• Posted by: Ines
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The steel pipe elbows are the main part of the pressure piping system used to change the direction of fluid flow. Elbows are used to connect two pipes with the same or different nominal diameters .

In this way the direction of the liquid turns to a specific direction from 45 degrees or 90 degrees. This change in fluid flow direction causes pressure losses to the system due to friction, impact acceleration…

Those elbows allow you to change the pipeline route required to convert corners or fix them in a limited space without permanently high purchase cost.

Classification of Steel Pipe Elbows

Steel pipe elbow can be classified through following various parameters:

Direction Angle

Length and Radius

Connection with Pipe

Material of Construction

The types of pipe elbow depend on the direction of the angle

Depending on the slope of the fluid flow of the pipe , we can divide pipe elbow into different degrees, like 45 degrees, 90 degrees, and 180 degrees.

It is the most common pipe elbow in the piping system. There are also 60 and 120 degrees accompanying some of the special pipe lines.

Types of elbows based on length and radius

The pipe elbow is divided into two groups, which define the distance that the flowing fluid changes direction. The center line from one end to the opposite side  is the so-called “center-to-face” distance. It is equal to the radius of elbow bending.

If the radius is the same as the pipe diameter (Center-to-Face dimension of 1.0 X diameter), it is called a short radius elbow (SR elbow) and is usually used in low-pressure and low-speed pipes or in narrow areas where clearance is the main problem.

If the radius is larger than the pipe diameter (the center to surface size is 1.5 X diameter), then we call it a long radius elbow (LR elbow) for high-pressure and high-flow pipes.

The types of elbows depend on the connection to the tube

Elbows, depending on their connection to the tube, can be classified as a Socket welded elbow ,Threaded elbow and Butt Welded Elbow

Socket welded elbow

The socket elbow is welded to the end of the pipe and fittings.

it has trapezoidal area at the end.

We can insert the end of the pipe in this section (the diameter of the SW elbow matches the diameter of the outer tube), then we do the welding work to combine them together.

So the actual diameter of the elbow end SW is greater than the elbow diameter.

Threaded elbow

Threaded elbow shape is similar to SW elbow, on the inner surface of the trapezoidal section . Formed in a thread it  facilitates installation and removal, also it is ideal for pipe maintenance and repair .

Butt welded elbow

Butt welding elbow is formed by polishing or pressing.

It directly connects with elbow welding and steel tubes

it has tilted ends to facilitate welding.

and it is  mainly used for high temperature and pressure

Types of Elbows based on Material of Construction

By classifying elbows according to their body material,  there are stainless steel elbow, carbon steel elbow, and alloy steel elbow.

stainless steel elbow has higher strength and higher corrosion-resistances.

carbon steel elbow is more resistant to natural disasters because of its strength and it is recyclable .

Alloy Steel Elbow has excellent strength to sustain highly hazardous chemicals and gases. it suits sensitive environment in power generation and nuclear industries.

We classified Pipes and Elbows through various parameters Direction Angle, Length and Radius, Connection with Pipe, Material of Construction.

There are other items that we didn’t mention, like Reducing Elbow, Wall Thickness of Elbows  which are not used on regular basis.

with this simple classification you can be no more confused about elbow descriptions, you will find out what exactly is your need before your purchase. Discover more