Condition of Delivery for Seamless Steel Tube

The condition of delivery for seamless steel tubes is typically specified by international standards such as ASTM (American Society for Testing and Materials), ASME (American Society of Mechanical Engineers), or API (American Petroleum Institute). The most common conditions of delivery for seamless steel tubes are:

1. Annealed and Pickled (AP): The tubes undergo annealing to relieve internal stresses and improve ductility, followed by pickling to remove scale and oxides from the surface. This condition is suitable for general applications where corrosion resistance is not a primary concern.

2. Annealed and Cold Drawn (ACD): The tubes are first annealed to improve ductility, and then undergo the cold drawing process to achieve the required dimensions and surface finish. This condition offers improved mechanical properties and dimensional accuracy.

3. Normalized (N): Tubes are normalized by heating them above the transformation temperature and allowing them to cool in still air. This process enhances the mechanical properties of the tubes and removes internal stresses.

4. Quenched and Tempered (QT): This condition involves quenching the tubes in a suitable medium, such as oil or water, and then tempering them at a lower temperature to improve toughness and strength. This condition is commonly used for tubes subjected to high mechanical and thermal stresses.

5. Normalized and Tempered (NT): Tubes are first normalized as described above and then tempered to achieve a suitable balance of mechanical properties. This condition is particularly common for higher strength applications.

6. As Rolled (AR): Tubes are supplied in the same condition as they were rolled without any subsequent heat treatment. This condition is typically used for low-stress applications where precise tolerances or special mechanical properties are not required.