ovality

[212197]

what are the adverse effects of excess ovality on :
1. shell having internal pressure
2.shell having external pressure
3. u tube

 

[TGS4]

1) not much unless there is cyclic service
2) it will greatly effect the buckling margin
3) I'll leave that for others to answer

 

[mk3223]

3) the excess ovality may reduce the flow, or the strength of the bend and cause buckling too.

 

[212197]

if impact of ovality is different for internal & external pressure, why UG-80 (a1 & a2) appear under external pressure requirements i.e. under UG-80 (b) (1)?

 

[TGS4]

Do not assume that there is any logic in the location of rules in VIII-1. This Code has been organically evolving for over 100 years without an overall vision.

 

[SnTMan]

TGS4, no need to pull your punches there...

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[mk3223]

By the UG-80, IMO, besides the same out-of-roundness limitations per UG-80 (a-1 &2) for both design conditions either under internal or external pressure cases, there are additional requirements for the external pressure case, i.e. UG-80 (b-2,3,4,5... etc.)

 

[EdStainless]

In case 3, it is only an issue when;
a. it is enough to restrict flow (as if the tight radius does not do that already)
b. this is not a 'regular' heat exchanger and it sees lots of pressure impulse loading, the fatigue life would be lower, but this would take higher stresses and lots of pressure cycles than are common in heat exchangers.

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P.E. Metallurgy, Plymouth Tube