Seamless steel pipe quality requirements in production

1. Chemical Composition

To enhance the uniformity and purity of the steel's chemical composition and reduce non-metallic inclusions, refining processes are utilized. This often involves using furnace refining equipment for molten steel and, in some cases, electroslag remelting to achieve higher purity and improved inclusion distribution.

2. Dimensional Accuracy and Shape

The key geometric dimensions of seamless steel pipes include:

Outer diameter

Wall thickness

Ovality

Length

Curvature

Pipe end cutting angle

Groove angle

Cross-sectional blunt edge alignment

These dimensions must adhere to stringent tolerances to ensure the pipe's suitability for its intended applications.

3. Surface Quality

Seamless steel pipes must meet "smooth surface" requirements as specified by industry standards. Common surface defects include:

Cracks

Hairlines

Internal and external folds

Rolling marks

Straight and spiral lines (internal and external)

Delamination

Scarring

Pitting

Convex areas

Scratches

Green lines

Concave areas

Among these, defects like cracks, folds, delamination, scarring, and significant pitting are considered dangerous and must be eliminated. Minor defects such as slight internal and external straight lines, spiral lines, and abrasions are more acceptable but still need to be controlled.

4. Physical and Chemical Properties

Seamless steel pipes must exhibit appropriate physical and chemical properties, including:

Mechanical Properties at Room Temperature: Ensuring the pipe's strength and ductility.

Mechanical Properties at Various Temperatures: Including performance at high and low temperatures.

Corrosion Resistance: Resistance to oxidation and various corrosive environments, such as acidic conditions.

These properties depend on factors like:

Chemical composition of the steel

Microstructural characteristics

Steel purity

Heat treatment processes

Additionally, the rolling temperature and the degree of deformation during the manufacturing process can also influence the pipe's performance.

By adhering to these quality requirements, seamless steel pipes can meet the rigorous standards necessary for their varied industrial applications, ensuring reliability and durability.