Surface Thermometers

Surface Thermometers

Surface thermometers are non‑invasive devices that infer medium temperature by contacting only the outer surface of a pipe, reactor, or vessel. Instead of penetrating the pressure boundary, the sensor is mechanically coupled to the equipment skin, enabling temperature measurement without process intrusion. This approach is applicable across industries and is highlighted as especially suitable for heavy‑duty processes with demanding conditions.

Non‑invasive measurement is particularly useful for retrofits and temporary campaigns. Because the sensor can be positioned flexibly at different points on a pipe - or moved between pipes - surface thermometers are well suited to adding measurements for energy monitoring, safety monitoring, or diagnostics without the construction scope associated with new thermowells and nozzle work.

The category also includes specialized “skin point” assemblies for high‑temperature equipment such as furnaces, fired heaters, and heat exchangers. By measuring pipe skin temperature, these assemblies can be used to check for build‑up on the inner wall, a condition that changes heat transfer and can elevate metal temperatures. They are engineered to specification to maintain thermal continuity under severe conditions including vibration, corrosion, and relative movement from differential thermal expansion.

Benefits typically include reduced installation risk, minimal process disruption, and faster deployment compared with invasive measurement points. When paired with a well-designed mounting approach and appropriate compensation/validation practices, surface measurement can deliver actionable temperature trending for utilities, energy optimization, and equipment protection programs—especially where the objective is comparative monitoring rather than custody-grade precision.

Typical applications include retrofit temperature points on steam and thermal oil lines, monitoring on large-diameter or hard-to-access piping, temporary measurements during troubleshooting, and permanent skin-temperature monitoring on fired heaters and exchanger piping where metal temperature is a critical integrity indicator.

Field Instruments & Controls, Inc. an exclusive authorized representative of sales and service for Endress+Hauser.