Should you use anti seize on pencil anodes ?

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Russell Clifton

Russell Clifton

Guru
Joined
Sep 10, 2012
Messages
877
Location
usa
Vessel Name
Sea Fever
Vessel Make
Defever 49 RPH
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?
 
Hi Russell,
I am not sure about the answer to your specific question (so I look forward to the responses), but it is OK to use a product like Rector Seal #5 on the threads of the brass plug where it contacts the item being protected (eg. hx, aftercooler, etc.). I have seen videos where "experts" have tested using a multimeter have tested and found there is still good conduction. So, I would guess that a small amount of anti-seize may be OK? Like I said, I am interested to hear from the experts.
 
I suppose you could use something like that. Personally, I think there are other areas you can save money with a much lower penalty cost should the anode loose conductivity with the holder.

Ted
 
Just soak the brass plugs in muriatic acid (pool acid) the zinc will dissolve.

However I use new plugs because the pipe threads on the plugs are, NPT, and designed to distort when tightened and make a good seal without any sealant. Used plugs are already distorted.

I have used rector seal to prevent drips and checked every one with an ohmmeter and always fund good conductivity because the distortion cause metal to metal contact while the rector seal is left to fill in the gaps.
 
you can check it with dmm and see if you get any increase in resistance. but for what its worth. cats procedure recommends using blue loctite on the anode threads. probably because they are more worried about them coming loose and being ineffective than getting them out easily.
 
Contrary to intuition, no matter how much grease or anti seize you put on the threads and whether it is conductive or not, there will be good continuity between the threads once you tighten it.


When you tighten the threaded joint you create tremendous point pressures that squeezes out all of the grease and assures good contact.


David
 
PJHoffnet said:
Great 'experimental data' driven article about it over on Sea Boards Marine's site. I use Rectorseal for each replacement
Click to expand...

Great data for a brass/brass fitting when elec conductivity is required, but brass is soft and will seal without much difficulty. There is no data for zinc to brass.
Due to the high expense of replacing heat exchangers I don't want any compromise on conductivity so I would not use teflon tape under any circumstances nor would I use rectorseal.

I use a permetex thread lubricant and have not had any issues with corrosion or continuity.
 
djmarchand said:
Contrary to intuition, no matter how much grease or anti seize you put on the threads and whether it is conductive or not, there will be good continuity between the threads once you tighten it.


When you tighten the threaded joint you create tremendous point pressures that squeezes out all of the grease and assures good contact.


David
Click to expand...

This has also been my experience. The hard part is dealing with the people who thing they "know" without actually testing.

Ken
 
I have used a little copper anti sieve for the plug threads. Have measured but anodes are being consumed.
I'm ready to try to reuse some plugs and plan is to use Loctite on rod threads... the anode rod shoulder bottoms against the plug and should complete the conductivity but threads should be sufficient even w Loctite. It fills voids but should not provide complete isolation.
 
You never have to throw away the plugs - hold with pliers and melt the zinc out with a propane torch. If the anode breaks off to begin with then you should have replaced it much earlier.
 
I have for years added a small bit of a sealer, now Rectorseal 5, to the anode threads and the brass cap threads. Now I can usually remove the pencil remains from the cap and the cap no longer weeps.

I do check with the ohmmeter when done just to be sure but I have never seen any sign of a problem.

After about three or 4 reuses I simply get new caps as they do get monkeyed.
I quit playing with drilling and tapping as , even though I am retired, it is not worth the aggravation or the time.

I've mentioned before that I keep several sets of each size of anode assembled in a small peanut butter jar so there is minimal monkeying at change over time.
Pull the old one, set aside, install the new. THe only monkeying needed is to apply the sealer to the cap threads.
 
From my materials engineering background, I'd say connectivity/continuity of the zinc is key to anode function. Hence, always used pipe dope on the brass threads rather than teflon tape.

If I change the zincs on a strict 12 month schedule, I usually salvage all the brass plugs. If I wait longer, I'll loose a few. I don't mind loosing a brass plug, but I really hate loosing a zinc in the hole.

