Re: pressure test thoughts

On Sep 7, 2005, at 5:19 AM, Venkat hariharan wrote:

> What if an existing piping is rerated to a higher pressure and the
> available pipe thickness just satisfies the new operating pressure,
> Is the 1.5xtimes test pressure is mandatory in this case? Can the
> piping withstand the new test pressure? Operating temprerature is
> around 350 deg F. Code allows only upto 33% overpressure for less than
> 10 hrs at any one time.

How certain are you about this? Again, referring to the ASME PV Codes, no such over-pressure is permitted under any circumstances of service. Commonly-held mis-information is that a 10% over-pressure is permitted, but that's an incorrect interpretation of the rules for safety relief valves, which state that the internal pressure may rise 10% only while the relief device is opening fully.
Christopher Wright P.E. |"They couldn't hit an elephant at chrisw@skypoint.com | this distance" (last words of Gen.

.......................................| John Sedgwick, Spotsylvania