Thread sealant on engine/stabilizer zincs

Anyone know what sealant I should be using when reinstalling zincs as shown in the pict?
Thank you

We don’t have stabilizers but on our engine pencil anodes I don’t use any thread sealant.

There are differing schools of thought on this subject. There is one that says any type of sealant will only serve to electrically insulate the zinc from the metal it's supposed to protect. That premise isn't completely valid since even though there may be some insulation from application of a sealant, the tapered thread provides enough metal - metal contact to provide electrical continuity. I don't think any conventional thread sealant inhibits that electrical connection to the extent that it need be a concern. That said, teflon tape seems to leave enough of a film of material that it may not be a good choice for zincs. Copper-based anti-seize compound is conductive, so it might be a good choice.
The other school says that since the thread of the zinc housing is brass, it deforms easily and will probably seal all by itself without any additional thread dope. Because they're typically changed out routinely, and they're brass, there's little likelihood that the threads will lock up.

I've done zincs both ways, can't say I've seen any difference.

If it seals without any sealant, why use it?

I started a thread about this last March. Here is what the guru had to say:

Originally Posted by Russell Clifton View Post
Since it is much cheaper to buy just the anode and reuse the brass pipe plug, that is what I have been doing the past few years. But when they are removed from the heat exchanger, it is usually difficult to unscrew the anode from the plug. Sometimes I will need to drill the remaining anode and re-tap the threads. I have had to discard many plugs in the past and I am getting low on them.

So I am wondering if using anti seize on the anode threads would be acceptable. Here is some information I found on the internet:

Graphite is an excellent conductor of electricity and high temperature solid lubricant (up to 900 degrees F). It is therefore widely used in formulations of anti-seize. In assemblies with electrical current running through a fastened joint such as the threads of spark plugs, ground screws, and antennae connections, anti-seize can be used with minimal increase to resistance. Corrosion of a threaded joint increases the electrical resistance. The use of anti-seize on these types of connections will ensure current is transmitted reliably by preventing corrosion.

What is the general consensus on doing this?
Graphite-based anti-seize should not be used in marine application, it is extremely noble, i.e. every other metal, when in contact with it and and electrolyte (seawater) will corrode. If you were going to use an anti-seize I'd use a nickel or copper base. However, I'd run a test, before and after coating the threads and screwing the anode into the plug I'd check the continuity, anything over one ohm is too much, make certain the anti-seize is not increasing resistance. The fact is, I don't believe you need anti-seize per se, you could use a dielectric grease like Teflon Superlube, or a conductant paste like Koper Shield.
__________________
Steve D'Antonio Marine Consulting, Inc.
https://www.stevedmarineconsulting.com

I believe the magazine Practical Sailor did a test a few months back and found that it did not matter using tape or compound or whatever. In all cases the sealant did not insulate and use whatever you like. That said, I like Steve's idea testing continuity to make sure.

If I am using an older plug, I will sometimes use Rectorseal 5. I was recommended by Tony Athens at some point and it seems to work well. However, yesterday when I checked my anodes, I took them out, checked them and replaced them. I didn’t bother with putting any sealant on them. I’ll check to be sure they aren’t weeping on the next trip.

I have never used a sealant and have never experienced a leak. Tapered threads and the fact that the pressre in the system really isn't all that much says a lot. I recently cross-threaded one and it didn't leak. As Comodave said, if it doesn't leak, why use a sealant. I guess fear that it might but think about it. If it were to begin leaking it would just be a dribble. Deal with it then IF it occurs.

Comodave said:

If it seals without any sealant, why use it?

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I've used sealant and not used sealant depending on whether the plug is new or not. Regardless, I use a multimeter to check for continuity. On my trawler, I now use aluminum anodes that have a stainless steel plug. For those I use a little multipurpose sealant and then check with the multimeter. In all the years of installing anodes, I've probably only had 2 or 3 that needed an additional tweak for proper continuity.

Ted

Use whatever sealant you want, then take ohmeter reading from brass cap to the metal case of whatever its screwed on, it should be about zero ohms. Then you know its making electric contact.
I sometimes use marine grease, or teflon paste T plus 2 or nothing at all.

https://www.homedepot.com/p/RectorSeal-T-Plus-2-in-4-oz-Teflon-Pipe-Thread-Sealant-23631/100201204

And that paste works great on rubber hose ends, prevents them from getting stuck.

O C Diver said:

I've used sealant and not used sealant depending on whether the plug is new or not. Regardless, I use a multimeter to check for continuity. On my trawler, I now use aluminum anodes that have a stainless steel plug. For those I use a little multipurpose sealant and then check with the multimeter. In all the years of installing anodes, I've probably only had 2 or 3 that needed an additional tweak for proper continuity.

