Brass to Aluminum.

[walleyes]

So I added one of the drain plug led lights to the boat today and I have a question. The plug itself is a very well made product no issues with it but I am concerned about the fact it is made of brass. The threads on the plug are 1/2” NPT and my drain plug hole is 3/4” NPT so a bushing is in order. My plan is to go with an aluminum bushing and use some teflon tape between the light threads and the bushing and have the aluminum to aluminum to the boat just to prevent any corrosion that may happen I don’t want the corrosion happening to the boat itself. My question for those in the know. Would the corrosion be enough to worry about while the boat is sitting in the salt water, keep in mind my boat is not moored for more than maybe a week to 10 days a year in the saltwater the rest if the time its used in fresh water maybe 100 hours a year and it sits in my shop when not in use. What are the thoughts in this, should I be concerned about it when it’s sitting in the chuck for a week at a time.
Actually reading the product details this is what they say the material is - ANTI-CORROSION:Titanic aluminum alloy housing.

Thoughts please.

 

[sly_karma]

Thread in pipe fittings is designed to be zero clearance. Teflon tape is applied not as a sealant but to lubricate the threads so that more turns can be engaged before cumulative friction locks everything up. The point of the thread cuts through the tape as the fitting turns, so in your application the dissimilar metals will end up being in contact.

 

[walleyes]

Thread in pipe fittings is designed to be zero clearance. Teflon tape is applied not as a sealant but to lubricate the threads so that more turns can be engaged before cumulative friction locks everything up. The point of the thread cuts through the tape as the fitting turns, so in your application the dissimilar metals will end up being in contact.

Yes for sure, the tape is to act as a anti seize for the threads on the light if some small corrosion starts not to separate the metals.

 

[ship happens]

Thread in pipe fittings is designed to be zero clearance. Teflon tape is applied not as a sealant but to lubricate the threads so that more turns can be engaged before cumulative friction locks everything up. The point of the thread cuts through the tape as the fitting turns, so in your application the dissimilar metals will end up being in contact.

Nice to finally hear that from someone else's mouth. The part about how teflon tape is a lubricant and not a sealant.



Do not put brass in aluminum whatsoever. No way to make that work. Period. Use plastic, or brass

 

[walleyes]

Have you ever heard of the material it’s supposedly made of the Titanic aluminum alloy ?

 

[ship happens]

Marelon is the only plastic I would trust below the waterline. I dont think they make bushings in Marelon.

 

[walleyes]

Found a good Nylon bushing today, bought a couple. Used a bit of sealant between the light threads and bushing just to ensure a positive seal. None into the boat as it’s a tight seal. It’s of good quality material so I’m confident in it and my mind is at rest as I have separated the metals. Did some digging on the interweb last night and using Nylon plugs as a bilge plug is not uncommon out there, a few guys prefer them as they don’t wear the threads on the aluminum but will wear the Nylon bushing instead.

 

[mikep]

I would not want something bronze.....which the underwater light fitting is made of anywhere near my aluminum boat.

 

[nicnat]

if you are on the mainland Martin Marine in N.Van has a good assortment of aluminum plugs, it's the only thing I used in my aluminum boats.