Galvanic Corrossion

[Lupino]

Hello All ,

I have received an NCR from one of our bigest end-users .
we prodcued the valves 8" ball valves in S.S 316, the system is Sour but the the Support legs for the valve is zinc plate carbon steel .
they claim that there is the possibility of galvanic corrossion on the site and they want the legs to be replaced by S.S.

I already explained them the Process of Galvanic Corrossion.....
in fact the valves were inspected and drawings were approved
on the other hand I am not sure about this statement but our end-users never used the valve's support legs on the site. they ususally cut that before/after installation.

they are now claiming that why didint you mentioned on the BOM that the Legs are in Carbon steel!

I don't know what to say but it is an every day discussion
any suggestion will be appreciated .

 

[pennpiper]

Lupino,
What Legs?

Sometimes its possible to do all the right things and still get bad results

 

[Lupino]

support legs for the valve.

 

[pennpiper]

Lupino,
More explanation is required on this.
- Who decided these Ball Valves needed support?
- Why do these Ball Valves need support?
- If they do actually need support, why not use a more common support method such as a Clamp-On ring (see image here:

https://www.google.com/search?q=cla...hXGt1kKHWLGCdIQsAQITA&biw=1024&bih=633#imgrc=

) with a nonmetallic barrier between the pipe and the clamp?
- Why not attach the support to the Pipe next to the Valve instead of running the risk of damage to the Valve and the voiding of the Valve Warranty?




Sometimes its possible to do all the right things and still get bad results

 

[Lupino]

thanks for your respond , actualy they have hasked for support because they may wanted to store the valves somewhere.
to be honest I tried to find our WHY!! but sounds like this matter did not came to attention of neither sales nore project coordinators and also not the inspector of the supplier.
we usualy keep the valves for a very shrt time before shipment in the workshop and these suports are design in our standard base. 99% of the time when valves are in customer site these support are being removed. I mean it may not even being asked by customer but now we provide this they are claiming !

I just explained them alittl ebit about Cathodic protection and ... but I have not recived any feedback from them yet!