Please note that keeping the thermocouple sheath in contact with the tube occasionally requires drilling through the tube support structure. Such movement will destroy the thermocouple if no compensation is provided. Tube growth compensation can be achieved with expansion coils or on the outside of the furnace fire box. However, compensation outside the furnace is, in many cases, the best approach. The optimum location for the expansion loops is just before the furnace firebox exit.
Theses are only guidelines.
Due to limitations of time, material and labor, compromises are often necessary. Such compromises however, may shorten the life of the Refracto-Pad thermocouple assembly. Nonetheless, the Refracto-Pad is relatively inexpensive in material and installation costs. This is especially true when comparing it to other tube skin designs.