ISO14692 modelling in Caesar II 5.10 (& below)

Since there are growing number of current projects are required to follow ISO14692 in GRE piping analysis, we are still "stuck" with Caesar II 5.10 (&below). Actual release date for C2 V5.20 are still unknown at the moment.

The are ways to "simulate" ISO14692, recommended by Mr Richard Ay (COADE, Inc.) using C2 v5.10 (&below). First, we need to know the major difference between these 2 codes:

1. SIFS are different for bends for piping diameters below 20”. ISO14692 had limit the SIF for Bend and Tee at 2.5 and 2.3 respectively.
2. Failure envelopes for ISO-14692 can be slightly more detailed (and therefore less conservative) often being defined by one more data point (having pentagon shape rather than trapezoid shape).
3. Allowable stress levels may be increased for Operating and Occasional load cases, by 24% and 33% respectively, as compared to Sustained load cases.
4. The “f2” term is excluded from the bending stress in ISO-14692, as opposed to being included in UKOOA. This resulting a slightly increase of Bending Stress in ISO14692.

Then, the "simulation" ways are:
1. Model and analyze the system in CAESAR II using the UKOOA code.
2. Make sure that the checkbox for “Exclude f2 from UKOOA bending stresses” is checked in the Configure/Setup.
3. If you have ISO 14692 failure envelopes, construct a trapezoid that will fully fit within those envelopes, and use those to get the values you need for UKOOA (Sa(2:1) and R).
4. Use a system factor f2 of 0.67.
5. Calculate the bend SIFs as per ISO-14692 and manually enter any of those which significantly differ from those of BS-7159 (which is what UKOOA references).
6. After analyzing your model, compare your Sustained stresses to 100% of the allowable, your Operating stresses to 124% of the allowable, and your Occasional stresses against 133% of allowable.
7. Where joint strengths may govern, you will need to check them manually against the forces from the CAESAR II local force report.

**p.s. From my experience, in step 6, I'll construct 3 types of Failure envelops, based on the size of 124% for operating and 133% for occasional stresses for easy comparison.

There are one more doubt for using ISO14692, is the "pressure stress multiplier, m" for the tee & elbow. The related explanation in ISO14692-3, Annex D.2.2.4 for elbow and D2.3.4 for tee. Both paragraph saying that if the fittings have been qualified according to precedure given in ISO14692-2, the pressure stress multiplier value may set as 1.

Else, there are some default value for bend, and formula to get the mutiplier value.