Leaks are Driving me ....

[WinterDeere]

Teflon tape is meant to be a lubricant, not a sealant.

Good post. While much of what you said was true, this one point is not correct. The reality is that NPT threads have a root/crest spec that is not ideal max sharp, as dictated by various standards (eg. ANSI/ASME B2.30.1), and are not just the result of worn out threading tools. Think of a properly formed thread as an equilateral trapezoid, not a triangle. The flat at the top of each male thread, and small fillet at the root of each female thread provide a spiral leak path. PTFE tape was designed to fill this spiral leak path, and is a required part of the system. The tape's lubricating function is a secondary benefit, saying it's there to lubricate and not seal is simply not correct.

 

[Hay Dude]

Leaks in general are the bane of my equipment owning existence. One axle seal drip can be VERY costly or time consuming (or both) to fix.

This one took a long time and the seals were not cheap, either. Getting king pin out was a real joy.

 

[Sodo]

PTFE tape is also ready for full pressure immediately.

I worry a little about the backstory of the ‘repair’ I did. Where the machine’s regular mechanic would not use Teflon tape. It leaked all over everything, for weeks. Operators had to add hydr oil - I saw it 5+ gallons low at one point. Then I come in (entirely different job) and not wanting to work under a leak, wrap the threads properly, the leak is stopped in 5 minutes. I am not a pro-mechanic, I’m just a guy.

I wonder if the pro mechanic told the machine owner that I have doomed his machine by using PTFE? He seems good (young fella) has a real nice service truck! And he shows up. I will ask how the (ex)leak is doing, see what the owner says.

 

[WinterDeere]

PTFE tape is also ready for full pressure immediately.
...
I wonder if the pro mechanic told the machine owner that I have doomed his machine by using PTFE? He seems good (young fella) has a real nice service truck! And he shows up. I will ask how the (ex)leak is doing, see what the owner says.

Good post. On properly formed fittings, PTFE tape is as good as any dope for most applications using quality fittings, and has the advantage of reaching full strength immediately upon assembly. While some dopes can be put to some use immediately, there are often limitations (eg. the ubiquitous Rectorseal No.5 can be put to use immediately in domestic plumbing under ~70 psi, but not in other applications).

So why has dope surpassed tape in popularity?

1. Cheap import fittings. The aforementioned galling that occurs, either due to poor tools, poor technique, or poor materials became a real problem in the 1990's, when most fittings went from domestic manufacture to overseas manufacture. This is when pipe dope seems to have really made huge gains in popularity, as PTFE tape does require a well-formed fitting to seal. Many of these issues have been resolved, with even many import fittings having pretty good quality and fit these days, although some (eg. sweat copper NPT adapter fittings) still seal better with dope (or even dope + tape).
2. Application of PTFE tape takes a little more skill and care than slathering dope onto a thread. This is a pretty low bar, I was taping fittings for my family's plumbing business at a very young age without trouble, but it's still an issue in the mind of many pro plumbers allowing their inexperienced assistants apply tape or dope.

 

[Oldtoad]

A right proper clinic on thread sealing, thanks all. Learned a lot!
The devil is in the details, however, stepping back a bit...
My main problem, black pipe used in place of high pressure fittings. No amount of dope or thread tape was going to fix that.
Thanks LD1

Unsupported valve is pretty common on a lot of log splitters and not a problem.

The bigger problem is your use of black iron pipe fittings that are rated for probably 1/20th of the pressure you splitter produces