B31.3 Sustained Case SIF Factor in Config File

Dear All,

Why this option is only used for sustained and occasional cases why not for expansion case “B31.3 Sustained Case SIF Factor” option in Config File.

What is the Technical reason behind that?

Give me some reference.

There is a long history behind this.Its like digging an age old grave.

In a nut-shell,B31.3 doesn't have SIFs for sustained case & therefore,there was no option but to use the same SIFs of expansion cases for sustained too!!!(Remember how these SIFs came into existence)
For a real understanding,calculate SIFs using Nozzle Pro which also calculates SIFs for Pressure & feel the difference between the two SIFs.

I dont know how to use Nozzle Pro

But Can you give me reference, so that i can understand technically..

why this option came in to picture only for sustained and occasional cases, why not for remaining operating and expansion cases.

Can any one share about this topic " B31.3 Sustained Case SIF Factor in Config File"

SIF for sustain case is long debatable issue as original work was based on fatigue failure. But now as per ASME B31.3, para. 320.2 , ed.2010 has defined 0.75 SIF to be used for SUSTAIN.

For "expansion" case, "full" i_i "in-plane stress intensification factor" and i_o "out-plane stress intensification factor" are considered in calculation of the
resultant bending stresses.

See B31.3/319.3.6 Flexibility and Stress Intensification Factors "In the absence of more directly applicable data, the flexibility factor k and stress intensification factor i shown in Appendix D shall be used for flexibility calculations described in para. 319.4."
Please see also the equations included in 319.4.4 Flexibility Stresses.

You may consider also this post ; however -as PRADEEPD said- B31.3 has now a new sub chapter addressing "ANALYSIS OF SUSTAINED LOADS"

Thank you pradeepd & Marioq

can i know why we are multiplying 0.75 to SIF

Because of that

SIF value reduced => bending stress reduced => code sustained stress reduced.

Same Question for occasional also ...
I think this option is used not only sustained but also for occasional.

can you provide me any reference, for this topic

Please take a look to the thread link I've posted and to the docs that Mr. John Breen mentioned in that thread.

I quote from Interpretation: 1-27/ B31.1:

Inquiry: Is it the intent that the stress intensification factors shown in Appendix D of each respective Code be applied for sustained and occasional loads as well as for expansion loads?

Reply: Stress intensification factors (SIFs) listed in Appendix D of the various ASME B31 Code Sections are intended for design against fatigue failure and were to a large extent developed from cyclic bending tests of piping components. Therefore, the application of the SIF for cyclic bending and torsion loads is appropriate.
Sustained and occasional loads may not be cyclic loads; however, it is the intent of the various Codes to provide adequate protection from component collapse. It has been shown that the SIF of 0.75 (but not less than 1.0) found in ANSI/ASME B3 1.1 applied to sustained and occasional bending and torsion loads provides a conservative margin against component collapse.

I think it's clear enough this is not about reducing Code stress.

Thanks alot Mariog

crystal clear

Dear Mariog,

I want to learn the procedure how to do slug analysis in time history method.

Can you give me any reference for same.

Dear All,

I want to learn the procedure how to do slug analysis in time history method.

Can any one give me suggestions/references for this procedure how to approach...

Durga,

You should have started a new Topic with this request. Time History slug analysis doesn't really relate to B31.3 Sustained SIF factors.

As to your question, open a Support Request (SR) on eCustomer and request the SNFAIL job. This is a time history fluid hammer job. The approach is the same for slug flow. The difficulty with slug flow simulation is in determining the size and timing of the slug. We have nothing to help you with this evaluation. I suggest you set up three scenarios: minimum slug, maximum slug, and most likely slug. If your system is ok in all three scenarios, that's great. If not, then its decision time with the owner ...

my mistake,

Thank you Richard Ay,

Can you help, how to open that support request..

I am out of the office right now, and I don't have the link. E-mail Loren Brown and ask: loren.brown@intergraph.com.

ok
thank you