Characteristics of large diameter steel pipes

Before storing large-diameter steel pipes, attention should be paid to prevent rain or impurities from being mixed in. For materials that have been rained or soiled, different methods should be used according to their properties, such as wire brushes for high hardness, and cloth for low hardness. Cotton etc. After storage, it should be checked frequently. If there is rust, the rust layer should be cleaned. Generally, after the surface of the steel pipe is cleaned, it is not necessary to apply oil, but for high-quality steel, alloy thin steel plate, thin-walled pipe, alloy steel pipe, etc., after derusting, the inner and outer surfaces should be coated with anti-rust oil before storage. This is particularly important for the storage of large-diameter steel pipes.

1. The warehouse should be selected according to geographical conditions. Generally, an ordinary closed warehouse is used, that is, a warehouse with a roof, walls, tight doors and windows, and a ventilation device;

2. Do not stack with acid, alkali, salt, cement, and other materials that are corrosive to steel in the warehouse. Different varieties of steel should be stacked separately to prevent confusion and contact corrosion;

3. Large sections, rails, steel plates, large-diameter steel pipes, forgings, etc. can be stacked in the open air;

4. Some small steels, thin steel plates, steel strips, silicon steel sheets, small-diameter or thin-walled steel pipes, various cold-rolled, cold-drawn steels and metal products with high prices and easy corrosion can be stored in storage;

5. Small and medium-sized sections, wire rods, steel bars, medium-diameter steel pipes, steel wires, and wire ropes can be stored in a well-ventilated shed, but the upper and lower mats are required;

6. The warehouse is required to pay attention to ventilation on sunny days, close it to prevent moisture on rainy days, and always maintain a suitable storage environment;

7. The site or warehouse where the steel is stored should be located in a clean and well-drained place, away from factories and mines that produce harmful gases or dust. Weeds and all debris should be cleaned up on the site to keep the steel clean;

When quenching and tempering the hardness of large-diameter steel pipes, it is necessary to take into account the characteristics of production. For products produced in small batches, different large-diameter steel pipes can have different hardnesses. Factories that produce large-scale production hope that most large-diameter steel pipes have the same hardness range or are Fixed in several hardness ranges, which is very convenient for tissue heat treatment production. Considering the use of large-diameter steel pipes, when determining the hardness of quenched and tempered parts, attention should be paid to the working conditions of large-diameter steel pipes and the shape of the parts. Generally speaking, the higher the hardness value, the higher the tensile strength, the yield strength, and the fatigue strength of the smooth sample, but the lower the plasticity index, the higher the brittle failure tendency and the increased sensitivity to stress concentration. To make the stress distribution uniform and reduce the stress concentration phenomenon when the notch (spline, groove, or section change is large), the lower hardness can get the large-diameter steel pipe with higher fatigue performance.