How to distinguish welded steel pipes from seamless steel pipes

In the vast ocean of the steel market, welded steel pipes and seamless steel pipes are two important members, each playing an indispensable role. However, for non-professionals, how to accurately distinguish the two is often a difficult problem.

Point 1: Welding marks
-Welded steel pipes: Carefully observe its surface, especially at the interface, you will find obvious welding marks, that is, weld ribs. This is direct evidence that the welded steel pipe is welded after curling and forming the steel plate or steel strip.
-Seamless steel pipe: In contrast, the inner and outer surfaces of the seamless steel pipe appear unusually smooth, with seamless interfaces and no welding lines, presenting a seamless beauty.

Point 2: Cross-sectional morphology
-Further, observe the cross-section of the steel pipe. The cross-section of the welded steel pipe may be slightly uneven due to welding, with subtle welding marks or deformation.
-The cross-section of the seamless steel pipe is more regular and has a higher roundness, showing an excellent level of manufacturing technology.

Point 3: Strength and pressure resistance
-Seamless steel pipe: Due to its smooth inner and outer surfaces and seamless interface, it is more uniform when under pressure, so it has higher strength and pressure resistance. It is often used in fields that require high-pressure and high-strength environments, such as petroleum, chemical industry, aviation, etc.
-Welded steel pipe: Although it can also withstand a certain pressure, its strength and pressure resistance are slightly inferior to those of seamless steel pipe. Therefore, it is more used to transport low-pressure fluids, such as water supply and gas pipelines in the construction industry.

Point 4: Production process
-Seamless steel pipe: It is made of solid round steel billet through complex processes such as heating, perforation, rotation, and drawing. The process requirements are high and the quality of the finished product is stable.
-Welded steel pipe: It is made by curling and forming steel plates or steel strips and then welding. The process is relatively simple and the manufacturing cost is low.

Point 5: Application field
-Seamless steel pipe: Due to its excellent strength and pressure resistance, it is widely used in many fields such as petroleum, chemical industry, aviation, aerospace, machinery, automobiles, nuclear energy, etc., and has become an indispensable and important material in these industries.
-Welded steel pipe: With its economical and practical characteristics, it shines in the construction industry, especially in the transportation of low-pressure fluids such as water and gas.

Through the above identification, I believe you can easily distinguish welded steel pipes from seamless steel pipes. When choosing, you may wish to combine actual needs, comprehensively consider factors such as performance, cost, and application scenarios, and make the most suitable choice for yourself.