Re: [PipingDesign] Bursting Pressure

From: <Christopher>
Date: Fri Oct 29 2004 - 13:59:00 EDT

On Oct 29, 2004, at 12:21 AM, cckla wrote:

> What is pipe bursting ?

Burst occurs when the pipe splits wide open under internal pressure. If you're talking about ASME pipe and pressure vessel design requirements burst in an otherwise undamaged pipe occurs at about 3 times the maximum permissible service pressure. If the pipe is damaged, say by a fatigue crack or a weld defect, bursting can occur at almost any pressure.

> How is it different than hydrostatic test ?
ASME Code vessels are tested at a pressure of about 1.3 times the maximum permissible service pressure. This is really a leak test, not a test of vessel strength. The 1.3 proof factor was forst used in riveted vessels to check the tightness of riveted joints.

> What should be the respective pressure or ratio compared to operating
> pressure ?

For pressure loading alone the maximum permissible ASME Code service pressure is the pressure which produces a stress of the material ultimate tensile strength/3.5. Some people will tell you that the vessel has a 'safety factor' (a stupid phrase) of 3.5. That's untrue, since pressure vessels often fail as the result of fatigue, not ductule rupture. The margin against fatigue is about 2, not including the effects of stress concentration.

Christopher Wright P.E. |"They couldn't hit an elephant at chrisw@skypoint.com | this distance" (last words of Gen.

...................................| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/~chrisw/ Received on Fri Oct 29 13:59:00 2004

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