Hello everyone!
I would like to open here about ISO 14692 qualified stress.
The ISO 14692 states that the sum of all axial stresss σa shall not exceed values defined by the factored long term envelope, that is,
σa,sum < (1-r)(σh,sum/2) + (f2)(A1)(A2)(A3)(r/2)(σqs)---eq.1
How to get the value of qualified stress σqs?
The Caesar II states that the qualified stress is same as the long term hoop stress,
σqs = σhl(2:1).
σhl(2:1) = 2 σal(2:1) ----eq.2
σal(2:1) = σhl(2:1)/2 ---eq.3
While the ASME B31.3 states that the HDBS shal be obtained by the procedure in ASTM D2992. HDBS shall be multiplied by a service factor of 0.5 to get the hydrostatic design stress or HDS.
HDS = HDBS * 0.5 -----eq.4
The equation 3 and eq. 4 looks like the same, so the HDS is equal to σal(2:1) and σhl(2:1) is equals to HBDS.
So I conclude that the qualified stress σqs is the same as HDBS. Please correct me if Im wrong with my interpretation, this is a very serious matter.
Thank you and regards,
Clyde
Edited by Clyde (10/12/11 11:16 PM)