Table of content
Introduction
Seamless steel pipe is a kind of steel pipe, which is usually distinguished from seamless steel pipe by straight seam steel pipe or ERW steel pipe. Do you know seamless steel pipe? What do you need to know to understand seamless steel pipe? In the following article, we will introduce the production process, use and comparison of seamless steel pipe with other steel pipes in detail.
What is Seamless Steel Pipe?
Seamless steel pipe is made of steel billet, which is pierced through the center axis to form a steel pipe. No welding and other processes are required. It is a push-made steel pipe.
How Are Seamless Pipes Manufactured?
Seamless steel pipe is made by hot rolling and extrusion. The specific steps are as follows:
- First, heat the round billet at high temperature.
- Use the mandrel to pierce the billet by rotation to form a hollow pipe.
- The pipe is stretched through the rolling mill and the stretch reducer, and then the required diameter and wall thickness are produced.
- Cool the steel pipe and cut it to length as needed.
What is Seamless Steel Pipe Made Of?
Seamless steel pipes are made of a variety of materials, depending on the purpose.
Common Material Types:
Carbon steel: Common material, medium strength, including Q235, 45#, 65Mn, etc.
Stainless steel: High strength and corrosion resistance. Mainly 304, 316, etc.
Alloy steel: High strength and heat resistance. Different element composition.
Duplex steel: High strength and corrosion and heat resistance.
Each material has different properties. The specific use environment is also different. Seamless carbon steel is mostly used in water treatment systems.
What is Seamless Steel Pipe Used For?
Seamless pipes are pushed from billets and have no welds, so they can withstand higher pressures and temperatures. Its application is also more extensive, some common applications are:
Oil and gas pipelines
Boilers and heat exchangers
Power generation and nuclear power plants and chemical plants
Automobile exhaust pipes, etc.
Seamless Pipe vs Welded Pipe: What’s the Difference?
| Feature | Seamless Pipe | Welded Pipe (ERW) |
| Seam or Weld | No | Yes (visible weld seam) |
| Pressure Tolerance | Higher | Moderate to low |
| Corrosion Risk | Lower (no seam) | Higher (weld seam vulnerable) |
| Cost | Higher | More affordable |
| Size Range | Smaller diameters | Available in larger diameters |
| Manufacturing | Complex | Simpler and faster |
Seamless pipes are mainly used in high-pressure and high-temperature pipeline systems.
Welded pipes are mainly used in low-pressure pipeline systems.
What is the Difference Between Seamless Pipe and Normal Pipe?
Ordinary steel pipes usually refer to ERW pipes and welded pipes. The difference between the two is: ordinary steel pipes have welds. Seamless steel pipes have no welds.
Features of seamless steel pipes:
High strength, uniform structure, high pressure resistance, high price
Because some high-pressure, high-precision refineries or chemical plants often use seamless steel pipes.
Pressure Rating of Seamless Pipes
Seamless pipes have no welds, so the general pressure rating is higher.
Pressure advantage:
The pressure of seamless steel pipes with the same material and specifications is 20%-30% higher than that of ordinary steel pipes. And high temperature resistance.
The pressure level mainly depends on: wall thickness, diameter, material and temperature.
Usually, there are some pressure levels in the standard, such as ASMEB16.10, APL 5L, etc.
What are the Types of Seamless Steel Pipe?
Seamless steel pipes are classified according to different materials:
Carbon steel seamless pipes
Stainless steel seamless pipes
Alloy seamless pipes
According to production standards, they are classified as follows:
ASTM A106
ASTM A312
API 5L
DIN 2391
EN 10216
Seamless Steel Pipe Sizes & Specifications
Seamless steel pipes are available in a variety of sizes and specifications. Here are just some common specifications:
| Outer Diameter | Wall Thickness | Common Lengths |
| 1/4″ – 24″ | SCH 10 to SCH XXS | 6m, 12m |
| 6mm – 610mm | 0.5mm – 50mm | Custom lengths |
NPS: nominal diameter
SECH: specification
LENGTH: length
What are the Benefits of Seamless Steel Pipe?
The main advantages of seamless steel pipes are as follows:
Uniform strength, no welds
High pressure bearing
Corrosion resistance
High temperature resistance
Smooth internal surface
Applicable to a variety of pipeline systems
What are the Disadvantages?
Of course, seamless steel pipes also have some disadvantages:
Higher price
Large diameter steel pipes cannot be made
Long production time
Steel pipes of the same specification are heavier than other process steel pipes
Summary
The above article introduces seamless steel pipes. Now let’s summarize that there are many materials for seamless pipe production, and you can choose according to your needs. Seamless pipes can withstand high pressure and temperature. They are widely used in corrosive environments.
So should we choose seamless steel pipes to lay pipelines? We need to make the choice based on various factors such as the objects to be transported and the construction environment.
