I. A molding process
(1) Seamless steel pipe
Seamless steel pipe is made by piercing the solid billet or ingot, and then processed by hot rolling, cold rolling or cold drawing and other processes. As the whole process does not produce welded seams, hence the name “seamless”. Hot rolled seamless steel pipe is one of the common types, it is molded by rolling process at high temperature, with good mechanical properties and dimensional accuracy.
(2) Welded Steel Pipe
Welded steel pipe is made by bending steel plates or strips into tubes, and then welding the seams together through the welding process. Common welding methods include high-frequency welding (ERW straight seam welded pipe) and spiral welding, etc. ERW straight seam welded pipe adopts high-frequency welding technology, which has high welding speed and high quality of weld seams, and is widely used in various fluid transportation fields.
II. Appearance Characteristics
(1) Seamless Steel Pipe
Seamless steel pipe has a smooth surface, no welded seams, good integrity and aesthetic appearance. Its surface quality is high, suitable for application scenarios that require high aesthetics.
(2) Welded steel pipe
Welded steel pipe can have welded seams visible on its surface as it is made by welding. However, with technological advances, some welded steel pipe will be weld treatment, making the weld seam becomes less obvious, and the overall appearance is closer to seamless steel pipe.
III. Performance Characteristics
(1) Seamless Steel Pipe
Seamless steel pipe is suitable for high pressure, high temperature and other harsh environments due to its high pressure-bearing capacity without welded seams. Its precision and finish is also relatively high, suitable for higher performance requirements of the occasion.
(2) Welded Steel Pipe
Welded steel pipe has a relatively low pressure-bearing capacity, but it is low cost and easy to process and install. Its strength and toughness are good, and its corrosion resistance is also good, suitable for high-volume, low-cost application scenarios.
IV. Price
(1) Seamless steel pipe
Seamless steel pipe manufacturing process is complex, superior performance, the price is usually higher than the welded steel pipe. However, the specific price will also be affected by market supply and demand, raw material price fluctuations and other factors.
(2) Welded steel pipe
Welded steel pipe is low-cost and suitable for high-volume, low-cost application scenarios. Its price is relatively stable and suitable for cost-sensitive applications.
V. Uses
(1) Seamless Steel Pipe
Seamless steel pipe is mainly used for high-precision structural steel pipe such as petroleum geological drilling pipe, petrochemical cracking pipe, boiler pipe, bearing pipe and so on. It is widely used in petroleum, chemical, electric power, nuclear energy and other fields, especially in the need to withstand high pressure, high temperature and corrosion and other harsh environments. In addition, seamless steel pipe is also commonly used in the manufacture of structural and mechanical parts, such as oil drilling rods, automobile drive shafts, bicycle frames, and steel scaffolding in building construction. Because of its hollow cross-section, a large number of pipelines used to transport fluids, such as oil, natural gas, gas, water and some solid materials pipeline.
(2) Welded Steel Pipe
Welded steel pipe is widely used in waterworks, petrochemical industry, chemical industry, electric power industry, agricultural irrigation, urban construction and other fields. In the field of construction, welded steel pipe is commonly used in steel structure frame, support and protection railing and other parts; in the field of pipeline transportation, welded steel pipe is used to transport water, gas, oil and other fluid media. In addition, welded steel pipe is also used in machinery manufacturing, automobile manufacturing, railroad and aerospace and other fields. Its high strength, good toughness, corrosion resistance, easy processing and other characteristics make it widely used in these fields.
Through the above comparison, it can be seen that seamless steel pipe and welded steel pipe have their own advantages, the specific choice needs to be based on the actual application scenarios and needs to decide.