Re: Vibration

Get the reading and have it evaluated - the vibration signature will point u to the proper action necessary to reduce/eliminate the amplication.

I didnt say CII is not req'd. What Ive said is CII will not provide u with the info needed to understand whats causing the vibration. Probably its due to pulsation and if that is the case a pulsation dampener is all u need.

When the corrective action require relocating support or adding new support or changing the mode shape of the piping system then CII can again be used to evaluate the stress level of the piping system after the mods have been in placed to validate that it still in compliant with the code requirement.

Note that at the very beginning, theres a big chance that that the piping in question has already been CII analyzed and yet during the running of the plant without any change in operating parameter or a field changes done on the piping system - it started to shake, rattle and roll. And to fix the problem, again u wanted to run a CII analysis - what for?

A lot of people is being reactive when faced with a problem related to vibration. If u lack the in-house expertise then the better way of handling this is to get a guy who knows vibration - especially if the piping handles a highly hazardous chemicals or its going to cost you significant loss if it fails.

• In PipingDesign@yahoogroups.com, Christopher Wright <chrisw@...> wrote:
  >
  >
  > On Apr 7, 2007, at 8:33 AM, Jun Atibo wrote:
  >
  > > And by the way, sway braces are not used to absorb vibration.
  Wrong
  > > application. And i can back this claim with several tech
  articles
  > > and books related to the use and mis-used of sway strut.
  > Right on. Likewise with dampers, (properly called snubbers, I
  think)
  > which are used to limit seismic displacements. To many people see
  a
  > piping span apparently vibrating and think that's the problem. It
  may
  > not the problem, only one of the symptoms. If the problem is an
  > improperly supported pump or flow oscillations, bracing the span
  > doesn't fix anything. It might even make things worse.
  >
  > Christopher Wright P.E. |"They couldn't hit an elephant at
  > chrisw@... | this distance" (last words of Gen.
  > .......................................| John Sedgwick,
  Spotsylvania
  > 1864)
  > http://www.skypoint.com/~chrisw/
  >