Ball Valve Gone Bad - Why?

[Dreaming Yachtsman]

The attached picture is of the formerly chrome plated bronze ball in a 1 1/4 inch 600 WOG bronze valve made by "Buck Algonquin." The valve was installed as the hull valve for my generator set cooling water suction in January 2005. You can still see a small section of chrome in place in the lower right corner of this picture but the rest of the chrome plating is history.

Would any metallurgists or other valve gurus out there care to venture a guess as to the cause of the chrome pitting so I can protect the replacement that I now must procure and install? The valve had no electrical connection to it and was located about 25 cm (10 inches) from the port Yanmar saildrive on my catamaran. Two other valves installed at the same time [one identical valve about 30 cm (1 foot) higher in the same hull and one 1 inch valve in the opposite hull] show no evidence of chrome pitting.

Thanks in advance for any help you can give me. The boat is on the hard in Guaymas, Mexico, but we would like to launch soon to avoid the fall rush.
[Edited to correct a typo. jcb]

[Alan Wheeler]

Yep, don't use the Chrome Balls. They will corrode. Use plastic or Bronze.

[Chief Engineer]

Just venturing a guess....you say there was no electical connection to it....what about the conductivity of salt water in a generator cooling circuit? Could a bonding wire to a zinc have protected it?

Just surmising...y'know

[Lancerbye]

That ball looks like it is being used as an anode in a galvanic circuit. Check your bonding on your genset and possible current leakage from the generator itself. Is everything clean and dry on your genset?

[Alan Wheeler]

anode in a galvanic circuit.

Yes it will be. Between the chrome and the bronze of the valave body. They are dissimilar metals sitting in salt water. That will cause the Chrome to lift right off pronto. Although Chrome is a passivating metal, it needs oxygen to create the oxide layer. There is simply not enough oxygen in water to create the layer. So the Chromium will eat away. This is also the main reason SST is not always good under water. Too little oxygen to allow the chromium to oxide.

[Lancerbye]

I agree with that Alan but I think this one is getting outside help since the other ones installed at the same time don't have this problem. Nothing like a little current path thru some wet or damp electrical connections on a generator to kick that process in high gear. Or maybe a bad ground.

[Pura Vida]

It could be a QC problem at the factory.

[Dreaming Yachtsman]

A conversation I had with J.D. at Downwind Marine in San Diego supports Pura Vida's opinion. He told me of a discussion he had with an employee of the valve manufacturer who had actually visited the factory in China. The rep said that when they make low cost valves, anything that even looks remotely like bronze is thrown into the melting pot, thus putting the metallurgy of the finished product in question. He said that more expensive valves have better quality control, though.

In my initial post I mentioned that there was no electrical connection to the valve. Specifically, it was not connected with a ground wire to any other component on the boat. It's only connection to the generator was through a 3 foot length of rubber hose, a strainer, the cooling water pump, and another run of rubber hose. Thus I don't believe the corrosion was caused by stray electrical current, especially since the generator has only about 230 hours on it. Now that we have a nice solar array, we hardly run the generator at all.

Thanks to everyone who has contributed to this discussion. On my last trip to San Diego I purchased Marelon replacements to hopefully prevent this problem from recurring. I have also added "cycling hull valves" to my monthly maintenance schedule, something I should have been doing but wasn't.

[Alan Wheeler]

Yep metal "quality" is a big concern and could well be the issue. All you need is a slightest amount of Zinc in the mix and you will have an issue with Bronze. The valve ball only needs the slightest of scratch or damage to the chrome and away it goes. It could be a number of things. IMO, seeing as pure Bronze valves are hard to find, expensive to buy if you do find them, Marelon is the best way to go.

[hellosailor]

"the factory in China. "
No one manufactures anything in China unless they are looking for the cheapest source. Is that any way to source out critical components?
'Nuff said.

[Dreaming Yachtsman]

Sorry if the pun in this subject line offends anyone - I just couldn't resist.

I just wanted to "close out" this thread by saying that after two hot sweaty days in the engine rooms, I have reinstalled the replacment valves and will hopefully not have any leaks when we splash the boat in a couple of weeks. We are presently on the hard in Guaymas, Sonora, Mexico, where daytime air temps are in the mid 90's F.

Thanks to everyone who contributed on this thread, especially Alan for your suggestion to replace bronze valves with Marelon.

An interesting but not terribly important development in this saga: while installing the replacement for the valve shown in my initial post, I discovered hidden behind another fixture a fourth valve that was installed at the same time. Its chrome was still intact so I lathered it with Lanocote and it works fine. This detail corrects my initial report of having had three valves installed at the same time - four were actually installed, two that failed and two that are still intact. I am wondering how long those two will last . . . . .

[Celestialsailor]

Unfortunately, Todays big Marine suppliy stores only look at the bottom line...$$$. Their profit is at the expense of the safety of our vessels. I try not to buy items made in China. It is difficult now a days however.

[GordMay]

Originally Posted by Celestialsailor

Unfortunately, Today’s big Marine supply stores only look at the bottom line...$$$. Their profit is at the expense of the safety of our vessels. I try not to buy items made in China. It is difficult now a days however.

I don’t think that there’s anything new, nor surprising, in that business looks to making a profit.
The challenge for consumers, is to convince business that their best interest lies in providing high quality “value” products, even if that results in higher prices.
Price is only one of several variables we should evaluate when we assess a product’s overall value.
Remember the old axiom, "Beware the cost of the lowest price." Cost of ownership, payback time and solving problems (all “value” qualities) are the true issues an educated buyer should really seek.

Celestialsailor’s general policy is the most effective strategy towards this end.