45° Short Radius Elbows and Long Radius Elbows

A 45° elbow is a pipe fitting used to change the direction of pipes in a piping system. Pipe elbows are classified by angle: 45°, 90°, and 180°. Depending on the engineering requirements, other non-standard angle elbows, such as 60°, are also included; however, you may have noticed that elbows are also classified by radius. Therefore, 45° elbows are also classified by radius into long radius elbows and short radius elbows.

A long radius elbow is relative to a short radius elbow; the existence of a short radius elbow necessitates the concept of a long radius elbow. 45° Long radius elbows are a more commonly used bend fitting for connecting to pipes or pipelines, often referred to as 1.5D elbows. 45° Short radius elbows are naturally shorter than long radius elbows. They are often referred to as 1D elbows. Short radius elbows are less common than long radius elbows. There are also situations where long radius elbows are used when space is limited, such as in marine engineering conditions.

Similarities between 45° short radius elbows and long radius elbows: 

Short-radius elbows and long-radius elbows share many similarities, for example, they connect to pipelines. Their function is to change the direction of the pipeline; their diameter, angle, material, wall thickness, etc., can remain consistent, etc.

Differences between 45° short radius elbows and long radius elbows:

(1) In terms of elbow length, it is obvious that long-radius elbows are definitely longer than short-radius elbows, by 0.5DN.

(2) In terms of fluid performance, long-radius elbows experience less wear than short-radius elbows, have significantly reduced corrosion, and lower resistance, making them significantly superior to short-radius elbows. Because of their shorter radius, 45° short-radius elbows make sharper turns, resulting in abrupt changes in flow direction, higher resistance, higher pressure loss, and a greater tendency to generate eddies and scouring.

(3) In terms of mechanical performance, short-radius elbows have more concentrated bending stress, resulting in relatively weaker fatigue resistance and pressure bearing capacity; long-radius elbows have a more uniform stress distribution, higher mechanical strength, and are more durable. 

(4) From the perspective of the application range of elbows, generally speaking, long radius elbows (R = 1.5DN) should be the first choice; short radius elbows (R = 1.0DN) are usually used in situations where size is limited. The working pressure should not exceed 0.8 times that of long radius elbows of the same specifications.

(5) Differences in applicable scenarios

45° short radius elbow:
1. Installation locations with limited space
2. Low-pressure systems with low requirements for pressure loss
3. Transporting clean, non-corrosive, and non-abrasive media (such as water, air)

45° long radius elbow:
1. Systems with requirements for pressure loss and flow pattern (such as pump inlets, long-distance pipelines)
2. Transporting abrasive, easily deposited, and high-velocity media (such as slurries, particles)
3. High-pressure and high-fatigue operating conditions

4. Pipelines requiring frequent cleaning or purging

Read more: 45 Degree Welded Elbows