Hot-Rolled Seamless Steel Pipes

Comparison Dimensions

Hot-rolled seamless steel pipe

Cold-drawn seamless steel pipe

Production Process

The pipe blank is pierced and hot-rolled after high-temperature heating, a hot-working process.

Using hot-rolled rough tubes as the base material, it is drawn into shape through multiple passes using dies at room temperature, belonging to the cold working process.

Specification Emphasis

Mainly producing medium and large diameters and medium-thick walls, typically covering φ57~φ630mm and wall thicknesses 3~60mm, with significant advantages in producing ultra-thick walls.

Primarily targeting small and medium diameters, thin/ultra-thin walls, typically covering φ6~φ219mm, wall thickness 1~20mm, with outstanding precision advantages in small specifications.

Dimensional Accuracy

Precision is generally average, with an outer diameter tolerance of ±0.5mm or more, and a wall thickness deviation of approximately 10%. Roundness and straightness are also generally average.

Excellent precision, with a standard outer diameter tolerance within ±0.1mm, and high-precision models reaching ±0.05mm, wall thickness deviation ≤5%, and high dimensional regularity.

Surface Quality

High-temperature oxide scale exists on both the inner and outer walls, resulting in a relatively rough surface, and minor defects such as pitting and scale may exist.

Smooth inner and outer walls without oxide layers, surface roughness can reach Ra0.8~1.6μm, with no obvious surface defects.

Mechanical Properties

The entire pipe has a uniform microstructure, good toughness, stable performance, and no work hardening effect.

Cold working refines the grain, resulting in superior strength and fatigue resistance; the cold-drawn state inherently possesses work hardening, and plasticity is restored after annealing.

Price/Cost

High production efficiency, high yield, and outstanding cost-effectiveness.

Multiple processes and lower yield result in a premium price compared to hot-rolled pipes of the same specifications. 15%~50%, the higher the precision, the greater the price difference.

Delivery Status

Mostly delivered in hot-rolled or normalized/annealed condition.

Mostly delivered in annealed or cold-drawn hardened condition; soft or hard condition can be customized upon request.

Core Application Scenarios

Suitable for municipal engineering pipelines, pressure vessels, general structural components, medium and low-pressure fluid transportation, pile foundation casings, and other conventional applications.

Indications include precision mechanical assembly, hydraulic cylinders, honed cylinder barrels, automotive parts, high-precision fluid piping, and other precision applications.