Siljan Allards has erected one of the largest pickling plants in the Nordic countries. The acid mixture we use for pickling is environmental friendly and also kind to the operator.
In the pickling plant, we can pickle objects which are up to ca 20 meters long, has a diameter of ca 4 meters and a weight of up to ca 30 ton.
During the manufacturing of stainless steel process equipment, some operations cause a decrease of the corrosion resistance and of the surface finish of the products:
During welding and other operations performed on stainless steel during manufacturing, a lowering of the corrosion resistance is obtained. As a result, the service life of that stainless steel product is decreased, especially if chlorides and similar impurities are present in the fluid.
During welding, a chromium rich oxide is formed on the top of the weldment and close to it. The chromium in the oxide is taken from the area beneath the oxide. As a result, that area contains less than ca 12 % chromium and is no longer stainless. That area therefore has to be removed to make the product stainless, i.e. pickling in an acid mixture must be performed.
During the forming of plate, e.g. in a press brake, iron from the tools can contaminate the stainless steel. At those places, corrosion can occur also under mildly corrosive conditions. The only efficient way to remove that iron contamination is to pickle the material in an acid mixture, suitable for stainless steels.
Other surface treatment techniques like sand or glass blasting or grinding removes, in the best case, oxides on the surface but does not necessary remove the area under the oxide which is depleted in chromium. As a result, the low corrosion resistance of that surface may remain which can cause corrosion attacks in service and a reduced service life.
| Siljan Allards AB, Phone +46(0)248-125
35 Fax +46(0)248-137 85 |
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