ERW vs EFW for Stainless Steel Welded Pipe
As a professional stainless steel welded pipe supplier, we have met a lot of clients who are asking for what is the difference between ERW and EFW.
When speaking of electric resistance welding pipe, most people may be not familiar with that. And they don’t know what kind of material it is. This kind of pipe is a special material used in electric equipment. Next, let’s come to see the differences between electric resistance welding and electric fusion welding.
What is ERW for Stainless Steel Welding?
ERW, which is short for electric resistance welding, has a big difference with electric fusion welding. For electric resistance welding pipes, they adopt pressure welding without filling metal, and there are no other components are filled in the weld lines. This method requires the high-frequency current to make the weld line reach welding temperature, and then form the weld line through the wringer. For the high-quality steel pipes, they have to weld-line or off-line heat treatment to refine the microstructure of the welding area, so that the ERW welded pipes can be tough enough as the base metal. And this cannot be achieved by submerged arc welding process.
What is EFW Stainless Pipe?
EFW, which is short for electric fusion welding, is one form of submerged arc welding. It is a technique that using metal heating between one or several consumable electrodes and the workpiece to combine the metal. And the arc will melt the metal and the filling materials. The whole process does not require the pressure, and the material filling will be fully achieved through electrodes. Gas fusion welding (GMAW) is one type of electric fusion welding (EFW), and its process is very similar to submerged arc welding, but it is shielded by inert gas, which is much more effective. As for spiral welding, it also belongs to submerged arc welding, and it comes with a spiral weld.
Which Is Better ERW vs EFW Pipe
For stainless steel ERW pipes, their welding is achieved through pressure without metal fillings, and there are no other components in the welding lines. This method requires the high-frequency current to make the weld line reach welding temperature, and then form the weld line through the wringer.
As for stainless steel EFW pipes, their welding is achieved through the metal heating between one or several consumable electrodes and the workpiece to combine the metal. And the arc will melt the metal and the filling materials. The whole process does not require the pressure, and the material filling will be fully achieved through electrodes. This technique is like submerged arc welding, but it is shielded by inert gas, which make it much more effective.
Characteristics of Stainless Steel ERW Pipes
The production process of ERW is simple, and its production efficiency is relatively high. Besides, this kind of pipe has a variety of specifications, and requires less investment in equipment. However, the strength of these pipes is lower than seamless steel pipe. Since the 1930s, with the rapid development of the producing techniques for the high-quality stainless steel and the progress of welding and inspection technology, the welding quality has been constantly improved. And with the increasing specifications of welding pipes, the seamless steel pipe has been replaced in more and more fields.
We hope that you can have a general understanding on the welding of stainless steel by this article, and get to know the differences between ERW and EFW. We frequently use online welding for thin wall thickness stainless steel tubes or food-grade ones, which does not require to filled with metal. And when the wall thickness is relatively thick, we often use EFW to weld.