Threaded pipe

A threaded pipe is a pipe with screw-threaded ends for assembly.

Tapered threads

The threaded pipes used in some plumbing installations for the delivery of gases or fluids under pressure have a threaded section that is slightly conical (in contrast to the cylindrical section commonly found on bolts and power screws). This is called a "tapered thread". The seal provided by a threaded pipe joint depends upon the labyrinth seal created by the threads; upon a positive seal between the threads created by the deformation of the threads when they are tightened to the proper torque; and sometimes on the presence of a sealing coating such as Teflon tape, or a liquid or paste pipe sealant.. Tapered thread joints typically do not include a gasket.

Especially precise threads are known as "dry fit" or "dry seal" meaning that no sealant is required for a gas-tight seal. Such threads are needed where the sealant would contaminate or react with the media inside the piping, e.g., oxygen service.

Due to the taper (cone) of the thread, when tapered threads are cut by a tap or a die, the amount of material being cut increases as the length of the thread is increased, and the force required to cut the thread therefore increases. It is therefore common to use powered tools when cutting tapered threads in pipes with diameters greater than one inch.

Tapered threaded fittings are sometimes used on plastic piping. Due to the wedging effect of the tapered thread, extreme care must be used to avoid overstressing the female component of the joint. Such fittings may split days, weeks, or even years after initial installation, and therefore many municipal plumbing codes restrict the use of threaded plastic pipe fittings.

Straight threads

Pipes may also be threaded with cylindrical threaded sections, in which case the threads do not themselves provide any sealing function other than some labyrinth seal effect, which may not be enough to satisfy either functional or code requirements. In these cases the seal may be provided by an O-ring seated between the shoulder of the male pipe section and an interior surface on the female part.

ee also

* Pipe (material)
* Plumbing
* Nipple (plumbing)
* AN thread
* British standard pipe thread (BSP)
* National pipe thread (NPT)
* O-Ring Boss Seal
* RIDGID, notable manufacturer of pipe threaders
* Taps and dies
* Buttress Thread Form

External links

* [http://www.cutting-tool-supply.com/TechTips/Tapping/NPTvsNPTF/NPTVsNPTF.htm NPT Vs. NPTF Taper Pipe Threads]


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Pipe (fluid conveyance) — For structural pipe, see Hollow structural section. For other uses, see Pipe (disambiguation). Steel pipes …   Wikipedia

  • Pipe fitting — is the occupation of installing or repairing piping or tubing systems that convey liquid, gas, and occasionally solid materials. This work involves selecting and preparing pipe or tubing, joining it together by various means, and the location and …   Wikipedia

  • pipe fitting — noun fitting consisting of threaded pieces of pipe for joining pipes together • Syn: ↑pipefitting • Hypernyms: ↑fitting • Hyponyms: ↑reducer * * * noun 1 …   Useful english dictionary

  • pipe vise — noun a clamp for holding pipe that is to be cut or threaded • Syn: ↑pipe clamp • Hypernyms: ↑clamp, ↑clinch * * * noun : a vise shaped to hold pipe for threading, cutting, or reaming …   Useful english dictionary

  • pipe wrench — noun An adjustable wrench (British spanner) with a toothed jaw for gripping pipe, frequently used by a plumber or pipe fitter, to loosen and tighten pipes with threaded connections. Syn: Stillsons, Stillson wrench, monkey wrench …   Wiktionary

  • pipe clamp — noun a clamp for holding pipe that is to be cut or threaded • Syn: ↑pipe vise • Hypernyms: ↑clamp, ↑clinch …   Useful english dictionary

  • pipe die — noun : a screw threaded die for cutting pipe threads …   Useful english dictionary

  • National pipe thread — Threaded pipe and elbow. The pipe has a male NPT thread, while the elbow s is female. National Pipe Thread Tapered Thread (NPT) is a U.S. standard for tapered threads used on threaded pipes and fittings. The taper rate for all NPT threads is 1⁄16 …   Wikipedia

  • British standard pipe thread — The British Standard Pipe thread (BSP thread) is a family of standard screw thread types that has been adopted internationally for interconnecting and sealing pipe ends by mating an external (male) with an internal (female) thread.TypesTwo types… …   Wikipedia

  • Ductile iron pipe — is a pipe commonly used for potable water distribution.[1] The predominant wall material is ductile iron, a spheroidized graphite cast iron, although an internal cement mortar lining usually serves to inhibit corrosion from the fluid being… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.