Tushar,
Please be careful with this one. Each code is drawn up with a specific
purpose in mind and the conditions in that code apply to that code only.
You can not mix and match codes requirements to suit yourself. I do not
want to embark on a big lecture here, but it is important that each code
is seen in total isolation unless codes actually refer to each other and
allow their cross use.
On the matter of nozzle loads: the pipe code concerns itself with stresses
in the pipe, a pump code concerns itself with bending the pump
sufficiently to misalign the shafts. The two requirements simply are not
compatible. It may well be OK to occasionally stress the pipe to 50%
above design or whatever, but it may not be OK to throw the alignment of
the pump out of wack by 50% occasionally. If a pump code requires no more
than a certain nozzle load then that is that, no arguments. I read the
requirement as being the maximum load allowable under ALL conditions. And
the same sort of logic should apply to vessel and other codes. You must
satisfy the requirements of both codes at the interface and that generally
means that you must err on the side of safety.
Regards,
Gordon Reddek
zope_tushar@fwuk.fwc.com
25/03/2004 02:14 PM
Please respond to PipingDesign
To: PipingDesign@yahoogroups.com
cc:
Subject: [PipingDesign] Nozzle Loads for Eqpts
Friends,
Piping exerts some loads on the equipment nozzles. The allowable nozzle
loads mentioned by any vessel or pump manufacturer are for design
conditions of the eqpts.
Sometimes the loads at design conditions are within allowable, but they
may
exceed at the occasional load cases like wind or seismic.
As per B31.3, we can use 33% higher allowable stress for piping. But the API codes for pumps etc do not mention any such factor. Is there any thumb rule or factor for occasional cases to analyse eqpt nozzle loads?
If we send these loads to the manufacturer, they will just approve those
without any modification in the nozzle design. This mean there must be
some
extra margin to cater for such cases. If anybody is aware, please
enlighten
me on this.
Best Regards.
Tushar Zope
Extn: 162
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[Non-text portions of this message have been removed] Received on Thu Mar 25 03:53:00 2004
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