Technical Teflon tape/thread sealer use

At the risk of sounding like Captain Obvious, never use tape on an electrical gauge sending unit. You need the electrical connection (ground).

 

If you put the tape on right, you'll have NO problems getting sufficient ground.

As the treads tighten the tape smooches out of the way of the high spots and into the low spots. That creates the seal and the ground.

Get the tape too thick and you could find problems

 

Just remember that the tapered threads are actually the seal, the Teflon or other compounds are actually a lubricant for ***embly purposes. If you were to look at thread sealing surfaces under a microscope it would be a pretty rough old road, the sealants and Teflon lubricate for tightening, the excess patch's the potholes so to speak.

 

I'll agree 100%, but it doesn't hurt to check continuity between the two parts after ***embly. You're looking for .2 ohms or less between them. Too much tape and/or not tight enough can cause problems...

 

I wonder if the automobile industry has gotten away from the use of NPT threads. My newer vehicles are so covered with plastic under the hood I would never know. As Vandenplas can attest, the hydraulic industry uses JIC flare or SAE O'ring fittings for high pressure connections and leaks are rare. We also have 4 bolt flange fittings, codes 61 and 62 for 3000 PSI plus systems. The JIC is a 37 degree fitting designed for standardizing aircraft landing gear during WW2. ( Think AN ). There is still some use of pipe thread on the low pressure side of industrial systems but it is NPTF (National Pipe Thread Fuel). But low cost, low use machinery can have NPT or NPTF components and of course they leak. I like the Loc***e products as mentioned previously. Even the improved NPTF connections will leak. Teflon tape ****s but sometimes we need a "Band-aid".

 

Two things are not allowed in my garage, teflon tape and chop saws. Lost a $1250 final round because of teflon tape from the filter fitting made it to the carb . Use Rigid pipe dope now.

 

If I had a dollar for every carburetor that has come into the shop in the last 40 years where the ONLY problem was Teflon tape residue plugging some p***age (normally an idle jet), I could buy Hawaii and retire!

Not quite as frequent but still way too often are the Rochester tripower end carbs with broken tops where the Teflon tape caused the fitting not to "feel tight". Yes, these fitting are NPT. Tighten it until the top breaks, and then back it out a quarter of a turn.

I thought I had finally found a legitimate use for Teflon tape a few years ago. Dad loved to mow gr***, and his eyesight was slowly failing. We had set out some small trees, and I used Teflon tape on stakes to mark the trees. But the deer ate the tape, so still have not found a good use for the stuff. Somewhere, there is probably some agency that would object to feeding the deer

So, my opinion: if you are an expert and feel the need for the tape, then use it. If you are not an expert, reread paragraphs 1 and 2 above!

Jon.

 

Loc***e 545 is bar none, the best thread sealant out there period!

 

What ever you decide to use , use what works best for you. The one part of this problem we all seem to agree on is “ Use it as directed “ not what some of us think is best . Follow the directions and we all should be having more fun driving instead of wrenching because of misuses . Just be safe , leaks in brake systems , fuel systems , hydraulic systems , any pressure systems in our mechanical hobby can cause terrible effects in the end .

 

Most folks go to the Internet to get some kind of information. It's today's world. Go google some stuff on how to properly use Teflon tape and your going to find **** like this claiming its correct.



I was taught how to wrap a fitting with Teflon tape by my Dad when I was 13 years old. At the age of 13 after being taught how- if I would have presented a wrapped fitting that looked like that I'd have been banished from the garage. If I installed something like that above I'd most likely would have gotten grounded.

Small fittings, AKA Rochester tri power type especially are really difficult. That's because the tape is wider than ALL of the available thread let alone skipping the fist 2 threads. The unwashed start tape at the base of the fitting and end up tape hanging over the fitting and into the fuel stream. Cut the tape in 1/2 lengthwise and your good.

If you don't see the problem with the above fitting pictured just leave the tape alone and throw it out of the garage. You'll just hurt yourself

 

We used Teflon Tape when I was in the USAF on C-130, 4 engine, turboprop, transport aircraft. The Military and the FAA don’t generally use stuff that doesn’t work.

 

Isn't there a special Teflon tape (yellow?) for petroleum based applications?

 

Yellow tape is for natural gas fittings.

 

Getting back to basics....
Remember Teflon no stick fry pans?
Teflon is a lubricant. Nothing sticks to it.
The only place it should be used is on water pipe connections.

 

The FAA's AC43.13 Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair Chapter 8-38f recommends against using teflon tape on fuel systems. Know the AC43 from building a homebuilt airplane and using it as a building guide. Teflon tape has its uses & one is to reduce the friction so it is easy to over tighten fittings. Comparison would be similar to standards for a lower torque for a lubricated bolts vs. the higher torque for a dry bolt to arrive at the same bolt tension. I had a project in the early 70's to replace galv. pipe air lines around a papermachine with screwed fittings . Stainless threads are really dry so the fitters were using teflon tape to make wrenching easier and to avoid leaks. There were a couple fitters pulling hard on the wrenches to really make sure the fittings were tight. They cracked a lot of fittings as the threads are tapered so the pipe acts like a wedge to split the fitting if it is too tight.

 

Whatever you use if not used correctly can wind up where you don't want it. a little goes a long way. Tape and dope aren't intended to fix damaged threads or fittings (although we've all done it.).

 

I thought the fittings were designed specifically that tape or sealant weren't necessary in the first place. Brake lines, and fuel lines come to mind. What am I missing?

 

I think it has become pretty clear throughout the thread that we're talking tapered threads only here.

 

Ah OK thanks. When I heard 'gas' I thought it referred to fuel. Oddly, I had the heater replaced in my house and they used the white stuff.

 

The brake system and fuel system can both have NPT tapered pipe thread fittings.

 

I know I'm Reviving an old post. But I have some of this Teflon paste that I'm wondering if I can use in an engine? Specifically for my tractor. This particular Bolt is in a coolant water jacket and I need to seal it. Would I be okay using this Teflon paste on this Bolt in a internal combustion engine to seal it from coolant? Obviously it's going to see higher temperatures. But I have read that this thread sealant is good up to 400° and 1200 PSI

 

Should be fine.

 

I learned how to plumb hot rods from an old retired Airforce gent. He worked on everything up thru SR71s. he reinforced the fact that teflon tape is ****, even good home plumbers don't use it.

 

I agree with this. ^^^^^^

 

My friend has a son who is a big shot recent graduate of hydraulic school, and he raises hell at me and his dad every time he see's teflon tape on the work bench. Don't use it ever...is what they taught him, but I still use it, not gonna throw it away. Wrap it the proper direction and don't go to the end of the threads

 

I've used teflon tape for many decades without any issues. The key to using it is to not wrap the tape out to the ends of the threads. Stop a thread short and it seals fine, with no issues of tape possibly getting into the system it's sealing.

 

​

 

The trick to using teflon tape is to be born left handed. Works every time.

 

Using teflon tape on a AN fitting thread would be OK if the part is well used, it helps the threads not gall, using on the taper doesn't help anything. We use dielectric grease at work on all Compressed Natural Gas fittings due to the stainless steel fittings galling. Most all the fittings on the buses are expensive and getting hard to find, gulling one can mean Out of Service for weeks or months trying to replace it.