"My roommate had a "unlimited BTU" gas fitter license (Canada Class "A") and this for a living and preferred "pipe dope""
I do this kind of thing a lot as we own and maintain our own water plant. My preferred sealant is the yellow PTFE tape that is used for natural gas.
It is quite a bit thicker than the white tape, it sticks to threads better and it is easier to work with, in terms of manual dexterity.
I never use the white tape for anything.
I don't like pipe dope at all and I only use it for large fittings that are going to be buried or inaccessible.
ALSO, helpful hint: If you are mixing plastic pipe (like schedule 40/80) and metal pipe, always have metal female couplings and plastic male couplings. A metal male going into a plastic female is one tighten away from cracking the plastic.
> ALSO, helpful hint: If you are mixing plastic pipe (like schedule 40/80) and metal pipe, always have metal female couplings and plastic male couplings. A metal male going into a plastic female is one tighten away from cracking the plastic.
Or buy transition fittings or "special reinforced" fittings. Or, if you trust them, use push-to-connect fittings -- SharkBite, John Guest, ProLock, etc. (ProLock appears to be a John Guest product that is also sold by SharkBite.)
I've seen plenty of female plastic threaded fittings break even when connected to male plastic threaded fittings. They're just not that strong under circumferential tension.
The color isn’t necessarily related to the tape density. I always use Merco Threadmaster M66 (I think this, or the M77, is the McMaster default for high-density tape), which comes in all colors. I’ve had cheap tape come prepackaged with products that’s almost transparent and not with bothering with.
I also find it really helps to use the right tape width for the fitting you’re working with. I work mostly on small laboratory/pilot scale stuff (that needs to come apart in a few years, so no dope). I rarely use a fitting larger than 1/2”, but when I do, it’s a pain to use 1/2” tape. 1” (or 1.5”) will make a much neater and more consistent job. Similarly, I prefer 1/4” tape for 1/8” and smaller fittings.
>ALSO, helpful hint: If you are mixing plastic pipe (like schedule 40/80) and metal pipe, always have metal female couplings and plastic male couplings. A metal male going into a plastic female is one tighten away from cracking the plastic.
At some point it becomes easier to just think about what you're doing avoid being ham fisted moron than it is to seek out parts and design things to be accommodating to that kind of behavior.
I've seen people suggest that white tape should only be 1.5-2 but yellow should be 5 or more, do you have thoughts on that? Is there a difference in usage or is it the same overuse pattern on both?
I don't think you can use too much tape. Suggestions that you can break fittings with too much tape are almost certainly incorrect - with either plastic or metal.
I usually do 5-ish wraps with the thick yellow tape - and that is true with schedule 40 PVC, plain old galvy, or with small stainless fittings.
I am wasting tape, and I know it, and I have no problem with that - and neither do the fittings.
You can definitely break a plastic fitting with too much tape. The tape and the plastic are deformable, and I’ve had taped PVC fittings effectively extruded by repeated installation with fresh tape (every time you install it, you need a little bit more). This effect will be amplified if you’re fitting is made out of a material more prone to creep like PVDF, PP, or Nylon. Granted, this isn’t a typical (or appropriate) use case, but it was a necessary kludge for a project I had.
You can get leaks with too much tape if it prevents you from reasonably getting the threads to seal. When this happens, you get a slow leak between the layers of the tape. I’ve seen water slowly bead out of fittings at 1000 psi due to this.
Also, too much tape can lead to contamination (the tape sticks to every piece of dust, lint, and oil in your workspace) and can make it easy to cross thread fittings (especially small plastic ones).
I do this kind of thing a lot as we own and maintain our own water plant. My preferred sealant is the yellow PTFE tape that is used for natural gas.
It is quite a bit thicker than the white tape, it sticks to threads better and it is easier to work with, in terms of manual dexterity.
I never use the white tape for anything.
I don't like pipe dope at all and I only use it for large fittings that are going to be buried or inaccessible.
ALSO, helpful hint: If you are mixing plastic pipe (like schedule 40/80) and metal pipe, always have metal female couplings and plastic male couplings. A metal male going into a plastic female is one tighten away from cracking the plastic.