Dear Sir,

I want to model and analysis the vessel which is having two shell and head plates. The inner plate thick is 6 mm, outer plate thick is 6 mm and gap between these plates is 6 mm. The stiffener (Flat bar) is placed and welded between inner and outer shell plates.

In this vessel are having around 6 nozzles. Out of these, 2 nozzles are inserted completely (inserted through both the shell plate), two nozzles are inserted up to outer shell plate thick and remaining two nozzles are not having any inside protrusion only on border of outer plate.

I want to how I can assume this gap between inner and outer plates and how to place the nozzles.

Inner head plate is mounted with inner shell by butt welding and outer head plate is mounted with outer shell by lap weld joint.

Kindly advice me in this regard to carryout this job.

Hi N

You are describing a jacketed vessel with an inner shell, and an outer jacket.

It is not possible to model that type of configuration directly using PVElite. However, it is possible to model the vessel as two separated vessels. First you model the inner vessel, with the external pressure set to the jacket pressure. Then you model the jacket as a separate vessel setting the design pressure to the jacket pressure. You may have to model the nozzles twice - once for the inner vessel, and once for the outer vessel, if the nozzle penetrates both the inner shell and the jacket.

You will have to add the weight of the jacket to the inner shell (or vice versa) so you can get the correct weight for the supports.

In this way, you can get a reasonable representation of the whole vessel.