Mailport: April 2014
Doubling Up Joints
I have been a Practical Sailor subscriber for some years, and I donít write letters to the editor often, but†I did note a statement in the March 2014 propane article with which I disagree. The article mentions using Teflon tape and thread sealant and states that using both is counterproductive. While outfitting my boatís water and propane systems, I asked my plumber whether I should use Teflon tape or the thread sealant, since he sold both of them. His response: ďIf you are like me and make 10,000 joints a year and donít want any of them to leak, I use both.Ē So I did as he advised. Now, years and a circumnavigation later, not a joint thusly fitted has leaked.
I have used PSís advice too many times to countóthe best examples being the LaVac head, the Brunton Weil Autoprop, and the WH Autopilot. Some of the worst head issues Iíve had were replacing the flap and joker valves in the LaVac while sitting upright on top of the stool. My Robertson Simrad autopilot, which I had professionally installed in New Zealand, was trash before I got to the Suez Canal, but the WH Autopilot I installed thousands of miles before our circumnavigation is still bulletproof. The Autoprop enabled me to motorsail extremely efficiently so that whenever our speed dropped below 6 knots, we motorsailed but we never had to conserve fuel.
Dr. H. Andrew Cserny
Gold Eagle, 42-foot Cross trimaran
Itís always great to hear field reports from readers. The pipe dope/tape discussion is one of those age-old arguments that fires the passions of plumbers around the world, and there will always be arguments as to which method works best. Indeed, there is no hard and fast rule, and using both together has, as your experience shows, worked for decades in many scenarios. Some industry professionals will say use both tape and sealant (a throwback to the days before sealing tape was made of Teflon and was not as reliable), but just as many (including our own LPG expert Capt. Frank Lanier) think itís not only a waste of time, but is counterproductive. Teflon tape is more of a lubricant for the joints to go together more easily and tightly, while pipe dope is more of a sealant. Using them both is like putting glue over plastic food wrap. The tape can prevent the sealant from sealing on the threads properly, and the dope works against the tape in fighting friction. There are also those that say that when using both, the Teflon actually wipes away the dope when threading the fittings together. Plumbers may use both in water lines to try to seal a fitting with a bad spot in the threads, but for gas, youíd want to simply replace the fittings. Bottom line: As long as the fitting passes a pressure test of 5 psi (per the American Boat and Yacht Council), then itís good to go, whether you use one, both, or none.
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