What is stainless steel pickling?

The purpose of stainless steel pickling is to destroy the oxide layers.
Pickling eliminates the oxides and stainless steel discolorations which appear after the welding process and enables any risk of localised corrosion starting to be avoided. It produces a “clean” metal surface capable of spontaneous self passivation. Pickling consists of removing a thin layer of metal using a mixture of hydrofluoric acid and nitric acid in suitable proportions.

Stainless steel - Pickling

|Pickling, to eliminate discolorations

The pickling operation enables elimination of thermo formed oxides which occurred during welding operations or heat treatments. There are different types of pickling:

  • pickling by immersion in a bath
  • pickling by circulation and spraying with washing balls inside the piping and tanks
  • pickling by applying a paste on the areas to be treated (welding beads)
  • mechanical or abrasive pickling
  • electrolytic pickling (with a tampon or brush)


In its workshop Technochim has a large size (7m x 2.5m x 3m) “fluonitric” (mixture of hydrofluoric acid and nitric acid) pickling bath. 

Technochim also offers electrolytic degreasing and has several stand-alone machines.

On its customers’ sites, Technochim operates either by connecting its anti-corrosive treatment skids to the plant and equipment to be treated, or by spraying pickling gel onto large scale surface areas.