A sensor assembly for accurately measuring the temperature of a process fluid flowing within process tubing is disclosed. A thermocouple sensor can be configured within a protective sheath with leads protruding from the sheath. A gland-like structure can be coupled to the sheath or machined integral to the sheath. The sensor assembly can be coupled to a closed loop. The sensor can be positioned within or in close proximity to the fluid flowing in the closed loop, and the sensor accurately measures the temperature of the process fluid flowing in the closed loop. The sensor assembly is easily assembled and/or disassembled allowing the sensor to be maintained.