[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

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