You can arrange for Van Leeuwen to grind and polish both the interior and exterior of your pipes. 
When stainless steel and stainless steel constructions are produced, annealing skin, mill scale and weld discolorations, among other things, appear on the stainless steel. Using stainless steel constructions can cause all kind of contaminants to accumulate on the surface. As they have a negative effect on the level of corrosion resistance, they are often mechanically removed, and this improves the quality of the material.
Grinding involves the removal of a small part of the material as well as of the contaminants on the surface by means of an abrasive consisting of granules, such as a stone, grinding disc or a band. A number of grinding treatments are often used in succession, involving the use of abrasives with smaller and smaller granules. Grinding can also be sometimes used as a pretreatment for other surface treatment techniques. The surface can be made smoother by polishing. This not only increases resistance to corrosion, but it also makes cleaning the surface easier and more effective, and it enhances the appearance.
Electrolytic and electrochemical polishing is a galvanic process during which the parts undergoing treatment pass through a circuit of chemical baths. The most important stages are the degreasing, pickling, and the electrolytic polishing itself. The steel is rinsed between each of these main treatment processes.