Many well-known catalogues (Omega, Cole-Parmer, etc.) have t/c's with welding pads. Type "K" (up to about 2200F) ought to be well suited for the temperature range. I don't know the details of the provisions one must make for cooling the t/c during installation. Also consider galvanic reactions with (weld pad metal) - (tank metal).
i use type K thermocoupels thy may be used til a temprature from 1200 celcius
wen you mesure in a tank you must put a pipe into the top of the tank and put the thermo couple in the pipe dont forget to use compensation kabel and connect it richt or you wil have a temprature difrens from about 30 celcius
