Lifting Lug Calculation

[kodzak1981]

Hi,

could anyone recommend me some good literature (procedure) for Pressure Vessels Lifting Lug calculation.

Thank you in advance.

 

[boilerone]

You must clarify if the lug is used when when the vessel is under pressure. Lifting lug, by definition, is for transportation and erection purposes only otherwise they should be called pressure part support attachments.

Plus, are you checking or designing the lug itself or the attachment to the pressure part? In other words, is the lug or the pressure part of your concern? The formulas are different.

Boilerone

 

[jamesl]

Check out Dennis Moss's "Pressure Vessel Design Manual" 3rd Ed.

It has a whole chapter (about 80 pages) discussing vessel erection and transportation. It covers different kinds of lifting devices.

 

[JStephen]

For the design of the lug itself (as opposed to stresses in the vessel), the design methods in ASME B30.20 and BTH, below-the-hook lifting devices, come in handy.

 

[AWDMIKE]

There are a few hits if you search this particular forum for 'lifting lug calculation' which may be of help to you.

There is an ASME standard called 'ASME BTH-1 Design of Below-the-Hook Lifting Devices' which provides minimum structural design requirements for below-the-hook lifting devices, such as your lifting lugs. This equations used in this standard bear many similarities to the AISC Steel Construction Manual, as you may have expected.

I believe both Compress and PV Elite have have built-in calculations for lifting lugs as well.

If you are also seeking information regarding any vessel stresses which occur as a result of erection, you may refer to the 'Pressure Vessel Design Manual', by D. Moss.

If you are looking for theory behind the various failure criteria to which a lifting lug would be subjected, it may be found in mechanics and strength of materials books, as they are just structural components. Welds may be studied in machine design books, such as Mechanical Engineering Design, by Shigley, or in a book such as Design of Welded Structures by Blodgett.

 

[roca]

IMO working with an experienced good engineer who has done this type of work time and time again in the past without issues is my recommendation.
Books and theorey are all good but books do not cover all the things you may come across in reality.

 

[JStephen]

Most of us don't have the option of changing employment just to learn how to design a lifting lug, though.

 

[kodzak1981]

Hi, thank you all for your answers....

I'll try find out BTH-1... Lifting Lug I need is for erection only.

I've seen codecalc calculation of LL but I couldn't manage to figure out from where did they get those formulas.

 

[bluedieselblack]

The COMPRESS PV Software Manual has a lift lug proceudre in Appendix C, 8 pages. Check their web site.

 

[PreVes]

If you have questions for the codecalc calculation then you should contact the codecalc technical support, but definitely read the Dennis Moss's 'Pressure Vessel Design Manual' 3rd Ed, just like jamesl mentioned.

 

[roca]

Hi JStephen
I have re-read my post and I didn’t ask the initial poster to change jobs.
I merely asked him / her to discuss this with an experienced colleague. If the poster is the only person available at his firm to do the lifting lug design then they have problems – similar to the recent post in the Asme (Mechanical) Code Issues forum where the poster wanted to know how to design a slip on flange on a Nuclear vessel.
No matter how many books you read and how many formulas you might re-derive from first principals there are still things IMO that the books may or may not tell you and that an experienced eye will spot. Depending on the complexity and size of the equipment involved – (and as we are in a pressure vessel forum this could include very large fully dressed columns or reactors) – you need to use the correct type of lug or trunnion, position it correctly, choose the correct shackles, ensure shackles and chains do not clash during the lift, ensure the equipment will not buckle during the lift, etc, etc.