Threads are a remarkably efficient mechanical device, ideal for connecting pipework. Depending on the material, they can safely transport all manner of fluids and gases while withstanding extreme environments and high pressures.
However, threads can be prone to wear. One cause might be expansion and contraction, a cycle that happens when pipes freeze and thaw. Threads might wear from pressure changes or when subjected to vibration. Any of these conditions can cause a leak. In a water pipe, that could mean flood damage running into thousands of dollars. A leak in a gas pipe has potentially lethal consequences.
Rather than replace entire sections of pipe, you can seal the thread with a range of products. Apply a sealant as a preventive measure or as a repair to prevent further leaks. In many cases, pipe thread sealants offer a rapid and comparatively low-cost solution. The following list looks at the best pipe thread sealant for a number of applications.
- BEST OVERALL: Gasoila – SS16 Soft-Set Pipe Thread Sealant with PTFE
- BEST BANG FOR THE BUCK: Dixon Valve TTB75 PTFE Industrial Sealant Tape
- BEST FOR WATER: Oatey 31230 Pipe Joint Compound with PTFE with Brush
- BEST FOR PVC: Rectorseal 23631 1/4 Pint Brush Top T Plus 2 Pipe
- BEST FOR GASES: Harvey 017065 Gas Line PTFE Thread Seal Tape
- BEST FOR EMERGENCIES: Rectorseal 25790 1-3/4-Ounce Tube No.5 Pipe Thread
What to Consider When Choosing the Best Pipe Thread Sealant
The aim is to prevent leaks, but the ways in which to achieve that can vary considerably. The best pipe thread sealant for one material is sometimes not appropriate for another. Various products can’t handle the pressures or temperatures involved in some situations. The following product features and shopping considerations can help determine which pipe thread sealant to purchase.
Type and Suitability
Pipe thread sealants divide broadly into three types: PTFE tapes, pipe dope, and anaerobic resins.
PTFE is short for polytetrafluoroethylene, a synthetic polymer. It’s commonly known as Teflon, though strictly speaking that’s a trade name. PTFE tape is highly flexible and easy to apply to all kinds of metal pipe threads. There are varieties for air, water, and gas pipes. Telfon usually is not recommended for PVC because it lubricates the threads. That’s not a problem with many materials, but it can make PVC threads too “slippery,” leading to damage from overtightening.
Pipe dope, also known as pipe joint compound, is a thick, brushable paste often compared with putty. It’s the most versatile of pipe thread sealants and highly effective in most situations. Many are called soft-set compounds. They don’t fully harden, so they can compensate for some degree of movement or pressure changes.
Pipe dope generally is the choice of professionals; because of its effectiveness on the various types of copper pipe used for water and plastics used for drains, you’ll find it in most plumbers’ tool kits. However, it’s more expensive than PTFE tape and not quite so easy to use, and most are solvent-based formulas.
Anaerobic resins do not require solvents to cure, but instead react to exclusion of air from the thread. The resin has properties similar to plastics, so they fill voids well and do not shrink or crack. They seal well even if there’s some movement or vibration.
However, these sealing resins require the presence of metal ions to cure, so they normally do not work on plastic pipe threads. They also can take up to 24 hours to seal properly. Anaerobic resins are a step up in price over pipe dope, making them the most expensive option. In general, resin products work best for specialist applications, rather than for general-purpose use around the home and yard.
Note: Very few pipe thread sealants are suitable for pure oxygen. Chemical reactions can cause fire or explosion. Any repair to oxygen fittings should be carried out by a suitably qualified professional.
In a nutshell, PTFE and anaerobic resin pipe thread sealers are good for metal pipes, and pipe dope can seal just about any pipe material. However, it’s important to check material suitability in detail. Metal pipes can include copper, brass, aluminum, galvanized steel, stainless steel, and iron. Synthetics include ABS, Cycolac, polyethylene, PVC, CPVC, and, on rare occasions, reinforced fiberglass.
Although some of the best pipe thread sealant is versatile, not all types work on all pipe materials. Failure to check whether a sealant can work effectively with a particular pipe material could result in additional leaks, leading to further rectification work.
It’s important to ensure that pipe thread sealant can deal with the environmental conditions present. Most of the time, sealant should be able to handle temperature extremes without freezing or cracking.
PTFE tape seems like a basic product, yet it’s surprisingly resilient. General-purpose tape, which is white in color, can frequently hold up to temperatures ranging from minus 212 degrees to 500 degrees Fahrenheit. Tapes used for gas, which are yellow, have a similar upper limit, but some can handle cold to minus 450 degrees.
Pipe dope and anaerobic resins don’t have quite the same flexibility when it comes to heat and cold. In general, they can tolerate temperatures of about minus 50 degrees to 300 or 400 degrees Fahrenheit. That is sufficient for many applications, though it might restrict outdoor use in some areas.
Most DIYers might never have to worry about high-pressure leaks. Natural gas runs between ⅓ and ¼ pounds per square inch (psi), and though a water leak might look dramatic, household water pressure is unlikely to exceed 80 psi.
However, in commercial installations, pressures can be much higher, and the best pipe thread sealant for these environments needs to be able to cope. The molecular structure of gases and liquids causes quoting of different pressure limits. For example, a pipe dope that can withstand 10,000 psi of liquid pressure will only be rated for around 3,000 psi of gas pressure.
