How to make high quality copper elbow

How to make high quality copper elbow?

This article presents several methods of positioning copper elbows with examples that are relatively simple and can quickly produce high-quality, dimensionally accurate copper elbows from copper tubing without creasing or ovaling.

20211013080927 45032 - How to make high quality copper elbow

When making copper elbows, bending springs are used to support the copper pipe wall. The bent spring is suitable for all copper pipe diameters from 10 to 22 mm in Table X and Table Y of BS2871 standard, and the maximum recommended copper pipe diameter for using the bent spring is 22 mm. With careful handling, semi-rigid copper tubes up to 22mm in diameter in Table X can be bent by hand without softening. Although most people who deal with copper tubing know that some of it is produced to British Standards, not as many people seem to know that there is a corresponding British Standard for bent springs (BS5431), according to which the correct size bent spring can be obtained for use with a wide range of copper tube diameters and wall thicknesses.
It is important to use the correct size bend spring to support the wall of the copper pipe when bending. If you use a bent spring that is too small, you can create creases and even break a very good quality copper tube during bending. Another common cause of copper tube breakage during bending is the use of rusty bend springs. Applying a small amount of grease or oil to the bending spring before use will not only help the operation of the bend, but will also extend the life of the bending spring.

The importance of scribing

When bending a copper pipe, it is beneficial to scribe the bend section, for example, the copper elbow can be positioned more precisely, which saves copper pipe and time, plus the copper elbow can be made to the correct bend radius so that wrinkles do not easily occur inside the copper elbow. There are two factors to consider when laying out the copper pipe, these are the “elongation” of the material when making the bend and the bend point. When a copper pipe is bent to go around a corner or obstruction, the copper pipe takes a shortcut, so the copper pipe elongates. The actual elongation of the copper tube depends on the corner of the bend and the bend radius used, which in turn depends on the diameter of the copper tube.
The bend radius of the copper elbow, which is usually made using a bending spring, is equal to four times the outside diameter of the copper pipe, which is slightly larger than the bend radius of a standard copper pipe bender, but the bend radius of four times the copper pipe diameter is chosen to make the arrangement of the copper pipe simpler. It should be noted that for all sizes of copper pipe bend radius measured along the inside of the copper elbow must not be less than 3 times the diameter of the copper pipe.

Accuracy of installing bending springs

For example, to scribe the bend section of a bend spring bent 90° copper elbow on a 22 mm diameter copper pipe with a distance of 200 mm from one end of the copper pipe to the center line of the bend, first, scribe the location of the measured distance, which in this case is 200 mm from the end of the copper pipe.
Then, determine the bend radius, usually the bend radius is 4 times the diameter of the copper pipe.
Now draw the beginning of the bending section, the location of the first line back 4 times the diameter of the copper pipe (88mm or 1 times the bending radius). The last to be drawn is the end of the bending section, its location for the first line forward 2 times the diameter of the copper pipe (44mm or bending half
half the bend radius). Next, insert the correct size lubricated bend spring and bend the copper tube to the desired angle.

Bending Point

For copper elbows with a bend radius equal to 4 times the copper pipe diameter, the “elongation” of the copper pipe is 1 time the copper pipe diameter. The bend point of a 90° copper elbow, which is located one time the diameter of the copper tube back from the measured distance, is the midpoint of the copper elbow and the location where the block is placed when the copper elbow is made with the knee block.

