Thread tape, thread sealant, or ????

[Elliott in GA]

Use a little common sense. Household plumbing and field sprayers do not crash and kill people.

Dan

Well, what if it was the plumbing in the airplane's lavatory, or it was an Ag spray plane?

 

[Sidekick]

I recently did battle with some china pipe threads and found the Blue Monster thread sealer to be the solution for me. I also had to chase the the threads both male and female. Some the tap and die went in and on smooth and some took a couple turns near the end to straighten.

View attachment 170043

I used Aviation Permatex on gas and oil fittings for years with no leaks. It was no match for the inferior pipe thread fittings I encountered on my last project.

I also add lamp wick to Chinese pipe threads.

 

[GeoHorn]

My boom sprayer has some form of paste sealant on all the pipe fittings. It doesn't take much to plug up the nozzles given how fine the tips are, so I'd use some kind of PTFE paste sealant rather than tape. I ordered the stuff shown below (will be here tomorrow) for the BSPP/NPTF to Summit Hydraulic 1/2" Ag couplers.

View attachment 170044

That reminds me of the motor oil additive which claimed to have PTFE in it to ”improve“ lubrication.
One of the oil analysis labs showed that only a few minutes of circulation thru a quality oil filter quickly removed it.

I wonder,…. if your sprayer nozzles are so fine as to easily clog…. if PTFE wouldn’t pose a problem.

(Teflon actually has limited and specific application. I suspect in pipe-thread-paste it’s purpose is more to reduce friction installing the fitting, thereby providing a tighter fitment…. rather than any sealing function of the teflon itself.)

 

[McMXi]

That reminds me of the motor oil additive which claimed to have PTFE in it to ”improve“ lubrication.
One of the oil analysis labs showed that only a few minutes of circulation thru a quality oil filter quickly removed it.

I wonder,…. if your sprayer nozzles are so fine as to easily clog…. if PTFE wouldn’t pose a problem.

(Teflon actually has limited and specific application. I suspect in pipe-thread-paste it’s purpose is more to reduce friction installing the fitting, thereby providing a tighter fitment…. rather than any sealing function of the teflon itself.)

That's exactly what PTFE tape or paste is for ..... to reduce friction so that the built in sealing ability of pipe threads work as they should.

 

[JohnDB]

I ordered the stuff shown below (will be here tomorrow) for the BSPP/NPTF to Summit Hydraulic 1/2" Ag couplers.

I'll be interested to hear how it works out. Which parts are BSP and which are NPT? Same tpi, but different thread forms I thought were not reliable for leak tightness, even with doping, in hydraulic pressure situations.

 

[hagrid]

Use a little common sense. Household plumbing and field sprayers do not crash and kill people.

Dan

Depends on how much effort you put into the endeavor.

 

[TheOldHokie]

PTFE is a solid at temps under 320C.

PTFE "thread paste" is a conventional pipe dope that contains PTFE fibers that act as a gap filler and lubricant.

Its just "ground up tape" in a carrier.

Dan

 

[McMXi]

I'll be interested to hear how it works out. Which parts are BSP and which are NPT? Same tpi, but different thread forms I thought were not reliable for leak tightness, even with doping, in hydraulic pressure situations.

The male 3/8 BSPP end of the adapter threads into the valve bodies at the rear of the tractor. The other male end of the adapter is 1/2" NPTF which threads into the female 1/2" NPT thread at the base of the 1/2" Ag coupler. I'm only using the PTFE paste for the NPT connections. The BSPP uses o-rings.

 

[TheOldHokie]

I'll be interested to hear how it works out. Which parts are BSP and which are NPT? Same tpi, but different thread forms I thought were not reliable for leak tightness, even with doping, in hydraulic pressure situations.

Hydraulic fittings use the NPTF thread form which is designed to seal pressure tight without sealant. Also known as Dryseal pipe threads. In practice sealants are often used eith NPTF fittings and they are good to several thousand PSI. Their main disadvantage is the threads deform during assembly and they are hard to clock. Not well suited to reassembly.

BSPP hydraulic fittings have a parallel thread that requires a face seal gasket of some type. Very similar to an SAE ORB fitting.

Dan