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chinus (Mechanical)
25 Apr 03 11:36
Looking for literature regarding this subject. We are building nitrogen storage tanks for off-shore use and need to engineer the padeyes. I have been looking around for code standars but have not found this particular subject yet. Any help would be appreciated,

regards,


Chinus
LSThill (Mechanical)
25 Apr 03 12:50
Hi chinus (Mechanical)

Do a search and you will fine the following

RMPE (Structural) 03/13/03 (posted 10/28/02) 17 replies
Tensile capacity/minimum engagement  
 
Mechanical Engineers Area - Piping & fluid mechanics engineering Forum
rrickey (Mechanical) 01/19/03 (posted 01/15/03) 2 replies
Has anyone had experience using MecaConsulting's Lifting lug program?
 
Engineering Codes & Standards Area - ANSI (standards) Code Issues Forum
frostrobn (Mechanical) 01/16/03 (posted 01/15/03) 1 replies
Applicable Specs. for lifting lug design
 
Structural Engineers Area - Structural engineering other topics Forum
frostrobn (Mechanical) 01/15/03 (posted 01/15/03) 1 replies
Applicable Specs. for lifting lug design  
 
Structural Engineers Area - Structural engineering other topics Forum
henerythe8th (Structural) 01/10/03 (posted 01/09/03) 4 replies
hoisting/lifting eye

Leonard@thill.biz
www.thill.biz
 
chinus (Mechanical)
25 Apr 03 12:52
Thanks for your help Isthill,

regards
Helpful Member!  chicopee (Mechanical)
25 Apr 03 21:14
the padeyes may require reinforcement on the shell as you dont want deformation when tanks are lifted. It all depends on weight, shell thickess, sling configuration to lift tank.  Weld analysis requires you to evaluate shear, tension and external moment on weld. Padeye thickness will be based on bearing pressure from shackles or hooks thru the padeyes and possible distortion of the padeye during lift.  There are good references on pressure vessels somcheck them out.
LSThill (Mechanical)
27 Apr 03 0:18
Hi chinus (Mechanical)


E. F. Megysey
Pressure Vessel Handbook
Pressure Vessel Handbook Publishing Inc.
P.O. Box 35365
Tulsa, OK 74153


Leonard@thill
www.thill.biz
chinus (Mechanical)
28 Apr 03 8:33
Thanks again all. It has helped me a lot.

regards,

deanc (Specifier/Regulator)
28 Apr 03 8:50
Also see Appendix G
EKK (Mechanical)
28 Apr 03 16:42
Hi,

I woudl suggest you to consult the BS 5500. I´m sure that you will find rules to calculate and design the pads.

Regards,
twjag (Structural)
29 Apr 03 20:57
chinus,

The lift lug is a non-pressure attachment, & is not in use when vessel is operating. Therefore, the design parameters should consider safe load conditions.

For design of the liftlug & attachment weld to vessel, we use the same factor of safety as for MSS Under the Hook Lifting device. It is 3:1 on yield. This translates to using AISC structural allowables + a 1.8 safety factor.
We also include an impact factor to account for dynamic loading during crane lift. Unless you know, or have control of, the lift crane, I suggest a 1.2 or 1.25 impact factor.
Per the above, design load = load x 1.8 (MSS factor) x Impact factor. Compare resultants to AISC allowables.

Unless you issue a required lifting schematic, showing required rigging arrangemen. consideration incorporation of all possible sling angles & the possible resultant out-of-plane loading on the lifting lug.

As to distribution of loads & stresses in the vessel wall, this gets a little more complicated to offer in this brief format. We use both FEA or known reliable emphircal methods. If not familiar with this aspect of design, I suggest you consult with a knowledgeable consultant or design source.
chicopee (Mechanical)
2 May 03 19:42
For welded connections rule of thumb for weld strength (for E70 welds) is .928 kips per inch of weld length per 1/16 th leg for 45 degree fillet.  This value can be used for welds subjected to combined shear and tensile stresses and is used by contractors welding padeyes on structural steel. fieldwelerecting .  
LSThill (Mechanical)
7 May 03 18:59
Hi chinus (Mechanical), twjag (Structural)and chicopee (Mechanical):


COMPRESS USER'S: "PRESSURE VESSEL LIFTING LUG ANALYSIS" go to Photo Gallery the very last two Photo for the PRESSURE VESSEL LIFTING LUG ANALYSIS SHEET. AT:

www.thill.biz

Leonard Stephen Thill
Leonard@thill.biz
www.thill.biz

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