For Permanent Linear Change Test specimens, how should length change be calculated?

For Permanent Linear Change Test specimens, the correct way to calculate length change involves measuring the length at each corner of the specimen and reporting the change as a percentage. This method provides a comprehensive assessment of how the entire length of the specimen has altered due to temperature exposure or other factors, ensuring that any potential discrepancies or anomalies at specific points are accounted for. By focusing on all four corners, this approach captures the overall dimensional stability of the material, which is crucial in evaluating its performance under typical operating conditions.

Using a percentage to report the change helps standardize the results, making them easier to compare with other materials or tests. This methodology aligns with industry practices aimed at obtaining precise and reliable data, which is vital for quality assurance and material qualification processes in refractory applications.