Passivation process of line pipe

Where the line pipe parts, such as electroless plating or other coating requirements, are generally required in pretreatment (including pickling go black, polished, etc.) through the passivation treatment to use when finished or assembled parts. Passivation can improve the thermodynamic stability of line pipe in environmental media, localized corrosion prevention line pipe, line pipe surface so that cleanliness has sufficient and can also eliminate thermal processing line pipe surface oxide.

Passivation process line pipe can be divided into two types of wet and dry. Concrete can be divided into many types. Passivation effect depends both on line pipe passivation process, but also on line pipe material itself, the specific factors are contained elements line pipe, line pipe metallurgical structure, line pipe processing status. In the composition of the elements, chromium, nickel and strong elements belonging passivating iron followed by passivation, and therefore, chromium and nickel content, the higher, the stronger the passivation of the line pipe. Austenitic, ferritic steel pipeline with a more uniform structure, can be passivated better, martensitic steel pipeline through heat treatment to strengthen its multi-phase microstructure of the organization, thus passivation is not strong. Line pipe by passivating the surface finish after machining is preferably, casting, sand blasting, etc. The resulting surface roughness is not conducive to passivation.