WIKA TW10-S Mode D'emploi page 8

6. Commissioning, operation
Due to the high thermal, chemical, and mechanical stresses to which ceramic and sapphire
thermowells are subjected during operation, a general indication regarding the service life can
only be given to a limited extent. This is particularly valid for applications in high-load processes,
such as gasification reactors. According to this, the process-related parts of the thermocouples
EN
are wear parts which are not covered by the warranty.
It is recommended to mount the temperature measuring instrument into the thermowell or
protection tube using a suitable sealing material to avoid, for example, humidity ingress.
In general, the tip of the thermowell should be placed in the middle third of the pipe, though
the position may differ in special cases. It must be ensured that the measuring element (Pt100,
thermocouple, bimetal, etc.) is completely exposed to the medium and is not shielded by the
flange stubs. If, as a result of a small pipe diameter, this cannot be ensured, a pipe expansion can
be inserted around the measuring point.
Expansion of the pipe diameter from DN 40 to DN 80
Screw-fitting thermowells
When using parallel threads, a suitable seal should be used when mounting. Tapered threads
can be sealed by suitable seals or an additional welded seam. The correct tightening torques and
suitable tools (e.g. spanner) should be used.
Weld-fitting thermowells
Weld-in thermowells can be welded directly into the process (pipe or vessel wall) or by using a
welding socket. During weld-in operation, the requirements of the relevant material data sheets
and the applicable directives and standards must be considered regarding the heat treatment,
filler rods or welding procedures.
8
WIKA operating instructions thermowells