PTFE Thread Seal Tape Density

Why would you want to?

It works perfectly well the way it is.

Use more wraps because any excess is forced out of the joint anyway.

http://www.walmart.com/ip/PERMATEX-80633-Thread-Sealant-PTFE-16-Oz-Brush-Can-White/40893605

Why did I think OP meant INCREASE?

Either way...
http://www.workshopwarehouse.co.uk/high-density-ptfe-gas-tape.html

From what I was able to find, tape manufactured to Specification EN751-3 GRp is labeled as being suitable for use with oxygen.

The particular sealant illustrated CANNOT BE USED if the material in the pipes being joined is an OXIDIZER.

Note the CAUTION: FLAMMABLE... on the label.

If you are joining pipe fittings conducting any oxidizer, be sure that the sealant is labeled as being safe for use with oxygen.

Mash it in a press? If it mooshes out to the sides, then this technique didn't work.

Buy the more dense one!

I adjust the knobs and dials on my PTFE tread tape making machine and each time I do it there are new characteristics. Try twisting your knobs.

Come on JE, get with it! The new PTFE machines run off 4G WiFi from my cell phone. No more knobs, dials, switches or levers. Check out the AP - PTFE Density Adjustment 4G WiFi AP for Android and iPhone.

You could change its temperature. The density of most things changes with temperature, Mildred.

Define density, and define change. Then let us know if you wish to decrease or increase.

Changing rolls of tape from the standard tape to the high density one might be a clue, or vice versa.

If you want see through tape, I suggest the high definition one. (A pigment above imagination.)

Different densities are commercially available. Grainger is one vendor in the US with many types available. http://www.grainger.com/category/adhesives-sealants-and-tape-thread-and-gasket-sealants-pipe-sealant-tape/ecatalog/N-85g/Ntt-teflon+tape?nls=3&ssf=3&sst=subset&ts_optout=true

Density, thickness, stretch and dielectric constants are all used to classify PFTE thread seal tapes....

Don't know why you would want denser but there are a few ways of improving the seal of pipe joints. 1. put a few more wraps on. This will make the tape denser when the threads are tightened up on it. 2. when you buy tape only buy the rolls that are marked with a "MIL Standard". Don't remember the number but all these are thicker than what the orange or blue box normally stock. Go to a plumbing supply house and buy a few rolls for the future. This is cheaper in the long run than gas/diesel for another trip in the future. 3. the pink tape for gas pipes is thicker but be cautious. Someone may think it is a gas line and treat it as such when it does not have fuel gas in it. 4.when putting the tape on tapered threads (such as NPT, "T" is "Tapered") realize that the area that seals is mid-length of the threads. Make sure this area is taped correctly. Threads on the opening end are too straight to seal. Threads on the larger (opposite) end are not deep enough to seal. 5. Make sure you are wrapping the tape in the right direction. Clockwise up the threads from the small, open end to the shallow threads on the other end of the threads. 6. Make sure you are using the correct amount of tape. Too little, not enough to seal and lubricate the pipe so that the threads can be turned to tighten fully. Too much and the threads will not go far enough together to seal. 7. for 3/4" pipe and smaller one layer is usually sufficient. For 1" and larger use two layers by overlapping each strip of tape more than half the width of the tape. As the pipe size increases overlap even more so the tape on the threads is thicker. It is also better to use 3/4" or wider tape for 1-1/2" and larger pipe threads. 8. Only attempt to tape the male threads. Yes, I have seen a few people try to tape the female threads. Enjoy yourself, sometimes pipe fitting can be fun. It is as good way to reduce the stress of pushing a hot pencil or mouse at a desk. Works for me. Good Luck, Old Salt

The mental picture of some of these guys tormenting a mouse by pushing it around on a desk I find somewhat troubling! LOL.

Through the years (even though I was initially trained very well as a tool plumber during a summer job in college), I had lost some of my Teflon tape mojo. I have found myself wondering why I could not always get a good fit or a seal - either too much tape, tape not started at the right point on the threads, etc. Thanks for the reminders.

Now, if one insists on drilling the hole in steel with the wrong (over-sized slightly) drill, the NPT tap will probably make threads that are a bit oversized as well, and fittings will want to screw in too far. I guess one could be tempted to simply put too many wraps of Teflon, and hope he gets away with it?

Agree. There are many more ways to mess them up, both by the "pipe fitter" and the manufacturer of the pipe/fittings. The one most annoying to me is when the face of the female fitting is irregular and one side has "partial threads" on it, threads that don't go completely around. One side engages but the other doesn't until several turns have been made. I usually toss this type of fitting out because it isn't worth the time and energy to use it. Also the center line of the female threads are usually not centered on the bore of the fitting.

Ironically the one I see the most, even from the old sage "master" plumbers/fitters is the tape wound around the male threads in the wrong direction.

Next would be the tape wasn't drawn tight enough as it was being put on so it slid off as the fittings were tightened.

