Quality inspection steps for stainless steel seamless pipes

The quality inspection process for stainless steel seamless pipes involves a series of seven critical steps.

Preventing Carburization During Heating:

When heating stainless steel seamless pipes, any oil on the surface can cause variations in the oxide scale, leading to carburization. The carburized areas on the base material beneath the oxide scale will be more prone to acid corrosion. This issue can be exacerbated by oil droplets from heavy oil burners during initial combustion. To avoid this, operators should avoid direct contact with the pipes using their hands and ensure no fresh oil comes into contact with the steel.

Thorough Degreasing Before Cold Processing:

If lubricating oil is present on the surface during cold processing, it must be thoroughly removed using trichlorethylene degreasing agents and caustic soda solutions. After degreasing, the pipes should be rinsed with warm water and then subjected to heat treatment to ensure any residual oil does not affect the quality.

Removing Surface Impurities:

Any impurities, particularly organic matter or ash, on the surface of the pipes can influence the formation of the oxide scale during heating. Ensuring a clean surface before heating is essential for maintaining consistent quality.

Ensuring Uniform Furnace Atmosphere:

Variations in the furnace atmosphere can lead to inconsistent oxide scale formation, resulting in uneven surfaces after pickling. To achieve uniform results, the atmosphere in all areas of the furnace must be consistent during the heating process.

Using Fully Dried Contact Materials:

Objects that come into direct contact with the heated pipes must be completely dry. If these objects are stored at room temperature after drying, they can absorb moisture, especially in high-humidity environments. To prevent this, it's best to dry the materials immediately before use.

Addressing Residual Oxide Scale:

Any residual oxide scale from previous processes can cause differences in the thickness and composition of the scale after heating, leading to uneven surfaces post-pickling. It's crucial to pay close attention not only to the final heat treatment but also to intermediate heat treatments and pickling steps to avoid this issue.

Avoiding Direct Flame Contact:

The oxide scale formed can vary if the pipes are exposed directly to the flame during heating. To prevent uneven oxidation, it is important to avoid direct contact between the pipes and the flame.

These steps are designed to ensure the consistent quality of stainless steel seamless pipes by preventing defects related to carburization, oxide scale formation, and surface impurities.