Dear all,

In saddle analysis of our equipment, base plate is undergoing bending in transverse direction.

However, we found that in PVelite calculation, effect of ribs (welded perpendicular to central web & base plate) is not considered. Hence, the required thickness is coming huge (in order of 100s of mm).

We cross checked the same model analytically using roarks guideline, the base plate thickness is coming less (about 25 mm).

Moderators are requested to please reply this matter ASAP.

Hello M.SHUKLA

Could you send you model to techsupport@coade.com for my attention? Also, please let me know which version of PV Elite you are using.

Hello, Shukla.

We have aware about your point few years back and did request clarification from Coade.

Mr. Mandeep replied : I would also tell you that the saddle baseplate analysis based on traverse load per Moss is quite conservative. In my opinions, you can disable the saddle baseplate analysis for the transport case.

This huge base plate thickness will be concluded when uplift occurs due to strong transverse load like wind or transportation acceleration (say on a FPSO).
Using concept by Moss, the modulus used to compute bending stress solely depend on rectangular cross section of base plate.As you said, contribution from ribs and web are excluded.

May be this is what Mr. Mandeep meant by "conversative" and his advise is to disable calculation of base plate for transportation case. Seems to be no permanent solution to provide clean report unless increase base thickness to un-releastic figures.

Wish Ray can share the reply after study via this forum discussion.

Tan

Please try this in PV Elite 2010, Ray has tweaked that calculation and now it is little less conservative.

But, you are correct the web and ribs are not considered in this calculation which is taken from Pressure Vessel Design Manual by Dennis Moss.

You would have to do a much more detailed analysis taking in to account web, ribs in to consideration.

Let us know how it works out.

Thank You Mr. Tan & Mr. Mandeep,

However, this question raised not due to any transportation acceleration but due to geometry of the equipment.

Mine equipment is a horizontal equipment with TL to TL of 6500 mm & above it there is a tower with a height of 7500 mm (TL to FF).

Due to this tower, transverse moment would get added in the transverse moment of horizontal equipment.

To simulate this condition, we applied x-axis force in "force moment" dialog box to get the desired transverse moment on each saddle.

I would definitely check this model in 2010 as soon as it's get purchased.

Just keep in mind that in PV Elite, the x direction is along the axis of the cylinder in a horizontal vessel and Z direction is what I called transverse direction (the other horizontal direction, coming towards you ). You should consider wind/seismic load in both directions.

Yes, i meant the z direction only (transverse direction).

It was a typographical error.