Steel pipe as an important raw material, its production, the requirements are strict, especially in some areas of harsh environment, there are certain standards for its quality, not careless, we must keep in mind, in order to meet the requirements of each customer.
Steel pipe quality standard:
1, precision seamless steel tube factory to introduce the chemical composition. Of harmful chemical elements As, Sn, Sb, Bi, Pb, and gas content of 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 state, usually by refining outside the furnace equipment to refining of molten steel, and even of the billet by electroslag furnace re-melting refining.
2. Dimensional accuracy and shape. The geometric dimensions of seamless steel pipe mainly include the outer diameter, wall thickness, ellipticity, length, bending degree, pipe end cutting Angle, groove Angle and blunt edge, the cross section size of heterosexual steel pipe and so on.
3. Surface quality. The standard sets the requirements for the smooth surface of seamless steel pipe, the common defects are crack, hairline, inside fold, outside fold, mangle, inside straight, outside straight, layer separation, scar, pit, bump, pit (pockmark), scratch (scratch), inside spiral, outside spiral, green line, concave, roll mark, etc. Among them, cracks, inner folds, outer folds, crushing, layer separation, scarring, pits and bumps are dangerous defects. Pockmarks, blue lines, abrasions, slight internal and external straightenings, slight internal and external spirals, dents and roll marks are common defects.
4. Physical and chemical properties. It includes mechanical properties at room temperature, mechanical properties and corrosion resistance at a certain temperature. Generally speaking, it depends on the chemical composition, microstructure and purity of steel, as well as the heat treatment mode of steel. In some cases, the rolling temperature and deformation degree of steel tube will also affect the properties of steel tube.
PREV:Future precision steel pipe production scale will continue to expand