Copper welding is more difficult compared to metal welding.
As a result, most people prefer to weld copper pipes using the welding technique.
However, we will show you how to weld copper pipes with the GTAW and GMAW welders.
Copper is a natural metallic form, directly usable or native metal, that does not need to be extracted from its mineral.
Like an old metal, copper’s human use as tools, weapons, or ornaments even preceded the first forms of writing.
The malleability, ductility, and high conductivity of copper and heat make metal a trendy industrial and construction material until today.
Copper is very viable and can become many different end products, such as cables, electric wires, cylinders, and pipes.
Why is it more difficult to weld copper cylinders?
Welding copper pipes can be complicated, if not difficult, due to metal’s excellent conductivity to heat.
This high thermal conductivity is why many artisans prefer welding or welding copper pipes instead of welding them.
This is because copper pipes’ union using strong or welded welding is less complicated and more controllable than the welding of copper pipes.
Besides, the union of copper pipes with welding is cheaper than arc welding. However, the joint resulting from welding or brazing is not as strong as welded copper.
This is because, with welded copper, the copper pieces are joined by fusion.
Types of the arc welding process
Although about five arc welding processes are used today, two welding methods can provide the best weld copper.
These are gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW).
Tungsten gas arc welding (GTAW)
Like most arc welding processes, GTAW welding, more commonly famous as Tungsten Inert Gas (TIG), uses an electric arc to heat and melt the workpiece and the filler.
A protective gas such as helium or Argon is introduced into the torch’s tip to protect the molten solder bath from atmospheric effects as it cools and solidifies.
Unlike most arc welding methods such as armored metal [SMAW], gas metal [GMAW], and flux core [FCAW]) that use consumable electrodes to pass the electric arc to the workpiece.
TIG welding uses a non-consumable electrode in the welding process and can create a weld joint between workpieces with or without filler material.
The filling material in the GMAW, SMAW, or FCAW processes also acts as the electrode that carries the electric arc to the workpiece, while in TIG welding, a separate filling cable is used.
Besides, a filler material may or may not be introduced throughout the TIG welding process.
Gas arc welding with gas (GMAW)
Also known as metal welding with inert gas (MIG), GMAW works like armored metal (SMAW) that uses its electrode as a filler.
However, during the welding operation, the SMAW system uses short rods as a consumable electrode.
In contrast, in MIG welding, a continuous “wire” electrode is automatically fed to the welding torch at a defined speed by the user.
In the same way, the shielding gas is fed to a regulated configuration.
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Although the TIG and MIG welding procedures are usually the same, there are some apparent differences between the 2, particularly in the equipment used.
TIG welding uses a constant current power supply to generate an electric arc. The heat remains constant with this power supply, while the electric arc distance and voltage change.
The negatively charged direct current (DCEN) is the preferred polarity used in TIG. However, DCEP (positively charged) can also be used, but it is not used so popularly.
On the other hand, MIG welding generally works with a constant voltage power source in which the voltage (in volts) remains constant while the current, along with the electric arc and heat, oscillates.
MIG welding generally works with DCEP, but it can also be operated with DCEN or alternating current.
As mentioned earlier, the electrode used in TIG welding is not consumable, while the MIG welding uses an automatically fed consumable electrode wire that acts as a filler.
The TIG welding filler wire is manually inserted into the weld pool.
Before starting any welding job, it is essential to search and choose the best available materials.
For example, the copper pipe workpiece, such as filler rods or cables, must be clean and free of dirt, oil, grease, paint, or other impurity.
The surfaces where the welding joint will occur should be thoroughly cleaned with the steel brush or wet/dry sandpaper.
In addition to this, metal coatings such as nickel-plated or nickel-plated copper cylinders should be avoided to reduce the risk of generating toxic fumes during the welding process.
Types of copper available
For copper materials, three grades of copper are available on the market today. These are the following:
Copper without oxygen
This material has the highest electrical conductivity and is the most easily weldable. However, porosity can be a problem if proper filling material, such as non-deoxidized filler metal, is not used.
