Thermowells

Thermowells

Thermowells are the process-wetted mechanical components that protect the temperature sensor insert from harsh operating conditions. They provide a pressure boundary interface that isolates the sensing element from high pressure, high-velocity flow, corrosive media, and mechanical impact while still allowing accurate thermal coupling. A key functional advantage is enabling replacement of the measuring insert without interrupting the process, supporting maintainability where shutdowns are costly or infeasible.

Thermowell selection is a mechanical-engineering exercise as much as a measurement decision. The thermowell must withstand process loads (pressure, velocity-induced vibration, thermal stress) while preserving adequate response time and installation practicality. Industry standards and certification requirements influence design choice, material selection, and documentation, making thermowells a frequent focus in project specifications and critical-service reviews.

The Endress+Hauser portfolio description highlights multiple construction approaches - welded/fabricated, barstock, and forged designs - paired with an extensive set of industrial and hygienic process connections such as threaded, flanged, weld-in, socket weld, compression fitting, and clamp variants. Material options range from stainless steels to high-alloy materials and ceramics, and designs may include extension necks where thermal decoupling or accessibility is required. Referenced design frameworks include DIN 43772, ASME B40.9, and NAMUR NE 170.

Manufacturing method aligns with service demands: fabricated thermowells are positioned as cost-effective with high design flexibility, while barstock designs (machined from a single piece) are widely applicable depending on geometry and material. Specialized geometries - such as helical designs for high-velocity applications - and hygienic elbow thermowells designed without welds or dead legs illustrate how thermowells adapt to both mechanical load cases and cleanability constraints.

Typical applications include high-pressure or high-velocity piping (steam, hydrocarbons), corrosive chemical services, abrasive slurries, and hygienic process lines requiring sanitary connections and cleanable geometry. Best practice selection aligns process conditions, required standards, connection type, and a validated strength/vibration sizing approach to ensure structural integrity and acceptable measurement dynamics over the intended lifecycle.

Forberg Smith, an exclusive authorized representative of sales and service for Endress+Hauser.