Hello PV Elite Forum Members

Does PV Elite have the ability to qualify the weld joints that connect the attachment to the Tank or does PV Elite only calculate the Stresses in the Tank Shell and Attachment without considering the stresses in the welds (i.e. it does not assess the weld strength and capacity)?

Thank you for your time and support.

Hello AbdulRalman

The principle in any code, such as ASME or API 650, is that the welding consumable be stronger than the parent metal. The welded joint itself is not analysed. The equations in the code asses thickness of the parent plates such as the shell courses and other components. I hope that addresses the question you raised.

Thank you Ray. YES, you addressed my question and that is exactly what I was asking about.

To reaffirm, the welding thickness shall be strong enough to transmit the loads between connecting members/elements. The strength of the welding consumable (tensile and yield) is one thing and the stress capacity of the weld group is another. If you have a material that is stronger than the parent pipe but the length of the weld is not long enough to take the load, the weld will fail.

The Code does not know how the designer intends to weld the components together so it is the designer's responsibility to verify that the welding configuration is strong enough to take the load.

I have asked a Vendor to verify that the weld thickness is sufficient for a certain weld configuration. They send me a WRC-107 Analysis by PV Elite and tell me that it is passing! My intuition was that PV Elite is mainly used to calculate the main thickness of the vessel. It is not intended to perform weld calculations. That is why I asked the experts and you gave me the answer (thank you).

Hello AbdulRalman

The welded joint is considered to part of the vessel. For example, if you were to have two cylinders welded together to make a longer cylinder, the weld would just be part of the longer cylinder.

I agree Ray for the case you mentioned, but this is not my case. If you have a welded attachment to the external side of the tank shell, the designer should evaluate the weld joint independently of the shell wall. They are two different things in this case.

Hello AbdulRalman

In the case of an attachment welded to the envelope of the vessel, the weld attaching the object to the shell should be analysed. For example, the welds attaching the nozzle to the vessel wall are analysed by PV Elite.

Ok Ray. May you please tell me how the input is fed to PV Elite to analyze different weld configurations? Does PV Elite allow for different fillet weld configurations (square, H or U, etc.)? What equations does it use?

Thanks

Ray, I would appreciate if you tell me how the input is fed to PV Elite to analyze different weld configurations, or did you mean something else? I just want to understand if PV Elite is capable of analyzing different type of welds or does it apply only to circular and square attachments?

Thanks for your time.

Hello AbdulRalman

PV Elite only analyses the welds for a limited number of attachment configurations. I mentioned the welding for nozzles. It also does it for lifting and tailing lugs, but for little else. If, for example, you were to attach a clip (perhaps supporting a platform for example), PV Elite cannot analyse the weld. Bear in mind that such configurations requires a fillet weld. In the case of a clip, the weld group is subjected to both shear and bending stresses. Once those load are identified the section properties of the weld group has to be established, from which proceeds the analysis by simple beam theory. This should be a fairly simple task for the engineer. I have done it many times in the past as a vessel engineer.

PV Elite really concentrates in the main on code calculations. It cannot cover every contingency. It would be nice if it did, but the field is too large to cover comprehensively.