Thermowells

Thermowells

Thermowells are the process-wetted protective components of a temperature assembly, shielding the sensor insert from harsh conditions such as high pressure, high flow velocity, and corrosive media while enabling insert replacement without interrupting the process. Selection is influenced by design and manufacturing approach (e.g., welded, barstock, forged), the required process connection style (threaded, flanged, weld-in, compression, clamp, and others), material choice (stainless steels through high alloys and ceramics), and applicable standards such as DIN 43772, ASME B40.9, or NAMUR NE 170.

A thermowell turns temperature measurement into a mechanical engineering problem as much as a metrology problem. The well must survive pressure loads, vibration, and vortex shedding while maintaining adequate heat transfer to the sensor. Geometry (stem length, tip shape, bore size) and installation (insertion depth, orientation, support) drive both durability and response time.

Benefits include maintainability and risk reduction. Removing or calibrating an insert without depressurizing the line or opening a vessel minimizes downtime, reduces exposure, and supports safer maintenance planning. Proper thermowell selection also protects the more sensitive sensing element from erosion and chemical attack, extending overall assembly life.

Applications include high-pressure hydrocarbon service, steam and hot oil distribution, high-velocity utilities, corrosive chemical processes, and any point where process integrity must be preserved during maintenance. Hygienic thermowells extend these advantages into sanitary environments where crevice-free design and cleanability are essential.

Selection typically begins with process data (pressure, temperature, flow velocity, density/viscosity, corrosion allowance) and required standards/compliance, then evaluates mechanical calculations, material compatibility, and installation constraints. Lifecycle considerations - inspection strategy, replacement intervals, and spares - often determine whether a more robust design is justified for critical points.

Instrumentation and Controls., an exclusive authorized representative of sales and service for Endress+Hauser.