Friday, December 4, 2009

[MW:3788] Re: Pickling and Passivation

Refer ASTM A 967, It includes several alternative tests, with
acceptance criteria, for confirmation of effectiveness of such
treatments for stainless steel parts and it supplements ASTM A 380

The tests in this specification are intended to confirm the
effectiveness of passivation, particularly with regard to the removal of
free iron and other exogenous matter. These tests include the following
practices:
Practice A-Water Immersion Test : for presence of free iron particles
imbedded in the surface.
Practice B-High Humidity Test : for presence of free iron particles
imbedded in the surface.
Practice C-Salt Spray Test : for presence of free iron particles
imbedded in the surface.
Practice D-Copper Sulfate Test : for presence of copper deposits.
Practice E-Potassium Ferricyanide-Nitric Acid Test : for presence of
free iron on the surface.

-----Original Message-----
From: Salvador, Camilo [mailto:cafsss@gmail.com]
Sent: Wednesday, November 25, 2009 4:21 PM
To: Materials & Welding
Subject: [MW:3742] Re: Pickling and Passivation

How can i ensure that there's no residual acid on the surface? Visual
inspection?
What's the best method of cleaning post passivation?

Most part of procedures are based on ASTM A-380, but this standard
doesn't give us details about the "accept criteria" of passivation.

Regards,

On Nov 24, 4:43 am, "Bathula Raghuram (Mumbai - PIPING)"
<R.Bath...@ticb.com> wrote:
> Done mostly for hygienic/aesthetic reasons, however a fine surface
> finish is also crucial to corrosion resistance. SS is protected by a
> thin chromium oxide layer mainly taking O2 from atmosphere. But during

> fabrication this self healing layer is disturbed due to mechanical
> work (grinding, welding, cutting etc.) and reduce resistance to local
> corrosion.
>
> The after treatment (pickling/passivation) will be determined on
> various factors, corrosion resistance of steel grade, corrossivity of
> the atm, hygienic condition aesthetic appearance etc.
>
> Scale or heat tint formed during welding required to be removed, hence

> recommended mostly for welds only; assuming the rest of base material
> passive layer is intact. Pickling is de scaling, cleaning process
> before passivation.
>
> ________________________________
>
> From: Agrawal Sunil (Mumbai -Stequ)
> Sent: Tuesday, November 24, 2009 11:33 AM
> To: materials-welding@googlegroups.com
> Subject: Pickling and Passivation
>
> Regard to Process Static Equipments, when it is necessary to carry out

> Pickling and passivation. If we don't do pickling and passivation, how

> it is going to effect the product when put in service?
>
> Sometime, only pickling and passivation is carried out only for weld
> portion, why it is so? Also sometime only pickling is carried out.
>
> Request to for guidance on above.
>
> Thank you,
>
> Sunil Agrawal
>
> Tecnimont ICB/ STEQU
>
> Filtered by Hosted Filtering


Filtered by Hosted Filtering


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