Pipe dope is also known as thread sealant. During the AHR Expo in Chicago earlier this year, I ran into my old friend John O’Reilly in the Uponor booth. I overheard him say that one of the companies he represents, in addition to Uponor, is Oatey, which galvanized my attention. I’ve been meaning to interview someone there for a long time regarding pipe dope and PTFE (Teflon) tape. John agreed to set me up with someone at Oatey.

Way back in 1972, when I was a wet-behind-the-ears apprentice at F. W. Behler, the journeymen I worked with used Teflon tape on the very fine threads on tailpieces for tub waste, overflow shoes and pop-up assemblies for bathroom sinks. No plastic waste assemblies in those days, and if you didn’t use Teflon tape, you could be sure the threaded assembly would weep water no matter how tightly you screwed the tailpiece into the fitting. Callbacks brought condemnation from our bosses, and no one wanted that unpleasant experience. Teflon tape was apparently very expensive in 1972 because it was kept under lock-and-key in the office and you had to sign out a roll with the understanding it was to be returned at the end of the day. In those days, no one took trucks home and we drove our own vehicles to and from work, so returning the Teflon tape at the end of the workday was not a problem.

Did you know that Teflon was invented because of an accident? Roy J. Plunkett was a young engineer who graduated with a PhD in chemistry from Ohio State University in 1936 and started working for DuPont, where he spent his entire career. Plunkett and two assistants were working on developing new HVACR refrigerants on April 6, 1938, and had mixed up a refrigerant batch that was stored in a pressurized cylinder overnight. The next morning Plunkett attempted to obtain some refrigerant gas from the cylinder, but nothing was released from the cylinder. Plunkett picked up the cylinder, which he could tell was heavy, obviously containing some refrigerant. Given that nothing would come out, he loosened the valve and eventually removed it, but still, nothing would come out. They cut the cylinder in half only to discover a lump of some substance completely foreign to them, but Plunkett immediately recognized it had properties that could be useful. It was polytetrafluoroethylene (PTFE), better known as Teflon.

Teflon tape was invented in the late 1960s, just a few years before I entered the trades. (My July PM Engineer column will reveal who invented PTFE tape.) The journeymen at our shop used fine threads of lamp wick yarn with either pipe dope or heatproof grease on those fine threaded tailpieces, but Teflon tape was a far better, and less messy, solution to ensure a leak-free assembly.

I met with Sean Comerford, manager of technical applications at Oatey, to talk about the wide variety of pipe thread sealants they manufacture, and the wide array of applications available for those of us who work in the mechanical trades.

Myth busted

One issue I often see on PHVAC blogs/sites is the controversy over using Teflon tape on NG or propane-threaded connections. I’ll freely confess, I too was taught by the journeymen at Behler’s not to use Teflon tape on gas lines, so I was not entirely sure where the truth lay for many years. Are all of the Teflon tapes OK to use with natural gas and propane?

Comerford says, “Correct, yes. They’re all good for that and they’re all good for potable water. The tape itself is chemically inert because it’s (Teflon) locked up in the actual product. So, yes, it’s been tested and approved for gas and potable water applications. Your local code and inspector may require you to use the yellow tape.”


According to Oatey’s website: “Oatey has the PTFE Tape you need, from economy-grade, low-density tape to MEGATAPE, the thickest tape on the market. Our PTFE tapes can be used on all threaded pipe, valves and fittings carrying acids, solvents, alkalis, steam, hot and cold water, LP gas, natural gas, air and almost any chemical. Weather-resistant, flexible, low dielectric constant, chemically inert and usable at low temperatures, all of our tapes perform over a temperature range of -450° to 500° F and up to 10,000 psi. They are non-hardening, non-toxic, non-stick and non-flammable.”

I asked Comerford if he could describe some of the issues he sees with usage.

“Lots of imperfections in metal threads can lead to leaks, not using the correct thread sealant for the application, as well as wrapping the PTFE tape in the wrong direction,” he says.

I know, whenever we pros see someone on YouTube wrapping Teflon tape counter-clockwise, it’s like someone dragging his or her fingernails across a chalkboard! Always wrap clockwise with the open threaded end facing you. Four or five wraps is all that’s needed. Many pros will then layer on some pipe dope, but always use a rag to wipe away any pipe dope from inside the nipple’s threaded end before assembly and then remove any excess to present a nice clean professional-looking assembly.

Whenever we pros see someone on YouTube wrapping Teflon tape counter-clockwise, it’s like someone dragging his or her fingernails across a chalkboard! Always wrap clockwise with the open threaded end facing you. Four or five wraps is all that’s needed.

And if you want your threaded connections to be bulletproof, Comerford says, “Hercules Megaloc with Kevlar was developed as an alternative to PTFE. It provides a great compact seal with threaded joints and cleans up easily with soap and water. Unlike many thread sealants, it also comes out of work clothes when washed! It is NSF61 rated, as are almost all of our thread sealants at Oatey.”

Lord knows, my jeans and uniform shirts ended up with lots of pipe dope (along with other chemical) stains that never washed out!

I was curious about technical service at Oatey and asked Comerford to expand on this issue.

“If anyone ever has any questions, the best thing they can do would be to contact Oatey directly via email or phone to be connected to our technical team,” he says. “That way, you can the most up-to-date information regarding any of our myriads of products.”

During our conversation, Comerford revealed he had been in the PHVAC trade as a service technician for around seventeen years. A late night Friday clogged sewer in a multi-story building kept him out from midnight to 4 a.m. Sewage was spewing from a lower-floor bathtub! The maintenance guy was up to his elbows in raw sewage, so Comerford (wisely) sought access on an upper floor in the fourteen-story building and spent several hours using a powered drain machine with sectional cables to clear the blockage. Arriving home after 4 a.m., and not at all able to sleep (we’ve all been there, right?), he went online and saw a job opening at Oatey and applied for the position. He was interviewed by an Oatey employee who just happened to be a master plumber! Comerford was offered the job and thus began his career at Oatey.

From my perspective as a master plumber, I find it comforting that Oatey has seen first to employ tradesfolk because they are intimately familiar with the challenges we face on a day-to-day basis and can direct the product development to ensure our lives benefit.

Oatey is an old, reliable company, having started in 1916. They are not, however, a bunch of old stick-in-the-mud mindset-run company. Via acquisitions and in-house product expansions, Oatey has managed to stay at the forefront of innovation and product development. My tool bag has always had Oatey products in it over my 48 years as an active PHVAC contractor.

Want to know how Oatey got its start? Check out this video.

A full rundown of Oatey’s thread sealants and specifications can be found here.