Lifting Lugs/WRC 107

[tovi]

I am designing lifting lugs using the Advanced Pressure Vessel program for a 120" OD horizontal pressure vessel weighing approximately 90,000lb. The lugs will be attached to the heads.
In order to be able to check the stresses per WRC 107, the program asks for a rigid square or rigid cylinder attachment. I have a rigid rectangular attachment.
I know there is a method for changing a rectangular attachment to a circular or square attachment per Pressure Vessel Design Manual by Moss, 3rd Edition, pg 268. However, I am told that not all of the formulas in Moss are correct.
Can someone tell me if these formulas are correct or perhaps give me some suggestions.
Thanks for the help.

 

[chaulklate]

I'll take a kick at this at the risk of being flamed by my colleagues...

Are Moss's formulas correct...are any of them really correct? They are theoretical and 'proven' based on research, testing, and judgement. A number of qualified pioneer-type engineers (like Moss) have put forth their theories which people like you and I have used for years instead of developing and testing our own. It comes down to a few things; whose theories and formulas you are taught in school, what your mentor uses and passes down to you in the workplace, and your personal comfort zone developed over time using those forumulas.

As for the circle/square thing, I think you can analyze it based on an 'equivalent area'. Basically, take the area of your lug and covert it to an equal sided shape of the same area and thickness. Again, this lends to theories and judgements.

I could be wrong, but I have no personal experience with anyone coming to me and denying Moss's formulas.

I should also point out that I'm not an engineer...I just play one on tv.

 

[vesselguy]

"A number of qualified pioneer-type engineers (like Moss) have put forth their theories which people like you and I have used for years instead of developing and testing our own."

Chaulklate,

FYI, I personally have worked with Mr. Moss at Fluor so I know a littl bit of background. The work he's put in his book is a compilation of different sources from the Fluor vessel handbooks and past papers by other Fluor employees.

Tovi,
There were many typographical errors in the 1st edition of the book from Moss. Dennis knew about this and he corrected them in the later edition. I found out there was a problem with the formulas when I type them in MathCAD and the dimensions don't balance. The formulas are "technically" correct but do check the dimensions to ensure the typo problems are gone.