Dear Members,

I have one vertical jacketed vessel with 2 lifting trunions attached to the jacket. OD jacket =1015mm, thickness jacket =6.35mm and TL/TL = 9265mm and empty weight is 8000kgf.

with these value i design trunions using codecalc but i confuse and not deeply understand to distinguish with axial,normal and tangential force when lifting orientation is vertical or horizontal. So put all force with 4000kgf (8000/2)and calculation passed without applied WRC analysis.

My client request me to perform WRC and result is failed, this WRC are mandatory?

Could anyone explain ragarding diffrential between force and WRC case?

Dear Faizol,

The WRC-107 calculation is for the localized stress around the trunnion. The other stress calculation is for the membrane and bending stresses that are not localized. You should consider both.

The axial force is parallel to the vessel longitudinal axis. This force will put the trunnion in bending.

The tangential force is acting perpendicular to trunnion and to vessel longitudinal axis. This force also puts then trunnion in bending.

The normal force is along the axis of the trunnion and radially outward from the vessel. This force just pulls on the trunnion. I think you would not have any normal force on the trunnion as it would cause the sling to slip away.

Most of the loads would be either axial or tangential. This depends upon the lifting mechanism, from horizontal to vertical or from vertical to vertical.

There is an example file Lugs.cci that includes some lugs, trunnions.

Let us know if you have further questions.

Dear Mandeep Singh, Thank you for your explaination but i not deeply understand regarding this matter, could you explain together with sketch that mechanism is from horizontal(fabrication site) to vertical(plan site)and i not discover your example file. i have problem to attach my file may be i will send through your email for your kind review and expected to got your assistance. Thank you.

Dear Faizol,

Refer to the attached sketch,

You need to compute the components as shown and enter those in.

So, in Horizontal position with trunnion, there will be Normal force.

In the horizontal to vertical position, there will a component of Axial and Normal force. This will depend upon the angle of the lift. You can try 30, 45, 60 degrees.

In the vertical position, you will have axial components.

These above force distribution will depend upon if you use a spreader bar or not.

The Lugs.cci file is located in the Examples sub-directory under PV Elite installation folder (if you just have CodeCalc then look in its installation folder). Typically this is "C:/Program Files/Coade/PV Elite xxxx"

Let us know if you have further questions. We are planning to include this in PV Elite in a future version.

Dear Mandeep,

Sir, as per previous post WRC 107 shall perform/consider at trunion.but when perform this,my result its failed. How to make it pass?

Thank.

ok, it depends on what is failing?

make sure you did not specify any internal pressure as this is lift condition.

make sure that you have the loads distributed correctly. You are specifying the loads on one lug.

You may have to add a re-pad or use a bigger one.

may have to add more supports during lift.

Hi Mandeep,
Please confirm that the normal force acting on trunnion is always co-axial with the trunnion centreline (refer to your sketch above - the vessel in horizontal position!) and the tangential force is always 'tangent' to the shell.
cheers,
gr2vessels

Hi gr2vessels,

That is correct.