The movable threaded mounting junction box type thermocouple consists of three parts: an independently removable metal protective tube, a rotating threaded interface with sealing function, and a closed junction box. The thermoelements are insulated from the protective tube by insulating material, and the signal is led out through the junction box terminals, achieving both mechanical and electrical separation. The so-called "screw-type thermocouple" is not an independent type in the industrial context, but rather a common name for the movable threaded thermocouple. The two are structurally identical – both use an external threaded protective tube screwed into the equipment's threaded hole, are equipped with an independent junction box, and possess the core features of being removable, rotatable, and having a replaceable probe. The term "screw-type" is merely a colloquial expression for the "threaded mounting" action, not a new category in terms of structure or function.
The movable threaded type (i.e., screw type) supports "install first, then adjust" – after screwing into the equipment's threaded hole, the probe can still be freely rotated 360℃ to accurately align with the temperature measurement surface, adapting to curved pipe walls, spatial interference, or installation deviations, relying on torque control to ensure sealing; this installation method requires no welding or clamping, achieving reliable fixation only through standard thread engagement. The operation is standardized, repeatable, and verifiable, conforming to industrial installation standards.
During maintenance, the movable threaded type (i.e., screw type) only requires unscrewing the protective tube and the temperature sensing probe. The junction box, cable, and seals can be reused for a long time. A single replacement takes 5-10 minutes, supporting periodic calibration and fault isolation; its "replaceable sheath" design is part of the standard industrial maintenance process, and there is no "single-use" or "irreparable" problem, which is fundamentally different from consumable designs such as snap-ring or
gasket types.
Featuring a metal protective tube and an IP65 or higher sealed junction box, this structure can withstand high temperatures (up to 1200℃), high pressure, strong vibrations, condensation, and harsh cleaning environments, making it suitable for continuously operating industrial systems. Its threaded interface is designed to industry standards (e.g., M33×2, 1″NPT), offering excellent fatigue and corrosion resistance, ensuring no loosening or leakage risks during long-term use.
Widely used in demanding environments requiring long-term stability, maintainability, and industrial compliance, such as pharmaceutical GMP reactors, food CIP cleaning lines, nuclear power auxiliary pipelines, and chemical high-pressure reactors. In these scenarios, "screw-type," as an alternative name for "movable threaded type," is the only standard-approved detachable installation solution.
This structure strictly adheres to GB/T 30429-2013 "Replaceable Sheath" and IEC 60584-3 "Detachable Installation" standards, featuring standardized interfaces and traceability. The term "screw-type" has no independent definition in national standards; it is merely an informal term used in engineering practice for "threaded installation type thermocouples," and its technical essence is entirely encompassed by "movable threaded installation junction box type."
If long-term operation, repeatable maintenance, vibration resistance, and industrial compliance are required, the movable threaded installation junction box type must be selected-and "screw-type" is simply a synonym; they are the same product, with no difference in selection.
Welding or forcibly fixing the junction box of the movable threaded type (i.e., screw-type) is strictly prohibited, as this completely negates its core advantages. During installation, a torque wrench should be used to control the tightening torque to prevent thread stripping or seal failure. Using power tools for forceful tightening is prohibited to avoid damaging the threads or internal insulation structure.
