Re: Nozzle Flexibility factors and stiffness

I can understand on a one-off design in which the nozzle configuration is really unique like those supplied by WFI. My question is on those nozzle joints that are commonly installed in the header or tanks or vessels meeting the Code requirement using the "area replacement" method and not subjected to cyclic loading as defined in the Code. Like u know joints made of stub, reinforcement pad or weldolet or hot tap (rated fittings supllied contractor)in which the external loads other than pressure are not heaven high. Lasting 50 years with high stress load - isnt it that just great. By the way if failure do happen (nozzle under high stress load)wouldnt the probabale scenario be leak before break? If that is the case is the money and time invested in the additional study be worth it?

• In PipingDesign@yahoogroups.com, Christopher Wright <chrisw@s...> wrote:
  > >Has there been any documented failure attributed to design
  oversight
  > >related to the above subject?
  > Local external loading, especially cyclic loading, is a source of
  fatigue
  > failures. The most notorious instance I know of first hand was a
  while
  > back in air receivers with the compressor mounted on the shell.
  The
  > presence of high stress at attachments has been well known for at
  least
  > 50 years--it was the motivation for Bijlaard's original work that
  went
  > into WRC107.
  >
  > Christopher Wright P.E. |"They couldn't hit an elephant at
  > chrisw@s... | this distance" (last words of Gen.
  > ___________________________| John Sedgwick, Spotsylvania 1864)
  > <a href="http://www.skypoint.com/~chrisw">http://www.skypoint.com/~chrisw</a>