Our Top Picks
It’s important to consider every aspect of a thread sealant’s technical specifications when selecting the right product for the job. In an effort to make that task easier for you, these top picks focus on the best pipe thread sealant for leaky pipes based on features like pipe type or use.
Gasoila is a nonhardening pipe dope that includes PTFE to help it remain pliable. With that, in addition to its high viscosity, the sealant is easy to apply with the brush provided, even when cold. These properties also mean joints can resist movement and vibration. This sealant is effective on all pipe materials in general use, both metals and plastics, as well as for pipes containing most gases and liquids. It’s safe with hydraulic lines and for those transporting gasoline and petroleum solvents, which can attack some pipe thread sealants.
Gasoila thread sealant can handle liquid pressures of up to 10,000 psi and gases to 3,000 psi. A working temperature range of from minus 100 degrees to a high of 600 degrees Fahrenheit is among the most versatile ranges for pipe dope. The sealant complies with common internationally recognized safety standards.
Dixon’s Industrial Sealant Tape is the kind of low-cost pipe thread sealant that should find a place in every tool box. It’s easy to use and, with no danger of it dripping onto delicate surfaces, there’s no mess to clean up. This white PTFE tape produces an effective seal in all kinds of metal pipework carrying water or air. It also can be used to beef up old screw threads when screws become loose.
The operating temperature range for this Dixon tape is from minus 212 degrees to 500 degrees Fahrenheit. Though suitable for many household and commercial applications, it is not designed for high pressure or for gas. This product is ¾-inch wide, which is ideal for most pipe threads. It comes with nearly 43 feet on a roll, adding to its economy.
Oatey’s 31230 pipe joint compound is a great general-purpose pipe thread sealant. The product’s primary purpose is for working with water pipes; the product complies with NSF-61, which specifies standards for products for municipal water supplies. However, it also can seal leaks in lines carrying steam, air, caustic liquids, and many acids. Oatey Pipe Joint Compound is suitable for iron, steel, copper, PVC, ABS, Cycolac, and polypropylene.
This soft-set formula will handle temperatures from minus 50 degrees up to 500 degrees Fahrenheit and pressures up to 3,000 psi in gas and 10,000 psi in water. With an eco-friendly and nontoxic formulation, it stands out as a pipe dope (though it can cause skin irritation).
The main challenge with using sealants on PVC threads is a tendency users have to overtighten the connections, causing cracking or stripping. PTFE tapes are not recommended because they lubricate the thread and make it all too easy to overtighten. Rectorseal T Plus 2 contains PTFE but also has resin fibers. These provide additional friction and a secure seal without the need for excessive force.
This soft-set compound is also suitable for most other pipe materials, both metal and plastic. It can seal pipes carrying water, gases, and fuels at temperatures from minus 40 degrees to 300 degrees Fahrenheit. Pressure limits are 2,000 psi for gases and 10,000 psi for liquids. It can also be pressurized immediately after use.
As a general rule, white PTFE tapes are for general-purpose use, and yellow PTFE tapes like this Harvey 017065 PTFE sealant are for gases. This heavy-duty tape conforms to the UL safety listing for gases. This Harvey tape is a versatile product; in addition to being recommended for natural gas, butane, and propane, it’s also suitable for water, oil, and gasoline.
This yellow tape can seal all metal and most plastic pipes; though, as with all PTFE tapes, it’s not recommended for PVC. Its thickness also supports activities like thread repair on bolts or valve fittings. The operating range for this tape is from minus 450 degrees to up to a toasty 500 degrees Fahrenheit, and its pressure rating is 100 psi.
Pipe dope is a versatile compound but usually comes in cans of at least 4 ounces. That’s just too much for most tool boxes. Rectorseal 25790 comes in a convenient tube to always be close at hand.
This soft-setting compound works on both plastic and metal pipe threads and is suitable for sealing pipes containing a wide variety of gases and fluids, including drinking water. When used with gas, air, or water at up to 100 psi, which covers most household installations, it can be pressurized immediately after the repair. The product’s temperature range is from minus 50 degrees to 400 degrees Fahrenheit, and maximum pressures are 12,000 psi for liquids and 2,600 psi for gases.
FAQs About Pipe Thread Sealants
At this point, you’ve learned about the various technical aspects to bear in mind when choosing pipe thread sealant. The top picks section lists some of the best pipe thread sealants for particular tasks, but if you still have unanswered questions, check the helpful information that follows.
Q. What is the best thread sealant for PVC?
Pipe dope generally works best on PVC, and Rectorseal 23631 T Plus 2 Pipe Thread Sealant is a top joint compound for this purpose.
Q. Is pipe thread sealant permanent?
Many sealants are designed to be permanent, though most can be disassembled if necessary. However, if a leak persists, it might be necessary to replace a pipe or fittings to resolve the problem.
Q. Does pipe thread sealant need to dry?
It depends on the product. Soft-set sealants, for example, never dry completely and are thus better at withstanding vibration or changes in pressure.
Q. How do you apply pipe thread sealant?
It depends on the type, but you should always start by cleaning the threads. PTFE tape is applied by winding around the male thread in a clockwise direction. After three or four wraps, break it off and press into the grooves. Pipe dope it usually brushed on to the male thread.