elbows of other degrees can be machined from standard elbows. Longer radius types, such as center-to-end dimensions that are three times the nominal size (3D), are even available.

Dimensions, dimensional tolerances, etc. for long and short radius elbows are defined in ASME B16.9.

Elbow Wall Thickness

The weakest point of the elbow is the inside radius. asme B16.9 standardizes only the center face dimensions and some verticality dimensional tolerances. The wall thickness is even standardized at the weld line location, but not for the rest of the elbow. The standard specifies that the minimum tolerance will be within 12.5% of the minimum ordered wall thickness of the pipe. Maximum tolerances are specified only at the end of the fitting.