On May 20, 2005, at 12:44 AM, Davis McConnico wrote:
> Solon Mfg is a major manufacturer with which I've dealt. A paper with
> experimental data is listed on their website.
Solon makes bellevilles. I was referring to those little split washers.
One of the abstracts on the Solon site says the following:
> A significant percentage of leaks in flanged joints is caused by
> inadequate bolt preload. Most of the research and testing that is
> conducted focuses on improved gasket materials and geometry.
That's absolutely correct.
> What I don't know about is whether maintaining the pre-load also helps
> prevent the nut from loosening.
That's the only thing that keeps bolts from loosening. It's also the
only thing that keeps bolts from fatiguing. The tension in properly
sized and pre-tensioned bolts doesn't cycle strongly with changes in
external loading because the clamping force on the joint tends to drop
as the external load increases, so the bolt load itself doesn't change.
Moreover, loss of preload decreases the friction which resists relative
movement across the joint, and relative movement leads to the bolt
unscrewing itself.
Christopher Wright P.E. |"They couldn't hit an elephant at <a href="/group/PipingDesign/post?postID=S1fI9tHv5KGcnGgV2BqcwsnGyBSeaai9Gvn_v2b2r-2L1AdpagR5p0DK8bgDCS1m3BdCU-uVPL1OlvE9">chrisw@skypoint.com</a> | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania1864)
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