Thread Dope
Cristoforo Kanoy
If you're using both, the tape would go on first. Which is immediately evident, if you've ever tried to apply them the other way round. There's open debate over whether or not there are any advantages to using both products together, or if each product by itself is adequate.
Pipe dope; also known as pipe joint compound, is used to seal and lubricate the threads of a threaded pipe joint. It's available for both water and gas lines. It's applied by simply brushing it on the male threads of the pipe joint, before the joint is fit together. Pipe dope never hardens, and will not crumble and fall out of the joint.
Teflon Tape dope; also known as polytetrafluoroethylene (PTFE) Tape, or thread seal tape, is also used to seal and lubricate the threads of a threaded pipe joint. It's available in high-density and low-density flavors, for water and gas pipe. PTFE tape is applied by wrapping it in a clockwise direction, around the male threads of the threaded joint. PTFE tape is available in color coded versions (pink for water, yellow for gas), as well as the common white variety.
Im only here because we argue about it at work all the time. I originally worked for a sprinkler company that put dope then teflon on, and thats how we did it, and if you didnt do it that way, you were simply doing it wrong, without a specific reason given. I then went to a company who did it the opposite way with again no believable reason given. I've never had a leak with either method so I don't think it really matters all that much. but since dope is supposed to be applied to male threads, I would prefer it be put on first, and then the tape has something to stick to when first applying it. Also it is much cleaner to handle that way.
At the end of the day I don't think it really matters, and if your pipes arent holding water it's not because of the tape or the dope, but rather the guy threading the pipes or wrenching them in. If you're breaking female fittings simply because you have teflon on the pipe, then you either need to pay greater attention when wrenching on the fitting or adjust your die head.
Many people frown on tape being used for gas piping. If the fitting was ever taken apart for service, shreds of tape can travel to gas valves, etc. Gas controls with shreds in them may very well not be covered by the warranty. Also, putting pipe dope on the male only keeps dope from being pushed into the system. Wiping any from the end will help. If the fittings leak they are probably just some of the cheap junk you can buy today, or someone locally ran the pipe tap/die in too far. As taps/dies are tapered that will oversize the female or undersize the male thread.
I've worked on 30 inch water main breaksAnd have installed hundreds of copper water services with brass fittings,fire hydrants ive taped live water mains worked on cla- Val's installed 10" gate valves, PVC plumbing. Installed thousands of water meters and customer shut off valves. 15+ years of plumbing outside of working for a water department for 10 years.
Put on some high density yellow or pink Teflon tape, then a thin layer of Rectorseal Tru-Blu. I have had good luck with this dope. DO NOT use low density Teflon tape or non setting pipe dope, in my experience it does not work as well. Only apply pipe dope lightly with a BRUSH, not a shovel.
There are manufacturers ( Rapid being one ) that WILL void warranty if Teflon is used on the gas going to equipment.. that being said for water seals I dope then tape only to have tape for a clean look
It's all relative. If you were dealing with three-quarter inch PVC or DWV of any kind obviously you just need Teflon. When you are dealing with plumbing, and heating systems in particular, you will want to use both. Teflon first. Dope second. The last thing you want to do is complete a job (especially big commercial) and have a leak in the system. Working in the fields for decades I can tell you I've seen far less leaks down the road on fittings that have both.
I find that on pvc fittings if tape is used it can crack the female fitting .I use dope only on pvc and tighten only as needed .not saying it should not be done but I find a tendency for that to happen
People often refer to "pipe dope" when talking about sealing threads of pipe fittings, but when I go to Home Depot or Lowes or whatever, I've never seen anything on the shelf labeled "Pipe Dope". This seems to be an old-fashioned word that people speak and understand, but it's not the correct, technical product name.
If I have been told that for a certain joint, pipe dope is a better choice than Teflon tape, what do I need to pick up at the hardware store? I don't particularly need a certain brand recommendation, but an example or picture of a product currently stocked at a major, national retailer would be great as an example. If the word "dope" isn't used, what other terms do I look for to find "pipe dope"?
All sources may be found in the image descriptions. Products are shown for educational purpose only and are not to be viewed as endorsement. Intending to include all major North American manufacturers, any additions are welcomed.
