Buttress thread

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Buttress thread form refers to one of several screw thread profiles.

Contents 1 Buttress thread in machinery 2 Buttress thread in oil field tubing 3 See also 4 References

[edit] Buttress thread in machinery

In machinery, buttress thread is a thread form designed to handle axial thrust in one direction only. The load bearing thread face is perpendicular to the screw axis^[1] or at a slight slant (typically 7 degrees)^[2]. The other face is slanted at about 45 degrees. The resulting thread form has the same low friction properties as square thread but at about twice the strength. In German it is called a "saw thread" (Sägegewinde) because the threadform resembles saw teeth.

One application in which the average person may see buttress threads is on a tube of toothpaste with a threaded cap. The threads to hold the cap on are sometimes made in buttress form.

Buttress threads have sometimes been used in the construction of artillery, because the thread can withstand the axial load placed on it when the powder charge explodes.

[edit] Buttress thread in oil field tubing

In oil field tubing, buttress thread is a pipe thread form designed to provide a tight hydraulic seal. The thread form is similar to that of Acme thread^[3][4] the force is transmitted almost parallel to the axis and thread is about the same strength as standard v threads.

[edit] See also

• Screw thread
• Acme thread form
• Square thread form

[edit] References

1. ^ Barnwell, George W. (1941). The new encyclopedia of machine shop practice. Wm. H. Wise & Co., 163. 
2. ^ US5,127,784 (PDF version) (1992-07-07) David Eslinger Fatigue-resistent buttress thread 
3. ^ US6,893,057 (PDF version) (2005-05-17) M. Edward Evans Threaded pipe connection 
4. ^ Oil field glossary entry for buttress thread