Could anyone explain why in CII only the SIF in the header reduces when the type of connection from "un-reinforced" is changed into "reinforced" ? acc. to the B31.1 there is only one formula to calculate SIF at the connection point.


thanks

h seems different,

Javian,

do you mean that "h" has to be calculated with branch attributes, too? if so, I have to disagree. my point was; why by reinforcing a pipe to pipe connection according to B31.1, only the SIF on the header reduces.

Javian is correct. The'h' factor for the reinforced and non-reinforced tee differs and thus so do the respective SIF's.

In each case the same SIF applies to header and branch. Also, SIF is independent of branch size. Read note (9) below B31.1 App.D Table D-1.

I think I have not clarified my situation; I have a 4 to 10 in pipe to pipe connection where the SIFs for branch and header are 3.471 and 5.284 respectively. I switch the type of connection to re-inforced with its pad as thick as the header's thickness. the new SIFs for branch and header are 3.471 and 2.688 respectively. as you can see the SIF for the branch side has not changed at all. I would like to know why.

thanks

Check the "branch equation" near the end of the table.