Pipe X temperature is equal to or greater/less than the maximum/minimum temperature limit of...

There are two variations of this Warning that are similar:

The following pipes had temperature equal to or less than the minimum temperature limit of X set in the Temperature Solver Limits panel under Steady Solution Control in the Analysis Setup window. Results are not reliable.
The following pipes had temperature equal to or greater than the maximum temperature limit of X set in the Temperature Solver Limits panel under Steady Solution Control in the Analysis Setup window. Results are not reliable.

The user has specified limits in the Temperature Solver Limits panel of the Steady Solution Control in Analysis Setup (only available when Heat Transfer With Energy Balance is enabled in Fluid Properties). These limits are intended to aid in convergence by restricting the search space while solving, and should generally be left as the AFT default values. This warning indicates that the final solution had one or more pipes outside the limit range, and the temperature results have been artificially limited by the Solver. The results are therefore not valid. To resolve this either remove or change the temperature limit.

Note: These limits should not be used as Design Alerts, or to approximate some physical phenomenon.