I will Probably get flamed for this, but here goes.

With respect to including sifs in B31.3 stress equations i have noticed the following 'apparent'
contradictions:
1.
Page 1-47 of Coade seminar notes suggests App D sifs (Ii,Io)be included in the calculation of the sustained loads Sl, and that the occasional loads be calculated likewise.
However, interpretation 6-03 specifically states that the application of sifs with respect to the sustained loads are not required.


2.Interpretation 1-34 would seem to contradict the reply given in interpretation 6-03 with respect to these sustained loads, stating that a sif factor of 0.75i-1i be used

3.Interpretation 6-03 whilst negating the use of sifs for the sustained loads, makes no mention of the occasional load.
However the Caesar help file SPECIFICALLY Quotes:
"B31.3 Code Interpretation 6-03 dated December 14, 1987 permitted users to ignore the stress intensification for sustained and OCCASIONAL loads.To comply with this interpretation, the user would enter 0.0."

The reason for my enquiry is thus, i have a prv system with operating pressures which are approaching the limits of the available pipe thickness.

do i apply sifs of 0.0,0.75 or 1.0 to the sustained and occasional loads?

my interpration is that a sif of 0i for the sustained and of 0.75i for the occasional are acceptable or have i misread the code?

i notice though that Caesar is not able to include
the varying sif factors as given above.

Please advise if possible

regards tim.