Richard,
In the seismic case 6 above, the thermal expansion T is not included, yet the most likely seismic event is during operation at T. Is the premis that the pipe has already expanded and T stress has dissapated or balanced and does not endanger the pipe once the pipe is stable, so only the added seismic OCC is stressing the pipe? (That implies cycling of the pipe T is worse than operating at the elevated temp.In an operating steam system that cycles only once a year, it implies T doesn't matter if it is within the material's T allowables.) Or is the T considered in the seismic case as if the seismic is applied to an already stressed pipe. Logically The T and seismic occur simultaneously. How Is Caesar or the code handling it?