Thread seal tape

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Thread seal tape is wrapped around the threads, lubricating the connection and allowing the two pieces to be screwed deeper together.

Thread seal tape (also known as PTFE tape or plumber's tape) is a polytetrafluoroethylene (PTFE) film for use in 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 popularly but incorrectly called Teflon tape in spite of DuPont, the holder of that trademark, no longer manufacturing it.[1] Thread seal tape lubricates allowing for a deeper seating of the threads, and it helps prevent the threads from seizing when being unscrewed.[2] The tape also works as a deformable filler, helping to seal the joint without hardening or making it more difficult to tighten,[3] and instead making it easier to tighten.[2]

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.

Types[edit]

Thread seal tape is usually sold in small spools.

There are two US standards for determining the quality of any PTFE tape. MIL-T-27730A (an obsolete military specification still commonly used in industry in the US) requires a minimum thickness of 3.5 mils and a minimum PTFE purity of 99%.[4] The second standard, A-A-58092,[5] is a commercial grade which maintains the thickness requirement of MIL-T-27730A and adds a minimum density of 1.2 g/cm3.[5] Relevant standards may vary between industries; tape for gas fittings (to UK gas regulations) is required to be thicker than that for water. Although PTFE itself is suitable for use with high-pressure oxygen, the grade of tape must also be known to be free from grease.

Thread seal tape used in plumbing applications is most commonly white, but it is also available in various colors. White PTFE is single density, yellow is double and pink is triple . It is often used to correspond to color coded pipelines (US, Canada, Australia and New Zealand: yellow for natural gas, green for oxygen, etc.). These color-codes for thread sealing tape were introduced by Bill Bentley of Unasco Pty Ltd in the 1970s. In the UK, tape is used from coloured reels, e.g. yellow reels for gas, green for potable water.

  • White – used on NPT threads up to 3/8 inch
  • Yellow – used on NPT threads 1/2 inch to 2 inch, often labeled "gas tape"
  • Pink – used on NPT threads 1/2 inch to 2 inch
  • Green – oil-free PTFE used on oxygen lines and some specific medical gasses
  • Gray – contains nickel, anti-seizing, anti-gailling and anti-corrosion, used for stainless pipes
  • Copper – contains copper granules and is certified as a thread lubricant but not a sealer

In Europe the BSI standard BS-7786:2006 specifies various grades and quality standards of PTFE thread sealing tape. [6]

Uses[edit]

PTFE tape can be used for propane on spud guns, for small diameter pipe like 1/4 inch meter equipment. Yellow tape is for gas because it is stronger and will not clog a gas valve.

Tape is typically wrapped three times around the pipe threads to ensure a tight seal and to prevent leaks

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.[7][8][9]

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.[10]

Hazards[edit]

Overuse or misapplication of thread tape may be a hazard. Excess application of PTFE 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.

Misnomer[edit]

Familiarity with the Teflon brand of fluoropolymers has led to the practice of errently referring to PTFE-based thread seal tape as "Teflon tape". DuPont, owners of the Teflon trademark, no longer manufactures any thread seal tape,[1] and the company has launched a campaign[11] against the practice.

See also[edit]

References[edit]

  1. ^ a b "History of Plumber's Tape". Dupont. Retrieved 2014-05-26. 
  2. ^ a b Cauldwell, Rex (Sep 2, 2008). Taunton's Plumbing Complete: Expert Advice from Start to Finish. Taunton Press. p. 38. 
  3. ^ Doran, David (Jul 24, 2013). Construction Materials Reference Book. Routledge. p. 274. ISBN 1135139210. 
  4. ^ "MIL-T-27730A, 15 Apr 1964, and Notice 1, 17 Jul 1994, and Notice2, 9 Feb 1998" (PDF). United States Government Services Administration (GSA), via National Institute of Building Sciences, Whole Building Design Guide (WBDG), [1]. 1998. 
  5. ^ a b "A-A-58092, 7 Jan 1997" (PDF). United States Government Services Administration (GSA), via National Institute of Building Sciences, Whole Building Design Guide (WBDG), [2]. 1998. 
  6. ^ BS-7786:2006 Specification for unsintered PTFE tapes for general use
  7. ^ "Thred Taper, automatic tape application machine". 
  8. ^ Assembly magazine. 1 June 2000. 
  9. ^ "Automated teflon-tape wrapping". Machine Design. April 2002. 
  10. ^ Hedrick, Dale. "Ear Lobe Stretching FAQ". Onetribe. Retrieved 9 November 2010. 
  11. ^ Real Teflon Brand DuPont