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Description / Abstract:
This Standard applies to thermowells machined from bar stock and
includes those welded to or threaded into a flange as well as those
welded into a process vessel or pipe with or without a weld
adaptor.
Thermowells manufactured from pipe are outside the scope of this
Standard. Thermowells with specially designed surface structures
(e.g., a knurled surface or a surface with spiral ridges) are
beyond the scope of this Standard, due to the difficulty of
providing design rules with broad applicability for these types of
thermowells.
Thermowell attachment methods, standard dimensions, parasitic
vibration of a sensor mounted inside the thermowell, and thermal
equilibrium of the sensor relative to the process stream are beyond
the scope of this Standard. In addition, thermowells fabricated by
welding, including flame spray or weld overlays, at any place along
the length of the shank or at the tip are outside the scope of this
Standard.
The application of the overlay to a bar-stock thermowell may
affect any number of critical attributes such as natural frequency,
damping, material properties, or surface finish. These changes are
difficult to account for in the calculations, therefore, there is
risk that an inappropriately designed thermowell could be
installed.