Quality standard of seamless steel pipe

1, chemical composition,

Of harmful chemical elements As Sn Sb Bi content of Pb and gas N H O proposed requirements, in order to improve the uniformity of the chemical composition in steel and steel purity, reduce the non-metallic inclusion and improve the distribution of tube billet, often by refining outside the furnace equipment to refining of molten steel, and even of the billet by electroslag furnace re-melting refining.

2, size precision and shape

Seamless steel pipe geometry includes steel pipe's outer diameter, wall thickness, ovality, length, bending, tube end cut slope, slope Angle and a blunt edge, straight steel tube cross-section size, etc.

3, the surface quality

"The standard stipulated in the seamless steel tube surface is bright and clean" requirements. Common defects are: crack, hairline, folding, folding and rolling, straight, straight, abscission, convex hull, hemp pit, pit, buckle (pitted), scratch (bruises), inner spiral, spiral way, the green line, JiaoAo, roller, etc. These cracks, folds, folding and rolling, abscission, scarring, indentation, convex hull allelic dangerous defects; Steel of the pits and the green line, bruises, mild straight, slightly inside and outside the spiral, inside and outside for general defects JiaoAo and roller.

4, physical and chemical properties

Including room temperature mechanical properties and mechanical properties under a certain temperature (thermal properties and low temperature properties) and corrosion resistance, such as oxidation resistance, erosion resistance, resistance to acid and alkali etc.) usually depends on the chemical composition of steel, organizational performance and purity of steel and steel heat treatment ways and so on. In some cases, steel pipe rolling temperature and deformation degree will also affect the performance of the steel pipe.

5, process performance, including the steel tube flaring, flattening, edge, bending, ring and welding performance.

6, metallographic organization, including the steel tube of low power and high power organizations.

7, special requirements, when the user use steel pipe outside the standard request.