Different steel pipes are standard in our daily lives. From fluid to gas, they help in the transportation process.
Among those, the ERW pipes are also well known due to their cost-effectiveness and durability. Their usability is booming due to their features. However, some people still ask: What are ERW pipes?
This question is common among newbies entering the world of piping. Electric Resistance Welded pipes are well known for their consistent thickness and durability. Their affordable rate further enhances their value.
However, many people are unaware of a lot of information. So, I will cover every detail regarding these pipes. So, let’s get started!
Overview of ERW Steel Pipes
ERW, or electric resistance welded pipes, is a seam-welded pipe type. They are made of high-quality steel coils that undergo the forming process. A series of rollers transforms the flat steel coil or loop into a cylindrical form. The edges of pipes are heated by electric current to seam-weld them.
Low-carbon steel is generally used to make ERW pipes. Moreover, some manufacturers use stainless steel. These materials are corrosion-resistant.
Therefore, they won’t rust easily when used for liquid transportation. Some manufacturers also provide pipes with a fusion-bonded epoxy coating. Such additional coating are excellent for making pipes rust-proof.
As you know, there are various welding types that vary in terms of their welds. However, these ERW steel pipes are welded using high-frequency electric currents. This current melts the edges of the pipes and makes a weld. This weld is not seamless and has visible lines. These pipes have many advantages. First of all, they are very durable.
The reason is that the weld produced by the current is very robust. These welds are as strong as the pipes, so they can bear high pressure from all sides. Moreover, even after a long year of use, they won’t leak. Above all, these pipes are inexpensive compared to other types. This makes them popular among low-budget customers.
Manufacturing Process of ERW Steel Pipe
It is a fact that the manufacturing process of ERW pipes is complex. It involves multiple steps that change the flat steel coil into a pipe shape. Let’s dive in and explore the detailed manufacturing process of these in easy steps.
1- Preparation of Raw Materials
First, you’ll have to arrange a long, high-quality steel coil. This coil must be long enough to make a decent length of pipes. Keep in mind that there are multiple types of steel available. They vary in terms of carbon content. Some of them have low carbon.
You should go with low-carbon steel as it has many advantages. First, this steel is easy to weld and does not pose any issues. Moreover, its forming process is also safe. It does not crack under the rolls. If you choose high-carbon steel, it will not support welding. It would need more current to produce a weld, increasing production costs.
Quick Tip: Steel pipes with a higher than 0.6% carbon content will be rigid. The chances of cracking upon welding will be high, leading to improper welding that is susceptible to breaking.
2- Forming the Steel Strip
This is one of the most critical steps in manufacturing ERW pipes. The flat steel coils first go through a trimming process. These steel strips have irregular shapes and sizes. The trimming process cut those irregularities. If these edges are not cut and smoothed, the weld produced as a result of welding will be very weak.
So, you should analyze the edges of the strips carefully. If you notice any minor irregularities, make sure to fix them. This pipe is based on a solid weld. But, due to these irregularities on the edges of the stripes, the weld could be compromised. This will affect the quality of the whole pipe.
3- Welding Process
The cylindrical-shaped pipes undergo the welding process. The edges of the pipes are bound together, and the weld remains visible at the joint. This welding is done through high-frequency electric resistance current. This welding process is very important for making the pipes of desired size.
Welding helps make continuous pipes. One aspect that I hate about this welding is that it leaves signs, and welds remain visible. This is why it is called seam welding. As you know, the welding process requires filler. However, for electric resistance welding, you won’t need a filter. Instead, the pressure roller will press the edges of pipes and make a weld.
4- Heat Treatment
I mentioned at the start that these ERW pipes are very durable and robust. Heating treatment is the primary reason for their durability. The pipes are heated to a high temperature and then cooled in the air, resulting in this significant temperature shift.
This heat treatment or temperature shift improves grain structure. Moreover, it also enhances the uniformity of the material. Due to this, the strength of the pipes goes up. This is why the ERW pipes are capable of bearing high-pressure flow. You won’t have any durability issues.
Quick Highlight: The heat treatment is also helpful in strengthening the welds. The residue present on the welds also gets removed with this heat. So, heat treatment is considered a must-follow step.
5- Sizing and Cutting
After the heat treatment, the pipes are ready to use. The manufacturers cut them through sizing mills. These mills are very efficient and ensure the exact diameter and roundness of the pipes. You can cut an ERW pipe into as many pieces as you want, depending on your needs. There are no limitations on the sizing of these pipes.
6- Inspection and Quality Control
Quality control systems are critical to each manufacturing process. They are a kind of additional quality check. They ensure that customers don’t get faulty pipes. For this, a dedicated team is set up to inspect the pipes. This team checks whether all the quality criteria are met.
