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Long radius elbows

The long radius elbow is the elbow which the radius of curvature of is 1.5 times the diameter of the pipe.  In a long radius elbow, the centreline radius is 1.5 times the nominal size of the pipe or you can say 1.5 times the diameter of the pipe. Normally long radius elbows are used in piping as pressure loss is less as compared to short radius elbow. It required more space than a short radius elbow.

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Description

The long radius elbow is the elbow which the radius of curvature of is 1.5 times the diameter of the pipe.  In a long radius elbow, the centreline radius is 1.5 times the nominal size of the pipe or you can say 1.5 times the diameter of the pipe. Normally long radius elbows are used in piping as pressure loss is less as compared to short radius elbow. It required more space than a short radius elbow.

What is the radius of curvature?

Radius of curvature is the curvature of a curve. The curvature of a plane curve is defined as the rotation rate of the tangent angle of a point on the curve to the length of the arc. It is defined by differentiation and it shows the degree of the curve deviating from the line. The reciprocal of curvature is the radius of curvature. The radius of curvature is mainly used to describe the extent of curvature variation of a point on a curve.

Technical requirements for the long radius elbow

It is required that the radius of curvature should be controlled. For example, if the radius is 1.5D, then the radius of curvature must be within the required tolerance range. Because most of these pipe fittings are used for welding, in order to improve the quality of welding, the end will be turned into the groove and it will keep the certain angle and edge. This requirement is quite strict, and the thickness of the edge, the angle as well as the deviation range are all defined. There are more requirements on the physical dimension of long radius elbows than those on the pipe fittings. The surface quality and mechanical properties of the elbow are almost the same as the pipe’s. To facilitate welding, the long radius elbow should be made of the same kind material of the pipe to be connected.

Long Radius Elbow VS Short Radius Elbow

The elbow is divided into its radius of curvature and can be divided into a long radius elbow and a short radius elbow. The long radius elbow refers to the outer diameter of the tube whose radius of curvature is equal to 1.5 times, that is, R = 1.5D. A short radius elbow means that its radius of curvature is equal to the outer diameter of the tube, ie R = D. Where D is the diameter of the elbow and R is the radius of curvature. Normal use of the length of the radius Sometimes to reduce the loss of resistance or elbow wear, the elbow with a larger bending radius will be used (in fact, it is not called elbow); when there is a limit on the installation position, a short radius elbow will be used.

When to choose a long radius elbow or a short radius elbow?

There are two types of pipe sizes for process installation, namely pipe outer diameter and nominal size. D, DN, refers to the nominal size of the pipe. It does not represent the inner diameter of the pipe or the outer diameter of the pipe. It is a nominal size designed and used. The elbow is the elbow, and the manufacturing method is divided into the push elbow, the extrusion elbow and the welded miter elbow. The structure length is 1.0D, 1.5D, 2.0D.

At present, there are two kinds of norms implemented in this area in China: metric and imperial. For example: 1.5D steel seamless elbow, DN100 outer diameter ¢108 and ¢114.3, actual structural length L152, DN200 outer diameter ¢219 and ¢216.3, actual structural length L302. In use, long radius elbow (R = 15DN): in general, should be preferred; short radius elbow (R = 1.0DN): mostly used in applications where size is limited. Its high working pressure should not exceed 0.8 times of the long radius elbow of the same specification.

Elbow (R=nDN): used to moderate the scouring and kinetic energy of the media at the bend, available to R=3DN, 6DN, 10DN, 20DN. According to different manufacturing methods, it is divided into push elbow, extrusion elbow and welded miter elbow.

Pushing elbows and extrusion elbows: Commonly used for welding mitered elbows on medium and small-sized pipes with strict media conditions: It is often used on large-sized pipes with moderate media conditions, and the bending radius is not to be less than its nominal diameter. 1.5 times. When the miter angle of the miter elbow is greater than 450, it should not be used on highly toxic, flammable medium pipes, or on pipes subjected to mechanical vibration, pressure pulsation and alternating load due to temperature changes.

So how do we buy qualified elbows? Detecting the back arc of the elbow: Seamless elbow detection of the thickness of the back arc is an important task. Many large pipe elbow manufacturers or strict engineering inspection of the back arc is a must. It is related to the safety and stability of the pipeline operation.

Everyone knows that both the seamless steel pipe and the seamless elbow are under pressure, that is, the pressure is very large when running. Under normal circumstances, the safety factor of the thickness of the seamless elbow designed and installed is about six times. For example, the 219*8 seamless elbow, the pipeline medium is ordinary water, the temperature is usually not higher than one hundred degrees Celsius, and the pressure required to blast such a seamless elbow is about 300 kg, that is to say, The pressure inside the pipeline needs to reach PN30, and the seamless elbow will be blasted, and the operating pressure of this elbow is probably about it. It is estimated that the maximum will not exceed PN6.4, which is generally around PN4.0, of course. With the corrosion of the pipeline, the seamless elbow will also be corroded to varying degrees. In order to ensure its safe operation, the necessity of overhaul is also great.

The current process of making seamless elbows will lead to the phenomenon of back arc thinning. Under normal circumstances, the wall thickness of the mouth will be about two millimeters thinner than the back arc. The common thickness and pressure are not thinner even if the back arc is thinned. There will be too many safety hazards, because the elbow has not been replaced until the elbow has a dangerous accident. But as a rigorous project, what is not the same, and the medium inside the pipeline is also responsible, not just water. There may be oil or other impurities, the temperature is high and the pressure is high, and the thickness of the back arc as the weak place determines the life of the seamless elbow. Therefore, the importance of detecting the back arc is naturally great. With the thickness gauge, read the thickness of a point at the elbow directly.

Features of long radius elbow

Long radius elbows are designed to provide a smooth radius transition between two pipes, and they come in a variety of sizes and styles.

They are often used in industrial applications where there’s a need to change the direction of the flow of liquids or gases, but they’re also useful in residential plumbing projects.

The most common long radius elbow is the 180° bend, which can be used in both horizontal and vertical applications. It has an internal angle of 180°, which means that it’s shaped like a U when viewed from above. The holes on either side of the U allow for easy installation with screws or bolts.

The 90° elbow is another popular choice because it can be used in both straight-run and corner installations. It has an internal angle of 90° and features two holes on either side for attaching it to other pipes via fasteners or clamps.

Applications of long radius elbow

This elbow is commonly used in industrial applications, such as the transport of raw materials, where the material needs to be transported from one location to another. The long radius elbow helps to minimize the change in direction that would otherwise occur if a short radius elbow were used. This minimizes turbulence and allows for the more efficient flow of materials through the system.

Another application for long radius elbows is in plumbing systems. These elbows can be used on pipes that lead up to toilets or sinks, reducing turbulence and allowing water or other liquids to flow smoothly without splashing or spilling out of the pipe.

Long radius elbows are also commonly found in cooling towers, where they help reduce turbulence within the tower and improve overall efficiency by allowing more even heat exchange between air and water molecules (or other liquids).