Nozzle loadings
Nozzle loadings
(OP)
Dear all,
Below highlighted is statement in the specification of a clinet, same i have seen in fourth edition of pressure vessel manual, out which first condition we are satisfying in our calculation, but i didn't exactly understood the requirement of second case mentioned in bold letters, Does it mean full vaccum condition or no internal pressure i.e atmospheric. and how can I satisfy the same in my calculation.
With regard to the radial load(F A), calculations shall be made firstly with the force acting radially outwards in conjunction with the internal pressure and then with the force acting inwards. In the second instance, the internal pressure shall not be used to oppose the compressive stresses due to the force acting radially inwards; for this load condition a null pressure condition is to be considered to exist
Below highlighted is statement in the specification of a clinet, same i have seen in fourth edition of pressure vessel manual, out which first condition we are satisfying in our calculation, but i didn't exactly understood the requirement of second case mentioned in bold letters, Does it mean full vaccum condition or no internal pressure i.e atmospheric. and how can I satisfy the same in my calculation.
With regard to the radial load(F A), calculations shall be made firstly with the force acting radially outwards in conjunction with the internal pressure and then with the force acting inwards. In the second instance, the internal pressure shall not be used to oppose the compressive stresses due to the force acting radially inwards; for this load condition a null pressure condition is to be considered to exist





RE: Nozzle loadings
RE: Nozzle loadings
The tensile stresses in the shell due to internal pressure will serve to counteract some of the compressive stresses in the analysis of the nozzle (or other) loads (for example, analysis as per Welding Research Bulletin WRC-107/WRC-537).
The specification copied above indicates that no advantage is to be taken for this result. Thus they are saying that internal pressure shall be "null", indicating no pressure differential across the pressure boundary. In other words, atmospheric pressure is to be assumed.
RE: Nozzle loadings
RE: Nozzle loadings
a) zero pressure at internal pressure design temperature
b) specified external pressure at external pressure design temperature.
Expecting a loss of internal pressure coupled with coincident external pressure developing would in most processes be a double-jeopardy event. Thus, I would not normally consider external pressure at internal design temperature as an additional load condition.
RE: Nozzle loadings
RE: Nozzle loadings
RE: Nozzle loadings
I would at least look into the case where liquid is being withdrawn from the tank at a negative pressure corresponding to the maximum inbreathing condition. It's not worst case vacuum - which would be double jeopardy, perhaps - but it is a valid case.
RE: Nozzle loadings
If I have designed vessel with stiffner ring for external pressure,
May I now how nozzle external load will effect the design for external pressure,
External load will be axial where as external pressure will be acting in radial from all direction even on nozzle, which means it not gona contribute much in increasing axial load on nozzle,
And as i have already mentioned Shell itself is efficient to resist F.V condition.
RE: Nozzle loadings
RE: Nozzle loadings
But as you said if a condition arises were nozzle axail load add up with load due to external pressure it will be the worst case,
But if we are providing PVSV do we have to consider this situation.