Corroded pipe nipple

I had that situation with a dometic copper A/C discharge tree connected to the a/c pump with a red brass nipple. Did not last a year. The way I fixed it was with a bronze pipe thread to hose barb fitting and another bronze pipe thread to hose barb fitting with a very short piece of hose double clamped in between the two hose barbs. Same length but now bronze on both ends. I can find the bronze to hose barb fittings virtually anywhere. I've never seen a bronze nipple to nipple.

Most likely electrolysis and erosion.

You will never find a bronze pipe nipple like that cause they are not made. They are all brass. There are some bronze close nipples from Groco etc.,that are large for seawater intakes, etc. but no length nipples made in bronze, all brass.
I do not think the close nipple you just put in is bronze....Good idea what Pascal and Capt J said.

Chances are if you used a nipple, it is not bronze but yellow brass. It too will fail. But they do make them: here are groco ones

https://www.westmarine.com/buy/groco--cast-bronze-threaded-nipples-npt--P011_332_001_520

I use Teflon tape, I find it's worn through in plenty of area and makes a good bond. It doesn't leak, you don't have to he-man tighten it so that it remains leak free...….IDK......

I've seen most manufacturers use pipe dope on water connections.

NEVER use brass on any through hull fitting or line, even at its terminal end. It will sink you sooner or later. Brass is best left for clocks and decorative feature above the water line. Safe alternatives are myriad, but all need to be inspected regularly.

A quick eye check: Bronze will be reddish, brass will be yellowish. Scrape thru the oxidation.

Also the use of plumbers tape (my term) should be left to a minimum because it can interfere with your galvanic grounding system, and in some case completely isolate the fitting. I'd check that seacock and any other metals in that distribution line Use compression fittings or a tapered thread

Teflon tape does in fact leak, quite often. As of the last ten years the are numerous other pipe sealant options are available in addition to teflon tape. Teflon tape often also acts as an insulator.

Try Loctite 565

Engineered for just about any plumbing circuit up to 2'' diameter and under 3,000PSI nominal operating psi, 565 suffices. Including potable water lines not exceeding 180F.

Agreed. My technique is to keep the sealant north of the first thread tooth. While I expect the threads amidst the dope to find some contact, I rely on the initial thread to make certain bond. Keep it clean.

And, yes, always always bronze. Brass will evaporate with the slightest electrolysis.

Is pipe available? Tapping a thread on it should be easy considering how soft it is.

I'm dealing with corrosion as well. Nasty stuff. Sourcing this for replacement.

Interesting. Is that outlet (?) always beneath the water line as it appears. If so, I think it would need to be bonded or otherwise protected with a zinc.