What are the general inspections of seamless steel pipes?

What are the general inspections of seamless steel pipes?

For the finished seamless steel pipe, some inspections must be carried out before leaving the factory, such as the chemical composition of the steel pipe product, the dimensional accuracy of the steel pipe product, hydrostatic test, spectral flaw detection, etc. Similarly, when users of seamless steel pipe products purchase seamless steel pipes, they should also do some simple acceptance of seamless steel pipe products, check the production standards of steel pipe grades, check the specifications of seamless steel pipes, measure the dimensional accuracy of seamless steel pipes and The number of steel pipes. Inspection and acceptance.

1. Chemical composition
Requirements are put forward for the content of harmful chemical elements As, Sn, Sb, Bi, Pb and gas N, H, O, etc., in order to improve the uniformity of chemical composition in steel and the purity of steel.
In order to reduce the non-metallic inclusions in the tube billet and improve its distribution, molten steel is often refined by refining equipment outside the furnace, and even the tube billet is remelted and refined by electroslag furnace.

2. Dimensional accuracy and shape
The geometric dimensions of the seamless steel pipe mainly include the outer diameter, wall thickness, ellipticity, length, curvature, cutting slope, bevel angle and blunt edge of the steel pipe, as well as the cross-sectional size of the heterosexual steel pipe.

3. Surface quality
This standard specifies the requirements for "smooth surface" of seamless steel pipes. Common defects are: cracks, hairlines, inner folds, outer folds, piping, inner straight, outer straight, delamination, scars, pitting, convex hulls, pits (pockets), scratches (scratches), inner spirals , Outer Spiral, Blue Line, Concave Correction, Roll Printing, etc. Among them, there are dangerous defects such as cracks, inner folds, outer folds, rolling, separation, scarring, pitting, and convex hulls; gravure printing and rolling printing are general defects.

4. Physical and chemical properties
Including mechanical properties at room temperature and at a certain temperature (hot strength properties and low temperature properties) and corrosion resistance properties (such as oxidation resistance, water corrosion resistance, acid and alkali resistance, etc.). Generally depends on the chemical composition and structure of the steel. The performance and purity of steel and the heat treatment of steel, etc. In some cases, the rolling temperature and degree of deformation of the steel pipe will also affect the performance of the steel pipe.

5. Process performance
Including flaring, flattening, crimping, bending, ring pulling and welding properties of steel pipes.

6. Metallographic structure
Includes low and high magnifications for steel pipes.

7. Special requirements
Requirements other than the standard put forward by the user when using steel pipes.

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