Einführung
Welded steel pipes are widely used in various industries. These pipes are also simply referred to as welded pipes, which have seams on their surfaces when steel plates or strip coils are rolled into cylindrical shapes. Simple production methods, such as ERW and SAW, are highly efficient and affordable. They can produce pipes for varying needs with different lengths, thicknesses, and diameters. These pipes are long-lived, high-strength, and corrosion-resistant. However, they may not have uniform strength like seamless pipes.
With the continuous evolution of technology, the welding and inspection of steel pipes have also evolved. Now the quality and specifications have increased. And you can find a wide variety of welded steel pipes.
As a buyer, you must choose the right type suited to your specific requirements. For that, you may have some knowledge. This article discusses the various types of welded steel pipes used in different applications.
Arten von geschweißten Stahlrohren
All the types discussed below are welded pipes, but they differ in production methods and applications. The main differences lie in their formation, heat application method, pressure, and diameter.
ERW (Electric Resistance Welded) Pipes
After the coil strips or steel plates are cold-formed into a cylindrical shape, the pipes are heated by an electrical current. High or low frequency current melts the edges of the pipe. They are then fused using squeeze roller welding, resulting in ERW-Rohre. This way, there is no need to use filler material during welding, forming a straight longitudinal seam. These seams are strong and barely detectable.
The process usually uses hot-rolled coil as the raw material. It gives tight control of wall thickness and outside diameter. The ERW method used in production has several benefits. It shines for its high efficiency and relatively low production costs. While it also saves material.
The application of ERW pipes ranges from aviation to the light industry. Some oil and gas lines with less demanding requirements may also use it.
HFW (High-Frequency Welded) Pipes
High-frequency welded Pipes are formed using high-frequency welding that uses 100 to 800 kHz current. Such high-frequency current, when it passes through strip edges, produces strong, consistent welds. That’s why HFW Pipes are high-strength, durable, and have excellent dimensional accuracy. They make a good option for high-pressure applications.
The HFW method allows for high production speed and consistent weld quality. It is cost-effective and commonly used for thin- to medium-wall line pipe and structural tubing. These pipes are suitable for transporting oil, gas, and water, as well as for construction.
LSAW (Longitudinal Submerged Arc Welded) Pipes
These steel pipes have a longitudinal weld seam that extends straight across the pipe till the end. They are usually 12-20meters long and can be produced by hot or cold rolling heavy carbon steel. LSAW-Rohre are thick-walled, ranging from 6mm to 50mm, and large-diameter pipes with an outer diameter of 406mm to 1422mm. Additionally, the quality and strength are impressive.
The production process of these pipes is relatively simple and cost-effective. They are used across various industrial sectors, including petrochemicals, construction, and agriculture.
SSAW / HSAW (Spiral Submerged Arc Welded) Pipes
These steel pipes are produced from a spiralled HR coil or steel plate, with the seam welded as it is wound. This results in relatively longer pipes with thicknesses ranging from SCH 40 to SCH 80. However, the forming angles are adjustable. This means you can adjust the diameter according to specific requirements.
The production of SSAW / HSAW pipes involves welding seams at high temperatures. This method can cost a little more due to its high strength. They are used in oil and gas transportation.
EFW (Electric Fusion Welded) Pipes
Electric Fusion welding technology is used to produce these pipes. It involves melting or compressing a steel plate using electric arc welding, fusing to form a weld. This technique uses high-voltage current, with filler material, if needed. These pipes formed by this method have a uniform, high-quality weld with a very low defect rate. They are suitable for demanding environments and load-bearing applications. They are used in industries including chemical, power and construction.
DSAW (Double Submerged Arc Welded) Pipes
The pipes are welded simultaneously from both sides of the seam, externally and internally, using the submerged arc welding method. The seam can be either spiral or longitudinal, rolling the plate to form a cylindrical shape with its edges bevelled to form V-shaped grooves. Double-sided welding produces high-quality, durable, and uniform pipes.
DSAW pipes are usually thick-walled and of large diameters. They are used in high-pressure applications where the structural integrity of pipes is integral. These include bridge construction, water engineering applications and others.
Schlussfolgerung
As we have discussed various types of welded steel pipes, you may have understood them well. These pipes differ in characteristics and production method. However, they are relatively affordable, high-strength, and serve a wide range of industrial applications. In short, a wide variety of steel pipes come with varied specifications serving various applications. When you are choosing steel pipes, you must determine your specific engineering needs. Proper installation and maintenance also affect the pipe’s performance. So, it’s important to follow the standard process!