On this same topic, I was cleaning out the heat exchanges on a pair a 3126b Caterpillars and noticed the heat exchanger end caps were not bronze (like on my older 3208s) rather there were made of a plastic material. The zinc rods were taped into these plastic end caps just like the similar bronze caps. The zincs seem to dissipate in a similar manner as on the 3208s with the bronze. Go figure? I didn't check the continuity of the plastic (it may be conductive). The engines are all painted up so I can't check it in place.
 
Russell Clifton said:
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.
Click to expand...

Graphite is also the most noble element on the galvanic scale and zinc near the very bottom. If you want to accelerate anode wasting adding a bit of graphite to the mix will certainly help in doing that.;)

I use Hercules Real-Tuff pipe dope, it's galvanically inert, & will allow for future disassembly and a leak free installation.

The real question is why anyone would expend the time or energy to re-use the brass portion? I thought sailors were the frugal ones..

We pay about .89¢ more for a Cummins anode with the brass end vs. the bare anode itself. You'll spend more in fuel warming up the engines than you would to just buy the whole shebang ready to add pipe dope and install.. If your costs difference is much more than this you probably need to find a better supplier of anodes..
 
Last edited:
Even teflon tape may not stop conductivity, If it is not wrapped too much and is securely tightened. Teflon tape might allow a unsophisticated user to over-tighten the fitting.

I prefer pipe dope of some kind if it is leaking. Mostly Rectorseal, if needed, and it may not be needed.

Using an ohmmeter will tell you immediately if it is working ok.
 
The plastic HE end caps have brass inserts which connect to the body via inserts in the bolt holes.
 
EngNate said:
You never have to throw away the plugs - hold with pliers and melt the zinc out with a propane torch. If the anode breaks off to begin with then you should have replaced it much earlier.
Click to expand...
For anyone thinking of doing this...


There are reports of water behind the zinc turning to steam and blowing the molten zinc out....so be careful...it has happened to me before I realized the effort to save very little money as CMS posted is a waste of my time...


I do keep a few of each...complete sets and caps/anodes in case I get a few stubborn ones.
 
As a former sailor, I am cheap. I reuse the brass plugs when I can. I use Rectorseal 5 on the plug threads but have not used anything on the anode threads. If there was an inexpensive and readily available anti-seize I could use on the anode threads, I’d be happy to do it.
 
I don’t use any kind of sealer on the anode when installing them and have never had any leaks. Maybe I am just lucky...
 
Comodave said:
I don’t use any kind of sealer on the anode when installing them and have never had any leaks. Maybe I am just lucky...
Click to expand...
I guess I am one of the lucky ones as well. I tighten firmly but am careful not to overtorque, no sealant, never a leak. Remember, this water circuit is a relatively low-pressure circuit. It is open at the other end. Tighten that fitting, start her up and, if it doesn't leak, well ......
 
No sealer. A little nail polish around the cap/zinc interface works well and looks good
 
Russell Clifton said:
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?
Click to expand...

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.
 
My plugs have been reused many times. I'm still using ones that came with the boat. I use a never seize like product on the zinc threads because it's easier to unscrew later. I don't use anything on the plug threads. The zincs seem to dissolve at about the same rate I saw in other boats and engines.
For you people with small engines that come w/o zincs, I usually find a place to put a zinc and afterwards, they dissolve just like the ones on the main engines.
 
Getting the old zinc out can always be a chore. If you want to save the plug, drill as close to the center of the old zinc with a smaller diameter drill bit, you can then use a flat blade screw driver or similar tool, to grip inside the hole and screw out. To clean the threads, get an end tap of the proper size thread of your plug, to chase out the threads.
It sounds like work but only takes a couple of minutes.
 
I just replaced my zincs (12 between both motors) last week. I usually buy just the anode and reuse the caps, but this time I couldn't get the old anodes out of most of the caps. Maybe I waited a little too long this time, or maybe the caps just finally had enough, who knows.


Anyway, at WM the pencils are dirt cheap with Port Supply, like .89 but the full zincs with cap are way more, like $7.50. So over $50.00 in savings to save the caps. Worth it in my opinion,
 
I get my zinc at boatzincs.com, Its the best price I have found.
 
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