High-accuracy temperature-measurement in creep testing of steels

Abstract

Thermocouples used for measuring temperature in a creep testing facility demands an accuracy of ± 0.5°C for a period extending from 10,000 hours to 100,000 hours and up to 250,000 hours in special cases. Accuracy of such an order may easily be obtainable by giving due care to vari-ous factors like good speed of response, minimisation of conduction and radiation errors, precision of thermo-junction location, thermojunction of minimum size, iden-tical thermal properties of both the thermocouples and measuring surfaces apart from maintaining accuracy in the cold junction compensation and linearisation. This paper aims at analysing the various factors contributing to inaccuracy in such measurements and suggests some remedial measures for further improvement in the thermocouple-based instrumentation system.