Seamless steel pipes
are made of steel ingots or solid tube billets through perforation into capillary tubes, and then made by hot rolling, cold rolling or cold drawing. Seamless steel pipes have a hollow cross-section and are used in large quantities as pipes for conveying fluids. Welded pipe refers to a steel pipe with seams on the surface that is welded after bending and deforming a steel strip or steel plate into a round shape.
ERW steel pipe refers to a steel pipe with seams on the surface that is welded after bending and deforming a steel strip or steel plate into a round shape. The billet used for welded pipe is steel plate or strip steel. Generally, the length is 6 meters, and the strength is lower than that of seamless steel pipes.
1. Process difference:
Seamless steel pipe: hot-rolled forming process is adopted. The raw material composition of the steel pipe, the cooling condition and the cooling state of the roll have a great influence on its outer diameter, so it is difficult to accurately control the outer diameter and has a large fluctuation range. Seamless steel pipes are mainly divided into hot-rolled seamless pipes and cold-drawn seamless pipes. Hot-rolled pipes are forged, pierced, rolled, and shaped. Generally, large-diameter and thick-walled seamless pipes adopt this form; cold-drawn pipes are formed by cold-drawn pipe blanks. The material strength is relatively low, and the external and internal control surfaces are smooth. Thin-walled seamless pipes are mostly in this form.
ERW steel pipe: It adopts cold-formed, high-frequency welding, and the sizing is completed by 0.6% reduction. The process temperature is basically constant at room temperature, so the outer diameter is controlled accurately and the fluctuation range is small.
The price of seamless steel pipes of the same specification is generally about 30% higher than that of welded pipes, and the difference between large diameters is even greater.
ERW is a high-frequency welded pipe, which is made of strip steel and has a lower cost.
The seamless steel pipe is made by heating and perforating a tube blank. The production process is more complicated and the cost is higher!
3.Different pressure-bearing capacity:
The pressure of seamless pipes is higher. Welded pipes are generally around 10 MPa. Now welded pipes are also seamlessly treated.