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Pickling problem before plating

We are manufacturers of electrical terminal blocks. we have metal contacts which are made of low carbon steel. we get this component Sursulfed to obtain increase in the hardness, strength and torque values. these components are then sent for pickling before zinc plating. during pickling we are facing problem of fumes with very foul smell. We are facing lot of cleaning problems after Sursulfing. can you suggest some pickling acid other than H2SO4 & HCl. else can these fumes (H2S) be prevented by addition of some additives?

Zankar Desai
Plating shop - Vadodara, Gujarat, India
2004

Mr Desai,

It is possible to reduce the fumes by adding a Fume suppressant to the acid. Your Plating Chemical supplier can help.

Use of a Good Pickling inhibitor plus Fume suppressant will help much more than just a simple fume suppressant.

There are a number of Alkaline based Oxidizing Rust and scale removers which function well in removing scale rust and black formations . These need heating to 90 centigrade.

Good Luck.

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016
2004

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First of three simultaneous responses --

Any strong acid will react with high sulfur steel to give the offensive fumes. Perhaps you should consider more conventional nitriding which does not involve the sulfur compounds that form part of the Sursulf process, so that you retain the original low sulfur content of the steel.

Bill Reynolds [deceased]
consultant metallurgist - Ballarat, Victoria, Australia
We sadly relate the news that Bill passed away on Jan. 29, 2010.
2004

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Second of three simultaneous responses --

Dear Sir,

Soaking in hot Alkaline permanganate followed by mild acid dip will solve your cleaning problem.

Shankara Narayanan N
- Bangalore, Karnataka, India
2004

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Third of three simultaneous responses --

Dear Mr Zankar Desai,

In my opinion, you should not use pickling at all before plating on your bridges as these will snap in service on account of hydrogen embrittlement during pickling. Your foul fumes are evidence of that.

Try Vibro finishing the parts and get them squeaky clean before mildly activating them in just 2% inhibited HCl before chloride zinc plating.

Regards,

Khozem Vahaanwala
Saify Ind

Bengaluru, Karnataka, India

2004

Dear Mr Desai ,
Your problem is very easy to sort out .u can use Anti-fuming Agent and that will immediately sort out your problem.

Regards

V.M.Kumar
- Mumbai, India
2005