standard for number of turns of teflon tape 1

[adtchad]

Are there standards for a minimum or/and maximum turns of teflon tape on a give NPT thread. In my company we use 1.5 to 2 turns, but not sure.

TIA,
Alfonso Del Toro

 

[TheTick]

Experience from my last couple home projects...

I like 4 turns. 2 just don't do. With 2 turns, it was too difficult to get drip-free. I started doing 4 turns, reasoning that there would be more tape-on-tape meshing. It works for me.

 

[SomeYahoo]

I agree with the 1.5 turns. From what I understand, the tape is to act as a lubricant only during tightening, allowing the threads to do their job. Filling any openings is a secondary purpose. Too much tape can make the threads too large and cause the fitting to crack.

 

[quark]

I never count the no.of turns and I use my own judgement unless it is a rigorous cost reduction drive. I have to disagree with GensetGuy about self sealing threaded fittings. It never happened in my experience.

 

[automatic2]

I start back one or two threads then wrap no more than two layers. I don't like too much tape and in my mind, it's purpose is to seal. I'll use a small amount of lub if required, and usually that's only the left over from dressing any injured thread.

 

[TBP]

What quality of tape is being used? If it's the thin, cheap white junk sold at home improvement stores, you'll need more wraps than if you're using the heavy orange stuff, like T-Tape.

Tape or dope is required to fill the spiral clearance between the crests and roots of pipe threads, as well as lubricate them. Unless you're using Dryseal NPTF threads (which require special taps & dies to cut them), you need sealant. I've never actually seen NPTF threaded pipe/fittingss or taps/dies. These threads are much more precise, and the crests and roots meet, to eliminate the spiral clearance. Lubrication is still advisable, especially with stainless steel.

 

[MintJulep]

Tapered pipe threads are an abomination, and should be outlawed.

However, it has been my experience that a good quality pipe dope works better than cheap Teflon tape.

 

[Pulpboy]

You can always use a Loctite thread sealant like 577 although clean up when removing is a little worse than good old teflon tape.

 

[TBP]

The biggest problem with screwed piping is that people think that anybody with a pipe wrench can do it. Hire proper licenced steamfitters to put it together, and ensure that they've got decent quality pipe & fittings, and most of the problems will simply disappear.

Most Loctite products are not rated for service over 300*F, which effectively eliminates them for steam service.

 

[Cockroach]

Personally, I tape the pipe threads like a hockey stick.

Starting at the tip or far end, I put an overlap of about half the width of the tape between successive wraps over the full length of engagement. My tendancy is to have a lot of tension on the tape itself, often it breaks so I need to start over again. But once at the top end, I repeat to go downwards to the point of starting.

This way, the tape doesn't unwrap as you're torquing the plug. There is no correct way, everyone is different.

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[jsummerfield]

I start the tape just covering the edge and wrap about 1.5 turns hten stretch until breaking the tape. This embeds into the threads. I see no problem with more turns. Avoid getting the tape into the pipe opening where tape fragments can be caught in filters or equipment.

Consider Teflon paste in lieu of or addition to the tape.

John

 

[mshimko]

From pratice, I use ~ 2 turns. I've found that only 50% overlap of the first turn (1.5 turns total) may not have enough "friction" to stay in place during assembly, but I don't want to use too much either. Hence, ~2 turns.