RE: RE: Galvanic corrosion

From: <Steve>
Date: Mon Jun 02 2003 - 04:47:00 EDT

Hi Jagdeep

Is it instrument air from a drier? If you use a desiccant drier, what is the desiccant you use? If refrigerant drier, what refrigerant? Any source of ammonia/ammonium will destroy copper. Black deposits are an indicator. If you have no drier, are you sure the problem is not erosion from water droplets or line crud? Instrument air is often in short supply and high line velocities do not argee with copper.
How do you know the problem is corrosion?

Cheers

Steve McKenzie

-----Original Message-----
From: jagdeep singh [mailto:jsingh11@rediffmail.com] Sent: Monday, June 02, 2003 8:10 PM
To: PipingDesign@yahoogroups.com
Subject: Re: RE: [PipingDesign] Galvanic corrosion

Hi Stev,
Thanks for showing interest. The copper tube has show corrosion at the Brass fitting end. The line is - Plant Air for the Instruments.
Jagdeep

On Mon, 02 Jun 2003 Steve McKenzie wrote :
>Hi Jagdeep
>which piece has corroded? As Geoff said dezincifation can occur.
>Is it the
>brass that has gone? Can you describe the line? Liquid and pH?
>Cheers
>Steve McKenzie
>-----Original Message-----
> From: Geoff Stone DD&D Australia
>[mailto:blenrayaust@yahoo.co.uk]
>Sent: Monday, June 02, 2003 5:25 PM
>To: PipingDesign@yahoogroups.com
>Subject: Re: [PipingDesign] Galvanic corrosion
>Possibly the grade of brass. Brass is known to to dezincify and
>the
>resultant
>mess looks like corrosion.
>--- punnu_h2003 <jsingh11@rediffmail.com> wrote:
>---------------------------------
>Thanks for some stuff on the subject. But I am specifically
>looking
>for the possible reason of corrosion when SS tube and a Copper
>tube
>have a Brass coupling to join them. What could have triggered
>the
>Galvanic Corrosion.
>-----Original question-------
>My question relates to the Compatibility of distinct materials
>when
>used in assembly. To be specific, there is a case where a SS tube
>is
>joined to a Copper tube wit a brass coupling. At the joint,
>corrosion
>has set in. Why and what is the cause? What metal properties of
>these
>materials are conflicting causing corrosion.? What is actually
>a
>Galvanic corrosion?Thanks. I hope to get good and informative
>response.
>Jagdeep
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Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Received on Mon Jun 02 04:47:00 2003

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