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Acceptance Criteria for Passivation of a Mfg Vessel
A client of mine hired a cie to passivate a new mixing tank (SS 316L); in the end they got a certificate on which it confirmed the passivation was complete and, among other things, that it had passed a "white cloth" test. The problem is when the owner passes a white pad on the tank's interior, there is some grey/black residue. The person that has done the passivation says it is normal. Do you agree? Should they insist the passivation specialist come back to finish the work? What are the client's acceptance criteria for passivation of a vessel?Josette Lapierre
- Montreal, Quebec, Canada
1) Residue is certainly abnormal for passivated 316L and proof of inadequate passivation.
2) This is a legal matter. What passivation specification (e.g., ASTM A967 [affil link] ) is required by the contract and the contractor's certification? Is this "white cloth" method and criterion clearly defined? E.g., per ASTM ASTM A380 [affil link] , paragraph 7.2.2: "Wipe Tests -- The presence of a smudge on the cloth is evidence of contamination."
3) 316L is perhaps the easiest alloy to passivate. Verify that the correct alloy was used for the tank.
- Goleta, California
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Il est certain que ce resultat de test est innaceptable. Nous effectuons ce type de travail a Montreal et un de nos moyen pour vérifier la qualité de notre travail est de passer un linge blanc sur les parois des réservoirs.
Ce problème provient généralement quand les réservoirs sont poli. Lors de cette étape, de la pâte est utilisée pour polir. Cette pâte est très difficile à enlever.
Si la première de dégraissage n'est pas bien complété, la passivation sera un échec.
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