TF Series
Industrial Thermowells for Temperature Sensors
TF series thermowells (protection tubes) are critical accessories for all temperature measurement applications. They isolate the sensing element from corrosive, high-temperature, high-pressure, and high-velocity process media — protecting both the sensor and personnel while enabling sensor replacement without process shutdown.
Overview
Thermowells are closed-end tubular fittings that protect temperature sensors — thermocouples, RTDs, and bimetallic thermometers — from direct contact with the process medium. In industrial environments where temperatures, pressures, flow velocities, and chemical exposure can damage or destroy sensing elements, a properly selected thermowell ensures reliable, long-term measurement while allowing sensor removal and replacement without draining or depressurizing the system.
The HMK TF series thermowells are manufactured in compliance with IEC international standards using blind-hole drilling technology for superior structural integrity. Available in three connection types — flanged (TF-10), threaded (TF-15), and welded (TF-20) — with multiple material options from standard 304 stainless steel for general service up to GH3039 nickel alloy for extreme high-temperature applications reaching 1300°C.
Each thermowell is pressure-tested at 15× its rated working pressure to ensure safe containment. X-ray inspection is available for critical applications requiring wall thickness and eccentricity verification. Custom dimensions, materials, and process connections can be manufactured to customer drawings with 2–3 week lead times.
Choosing a thermowell? The thermowell is Stage 2. See our complete sensor selection guide to first nail down the right thermocouple or RTD before specifying flange or thread type.
Technical Specifications
| Parameter | Specification |
|---|---|
| Product Series | TF-10 (Flanged), TF-15 (Threaded), TF-20 (Welded) |
| Compatible Sensors | Thermocouples, RTDs (Pt100), Bimetallic Thermometers |
| Connection Types | Flanged, Threaded (NPT/Metric), Welded |
| Nominal Pressure | Up to 38 MPa (varies by model) |
| Medium Flow Velocity | 5 – 100 m/s (varies by model) |
| Sensor Connection Thread | M20×1.5, 1/2″ NPT (customizable) |
| Insertion Lengths (U) | 50 mm – 1130 mm (model dependent) |
| Bore Diameter (d0) | Φ7 mm / Φ9 mm |
| Manufacturing Standard | IEC International Standard, blind-hole drilling |
| Pressure Test | 15× rated pressure (hydrostatic) |
| Inspection | X-ray inspection available for wall thickness and eccentricity |
| Custom Manufacturing | Available per customer drawings |
Material Selection Guide
| Material | Temperature Range | Characteristics & Typical Use |
|---|---|---|
| 304 SS | -200°C to +800°C | High temperature and corrosion resistance. General-purpose heat-resistant steel. |
| 316L SS | -200°C to +750°C | Ultra-low carbon, excellent corrosion resistance. Ideal for corrosion-resistant applications. |
| 2520 (310S) | -200°C to +950°C | High nickel-chromium content. Oxidation, corrosion, acid/alkali, and high-temperature resistant. |
| GH3030 | 0°C to +1100°C | Nickel-based superalloy with excellent oxidation and wear resistance. Heat-resistant steel. |
| GH3039 | 0°C to +1300°C | Nickel-based superalloy with superior oxidation and wear resistance at extreme temperatures. |
| PTFE | -150°C to +300°C | Resistant to virtually all organic solvents. Used for corrosion-resistant piping. Flange connection only. |
Key Features
IEC Standard Design
All thermowells are designed and manufactured according to IEC international standards with blind-hole drilling technology, ensuring consistent wall thickness, concentricity, and structural integrity across every unit.
High Pressure Resistance
Rated up to 38 MPa nominal pressure with hydrostatic proof testing at 15× the rated value. Suitable for high-pressure pipelines, reactors, and vessels in petrochemical and power generation applications.
Wide Material Selection
Six standard material options from 304 SS for general service to GH3039 nickel superalloy for extreme temperatures up to 1300°C. PTFE lining available for aggressive chemical environments.
