CAESAR II Stress Analysis Input Checklist & Boundary Condition Guide

Prior to opening CAESAR II, the stress analyst must assemble certified engineering inputs: 1. **Latest Piping Isometrics / 3D Model:** Verifying accurate 3D coordinates, elevations, and line orientation. 2. **Process Line List:** Extracting design pressure, design temperature, operating temperature, fluid specific gravity, and test media density. 3. **Piping Material Specification (PMS):** Material grade (e.g., ASTM A106 Gr. B, A312 TP304L), pipe schedule, corrosion allowance, and mill tolerance. 4. **Valve & In-line Instrument Cut Sheets:** Vendor-certified valve weights, actuator heights, and center-of-gravity offsets. 5. **Equipment Nozzle Load Data Sheets:** Allowable nozzle forces and moments from rotating equipment vendors (API 610, API 617, NEMA SM 23) or pressure vessel fabricators.

Treating an equipment nozzle connection as a 100% rigid zero-movement anchor ($DX=0, DY=0, DZ=0$) is a major engineering flaw when the connected vessel operates at high temperatures. Thermal vertical growth ($Delta Y$) of a top vessel nozzle is determined by: $$Delta Y = alpha imes L imes (T_{operating} - T_{ambient})$$ Where: - $alpha$ = Mean coefficient of thermal expansion for the vessel shell material. - $L$ = Distance from the vessel support base (skirt or lug) to the nozzle centerline. - $T_{operating} - T_{ambient}$ = Temperature differential. This calculated displacement must be entered into CAESAR II as an imposed anchor displacement ($DX, DY, DZ$) for each operating temperature case, accurately capturing nozzle uplift on connected piping.

Real-world pipe supports do not exhibit infinite stiffness or frictionless sliding. Stress engineers must configure: - **Restraint Gaps:** Specifying actual guide clearances (e.g., $1.5$ mm gap on lateral guides). - **Friction Coefficients ($mu$):** * Steel-on-Steel support sliding: $mu = 0.30$ * Steel-on-Concrete: $mu = 0.40$ * PTFE / Teflon slide plates: $mu = 0.10$ * Polished Stainless on Bronze: $mu = 0.15$ - **Rotational Stiffness:** Specifying rotational restraints ($RX, RY, RZ$) only when the physical structure possesses sufficient rigidity to prevent rotation under maximum pipe bending moments.