How to protect Serration of Flanges during Hot dip galvanization

[aly mhaskar]

Dear All, Presently we are doing hot dip galvanization of pipe spools where we have to protect the serration of flanges during galvanization.   Can any body suggest what can be applied on serration to protect it from adhesion of ZINC on serration.   Thank you in advance.   Mhaskar Aly Kuwait

[Chaitanya Purohit]

Molycoat

is the high temperature grease which can withstand beyond 900 deg C. Check with supplier / manufacturer to use the same for your said application.

l am not sure but I hope it will serve your purpose

Regards..

[santosh bhandary]

AT WHAT TEMPERATURE HOT DIP GALVANIZATION IS DONE?

[Aly]

The Galvanization temperature is 450 Deg C .        -------Original Message-------

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[Richard Bonardo]

Aly :

I have done it before,and it just working fine. It is true that there are small amount of melting zinc will fill the gaps between serration but per my past experience there are still enough roughness to hold the gasket.

I did it on 2 ", 4 " and 6 " flanges for your info.

Regards
Richard Bonardo
QA/QC Engineer
PHE-ONWJ

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From: Aly <mhask...@gmail.com>
To: material...@googlegroups.com
Sent: Tue, 24 August, 2010 1:03:42 AM
Subject: Re: [MW:0] How to protect Serration of Flanges during Hot dip galvanization

[MNS]

Molykote 1000 of Dow Corning Product will withstand upto 650 deg C,
anyway you can apply that uniformly and do hot dipping; but ensure no
removal of the coating while dipping.

[Hamid Jabbari]

Does any one know how could i remove the hot galvanized coating from face of flange?
plz advise

[Shridev Kurup]

Dear Hamid,
Galvanised flanges mostly used in utility services  not in hydrocarbon service where leak and leakage is  catastrophic.  If galvanising is applicable in to your project flanges than specific requirements of flange seration roughnes will not be there in specs and piping class. Please read the applicable piping class material requirements. Gaskets types will compensate on the galvanised face.

If required before galv.additional temporary  arrangements can be prepared with thin metal sheets but that also will not give full assurance.

But please reverify against your requirements and address this to your client or customer.

If already this product is mistakenly galvanised than machining will be only solution on loose flanges. .and very difficult on spools.
Regards

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[Perumal Govindan]

Hi
I am forgetting the cheminal name, which will be applied on the serrated surface before HDG bath, once done it will be cleaned to recover the serration.

Requested to contact the HDG agencies for more details.

With kind regards
Govindan
Kuwait

[Perumal Govindan]

Hi

Request Client to accept or re machine it with the manufacturer or machine shops.

No chemical is available to clean, since the serrated surfaces might have fused.

With kind regards
Govindan

On 11 Feb 2016 07:00, "Hamid Jabbari" <lif...@gmail.com> wrote:

[Shashank Vagal]

Removing galvanizing:

Try using 50% dilute HCl, dip your part in it till the bubbling stops, then wash off / rub off with baking soda.

Vinegar also is useful. 

But take care not to inhale fumes.

 

BR,

Shashank C Vagal 

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From: Perumal Govindan <perumal...@gmail.com>
To: material...@googlegroups.com
Sent: Friday, 4 March 2016 7:56 AM
Subject: Re: [MW:24429] Re: How to protect Serration of Flanges during Hot dip galvanization

To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/CANiuf9ezuZ21SrWWWCy-jg6M4q5HRtC8h4FopYjcp5mscRMMyw%40mail.gmail.com.