Thread seal tape (also known as PTFE tape or plumber’s tape) is a polytetrafluoroethylene (PTFE) film tape commonly used in plumbing for sealing pipe threads. The tape is sold cut to specific widths and wound on a spool, making it easy to wind around pipe threads. It is also known by the genericized trademark Teflon tape; while Teflon is, in fact, identical to PTFE, Chemours (the trade-mark holders) consider this usage incorrect, especially as they no longer manufacture Teflon in tape form. Thread seal tape lubricates allowing for a deeper seating of the threads, and it helps prevent the threads from seizing when being unscrewed. The tape also works as a deformable filler and thread lubricant, helping to seal the joint without hardening or making it more difficult to tighten, and instead of making it easier to tighten.
Typically the tape is wrapped around a pipe’s thread three times before it is screwed into place. It is commonly used commercially in applications including pressurized water systems, central heating systems, and air compression equipment.
PTFE thread seal tape applied on an NPT fitting, in the direction of the threads. Thread tape is appropriate for use on tapered threads, where the sealing force is a wedge action. Parallel threads may not seal effectively with or without tape, as they are intended to be sealed by a gasket. Thread sealing tape is almost entirely applied by hand, although at least one machine is available for production wrapping of fittings.
PTFE tape is also commonly used in the stretching of body piercings, through a process known as taping, because it is inert and safe for this use. The wearer wraps layers of the tape around a plug, slowly increasing the size and thus slowly increasing the size (gauge) of the piercing.
Overuse or misapplication of thread tape may be a hazard. Excess application of PTFE thread tape can prevent mating threads from fully engaging, reducing the shear point of the threads. Combining thread-seal tape with a pipe dope compound can also overload threads. Also, internal overhangs of loose material may constrict a joint or slough off and form a foreign body that could jam a valve seat. Therefore, use of PTFE tape as a thread sealant is generally not considered appropriate in fluid power (hydraulic) systems.
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Familiarity with the Teflon brand of fluoropolymers has led to the practice of erroneously referring to PTFE-based thread seal tape as “Teflon tape”. Chemours, the owner of the Teflon trademark, no longer manufactures any thread seal tape, and the company has launched a campaign against the practice.
The term “plumber’s tape” has been applied to thread seal tape in recent years. In the plumbing trade, plumber’s tape is the name given to a strap of material with holes in it used for supporting pipes and fixtures.