Nowadays, for corrosion in the saddle bolts be considered, you have to mark "corroded weight" (see https://communities.bentley.com/products/pipe_stress_analysis/w/pipe_stress_analysis__wiki/69792/26-why-corrosion-allowance-is-not-taking-in-consideration-for-anchor-bolts ). However it would be desirable to check the saddle bolts in the corroded condition when the internal corrosion of the equipment is still null (full weight).