SIF CROSSES

[psapiensone]

I need help for find the SIF in a CROSSES and input in Cesar.

Regards.

 

[MJCronin]

paulus....

You won't find them in CEASAR-II....

Crosses should not be used in piping systems subject to detailed stress analysis.

-MJC

 

[Berndt]

Hi PaulusP,

Although crosses are defined in B16.9, no SIF's are indicated in the B31 codes. The only way I know of that you will be able to determine these would be by using FEM programs such as FE/PIPE.

 

[JohnBreen]

........and if there is ANY WAY possible to avoid using a cross you should do it.

 

[psapiensone]

Friends, thanks for your answers, the problem is very big now because the client want to use crosses (very crazy) in your project (delayed coker) for cleaning lines.
I find information about SIF in an old paper, and in conclusion is possible to use SIF of normal TEE x 1.5 that they tell me?

Anyway, the problem is very interesting

Thanks.

Pablo

 

[MJCronin]

pablo...

Suggest to the client that you have extreme difficulty using crosses in a piping system because of deep religious reasons.

Tell him that B16.9 crosses have been desecrated by indescriminate use in piping systems in the past, and that you do not want to continue this practice.

Then.... make your eyes really big and look at him for a long time without blinking.

....only a suggestion ; )

-MJC

 

[carthago]

..About crosses..
I believe API 6A (used for christams trees ..which is also a bit religious too -lol )has standards and sizes about crosses (flanged) used for high pressure systems up to 10 000 psi and for diameter ranging from 2 to 10 " ( to check !)

The solution in my opininion to get the SIF's is too use finite elements
or for CAESAR runs..make assumption and uss two tees not far from each other ( say 2 to 5 mm)

 

[JohnBreen]

all the crosses that I have seen used in delayed cokers were castings.

The 1.5 time the B31 SIF number that you quoted is completely a fable. You might as well choose any other multiplier as you will be just as correct. The B31 Codes tell you to use the SIF's in Appendix A in the absence of better data - find better data

John