PIPESTRESS - Class 1 piping analysis ( fatigue )


Class 1 piping

Connected directly to the nuclear reactor (= primary loop)
Critical safety-related component
High material, fabrication, inspection and design requirements


Design transients for Class 1 pipinng


Detailed stress analysis

According to ASME III NB-3600, RCC-M and KTA codes
Precise stress evaluation at fittings and near geometry or material discontinuities
Evaluation of thermal stresses due to fluid transients
Fatigue usage factor calculation
Elastic shakedown criteria
Simplified elastic-plastic analysis
Thermal ratchet criteria



Radial temperature gradient  ΔT1 and ΔT2

Axial temperature gradient Ta-Tb




Environmental effects Reg. Guide 1.207

This feature was implemented in the version 3.6.2 of PIPESTRESS

Since this is a new Reg. Guide and the calculations will be necessary for licensing, continued development of rules for environmental fatigue such as a detailed calculation of strain rate is in progress in cooperation with regulatory organizations and several Licensees.

 Examples of fatigue analysis reports which include the environmental factors are shown below.


Cumulative usage factor report


Fatigue analysis legend report


Fatigue analysis summary report


Stress range check report