Oxygen-free copper does not contain more than 0.02 percent oxygen.
Deoxidized copper with phosphorus (P)
The use of deoxidized copper with P avoids any danger of porosity in the welded product.
It can contain approximately 0.05 percent phosphorus and arsenic.
Copper tone resistant
This material is the least desirable grade of copper, as it inherently contains the most significant amount of oxygen (less than 0.1 percent) in the form of copper oxide (CuO).
Types of filler wires
To obtain the best copper welding results, either with TIG or MiG welding, it is essential to use filler metals containing manganese (Mn) and silicon (Si) as deoxidants.
The most frequently preferred fillers are ErCu and ErCuSi-A. The ErCu filler contains 0.45 Mn and Si with 0.8 percent tin (Sn) to facilitate fluidity.
ErCuSi-A is the preferred input metal for welding oxidized copper with P, as hard pitch copper containing 1 percent of Mn and 3 percent of Si as deoxidants.
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Another essential element in copper welding is appropriate shielding gas while welding.
Typically, Argon (Ar), helium (He), or the combination of the two gases (such as the mixture of argon / 75 helium) is convenient for welding copper depending on the thickness of the workpiece; However,, one hundred percent helium gas is currently gaining popularity.
How to weld a copper pipe step by step
Due to copper’s high thermal conductivity, it is essential to preheat the metal (if it has a thickness of more than two mm or 0.01 inches) before any welding can be performed.
The pipe segments to be joined must be preheated evenly. Preheated copper dissipates heat slowly after welding and reduces the risk of cracking.
Depending on the thickness, copper is preheated from 10 ° C – 400 ° C.
The welding process
Before welding, the copper parts (copper pipes and fittings must be joined) are assembled before welding.
When the desired preheating temperature is reached, welding begins by producing a molten puddle where the filling is introduced.
The filler wire should be introduced as soon as the puddle appears and proceed around the pipe where the joint is made.
It is essential to move quickly to weld at a less desirable speed that can cause oxidation and ruin welding work.
Proper use of heat and gas
As a general rule, when copper TIG welding less than 0.01 inch or two mm thick, Argon should be used as a shielding gas with around 160 amps of current.
However, as the thickness of the copper pipe increases, the current must also be increased proportionally. For example, in copper welding with a thickness of 5 mm, TIG welding requires a preheating of 50 ° C and a protective argon/helium gas and mixing up to 300 amps of power.
In comparison, MIG welding requires a preheating of 10-100 ° C and up to 240 amps of power with Argon as a shielding gas.
Whether you are using TIG or MiG welding, it is advisable to use pure helium as a shielding gas if welding is less desirable.
One hundred percent of helium shielding gas provides better heat levels that result in a faster welding process and better welding quality than using Argon.
Welding work is related to heat and electricity and possibly toxic gases that can be removed.
Therefore, safety is of the utmost importance, especially when welding non-ferrous metals such as copper.
Finally, TIG and MIG welders should wear appropriate safety equipment, such as safety clothing, leather gloves, headgear, eye protection, and a breathing mask.
How to weld a copper tube with water
Do not try to weld pipes that have water. When you repair or tie existing copper pipes, it is common to find water in them even after closing the valve and draining the pipes.
Welding a joint in pipes that contain even small amounts of water is almost impossible.
Most of the torch’s heat converts water to steam, so copper won’t get hot enough to melt the weld.
In that case, stop the water dripping with a pipe plug. Push the pin into the pipe with the applicator tube provided.
When finished welding, dissolve the cap by holding the torch below the plug’s point. 1/2 inch plugs or 3/4 in. The pipe is sold in centers of origin and hardware stores.
An old trick was to put a wad of soft white bread in the pipe to stop the water jet temporarily.
This works but risks clogging aerators and valves with partially dissolved bread.
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