Epoxy and Rectorseal #5

[Not]

Yes, I’ve read Tony’s sealant tips about NPT, SAE and push lock connectors. Epoxy and Rectorseal #5 are in hand. The part I’d like clarification/advice on – epoxy on NPT threads. Specifically, what is the best practice on selecting which NPT threads should have it as opposed to Rectorseal?

I’m about to undertake a complete replumbing of my fuel system, with the exception of the return line. I’m replacing everything from the 1/2″ NPT bung on my aluminum tank forward to the engine. This includes numerous fittings/valves, the Seaboard double double filter setup with priming bulb bypass, heater circuit, fuel level site gauge – you name it, it’s getting replaced. With the exception of the female SAE push locks, I think every fitting/valve will have NPT on at least one side.

So, at least in my case – nothing is technically “permanent”. Even the original stainless bung that threaded into the aluminum tank had enough surface corrosion for it to get flagged on a survey for replacement. Yes…it lasted 30+ years, and the actual threads looked fine when removed. However, were it epoxied in – what kind of grief would I have encountered replacing it?

I guess a big part of the question, is understanding how “permanent” epoxied NPT threads will be. Can one simply apply heat to the joint, along with some cussing and adequate torque to remove? Or should it truly be considered a permanent joint once epoxied?

Topic

[Not]

Thanks, Rob – I’ll fetch some Tru-Blu.

I’ll try it everywhere first, but I do have a couple joints that may need epoxy for the reason you mentioned – orientation. Seems like there’s always that valve or elbow that feels too loose when oriented correctly, but too tight to get another turn out of.

[Rob Schepis]

Will Giese wrote:

epoxy on NPT threads. Specifically, what is the best practice on selecting which NPT threads should have it as opposed to Rectorseal?

For NPT go with Rectorseal #5 or Rectorseal Tru-Blu. On my zincs I use #5, for the fuel lines and such I use Tru-Blu. Did new pickup tubes, valves and a full SMX twin install last winter with the Tru-Blu on every NPT and not a single weep.

As to epoxy on stuff like this – pretty much permanent connection unless it is something totally safe to add heat to remove which does not apply to many things in a tight engine room. Save the epoxy for those nuisance connections. This AP pump had an annoying sweat type leak (maybe an ounce or two a season) since the day I installed it in 2014. Finally pulled it last winter and redid with Tru-Blu, still leaked, pulled it again and JB Weld, been 100% dry ever since. Threads must have been damaged or ?? but the JB did the trick. Also used JB on the drilled and tapped gear fitting connection due to small fittings and high pressure. JB can also be good when you can’t get a fitting to orient in the right position … either too loose and you can’t get another 360deg out of it.

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Not, Tony Athens

[Author]

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