If they find something wrong, they will reject the pipe. Only pipes approved by the quality control team are sent to the market. The manufacturer of ERW pipes takes the inspection process very seriously. Bad quality affects the company’s reputation.
Advantages of ERW Steel Pipe
There are many advantages of ERW pipes. Among those, durability and cost-effectiveness are at the top. You won’t face issues such as leakage, etc, with these pipes. Here is the list of their potential benefits:
- High production efficiency: The production process of ERW pipes is very efficient. It does not use high quantities of fuel or premium raw materials. In the end, it gives very smooth and durable pipes. You can produce as many pipes as you want. There is no restriction on production quantity.
- Smooth surface finish: Manufacturers use skin pass mills to improve the surface finish. So, the edges of these pipes are very smooth. Due to this smoothness, the welding process becomes more convenient. Moreover, some manufacturers apply coating on these pipes to rust-proof them.
- Uniform Thickness: This is the feature I love the most. All the ERW pipes have equally uniform thicknesses without any bumps. This is because the rollers make a perfect shape. Due to this uniformity, there is less chance of leakage. The heat treatment further enhances their mechanical strength.
- Versatility & Usability: You can use ERW pipes in different industries. They are not restricted when it comes to its purpose and usability. Many people use them for water, oil, and glass transportation. Moreover, their use in construction, plumbing, and agriculture is expected. Moreover, they are very flexible. You will get in any size and length with ease.
- Cost & Affordability: These pipes are very affordable compared to their counterparts. The lower price of these pipes is due to their inexpensive raw materials. Moreover, the simple manufacturing process further makes it less costly. As a result, the customer gets pipes at quickly affordable prices.
Applications of ERW Steel Pipe
The ERW pipes are very versatile. Their usability has no limitations. Their presence is dominant in almost every sector. The most common use is in the transportation of liquid and gas.
Here is the list of the industries that use these ERW pipes:
| Industries | Applications |
| Construction | Building structures (columns, beams) |
| Transportation | Water, oil, and gas pipelines |
| Automotive | Exhaust systems |
| Machinery and Equipment | Boilers and Heat Exchangers |
This list could be more extensive regarding the usability of these pipes. However, I listed only a few of the most important industries where this pipe is used. You’ll see them in many fields and sectors. Their easy production process and low costliness make them stand out. So, people with tight budgets prefer buying them.
Comparison with Other Types of Steel Pipes
I want you to understand these ERW pipes in more detail. Therefore, I will compare them with some other types of pipes. This will help you better understand how this pipe is different from other types.
1- ERW vs. Seamless Steel Pipes
Unlike ERW, these seamless steel pipes don’t have welds. Instead, they are made from a solid billet, which is extruded instead of welding.
The seamless steel pipes are robust and durable. The reason is that they don’t have welds that could make the pipe susceptible to rust. However, they are costly.
2- ERW vs. Spiral Welded Steel Pipes
These spiral pipes are an inferior option to the seamless pipes. The steel sheet is welded spirally, and the weld will remain visible. As a result of this welding, this pipe is made.
However, the welds present on these pipes make them weaker. Remember that their prices are lower than seamless but higher than ERW pipes.
Quality Standards and Certifications
There are many strict standards. The ERW pipes must adhere to these standards. Pipes that are not in compliance with these standards are considered unreliable. Keep in mind that each quality standard has its criteria and quality guidelines.
The ERW pipes must have to fulfill their criteria. Different organizations make these standards. Here is the list of standards along with their organizations.
| API Standards | Organization |
| API Standards | American Petroleum Institute |
| EN Standards | European Committee for Standardization |
| ISO Standards | International Organization for Standardization |
| ASTM Standards | A very well-known American Society for Testing and Materials |
FAQs
Q1: What are the distinctions between ERW and seamless pipe?
ERW pipes are the result of welding through electric resistance welding. This weld will make it weaker. On the flip side, the seamless pipes don’t have any seams. It is made as the result of extrusion of the steel billet. It is more expensive and durable.
Q2: What is the ERW pipe used for?
ERW pipes have many uses. They can transport liquids and gases and are used for construction work. Their usage in the automotive industry is also booming.
Q3: What are the advantages of ERW tubes?
ERW tubes are generally less expensive and more durable. They are highly flexible and can be of any size and length, so they will efficiently fulfill your needs. The other tubes and pipes are expensive and unsuitable for budget-conscious persons.
Conclusion
ERW pipes are undoubtedly excellent options. They are inexpensive and offer decent durability. One thing that I like about these pipes is that they are versatile. You can use them in almost every sector or industry without any hesitation. In this article, I’ve explained all the ins and outs of these pipes.