dear guys,

anybody has experience with heat exchanger tube temperature measurement?
we're already install weld pad type, but the measurement result was not accurate, due to the environment temperature was higher than tube it self. inside the tube is a high pressure saturated steam, outside of tube is a flue gas with temperature up to 1100 deg.C.
1. if you're all has the experience for this measurement, would you share to me?
2. anybody know at what temperature maximum allowable for MgO (magnesium oxide) insulation for thermocouple still worked properly? the application was direct measure without thermowell.

thks b4
BY