Poisson Effect and Pipe Length Shortening Under Pressure
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For pressure pipes, the pipe load determines the main stress situation in the cross section, with tensile stress being dominant. When a pipe is subjected to internal pressure, its diameter increases. The Poisson effect describes the phenomenon where, as a material expands in one direction (circumferentially, due to increased diameter), it contracts in the perpendicular direction (axially).
Consequently, under internal pressure, a pipe not only increases in diameter but also shortens in length. This axial shortening due to the Poisson effect necessitates the use of tensile resistant end-joints for long pipes installed in one continuous piece. Methods like butt welding provide this required tensile resistance, unlike standard rubber ring seal joints which might allow for some movement.
FAQ Section
What is the Poisson effect in relation to pipes under pressure?
The Poisson effect causes a pipe under internal pressure to shorten in length as its diameter increases.
Why does the Poisson effect require special consideration for jointing long pressure pipelines?
The axial shortening caused by the Poisson effect requires tensile resistant joints for long pipe sections to prevent the joints from separating or experiencing excessive stress.
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Navdeep Singh Chawla
