calculation of sustained sag value and its relation to corro

We have 12" line of storm water , 10 mm thick , 6 mm corrosion allowance ( dictated by Gost code/client)
If we calculate sustain sag for above line for say 6 mtr span on rack at mid node , the sag remain same if I change corrosion allowance from 6 to 0.
This implies that Caesar do not consider corrosion allowance at the time of sag calculation..
- Flagging all case corroded to ,'True ' do not change sag value obtained in 'False'
- Is there any other corrective setting in Caesar config ?
-Is it like that Caesar calculates Restrained loads in uncorroded thickness hence displacement like sag is calculated without CA
- Or is there any specific Codal reason for not considering CA in sag calculation

Please reply.

Corrosion is a random pitting of the pipe wall, not a uniform boring of the inner diameter. As such, corrosion is a random event. Historically the piping codes have ignored the weight loss due to corrosion, in recognition of the previous statements. Instead, the piping codes only consider corrosion in the final stress calculation.

A model will produce the same results for displacements, reactions, and element forces with or without corrosion specified. The difference between the two (corrosion) situations will be in the stress results.