UNDERSTANDING HARD TO INTERPRET FIELD HARDNESS VALUES FOR COMMON PRESSURE VESSEL AND PIPING STEELS

摘要

Often when reviewing field hardness values, if the results are not consistent with expectations, the values measured are dismissed. However, field hardness tests can provide extremely valuable information when evaluating piping and pressure vessel anomalies. In the specific failures and equipment examinations discussed in this article, field hardness tests gave the most insightful information for assessing challenging material anomalies compared to other laboratory and field tests. This article summarizes laboratory examinations designed to gain a better understanding of Ultrasonic Contact Impedance (UCI) hardness test results taken in the field. Moreover, examples of cases where anomalous hardness values of new steel parts were associated with metallurgical and physical irregularities are shown. In all the cases, the UCI values measured were relevant and accurate.