longitudinal stress in pipe under internal pressure
longitudinal stress in pipe under internal pressure
(OP)
Hi,
An elementary question for the experts.
For piping under internal pressure, the longitudinal stress in pipe elements is the sum of a) stresses due to bending and b)longitudinal (or meridional) stress due to pressure ( pD/4t)
Question is, for a section of piping within 2 expansion joints, is it correct to say that the b) above (i.e., meridional stress) does not exist? For, the pressure force at the pipe closure / end can not transmit through the exp joint?
thanks in advance,
An elementary question for the experts.
For piping under internal pressure, the longitudinal stress in pipe elements is the sum of a) stresses due to bending and b)longitudinal (or meridional) stress due to pressure ( pD/4t)
Question is, for a section of piping within 2 expansion joints, is it correct to say that the b) above (i.e., meridional stress) does not exist? For, the pressure force at the pipe closure / end can not transmit through the exp joint?
thanks in advance,





RE: longitudinal stress in pipe under internal pressure
RE: longitudinal stress in pipe under internal pressure
RE: longitudinal stress in pipe under internal pressure
I think that your assumption is a reasonable one for the situation describe in your post.
RE: longitudinal stress in pipe under internal pressure
See http://www.datagenetics.com/blog/december22013/ind... which explains the axial stress better,
see also http://www.eng-tips.com/viewthread.cfm?qid=238877 and
http://www.eng-tips.com/viewthread.cfm?qid=238877
I can see your point though - assuming your pipe is free to move within two end caps, is there a force?
The issue will be how much your pipe is truly free to move relative to the end caps without spring force or friction.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: longitudinal stress in pipe under internal pressure
End cap stress cannot be transmitted through expansion bellows, so axial stresses cannot be found within any straight piece of pipe adjacent to an expansion bellows. However end cap pressure force must somehow be resisted in that pipe, so somewhere between the expansion bellows and the end cap, the pipe must be restrained. If not restrained, your pipe will pull out and away from the expansion bellows. In the restrained portion of that pipe, axial stress will be the result of end cap pressure stress (tension), PD/4/t, + poisson effect stress, poisson's ratio * PD/2/t (also tension), plus any thermal stress, - a dT/E, positive temperature differential yielding a (here negative) compressive stress component.
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RE: longitudinal stress in pipe under internal pressure
I am aware of the main and intermediate anchors across the exp joints and have taken care of the pressure thrusts accordingly. Was just unsure if the intermediate pipe still has any longitudinal pressure stress.
cheers
RE: longitudinal stress in pipe under internal pressure
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: longitudinal stress in pipe under internal pressure
I hate Windowz 8!!!!