Extraction of the force of the bending spring

When making the copper elbow, the inside and outside of the copper elbow are pressed tightly against the bend yellow, pinning it to death, so in order to make it easier to remove the bend yellow, the angle of the bend when making the copper elbow should be slightly larger than the angle needed, and then pulled back to the correct angle needed. This will eliminate the pressure acting on the spring, so that it can be drawn out without any trouble. If a small torque is applied in the direction of the bent yellow winding when drawing the bent yellow, the torque acts to reduce the diameter of the bent yellow so that it can be drawn out more easily.
When making an copper elbow less than 90°, whether it is an copper elbow or a pair of copper elbows or a metabolic bend, the “elongation” will be relatively reduced. If an copper elbow turned at an angle of 45 °, the bending point in the measured distance back half the diameter of the copper pipe.
Similarly, the length of the bending section is also half of the 90 ° copper elbow, so the bend starts at the measured distance backward 2 times the diameter, the end of the measured distance forward 1 times the diameter of the copper pipe.
90 ° and 45 ° copper elbow positioning method can also be part or the entire production of Yuan Bao bend. When making a metabolic bend to pay attention to if the copper pipe needs to be insulated, should leave sufficient spacing, especially when using the insulation thickness specified in the water supply specifications.
Compared with the bender bend, the advantage of using the bend yellow to make the copper elbow is that the bend radius is variable, so that the copper pipe spacing at the copper elbow can be kept consistent, so that the appearance of the copper elbow is improved. Because the bending radius is concentric, the two copper tubes match each other and the spacing is uniform.
It is possible to know how to determine the bend radius of the outside copper elbow, and once the bend radius is determined, the beginning and end of the bend of the 90° copper elbow can be easily delineated as described earlier.

How do I weld copper pipe to the copper elbow?

A metal like copper could be attached using several processes. For instance, soldering, brazing, and welding are key joining processes. Choosing the method of connection depends on the type of alloy used, the strength requirements, as well as the application.

Pure copper is pliable and forming components from this metal is effortless. In comparison to other alloys (including Cu alloys), the pure metal is not hardenable like regular steel-grades because there is no change in their phase. The application of heat melts or softens this metal. As a result, unalloyed Cu components lose their strength, especially in HAZ or heat affected zones. It has a high rate of thermal conductivity. Therefore, forging any joint requires a pre-heat treatment, even if the thickness is moderate at best. Furthermore, the distortion of the component could be a problem due to a higher coefficient of thermal expansion. The issue occurs expressly on the closure of gaps during welding.

weld - How to make high quality copper elbow


This welding process is apt for systems that have a thicker wall thickness, and when the material to be attached is the same. The temperature for this process is the highest amongst all the three techniques. Typically methods such as gas tungsten arc, Electric resistance, Oxy-fuel, submerged arc, or shielded metal arc aid to weld this metal.


Similar to soldering, the difference in this mechanical process is the temperature of the melted filler metal, for this operation is higher than a solder. Though HVAC systems require a secure connection, it is ok to either braze or solder the copper tube.

In instances where fittings, like the copper elbow, are of another alloy or metal grade, a solder performs the task adequately. An copper elbow is a variety of fitting that influences change in the direction of flow. Commonly copper elbows influence the directional flow at angles of 22.5, 45, and 90 degrees. Generally, fittings like the copper elbow are a part of a piping system via internal threads, as both the copper tube and fitting are products that have internal threads. However, unlike other materials, a copper pipe in a copper-based HVAC system tends to be soft and weak to form a threaded connection. Hence, the copper elbows are attached to an arrangement by exercising a sweat connection. In such an organization, the copper elbow fitting has a bore constructed a little larger than the copper tube. A slight enlargement of the fitting makes it easier to slip on to the copper pipe. Once the copper elbow fitting slips over it, the nexus is soldered.


The term sweat connection obtains its name from the process it undergoes. The attachment of the fitting or the copper elbow is by the heat received when exposed to a propane torch. The heat treatment causes the metals to melt and fuse. Therefore a leak-free and tightly integrated joint is obtained. Using this method is an efficient way to join thinner cross-sections even if both the fitting and copper pipe vary.

Following a strict method ensures good quality welds between the fitting and the copper pipe. First, the welder needs to polish and smoothen the copper tube with the use of an emery cloth or a woven abrasive pad. Any synthetic material abrasive woven pad can clean copper. Once the surface is free from blemishes, using a flux brush, the application of a layer of flux is the next step. After the removal of excess flux, the torch flame directly heats the fitting. The flux in the fitting acts as a guide by bubbling, which in turn causes steam. Once the solder on the copper pipe melts, it is adequately hot. Different areas of the fitting joints could make an efficient soldered connection. Once the joint is sufficiently cold, the piping system can undergo a test. A leak in the system would require reheating up to the point when the solder melts and joint disassembly. Following the joint disassembly, the welder will have to clean, flux, heat as well as solder them again.

Source: China Copper Elbows Manufacturer – Yaang Pipe Industry Co., Limited (

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

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