Bronze Thru Hull and Stainless Steel Sea Cocks. Is that OK?

[gypsylounge]

I have two raw water intake seacocks screwed onto thru hulls, typical fiberglass boat installation. My seacocks were not of the highest quality and the handles on both units have failed. I have purchased two new very high quality Groco (IBV-1500-S) solid Stainless Steel Seacocks. I am just about the put them on and thought I might check with all you experts to see if there would be any problems with this. The Thru Hulls are both bronze and I will be putting these 316 Stainless seacocks on them and bonding them with the rest of the system.
Any immediate issues? I have done a seach for stainless/ bronze corrosion and have not found anything relating to this type of installation.
Thanks in advance for any help or suggestions you might have.
Ryan
"The Gypsy Lounge"

 

[njsail]

Why would you want to mix bronze and stainless? Can you return the stainless seacocks and go with the standard high quality bronze model? I just replaced several of my seacocks and thru hulls due to a few handles under my head sink rusting through. Why anyone would make a seacock with a steel handle is beyond me but someone did - and they were used by the manufacturer. Now the problem is solved. Good luck

 

[Maine Sail]

You will have an electrical difference in the metals as 316 passivated and 85-5-5-5 bronze are not in the same spot on the galvanic scale. Best not to mix metals below the waterline. Groco also makes the IBV valves in bronze.

When looking at the voltage differences as measured with a silver/silver reference half cell in salt water we have:

Thru-Hull - Bronze ASTM B62 (thru-hull) (85%Cu, 5%Pb, 5%Sn, 5%Zn) = -240 to –310 mV

Valve - Stainless Steel, Type 316 (passive) 3% Mo = 0.0 to –100 mV

That is far to great a spread for my personal comfort level...

 

[Bill Roosa]

Re: Bronze Thru Hull and Stainless Steel Sea Cocks. Is that

i agree with MS, you are making a battery that will self distruct in fairly short order. the thru-hull to seacock connection is not one that I'd want to have fail as you are left with using your wood cone hole pluggers. that is assuming it happens while you are at the boat.
don't park the boat in deep water, you may be able to recover it, have a BIG bilge pump and make sure you have shore power connected. Perhaps someone will note that the bilge has been running for a long time as tell the marina.