|
Pickling or chemical descaling is but one of several pretreatment steps available for preparing an article for further processing such as passivation or electropolishing, or to perform a superior cleaning operation of welded structures.
Prior to pickling, the heavy surface soils such as oil, grease, buffing compounds, drawing compounds, some scale, heavy rust, dye and paint markings, tape, adhesive residue and other foreign substances must be removed. This step may be accomplished by the use of alkaline cleaners, solvent cleaning, vapour degreasing, ultrasonic cleaning, steam cleaning, water-jetting, or other mechanical cleaning. Pre-cleaning is not required if oxide or scale is the only soil on the surface.
Pickling is typically performed to remove tightly adherent oxide films resulting from hot-forming, heat treating, welding and other high temperature operations. Welding or heat treatment often produces complex oxides that can vary in color. All these oxides are generally referred to as "scale" and must be removed. Where applicable, alternative mechanical methods such as blasting, shot peening, tumbling, and wheel abrading may also be performed. Abrasives containing iron should not be used. In many cases, pickling of stainless steels is performed in two steps, one for softening the scale and one for final scale removal. Over-pickling, under-pickling and pitting usually are the direct results of lack of control over process variables including acid concentrations, solution temperature and contact time. We design pickling products to achieve safety from this.
an ACTIVE deal with |
PASSIVATION |
|
|
|
|
|
