Seamless steel pipes are made of steel ingots or solid tube billets through perforation and then made by hot rolling, cold rolling or cold drawing. Seamless steel pipes have a hollow section and are used as pipelines for conveying fluids. ERW welded pipe refers to a steel pipe with seams on the surface that is welded after bending and deforming into a round shape with a steel strip or steel plate. The billet used for welded pipe is steel plate or strip steel. Small diameters are usually straight seam welding, and large diameters are usually spiral welding. Due to the poor mechanical properties of the welded seam of the welded pipe, its application range is limited, but the price is cheap. The significant difference is that ERW welded pipe has welds, while seamless steel pipes have no welds. Of course, if the ERW welded pipe is handled well, the layman will not see the difference.

Ordinary steel pipes, such as water pipes, are generally welded by bending a flat plate, and you can find a weld on it; the thicker diameter is usually a spiral weld. The seamless steel pipe is generally formed by processing the molten steel through the annular slit and then forming by stretching and other treatment processes, so that there is no weld. In terms of performance, especially the pressure-bearing capacity, it is greatly improved compared to ordinary steel pipes, so it is often used in high-pressure equipment. Such as pipeline connection of hydraulic equipment, etc. The welding seam of ordinary steel pipe is its weak link, and the quality of the welding seam is also the main factor affecting its overall performance. People who have lived in the north generally have experience of water pipes or heating pipes being frozen and exploded in winter, and the places where they exploded are usually welds.

Tips: ASTM A53 covers seamless and welded steel pipe with nominal wall thickness. The surface condition is usually black and hot-dipped galvanized. ASTM A53 is produced mainly for pressure and mechanical applications, and is also used for transport of steam, water, gas line pipes.
ASTM A53 Grade B is the material under the American steel pipe standard, API 5L Gr.B is also the American standard material, A53 GR.B ERW refers to the electric resistance welded steel pipe of A53 GR.B; API 5L GR.B Welded refers to the material Welded steel pipe of API 5L GR.B.