Pipes play an indispensable role in both the grand stage of industrial construction and the subtle scenes of daily pipeline laying. Among them, ERW pipes, DOM pipes and seamless pipes are star products, widely used in many fields such as petroleum, chemical industry, machinery manufacturing, construction, etc., supporting the operation of modern society. But what are the differences? Let’s take a closer look at the unique features of these three types of pipes.
ERW pipe: A new pipeline star born from electricity
ERW pipe, scientifically known as Electric Resistance Welding, utilizes the skin effect and proximity effect of electric current to heat and melt the edge of the tube blank, and under the action of the extrusion roller, welds the two edges together to form a longitudinal weld of the steel pipe. The manufacturing process is to unwind, flatten and form the steel strip, then use the resistance heat generated by high-frequency current at the edge of the steel strip to melt it, and then weld the edges together through the action of the extrusion roller to form a continuous longitudinal weld.
This production method is efficient and highly automated, able to meet large-scale production needs, and is widely used in oil and natural gas transportation, as well as building structures, machinery manufacturing and other fields.
DOM pipe: a precision product made by drawing process
DOM pipe is Drawn Over Mandrel Pipe, which is manufactured by drawing process. The production process usually involves putting the pre-treated steel pipe blank on a mandrel and drawing it through a drawing die. Under the action of the drawing force, the dimensional accuracy and surface quality of the steel pipe are significantly improved, and the organizational structure is also denser and more uniform. This process can accurately control the outer diameter, inner diameter and wall thickness of the steel pipe to produce high-precision, high-performance pipes. It is often used in fields with extremely high requirements for dimensional accuracy and surface quality, such as drive shafts in automobile manufacturing and oil pipes in hydraulic systems. In these fields, DOM pipes ensure the stable operation of equipment and high quality of products with their excellent accuracy and performance.
Seamless pipe: an all-rounder without welds
Seamless pipe is a rolled steel pipe without welds. It is made of hot-rolled steel, or, if necessary, the hot-rolled pipe is cold-processed to obtain the required shape, size and performance. The manufacturing process of seamless pipe is relatively complicated, and the common methods include hot extrusion, cold pressing, oblique punching, cold rolling, pressing, cold drawing, etc. The biggest feature of seamless pipe is that there is no weld, which makes it excellent in strength and pressure bearing capacity, and can withstand higher pressure and harsh working environment. It also has good mechanical properties, good corrosion resistance, smooth surface, good fluid transmission performance and strong machinability. Due to these advantages, seamless pipes are widely used in fields with high requirements for pipe materials, such as the petroleum and chemical industries, for transporting various fluid media such as oil, natural gas, water, steam, etc.
The essential differences between the three types of steel pipes
1. Production method
ERW pipe (electric resistance welded pipe):The strip is rolled into a cylindrical shape, and the edges are heated by high-frequency current and pressed together. The advantages are fast production and low cost, but the weld may have microscopic defects (such as impurities or lack of fusion).
Seamless pipe: The solid steel billet is heated and pierced before rolling (hot rolling) or cold drawing. There is no welding process in the whole process. The process is complicated and energy-intensive, but there is no hidden danger of welds, and the overall performance is more reliable.
DOM pipe (double-drawn precision pipe): Using ERW tube or seamless tube as raw material, it is cold-drawn/cold-rolled for secondary forming, and some parts are annealed. The core is to eliminate the influence of welds through cold working (if the base material is ERW) and improve dimensional accuracy.
2. Welding problems
ERW pipe: There are obvious welds, and the welding quality needs to be tested.
Seamless pipe: No welds, uniform structure.
DOM pipe: There may be traces of welds (when the base material is ERW), but the influence is weakened by processing.
3. Mechanical properties
ERW pipe: moderate strength, suitable for ordinary pressure-bearing scenarios.
Seamless pipe: strongest compression/tensile resistance, resistant to extreme pressure or temperature.
DOM pipe: performance is close to seamless pipe, but lower cost and smoother surface.
4. Appearance:
The ERW pipe has an obvious weld, which is the most intuitive difference between it and the other two pipes;
the DOM pipe and seamless pipe have no obvious weld on the surface, and the appearance is smoother. Among them, the surface quality of the DOM pipe is particularly excellent, and almost no flaws can be seen.
5. Price:
ERW pipes have high production efficiency and low cost, and are relatively affordable.
DOM pipes have high prices due to their complex processing technology and high precision requirements.
Seamless pipes have complex manufacturing processes, long production cycles, and high requirements for raw materials, so their prices are usually higher.
6. Applicable scenarios:
ERW pipe: low-cost needs for building supports, ordinary pipes, furniture, etc.
Seamless pipe: oil and gas high-pressure pipelines, boiler components, nuclear power equipment.
DOM pipe: precision instruments, automotive hydraulic systems, high-precision mechanical parts.
How to choose between three pipes?
1. Look at the pressure requirements
Select ERW pipes for low pressure, seamless pipes for high pressure, and DOM pipes for medium pressure and precision.
2. Look at the surface requirements
The surface of DOM pipe is the smoothest, followed by seamless pipe, and the weld of ERW pipe may be rough.
3. Look at the budget
ERW pipe is the most economical, seamless pipe is the most expensive, and DOM pipe is between the two.
Read more: ERW Pipe vs. LSAW Pipe