AS you mentioned the alignment of the drill and the tap are extremely important. Drill the hole out of alignment and the pipe usually won't thread into the female. I have found that many people will run the tap too deep when they are tapping the hole for the pipe. The seal parts of the male and female threads done meet each other and there is too much slop. Same for threading pipe. Run the die too far on and the pipe goes too far into the fitting to seal.

Good Luck, Old Salt

Could you please provide a link to the thread tap and die chart you pasted into your post?

I promise to stop using over (or under-sized) drill bits when working female threads of any type, and also promise to make sure stock for threading male threads is also of the right gauge before threading. I really promise.

For the chart shown, go to this site and scroll down towards the bottom

http://terrylove.com/forums/index.php?threads/measure-black-iron-pipe.58457/

The following Google searches may be of interest to you or others:

pictures of npt pipe threads

differences between threading pvc pipe and steel pipe

pvc pipe joined to metal pipe

Another joining system that hasn't been mentioned is threading and joining of pvc plastic piping. Compared to metal pipe pvc pipe is relatively compressible and flexible. The thicker the wall thickness dimension, the higher the schedule number, the stronger the walls and less deformation. Because of this a special die must be used when threading pvc pipe and only a few common joints acceptable.

When threading pvc only sched 80 or thicker walled pipe can be used. All pvc male connection fittings contract/expand and the pipe squeezes to a smaller dimension. The male threads then are too shallow when they are cut with the regular metal pipe die. For pvc special die cutters are used to compensate for this problem. They cut a deeper thread that will relax to the spec thread dimensions when the die is removed. Threaded PVC to threaded metal pipe joints must always use a metal female to a pvc male connection. With this the compressibility of the pvc is used to an advantage for a good seal. When a metal pipe is threaded into a pvc female thread the pvc simply expands and weakens the joint. Too much insertion of the metal male thread and the pvc female fitting will simply crack/break and fail.

Teflon tape is the only joint sealant that should be used for metal-pvc or pvc-pvc . Many of the liquids/pastes have a petroleum base that is incompatible with the pvc and will cause the joint to fail.

Before anyone who is not familiar with working with threaded pvc pipe attempts to do it they should do a few Google and YouTube searches on the subject. To do it incorrectly could cause the fixtures to fail. This would waste a lot of money, materials and patience.

Good Luck, Old Salt

One of our projects dealing with supply to 93% sulfuric acid to chemical pump from IBC containers, we used a mix of black polypropylene along with CN7M stainless steel (could also be called Carpenter 20 or Alloy 20, so I believe). We found early on while using stainless - stainless threaded NPT joints on pipe tees from hose barbs, that galling had taken place on all the parts fitted up by our supplier (they did this in haste). Time is everything when attempting to reduce/eliminate galling on stainless steels.

I solved the problem primarily by removing all stainless steel pipe fittings other than the threaded hose barbs. I used black polypropylene fittings (FNPT) throughout the remaining fittings, and there is no need for Teflon tape or other sealant. The PP fittings "stretch" slightly when the threads are engaged on stainless (or other) steel, and this leads to a much tighter thread engagement, no galling, no leaks.

I also found that when adapting tubing (black PP) to the chemical pump, I needed to use Kynar FNPT pipe coupling fittings on the MNPT pump suction and discharge fittings, and then use a male compression adapter. The female compression adapters have too thin of wall on the pipe threaded part, and will easily split out and leak.

Re:"..."MIL Standard". Don't remember the number..."

Found a roll that technician who serviced oxygen and nitrogen piping and tanks, cryogenic liquid and compressed gas gave me at one job.

MIL SPECT-27730A stamped on roll along with size 1/2"x520" and "Made in Malaysia".

White tape on blue roll, with white cover/case for roll.

Hope this helps.

Casper

For those who may not know, a long-time pipe joint compound used in ammonia refrigeration is "X-pando". It is a gray powder that is mixed with a small amount of water, and brushed onto the threads of the male pipe fitting. It expands into the made-up joint, which then becomes difficult to take apart.

This material is a kind of clay or other like mineral quarried from Vermont or some such place. It is a family enterprise that was inherited by D. Keith Mano, who was a popular short-story writer in the 1970s-80s for Playboy Magazine, among others. I never met him, but my boss of the time did.

Virtually everybody in the ammonia refrigeration field is familiar with it, and it is great for many other piping services, potable and otherwise.

Still used for many other types of chemicals and applications. I still have some but very seldom use it. Mostly for sentimental reasons.

Do you remember when either sewing thread or string was used within the narrow "valleys" part of the male threads for steam service? This was done before putting the pipe dope on and the fittings threaded together.

Good Luck, Old Salt

I never worked much in steam, which was really weird, because my union classification umpteen years ago was "building trades journeyman steamfitter". But what the hey, I know pipe, although I'm starting to forget the wall thicknesses I once knew. (Consequence of retirement.) My real field was ammonia refrigeration.

So when one uses this compound, is it mandatory to make the incantation: "Presto X-Pando?"

There is some other clay mineral used in HAZWOPR for closing leaks on drums with hazardous waste in them, usually associated with a driven in wood wedge. I have already forgotten the name of this...let me see....ah, it is "Plug-'N-Dike". I had something like "plug a dyke" in mind.