Thermocouple Sheath Oxidation Protection Coating — Incure Epo-Weld™ HTSG-791
A temperature reading is only as reliable as the probe taking it. When a thermocouple sheath or sensor housing oxidizes and corrodes in a hot process, it wears thin and the probe has to be replaced, often in the middle of a production run. A thermocouple sheath oxidation protection coating extends the probe's life. Q: How Does a Coating Protect a Thermocouple Sheath? A: It Adds a Sealed, Heat-Stable Barrier Between the Sheath Metal and the Process Sheathed thermocouples and sensor housings are usually made from heat-resistant alloys. Even those alloys oxidize over time in hot, oxidizing atmospheres. Corrosive gases, salts and process splash speed the damage. A protective coating puts an inert layer between the sheath and that environment, so the metal underneath degrades more slowly. Incure's Epo-Weld™ HTSG-791 is a single-part silicone-glass coating suited to this job. Its silicone binder is filled with glass frit that fuses during a heat cure into a continuous inorganic glass film. Incure rates it for continuous service up to 1,400°F. The catalog specifically lists thermocouple sheaths, sensor housings and probe bodies among its applications, to guard against oxidation and chemical contamination in extreme-temperature measurement. Why a Glass-Based Barrier Suits Sensors Chemically inert after cure. Incure describes the fused glass matrix as chemically inert and non-absorbent to moisture, with resistance to humidity, acids, alkalis and salt spray. That combination matters for probes in flue gas, chemical process lines and outdoor equipment. No carbonizing or outgassing. Organic paints and polymer coatings carbonize when heated beyond their limits. Incure states HTSG-791 provides stable oxidation protection across its rated range without degradation, outgassing or delamination. Outgassing near a sensor is unwelcome, because it can deposit residue on nearby surfaces or windows. Thin and conformable. At 400–800 cps, HTSG-791 brushes onto small diameters, bends and fittings. That makes it practical on probe bodies and compact housings, not only flat panels. Email Us with your sheath alloy, probe dimensions, process temperature and atmosphere to confirm whether HTSG-791 suits your sensors. Coating Without Disturbing the Measurement A sensor coating has to protect the probe without changing what it measures. A few practical points help. Keep the film thin where response time matters. Any added layer on the sensing tip adds a little thermal mass. Coat the sheath length exposed to attack, and judge whether the very tip needs the same build as the body. Do not coat electrical connections or seals. Mask terminal heads, connector threads and any surface that must stay conductive or mate with a fitting. Coat before installation where possible. HTSG-791 needs a 1-hour cure at 400°F to fuse the glass. That is easiest on the bench in an oven before the probe goes into service. Verify after coating. Check a coated probe against a reference reading before relying on it in a controlled process. Applying HTSG-791 to Probes and Housings Clean and dry. Remove oils, handling residue and loose oxide. Incure specifies application to a clean, dry substrate. Brush or spray an even coat over…