Summary of the difference between seamless steel pipe and welded steel pipe
API 5L/ASTM seamless steel pipe and ERW welded steel pipe have the following differences:
1. Appearance differences
Seamless steel pipe is made of steel billet. Outer surface defects in the steel billet cannot be eliminated by the hot rolling process and are only polished after the product is completed. In the process of wall reduction, defects can only be partially eliminated.
Welded steel pipe made of hot-rolled coil as raw material, the surface quality of the coil is the surface quality of the pipe, which is easy to control. The surface quality of hot-rolled coil is high.
Therefore, the surface quality of welded steel pipe is much better than that of seamless steel pipe.
2. Molding process differences
Seamless steel tubes can be formed in one pass during the rolling process.
Welded steel pipes are made of steel strip or steel plate, by bending and different welding processes.
Third, performance and use
Seamless steel pipe has better pressure bearing capacity and is stronger than ERW welded steel pipe. Therefore, it is widely used in high-pressure equipment, heat, boilers and other industries.
Generally, the weld of welded steel pipe is a weak link, and the quality affects the overall performance.
In general, welded steel pipes can withstand 20% of the working pressure than seamless steel pipes. This reliability is the main factor in people’s choice of seamless steel pipes. In fact, all industrial piping is done with seamless pipes, simply because the pipes are subjected to extreme thermal, chemical and mechanical workloads. In the aerospace, automotive, and electronics industries, where budgets are relatively low, welded pipes are preferred and work on pipelines is less stressful.
4. Available size differences
For most seamless steel pipe manufacturers in China, the original seamless pipe they produce has a maximum outer diameter of 20 inches and 508 mm. Due to device limitations, it is typically less than 16 inches, 406.4 mm. If the customer wants to buy seamless steel pipe above the above specifications, it should be heat expanded. But usually the quality of this heat-expanding seamless steel pipe cannot be compared with the original seamless steel pipe.
Conversely, welded steel pipes do not have these limitations, ranging in size from 1-1/2″ 48.3mm to 100″ 2540mm.
5. Costs and Prices
Seamless steel pipes usually cost more than welded steel pipes due to raw materials, manufacturing equipment and processes. But sometimes forced by market pressure, welded pipe price is more expensive, so in this case, please do not hesitate to buy the same size seamless steel pipe.
Seamless steel pipes are round steel billets, manufactured by hot-rolling, cold-rolling or cold-drawn processes with no seams.
The welded steel pipe is made of flat steel plate with welds on the pipe body. Including ERW tube, LSAW tube, SSAW tube.
The Hengtong tells you the difference between seamless pipe and welded pipe in terms of raw material, manufacturing process, performance, appearance, size, application, cost and price.
How seamless steel pipes are made.
API 5L and ASTM seamless steel pipes are made from steel ingots or solid tubes, through perforated tubes, which can then be formed by hot rolling, cold rolling or cold drawing. Hot-rolled seamless steel pipe is made of billet forging, perforation, rolling, shaping and other processes. For large-diameter pipes and thick-walled seamless pipes, this method is usually manufactured. The cold-drawn seamless pipe adopts cold-drawn molding technology. The material strength is low, and the appearance and internal control surface are smooth. Small diameter thin-walled seamless tubes are often manufactured in this way. Seamless steel pipes are rolled from carbon structural steel, low alloy structural steel or alloy structural steel and stainless steel. Seamless steel pipes are used in different industries: pipelines, thermal services, machinery industry,
How welded steel pipes are manufactured
API 5L or ASTM welded steel pipes include LSAW tubes, SSAW pipes, and ERW steel pipes. These pipes are made of steel strip or steel plate. The manufacturing process first bends the steel plate and then welds it into a round, square and other shapes. Welded steel pipe has the characteristics of high production efficiency, low cost and material saving. It has been widely used in aviation, aerospace, energy, electronics, automotive, light industry and other industries. High corrosion resistance in acidic environments.
Why do you prefer to buy seamless steel pipes?
The reason most people prefer seamless steel pipes over welded steel pipes is that seamless pipes can withstand extremely high pressures without cracking. But seams or welded pipes can’t do this because the weld joints crack easily under high pressure. In addition, it is easy to accurately calculate the pressure of the seamless tube. Seamless tubes are also thinner and lighter than welded tubes, and they are also uniformly shaped because they are uniformly extruded from alloys. If you want to buy the best quality seamless steel pipes, you should use Hengtong Steel API 5L and ASTM seamless steel pipes.
