SS Camlock Installed with CS Threaded Flange

[Abu Bakar]

Hello everyone,

I am clearing the doubt that has been stuck in my head for so long.

I have seen a lot of application where a Stainless Steel threaded camlock is installed with Carbon Steel threaded flange. I know in term of galvanic corrosion, SS and CS are not a good mating combination. But for some reason I keep seeing that application being used onsite. I am not sure if that is just people being ignorance about it, or am I missing something. Maybe I am the only that's thinking it's wrong to do that.

Would appreciate any opinions to close this doubt.

Thank you in advance!

 

[Compositepro]

Rusty and pitted Camlocks do not work very well. Rusty pipe can still work fine.

 

[TugboatEng]

If the fluid or the environment are not wet there will be no galvanic corrosion.

There are no carbon steel camlock fittings.

Some of the fittings have carbon steel or 400 series stainless steel pins for the cams. Those can be a problem in corrosive environments.

 

[WKTaylor]

Stainless steel [SStl, CRES] and HRA alloys... high in nickel... are VERY dissimilar to carbon steel and will promote corrosion of the CS in almost any environment with electrolyte and O2. Isolation [coatings, gaskets, sealants, etc] will help... but not for long.

Regards, Wil Taylor
o Trust - But Verify!
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[EdStainless]

The SS will be more noble, and it can accelerate the corrosion of steel that is nearby.
But since the steel parts are large, thick, and aren't part of the coupling then they can corrode without hurting.
You will only see the galvanic effects if both parts are in the electrolyte.
The more corrosive the fluid the more the impact.

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P.E. Metallurgy, consulting work welcomed

 

[mk3223]

is the camlock connected to the pipe for the loading/unloading purpose? It my be used in a short duration in each operation and the liquid will be emptied out after.

 

[TugboatEng]

I swapped out all of the stainless steel camlock fittings on our tugboats with brass. For whatever reason my industry orients the female sockets upwards so every combination of materials except brass is prone to seizing when not regularly separated. Brass is less galvanically active against the steel pipe. I wrap the transition with Denso tape. Don't forget the Viton gaskets. As the gaskets take compression set the tension on the ears is lost and that causes the camlock fittings to pop open.

 

[EdStainless]

TBE, that brings back a memory from the farm.
I spent two days swapping all of the camlocks so that they didn't face up.
New thread tape and gaskets in all of them while I was at it.
The other advantage with brass is that is have some self-lubricity.
But brass is limited in the chemicals that it will handle.

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P.E. Metallurgy, consulting work welcomed