ANALISIS KONDISI PIPA PRIMARY SUPERHEATER BOILER MENGGUNAKAN ULTRASONIC THICKNESS

Abstract

The integrity of superheater tubes is critical to the reliability and operational safety of steam boilers in thermal power plants. This study assesses the condition of the Primary Superheater Flue Gas Outlet of Boiler Unit #51 at PT Amman Mineral Nusa Tenggara using Ultrasonic Thickness Measurement (UTM) data from September 2024 and April 2026. A total of 32 tubes were evaluated using descriptive statistics, paired t-test, Pearson correlation, and Measurement System Analysis (MSA). The results showed that the average tube thickness increased from 6.332 to 6.449 mm, with a statistically significant difference between the two inspection periods (p < 0.001). However, the low Pearson correlation coefficient (r = 0.1633) indicated weak correspondence between measurements. The MSA yielded a Mean Error of 0.1166 mm, RMSE of 0.1368 mm, and Coefficient of Variation values of 0.97% and 0.78% for 2024 and 2026, respectively. These results indicate good measurement precision but reveal a systematic positive bias that should be considered when interpreting thickness changes. No significant wall thinning or localized degradation was identified. Therefore, the Primary Superheater Flue Gas Outlet remains in a serviceable condition. Integrating statistical analysis with MSA provides a more reliable basis for interpreting UTM results and supporting condition-based maintenance decisions.