Full definition
A thin, non-adhesive polytetrafluoroethylene (PTFE/Teflon) tape wound around male pipe threads before assembly to fill the micro-gaps between thread crests and roots, creating a leak-tight seal for threaded piping connections. PTFE tape acts as both a lubricant (reducing thread galling during assembly, especially stainless steel to stainless steel) and a sealant (the soft PTFE fills thread imperfections). Standard widths: 12 mm (1/2", for threads up to 1"), 19 mm (3/4", for 1-2" threads), and 25 mm (1", for larger). Thickness: 0.076-0.1 mm. Density grades: standard (white, general plumbing), high-density/mil-spec (thicker, industrial), and yellow (gas-rated, heavier construction per UL listed). Application: wrap 3-5 turns clockwise (looking at the thread end) starting 1-2 threads from the end. Temperature range: -200 to +260°C. Chemical resistance: virtually universal (PTFE resists all chemicals except molten alkali metals and fluorinating agents). Per MIL-T-27730 for military spec. Not recommended for: hydraulic systems (tape fragments can contaminate fluid and clog valves) or oxygen service (use oxygen-rated tape). Brands: 3M, Oatey, Loctite, La-Co.