Conical opening in torispherical head for an agitator 2

[B_1]

Hi there,

I am struggling to find a relevant section in ASME VIII that can help me determine the required geometry for a conical opening on a torispherical head. The opening is not radial and is offset from the center of the torispherical head so it is till in the spherical region.

So far I have modelled it as a cylindrical nozzle in PVelite and NozzlePro but woul like to know how to do this better.

If there isnt a section in ASME VIII then any advice in creating this in either PVelite or NozzlePro is welcome.

Thanks

 

[marty007]

This geometry is not handled is ASME VIII-1.

Paragraph U-2(g) was re-written in ASME VIII-1 in the 2019 code edition. You now have three specific options to support your design (read the code for precise wording...):
1) Proof Test
2) Find a calculation method in another widely accepted code or standard.
3) Follow the rules of ASME VIII-2 per Appendix 46. ASME VIII-2 won't have any rules in Part 4 to handle this, the only option here will be Part 5 (FEA).

I suspect you'll be stuck with FEA analysis per ASME VIII-2... Here you'll have to analyse all of the failure modes (plastic collapse, local failure, buckling, ratcheting, fatigue (if applicable).

 

[SnTMan]

Often better to just design what you can calculate rather than trying the other way around...

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

With the large cone diameter do calculation as equivalent cylindrical nozzle.

Regards

 

[marty007]

Often better to just design what you can calculate rather than trying the other way around...

Amen, star for you!

With the large cone diameter do calculation as equivalent cylindrical nozzle.

Can you please explain how this method aligns with the revised wording of paragraph U-2(g) in the 2019 edition of VIII-1?

 

[XL83NL]

I don’t see any direct reason why r6155 couldn’t be right, except that the additional stresses inherent to a conical design need evaluation as well. Which is were it might become tricky.
Even EN 13445 doesn’t have rules for this afaik.

What size is this conical opening? Why does it need to be conical? Can you replace it with something else;
- a large opening, equal to the greater of the two conical diameters, combined with either a flat end plus nozzle, or WNRF plus BLRF?
- or use a short piece of pipe combined with a B16.9 reducer?



Huub

 

[r6155]

1)The opening is elliptical and the nozzle is conical
2)Conical nozzle is used to easy cleaning basically when the nozzle is horizontal. It is applied in the nuclear industry, food, pharmaceutical, etc
3)UG-36 is clear, hence U-2 (g) not apply.

Regards

 

[geesamand]

Whatever you choose, ensure you calculate deflection for the tank nozzle and confirm it meets the agitator manufacturers deflection requirements. All coded calculations go out the window when the agitator rocks around on the nozzle.

David

 

[saplanti]

Is the vessel presurised? Some cases the vessel is manufactured to ASME VIII but under hydrostatic pressure in operation. In such cases you do not need to comply ASME design rules.

 

[saplanti]

Assuming the vessel is pressurised, you can check the vessel openin for the largest opening diameter in case the opening iooks like elliptical. You can use the same rules for the reinforcements. Check the reinforcement limitations within the code.[pre][/pre]