Max Allowable Moments and Forces?

[RBMECH123]

Can anyone tell me how to explain or understand what the maximum allowable moments and forces would be on pipe supports, when after doing a stress analysis, only gives a 23% of the stress allowable? I'm getting a +10ksi moments and from my experience, wouldnt give a client anything more than 3ksi. I am using X52 carbon steel, 20" pipe. Please help, anyone. I fairly new to the stress world and wondered if theres something relative to API, WRC, Nema, etc.

Thanks,
Rich

 

[khardy]

You want to know the allowable moments and / or stresses in the pipe supports? Or do you want to know the allowable moments and / or stresses in the pipe?

If for the supports you need to look at a relavent code; for steel supports I would use AISC's "manual of steel construction."

If you looking at the pipe then the proper code depends on the application. For example, ASME B31.4 might apply to a bulk product pipeline.

 

[MJCronin]

Rich...

Your question is not clear.....

I suggest that you contact COADE, and ask them specifics about your particular stress analysis and methods of modelling.

Having large moments and forces from the stress analysis of a 20"NPS system is not hard to believe...

-MJC

 

[Zapster]

I'm getting a +10ksi moments and from my experience, wouldn’t give a client anything more than 3ksi… I fairly new to the stress

Perhaps I am stating the obvious, you are participating in a pipe design when you lack the experience to do so.

Use the relevant pipe code for the design of piping system and supports. One of support guidelines might be: MSS SP-58 Pipe Hangers and Supports - Materials, Design and Manufacture

 

[JohnBreen]

Here we go again - TO WHAT CODE ARE YOU DESIGNING THE PIPING SYSTEM?

As stated above, your question is quite ambiguously worded.

Where are you forces and moments being calculated? forces and moments IN THE PIPE (at the pipe supports) must be "translated" into stresses that are to be compared to the Code allowable stress. The ASME B31 Codes for Pressure Piping do not specify "allowable forces and moments".

Pipe hanger hardware is "load rated" and you need to know what that means. If you are concerned about forces and moments in the pipe support hardware you need to read and understand this:

http://www.anvilintl.com/db/catalogs/Pipe_Hanger_Design-07.pdf

If you are concerned with forces and moments being transferred to the structures that will support the pipe you need to go talk to the structural engineers that designed the structures (you need to do this anyway).

I would urge you to buy and read one of the several books on piping design and stress analysis. If you search this discussion forum for "books" you will find a wealth of suggestions. Similarly if you search this forum for such topics a "piping stress analysis" you will find previous discussions that you would be well advised to read and understand.

Regards, John

 

[StressGuy]

I have to agree - the question from the OP makes no sense. I can only try to guess at what a 10ksi moment is supposed to mean. I think you need to take another look at your post and take another shot figuring out what you're really asking for. As you can see from the others, nobody here can help you with the information you've supplied.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.