Steel pipesare used in a variety of different applications. From the water supply to gas pipelines, steel pipe is an important part of our everyday lives. Although it seems like there is only single type of steel pipe, there are actually many different types that vary by thickness and flexibility.
This blog post will give insight into some of the common fabrication techniques used by steel pipes manufacturer: ERW (electric resistance welded), SMAW (stick welding) and EFW (electric fusion welded).
What is the whole process?
- ERW: Electric resistance welded pipes are made by rolling steel sheets and welding them together to form a tube. This process is very quick, which makes it possible for ERW steel pipe fabrication techniques to be used on large scale projects.
It can also handle high pressures of up to 20 times the pressure rating, with no loss in strength. In contrast, electric fusion welded (EFW) steel tubes must use much thicker metal that limits their ability to withstand high pressures.
- SMAW: Stick welding involves using an arc welder and rods or wire as filler material to create strong joints between two pieces of metal without melting either side’s surface layer.
The technique has been around since WWII when metals were hard to come by. It is still used now in many countries where welders are more skilled than those who use the ERW technique, such as India and China.
- EFW: Electric fusion welding involves inserting a metal tube into one area of molten material to create heat that melts both pieces together at their junction. This process can be done with steel sheets or tubes which will then become an integral part of the final product’s interior surface layer, so it cannot be visually inspected.
Because this can’t easily be seen, EFW steel pipe fabrication techniques are often not preferred for high-pressure applications like gas pipelines because there may be weaknesses between layers only detectable through x-rays or other tests on a finished piece of tubing made from these materials.
Special facts about steel:
- Steel is a fairly simple material to work with, so it can be cut into shape using various types of tools. In contrast, copper and aluminum are much more difficult metals to fabricate because they must be stretched in order for the metal’s natural properties to take hold.
- When rolled, steel pipe must be done so slowly and carefully to avoid damaging the material. Copper or aluminum will often crack if they are not handled correctly when being machined and cut into shape.
- Steel pipes can be cut or welded together without a specific seam, unlike copper and aluminum which require solder in order to make the connection. This makes steel pipe much easier to work with for fabricators who need to join several pieces as part of their process.
When joining two lengths of ERW steel tubes, it is best not to use clamps because they could cause damage that would weaken the joint’s integrity.
Instead, you should choose either twist or lap joints:
- Twist Joints: Twist joints are when one tube is rotated over another so that both ends protrude from the same side. The end of each section must then be flattened out and hammered flat against an anvil before welding them together at 90 degrees.
- Lap Joints: Lap joints are when one tube is overlapped over another so that they both protrude from opposite sides of the joint. The two tubes must be cut to length and then hammered flat against an anvil before welding them together at 90 degrees on all four corners.
A disadvantage of steel pipes is their weight compared to copper or aluminum, which causes a cost difference in transportation costs if you need to ship your product long distances by truck or rail.
Depending on how much pipe fabrication equipment you have access to, it may not always make sense financially for some fabricators who work primarily with smaller diameter pipe material (less than 12 inch).
These companies would often rather purchase finished products than spend money setting up shop just to do the hard part of the production.
Pipe fabrication techniques are complex and require a team of knowledgeable people to work together. It’s important that the right equipment is used, the correct measurements are taken, and workers take precautions necessary for their safety while working with strong steel pipes. The end result will be a well-built structure made from quality materials that can last many years without needing replacement or repair.