Checking Lifting Lug Calcs

[julesomar]

I am trying to check some lifting lug calcs using Pressure Vessel Design Manual (by Moss) mainly. I have come across some conflicting methods / conventions when compared to other literature. The scenario is:

standard plate-type lifting lug with gusset, checking the lug-to-pad weld when lifting the vessel from the horizontal position using a spreader so that no (or neglible) bending occurs parallel to the lug.

Lest I am mistaken, there is a direct shear acting (= F/A), and longitudinal & transverse shear due to the moment. Generally, I have seen the moment arm being taken as the distance between point of lifting and the c.g. of the weld. Is this a conservative calc. since we are essentially neglecting the gusset support? Can someone breakdown the mechanics of this?

 

[LSThill]

julesomar (Mechanical)

Two example is listed on

http://www.thill.biz/

go to the Photo Gallery END "LIFTING LUG ANALYSIS"

Regards
Leonard Stephen Thill

L S THILL

 

[roca]

Be carefull with the earlier editions of the Pressure Vessel Design Manual (by Moss) - it was littered with errors - I think this has been mentioned in previous posts in the past. Not sure what the latest edition (3rd...?) is like as I don't have a copy of it

 

[julesomar]

Thanks for the initial feedback. Roca, I have heard the Moss text has some errors. Again though, I am interested in the fundemental mechanics / assumptions at play - does the presence of the gusset / support plate connecting the shell to the lug mean that the calculations presented in Moss / other handbooks are simplified?

Lsthill, in your analysis, the moment arm distance is taken from the centre of the pinhole to the base of the lug. How does having a support plate welded to the lug (say halfway down) affect the resulting shear?

 

[LSThill]

julesomar (Mechanical)

What type of Lifting lug are design:

Pressure Vessel Desing Manual
Third Edition
Dennis Moss, fluor, california, USA:
ISBN 0-7506-7740-6 (HARDCOVER:ALK.PAPER)
Pressure vessel design manual: illustrated procedure for sloving major pressure vessel design problems:

Chapter 7
Transportation and Erection of Pressure Vessels, 365
Procedure 7-1 transportation of Pressure Vessel365
Procedure 7-2 Erection of Pressure Vessel 387
Procedure 7-3 Lifting Attachment and Terminology 391
Procedure 7-4 Lifting Loads and Forces, 400
Procedure 7-5 Design of Tail Beams, Lugs, and Base Ring Details, 406
Procedure 7-6 Deaign of Top Head and Cone Lifting Lugs, 416
Procedure 7-7 Design of Flange Luge, 420
Procedure 7-8 Desing of Trunnions, 431
Procedure 7-9 Local Loads in shell Due to Erectin Forces, 434
Procedure 7-10 Miscellaneour 437

If using any pressure vessel application software like CODEWARE

http://www.codeware.com

COMPRESS, PVelite has detail claculation for the Procedure.

Regards
Leonard Stephen Thill



L S THILL