Thread sealants on NPT and others?

[WinterDeere]

Teflon can and will get into the hydraulic system and clog valves and such. I have personaly pulled it out of places it shouldnt be.

Only when wrapping the fitting incorrectly. When wrapping a fitting with tape, you are supposed to keep it off the first thread completely, for precisely this reason.

Tape is also less likely to find its way into the system than dried and hardened dope, upon disassembly.

 

[Mcdust]

Lots of old threads and various opinions, but would like to revisit. I've not done much but all the NPT I've done (Kubota B21 2000# nominal) have been "dry" and not leaked. But I gather that is not the norm.

Teflon tape seems to be on no ones "good idea" list.

Various other solutions, loc tite, 3 Bond, and others, seem to be favored. At least on NPT.

Some say to use nothing on JIC or oring boss. But I have found, taking stuff apart, that corrosion can be and issue on those, so maybe using a modest amount of low strength thread locker or non hardening sealer, just to keep water out, is not a bad idea, but just on the threads.

Let the games begin.

 

[Mcdust]

Good post. Only NPT (tapered pipe) receives a thread sealant, as it has a spiral leak path formed by the flattened crest and filleted root of the thread. The sealant (tape or dope) is designed to fill this spiral leak path.

NPTF is a special variant of NPT, and can sometimes mate without leaking, as the crest and root are better matched to eliminate the classic NPT spiral leak path. But even there, sealant is recommended to provide sufficient lubrication to draw the tapered threads tight.

All other fittings, such as JIC, ORFS, and ORB, do not get thread sealant. The thread is not the sealing mechanism in these fittings, but rather only provides the mechanical clamping means, holding the two halves together around the o-ring or tapered cone seal. Using thread sealant on these fittings is more likely to cause, than to resolve, any problems.

As to tape versus dope, both work equally well, when used properly. The reason "tape is evil", is because it takes more skill to properly apply it, and so many do it wrong. Any idiot can slather dope on a fitting, as so it's become the preferred method, for most.

I use Gasoila on almost everything. Good with gas and oil as the name implies and also is usable on plastic which Rectorseal is not. Good luck, Alec

 

[WinterDeere]

I use Gasoila on almost everything. Good with gas and oil as the name implies and also is usable on plastic which Rectorseal is not. Good luck, Alec

By "everything", I hope you just mean NPT fittings for all fluids.

Rectorseal No.5 is listed for use on PVC, but not CPVC, or some other plastics.

Gasoila is good stuff, my local propane guys swear by it. It's becoming more popular, with more approved application range, whereas Rectorseal No.5 has been the standard for plumbers for many years.

For hydraulics, I use either tape or a specialty dope made Henkel.

 

[Discount Hydraulic Hose]

you should all ways use teflon tape or paste on all NPT Threads. Jic or ORB do not require any.

 

[pecans]

Lots of old threads and various opinions, but would like to revisit. I've not done much but all the NPT I've done (Kubota B21 2000# nominal) have been "dry" and not leaked. But I gather that is not the norm.

Teflon tape seems to be on no ones "good idea" list.

Various other solutions, loc tite, 3 Bond, and others, seem to be favored. At least on NPT.

Some say to use nothing on JIC or oring boss. But I have found, taking stuff apart, that corrosion can be and issue on those, so maybe using a modest amount of low strength thread locker or non hardening sealer, just to keep water out, is not a bad idea, but just on the threads.

Let the games begin.

Teflon Tape or Teflon in a tube has worked well here for about 40 years. Protects the threads as you note as well as seals. Enjoy your games... serious business here.

 

[jjp8182]

I use Blue Monster on everything

Same here. I keep a bottle of Blue Monster thread sealant and role of Blue Monster tape on hand since they're suitable for use with many types of fluids/gases -- and all the ones I work on around my property (which largely eliminated the need to keep multiple different rolls of tape around -or to track what is compatible with what for the existing stuff I work on).

I've yet to have issues by following the instructions for use posted above for using tapes - and the Blue Monster tape seems to hold together better than other tapes I've used if/when you need to dissemble a fitting shortly after assembly. So I suspect that will be the case even after a few years (kind of doubting any of them would get better at holding together during disassembly with age).

 

[Barnowl]

I’ll throw in my 2 cents, backed by about 10 years of real world experience and actual real world testing. I designed and installed commercial and hospital systems that dealt with sterilant, which back in the day used a high percentage of Freon 12 as a carrier gas. We reclaimed the Freon so our piping systems had to deal it both in liquid and gas form. Every system had to have each joint tested with a gas Freon detector, at parts per million. Before we put anything in service, we put in some gaseous Freon 12 and believe me, it could find a leak. Our systems were primarily threaded NPT brass, 1/2 to 2”. We also used stainless npt, which can be very tough to seal for a gas.
Loctite Hydraulic (red) worked reliably! I think today it’s called 545, but I’m not certain. I still have my bottle from 25 years ago, a little goes a long way. Basically the RED was the ticket!

We also tried Loctite Pneumatic/hydraulic sealant, purple. While it worked good, we found it did not work as well as the red Hydraulic sealant, in our challenging applications.

When using either, I recall you must have clean threads, clean of cutting oils etc. I think they used to sell a primer, but just make sure you have clean threads. I doubt many will be cutting your own threads as we did.

I still use teflon tape and especially good teflon paste. However, The hydraulic sealant will give you an excellent seal, without the mess of a teflon paste or risk of tape in your system. One local and very major corporation here, that you’ve all heard of, banned teflon tape in their huge complex. They just had too many issues with folks overapplying it and getting into critical systems.

Loctite Hydraulic sealant was never cheap, but you don’t need much and that bottle will last the average guy a long time.

 

[ManUpNawth]

In my experience, Loctite 545 does a great job...if the fitting is new or at least has only ever had a pipe sealant on it but never had PTFE tape. If a connection previously had PTFE tape, the person probably "did it wrong", meaning they both wrapped it more than 2x max and cranked it down as tight as they could, a combination guaranteed to deform (if not split) the nut end. Loctite doesn't work well if the nut is deformed. So in those cases you're going to have to use PTFE tape again or it will leak/weep.

 

[MHarryE]

I had the experience of Industrial Engineering at our plant getting the idea they could save time and money by switching from Loctite 545 to Teflon tape installing the single pipe thread port we had on a new model, the exit from the tank to pump inlet. To us, any leak was considered a failure, part of our measure for Dealer Repair Frequency. Our pre-production fleet began having leak problems from the HMU (hand metering unit or steering control). We kept having to have HMU's replaced on our test fleet, drove us crazy. But nice to have resources so we sent some units to test lab at HQ for analysis. Through high magnification, they found small narrow pieces of material between the seal lip and shaft. Spectrometry proved it to be Teflon, specifically Teflon fibers like in Teflon tape. Back to the assembly line to investigate how Teflon tape got in our plant and discover the root of our problem was a cost reduction by Industrial Engineering. The worst thing is getting that stuff out of a contaminated system. In our case no solution - following our evaluation sell the machines with the customers knowing there will be an oil weep (price discounted accordingly).