"Lifting" lugs on heads?

[KLee777]

I have an interesting request I've not come across before.

We have a vertical, ASME VIII-D1 vessel with some sort of rotating equipment inside, the driver of which is mounted onto a studded outlet in the bottom F&D head. (Sorry I don't know exactly what it is, the vessel drawing is written in German which I do not read.)

The unit engineer has informed me that they need to periodically remove this ~1,000 lb driver from the outlet. However, when the vessel was set in the structure, they did not take removal of the driver into account when designing the platform. Currently, they must rig up on the driver and pull it off to the side, etc etc. Apparently it's a safety issue.

So I've been asked to design some "lifting" lugs to attach to the bottom head to facilitate the removal of the driver by attaching to the lugs and lowering it safely to the platform below. I've never been asked to put lugs directly onto a head - you know, ear-type lugs welded perpendicular to the head surface.

Is there anything in the code stopping me from doing this? I can design the lugs easily enough, but what about the stresses in the head? Really, I'm not too concerned as the head is 0.60" thick and the load is only 1,000 lbf total. But I'd like to be able to back that up with some calcs.

Thoughts? Advice?

-KLee

 

[SnTMan]

No, done all the time. A WRC 107 type calc is what you need, and you may find something in Moss.

No pressure stress present, all thickness available to resist the lug loads.

Regards,

Mike

 

[KLee777]

Thanks, Mike. But should I use WRC 537 instead? As I understand it, it superseded WRC 107.

I don't have a copy anyway, so probably a moot point.

 

[SnTMan]

KLee777, yeah, that'd be an option, but really, any applicable method would be fine. As I said, Pressure Vessel Design by Moss probably has something usable, free access to ASME members.

If doing by "hand", the simpler method, the better.

Regards,

Mike

 

[KLee777]

I'll check my copy of Moss, thanks.

 

[gr2vessels]

Klee777,
WRC 537 is in fact the upgrade bulletin of WRC 107. It calculates the stress in the shell/heads generated by solid attachments based of graphs converted to formulas. There is a number of free WRC 107 calculators on the internet, including those spreadsheet type. You can also review the previous post in this forum with suggested various calculators. Just remember, you still need to calculate separately the lug(s).
Cheers,
gr2vessels

 

[jharris3]

There is also a nice option in Blodgett's Design of Weldments; intended for hangars on pressured piping. That one is doable by hand or a simple spreadsheet.