Pickling, Neutraliza and Passivation of Duplex (S32304) of Multiple Effect Distillation Unit . 1

[chemengineerjunior]

Hello All ..
We are doing a project for pickling,nuetralization and passivation of bottom weld plate of Multiple effect Distillation Unit ( Desalination )( Evaporator ).

So our plan is to use S weld Clean for Pickling and Sweld passivator for passivation .

I have few doubts as i am doing this for first time hope some can help

1) We are doing Pickling in a confined space area, and our pickling agent has nitric acid 10 - 20 %, will it create fumes when we apply ?
will a full face mask help us against fumes ?
2) Its adviced to mix pickling agent with water ? what proportion should we need to mix ?
3) After Pickling is it possible to nuetralize with water ( ph >6 needed )? Do we need caustic or soda ash ?
4)Can pickling agent can applied using acid resistant brush or by spraying on weld joints ?

Can some one help me out of this.

 

[EdStainless]

I don't have an MSDS for this stuff, but I sure wouldn't breath the fumes.
I am sure that SWeld advises full protection.
It is a gel, so it won't spray, and do not thin it.
It is commonly brushed on, they provide them also.
You rinse afterward and SWeld makes a neutralizer.
This will take 60min or longer, so be patient.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[chemengineerjunior]

@Edstainless Thanks for your repl

as we consider 20 - 30 % Nitric acid <10% Hydrofluoric acid in the chemical composition we are giving following PPE .

PPE including PVC suite, fresh catridge mask full face / face shield , Rubber gloves ( acid resistant ), rubber boot.

After passivation do we need high pressure water wash ?

 

[EdStainless]

Just enough pressure to get a good rinse. Being good and thorough is more important.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[pradipgoswami]

Hi chemengineer junior,

Any pickling product would involve highly toxic acids which produces strong fumes. Acids e.g HNO3, HF & H2SO4 are common pickling agents. As mentioned above by Ed Stainless, familiarizing with the MSDS beforehand is a must.Also the MSDS needs to be approved by someone looking after health and safety facilities available and the training of the personnel involved.Fume extraction and use of face mask should be must. The fumes generated by all of the above acids have serious effects on the respiratory system, even a short exposure could be harmful

The attachment is a popular handbook on published by Avesta Chemicals(Now Bohler Welding).. May be you'll be able to generate more ideas about the safety and other issues involved in the process, after reading through the contents.

Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299
All provided answer are personal opinions or personal judgements only. It's not connected with any employers by any means.