Ted

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Do you have a source for those AL pencil anodes?

Boatzincs.com should have them.

Bruce Palmer said:

Boatzincs.com should have them.

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I’ll check again, but last time I checked they didn’t.

FYI Cummins specifies Rectorseal T Plus2 or Hercules Pro Dope, I just use the Rectorseal, easy to find.

dhays said:

Do you have a source for those AL pencil anodes?

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I've had the best experience w Performance Metals Al pencils. I buy direct and found they have the widest selection of pencils and complete units. They also have the reinforcing rods in the center that help reduce break offs.
Some other suppliers had some but not all anodes I needed until I found the above.

Bacchus said:

I've had the best experience w Performance Metals Al pencils. I buy direct and found they have the widest selection of pencils and complete units. They also have the reinforcing rods in the center that help reduce break offs.
Some other suppliers had some but not all anodes I needed until I found the above.

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Same here. Performance Metals pencil zincs are top quality and they have a lot of choices on aluminum pencils.

I use Tef-gel on all sealing fasteners and Alco grease on anything that is in contact with seawater. In and out twice

Bacchus said:

I've had the best experience w Performance Metals Al pencils. I buy direct and found they have the widest selection of pencils and complete units. They also have the reinforcing rods in the center that help reduce break offs.
Some other suppliers had some but not all anodes I needed until I found the above.

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I’ve tried calling them in the past with little luck. I sent them an email today. Maybe they will respond.

Dave, I’m guessing you’ve already seen their page on aluminum pencil anodes. If not: https://performancemetals.com/collections/pencil-anodes

I had no problem contacting them.
Apparently they sell through distributors but when I gave them my location they said they didnt have a dealer in my area and no problem if I ordered direct.
Other online didnt list all of the ones I wanted and suspect they only stock most popular and order odd ones as needed.

dhays said:

I’ve tried calling them in the past with little luck. I sent them an email today. Maybe they will respond.

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I got an email reply today from Martin Wigg at Performance Metals. Very quick response. He wrote that I can purchase directly from them so I’m starting that process.

It is worth noting that pipe threads are designed to distort and seal when tightened, one time only. Reused plugs are less likely to seal without some sealer.

The Yanmar engine manually specifically indicates that thread tape or sealants should not be used on the zincs. The PO of my vessel used thread tape on them, and after a season, when I replaced them they looked perfect.

I didn't use thread tape when I replaced them. The following year they were more than 50% gone. This tells me that the zincs were doing their job, however the thread tape was clearly preventing them from doing so on the previous installation.

NPT threads are not designed to seal without sealant. The thread form has blunt thread tips and roots, and the tolerances for tip and root clearance do not preclude leakage. They are normally tap or die cut and a tapered thread cut that way necessarily has a step the the thread where the tap or die is reversed. Yes, often you can tighten them enough to distort and seal - but they are designed to use sealant. A variant, "NPTF" threads (F is for Fluid) is designed to seal, the specs are tighter and the thread profile is designed to contact at the tip and root. You will not find these in a normal zinc plug or its mating hole though.

For those of you who have not discovered Martin Wigg as Performance Metals as a source for Secure-Core AL anodes and who have managed to break off zinc anodes in the brass cap, just toss those caps in a jar with some pool muriatic acid for a half hour or so.

rgano said:

For those of you who have not discovered Martin Wigg as Performance Metals as a source for Secure-Core AL anodes and who have managed to break off zinc anodes in the brass cap, just toss those caps in a jar with some pool muriatic acid for a half hour or so.

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I finally connected with Martin Wigg and he is sending me some anodes. Hope to have them soon. Nice guy.

If you opt to use a paste sealant, apply it only to the wider section of the plug's NPT threads. Doing so will allow the uncoated, narrower section of threads to make good/better low resistance contact with the female threads of the heat exchanger or other part being protected. I'll reiterate, take a few minutes to check resistance to make certain it's under 1 ohm.

(In Kaohsiung, Taiwan)

Comodave said:

If it seals without any sealant, why use it?

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+1

rgano said:

For those of you who have not discovered Martin Wigg as Performance Metals as a source for Secure-Core AL anodes and who have managed to break off zinc anodes in the brass cap, just toss those caps in a jar with some pool muriatic acid for a half hour or so.

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+1 on the muriatic acid trick. Removes all the zinc, leaves a nice, clean cap ready for the next zinc to screw in.

about the only sealant that might insulate a pipe plug is teflon tape, depends on how thick the tape and how loose the plug.
NPT means taper, the threads actually grind into each other, a soft sealant will be displaced. And we are talking low voltages and low currents involved with galvanic scale, so as long as ohms between plug and base metal are basically zero its going to work ok regardless of how much thread is covered.