¨Passivation de l'acier inoxydable

Bonjour, voilà ce qu'on trouve sur le manuel des compensateurs de pilonnement de BOP sousmarins à propose des aciers Inoxydables:

ça vous permettra de vous mettre à l'Anglais pour certains:

.... type 300, 302 303 304...type 347 is good welding grade but Type 316  (which is mobdyenum stabilized against carbide precipitation) is desirable because of its greater corrosion resitance in the presence of sea water. Bare stainless is not corrosion proof; in fact it may rust quite readily if it is not properly cleaned and passivated to build a tough chromic oxide film. It is this surface which is the barrier to corrosion and rusting.

Passivation stailess steel pipe:

....it is not stainless until achromic oxide film bilds on its surface. This willl occur due to the exposure to oxygen of air.The passivation process is intended to hasten and enhance the creation of this oxide as well as to bild a thicker and tougher film.

The passivation process will not be satisfactory unless the surface is first cleaned.....

Caution: Do not clean stainless steel with an ordinary wire brush which will leave traces of iron on the surface.

Swabbing with the pasivation solution will remove most loose solids. In extreme cases a preliminary acid wash can be used for cleaning if this wash is neutralized and rinsed away prior passivation.

Passivation is accomplished as follow:

  1. Immerse , flush or swab with warm 20%-40% nitric acid for one hour or longer.

  2. Flush surface with clean fresh water (not sea water) to remove all traces of acid.