Pipe dope is a general term used to describe any lubricant, sealant, or adhesive designed to aid in making pipe joints leak proof. It can be used to describe dopes in various forms, including pastes, tapes, putties, etc.
there have already been plenty of answers to this here. i would add that its important to not confuse pipe dope (which is typically a sealant for threaded connections) with either thread locker (a glue that holds threaded connections from vibrating loose) or antiseize compound (a material that keeps threaded connections from galvanically fusing). these are three fundamentally different classes of products that are not interchangeable.
its also important to understand that pipe dopes are available in different formulations and with different additives for doing different jobs (gas lines, fuel connections, water lines, stainless alloys, etc)
Thread sealant, commonly known as "pipe dope," is used on a pipe to help secure a seal between threaded connectors. It comes as either a paste or tape and helps fill the threads between the pipe and fitting.
When performing any plumbing project, choosing the right thread sealant is important. Whether you are a DIYer fixing a leaky shower head for the first time or a seasoned plumber needing a few reminders, here is how to create a watertight and airtight seal using pipe dope.
There are a variety of dopes on the market today. A pipe joint compound should be selected based on pipe and fitting material compatibility, chemical compatibility, and temperature performance ranges. Let's take a look at the most popular pipe dopes offered by Oatey:
Hercules Pro Dope is a versatile thread sealant paste that is lead-free and nontoxic. The oil-based compound is easily applied with a natural bristle brush and does not drip. Pro Dope prevents rust and inhibits corrosion by forming a protective coating on threads. It is non-hardening, and the sealed joints can be disassembled without damage to pipe fittings or threads.
Hercules Megaloc is a multi-purpose thread sealant that creates a stronger seal by adding Kelvar into the advanced pipe joint compound formula. These individual strands of Kevlar are mixed into the compound during the manufacturing process and as the threaded joint is being assembled, these strands are compressed into the root of the threads, creating the best possible seal in the market today. Its odorless formula is non-separating, non-flammable, and non-hazardous, and it resists hardening and cracking.
Oatey Great White Pipe Joint Compound With PTFE is a white-colored, non-hardening, non-separating, nontoxic paste that lubricates and seals all threaded joints. This compound permits a tighter assembly with lower torque for secure permanent sealing of all threaded connections. Allows for easy disassembly without stripping or damaging threads.
Oatey pipe dopes can be used on lines carrying natural gas, air, steam, hydronic heating, ammonia, brine, diluted acids, sprinkler systems, and many more. Be sure to check the pressure rating for liquids and air/steam before applying.
Oatey thread sealant products are soft set and do not have a cure time. As soon as the system is put together, you can start to use it. You can easily apply pipe joint compounds with a natural bristle brush.
When applying a pipe joint compound, remember that you are filling the thread openings, so using the mixture in the same direction as the threads will sometimes lead to poorly filled joints. Brushing across the threads will provide better coverage and will ensure that you always fill the threads.
Make sure to clean all pipe threads. Be sure all joints are free from rust, scale, grease, and other contaminants. Remove any debris with a clean cloth or wire brush. Stir contents thoroughly and apply evenly to male threads.
You can also use Hercules Megatape, an all-purpose PTFE thread-sealing tape designed for threaded pipes. Wrap it clockwise around the male thread first, then add the thread sealant. The thread sealant will fill any gaps caused by tape failures and ensure a proper seal. Watch this video to learn how to apply PTFE thread sealant tape properly.
If you need to remove the sealant for any reason, we recommend wiping it off with a rag and using a wire brush to scrape between the threads. You can also use soap and water or a vinegar-and-water mixture to clean the joint further.
You can find that information on the thread sealant container or check with the manufacturer. Almost all Oatey thread sealants carry an NSF 61 rating, which means they are safe to use with potable water.
If you used pipe dope to stop a leak, but it's still there, you may have accidentally cross-threaded the pipes. You should not continue to add more material. Instead, it's best to call a plumbing professional to fix the connection.
Pipe dope is any thread lubricant, thread sealing compound, or anaerobic chemical sealant that is used to make a pipe thread joint leakproof and pressure tight.[1] It is also referred to as "thread compound" or "pipe thread sealant."[2] Although common pipe threads are tapered and therefore will achieve an interference fit during proper assembly, machining and finishing variances usually result in a fit that does not result in 100 percent contact between the mating components. The application of pipe dope prior to assembly will fill the minute voids between the threads, thus making the joint pressure tight. Pipe dope also acts as a lubricant and helps prevent seizing of the mating parts, which can later cause difficulty during disassembly.
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