bwerner
Mechanical
- Mar 31, 2010
- 1
Normally I put the tailing lug on the shell of vertical vessels with no problems as this is a standard feature in Compress.
However, there are situations in which the shell thickness is thinner than the head thickness and then it may be advantageous to put the tailing lug onto the bottom head near the knuckle. Unfortunately, this is not supported by Compress so I am working on determining the stresses that the load puts onto the membrane of the vessel at this location.
I need to consider that now the lug is on a curved section, so I put a standard lug onto the top head knuckle to see how compress calcs this. They use a value referred to as the "Equivalent Inner Diameter".
I am left with 2 questions:
Does anyone know if this value is meant to replace the ID on a shell designed lug in order to account for the curved surface of the head?
And
In the calculation for the equivalent ID, they describe 'x' as "the distance between the axis of semi-ellipsoidal head and the center of the lug". What is this referring to? On a 42"ID head it calcs a value of 3.42" so its certainly not the axis of the vessel.
Thanks!
However, there are situations in which the shell thickness is thinner than the head thickness and then it may be advantageous to put the tailing lug onto the bottom head near the knuckle. Unfortunately, this is not supported by Compress so I am working on determining the stresses that the load puts onto the membrane of the vessel at this location.
I need to consider that now the lug is on a curved section, so I put a standard lug onto the top head knuckle to see how compress calcs this. They use a value referred to as the "Equivalent Inner Diameter".
I am left with 2 questions:
Does anyone know if this value is meant to replace the ID on a shell designed lug in order to account for the curved surface of the head?
And
In the calculation for the equivalent ID, they describe 'x' as "the distance between the axis of semi-ellipsoidal head and the center of the lug". What is this referring to? On a 42"ID head it calcs a value of 3.42" so its certainly not the axis of the vessel.
Thanks!