Three Connection Types
Flanged (TF-10), threaded (TF-15), and welded (TF-20) process connections cover every installation scenario. Thread and flange sizes customizable to match existing process fittings.
Easy Sensor Replacement
Thermowells allow temperature sensors to be removed, inspected, and replaced without shutting down the process or breaking the pressure boundary — reducing maintenance downtime and costs.
Custom Manufacturing
Non-standard insertion lengths, bore sizes, materials, and process connections available per customer drawings. PTFE-lined and wear-resistant coated variants for special applications.
TF Series Models
TF-10: Flanged Thermowells
Flange-mounted thermowells for heavy-duty applications. Available in 8 structural variants (A through H). Nominal pressure up to 38 MPa with medium flow velocity up to 80 m/s. Ideal for reactors, pressure vessels, and large pipelines.
TF-15: Threaded Thermowells
Compact threaded thermowells with NPT or metric thread connections. 14 structural variants (A through N) covering the widest range of configurations. Nominal pressure up to 30 MPa. Perfect for pipe taps and smaller process connections.
TF-20: Welded Thermowells
Direct weld-in thermowells for permanent, leak-proof installations. 11 variants (A through K). Nominal pressure up to 38 MPa with flow velocity up to 100 m/s. Best for high-pressure and high-vibration environments.
All TF series models feature M20×1.5 or 1/2″ NPT sensor connection threads (customizable). Insertion lengths range from 50 mm to 1130 mm depending on the model. Detailed dimensional drawings and specifications for each variant are available upon request — contact our engineering team for selection assistance.
Applications
Oil & Gas Processing
Protecting thermocouples and RTDs in refinery distillation columns, heat exchangers, and pipeline monitoring. High-pressure flanged models (TF-10) withstand demanding petrochemical process conditions.
Power Generation
Boiler flue gas, steam turbine, and condenser temperature measurement in coal-fired, gas, and nuclear power plants. GH3030/GH3039 materials for high-temperature zones above 1000°C.
Chemical & Pharmaceutical
PTFE-lined thermowells for corrosive acid, alkali, and organic solvent environments. 316L models for sanitary pharmaceutical processes requiring clean, corrosion-resistant measurement points.
Steel & Metallurgy
Extreme-temperature thermowell installations in blast furnaces, coke ovens, and continuous casting lines. Nickel superalloy materials for prolonged exposure above 1000°C with wear-resistant coatings.
HVAC & Water Treatment
Threaded thermowells (TF-15) for chiller loops, cooling towers, and water treatment facilities. 304 SS models provide reliable, cost-effective protection in moderate-temperature applications.
Food & Beverage
Sanitary thermowell installations for pasteurization, fermentation, and CIP cleaning processes. 316L stainless steel with smooth surface finish ensures hygienic measurement in food-grade environments.
Ordering Guide
| Code | Description | Options |
|---|---|---|
| TF | Product Series | Thermocouple / RTD / Bimetallic thermometer installation sleeve |
| 10 / 15 / 20 | Connection Method | 10 = Flange, 15 = Threaded, 20 = Welded |
| — (A–K) | Structural Style | See external dimension drawings for each variant |
| S / L / S25 / GH30 / GH39 / F / FJ / PM / NM / T | Sleeve Material | S=304, L=316L, S25=2520, GH30=GH3030, GH39=GH3039, F=PTFE Lined, FJ=Sintered PTFE, PM=Spray Wear-Resistant, NM=Welding Wear-Resistant, T=Custom |
Example: TF10-A-S = Flanged thermowell, Type A structure, 304 SS material
Note: PTFE lining (F) or sintered PTFE (FJ) connection method can only be flange type.
Frequently Asked Questions
Need Help Selecting the Right Thermowell?
Our application engineers can recommend the optimal thermowell type, material, insertion length, and process connection for your specific process conditions. Whether you need a standard catalog thermowell or a fully custom design manufactured to your drawings, we provide competitive factory-direct pricing with 2–3 week delivery.
Our engineers typically respond within 12 business hours with a detailed technical proposal and quotation.