Thermowell Type Bimetallic Thermometer For Petrochemical Industry

Thermowell-type bimetallic thermometer is a medium and low-temperature measuring instrument with an independent protective thermowell. It is specially designed for harsh working conditions such as high temperature, high pressure and corrosiveness.

A complete thermowell bimetallic thermometer consists of three parts:

1. Thermowell:
   • Material: Selected based on the characteristics of the medium, such as 304/316 stainless steel, Hastelloy, Monel, etc.
   • Connection method: Threaded connection (such as NPT, G, M), flange connection, welded connection, etc.
   • Structure form: Straight, conical, stepped, etc., to adapt to different flow rates and pressures.
2. Bimetallic thermometer head:

   It is the pointer-type or digital display head we introduced earlier.

3. Connection head/installation accessories:

   Used to firmly install the thermometer head on the thermowell, usually with an adjustable angle device to facilitate adjusting the dial to the best viewing direction. Common interface threads include M27*2, G1/2, etc.

   Assembly method: Insert and fix the sensing tube (probe) of the bimetallic thermometer into the thermowell already installed on the equipment, ensuring good contact between the end of the sensing tube and the bottom of the thermowell to ensure the best thermal conductivity and response speed.

• Extremely high safety and reliability: It provides solid physical and chemical protection for the thermometer, making it suitable for harsh working conditions.
• Easy online maintenance: The thermometer can be removed at any time for calibration, replacement or repair without affecting production or discharging the medium, significantly reducing maintenance costs and risks.
• Extended instrument lifespan: It effectively prevents direct corrosion, erosion and wear by the medium, allowing the core thermometer to operate stably for a long time.
• Strong versatility: Different types of thermometers (such as bimetallic, thermocouple, and thermal resistance) can be inserted into the same thermal sleeve, providing flexibility.

1. Measuring range: Conventional -50℃ to 500℃, high-temperature type (with high-temperature alloy sleeve) up to -80℃ to 800℃, low-temperature type from -100℃ to 100℃.
2. Accuracy grade: Industrial grade 1.0 (commonly used), precision grade 0.5, repeatability better than ±0.2%.
3. Pressure resistance: Conventional ≤ 40MPa, high-pressure custom type up to 63MPa, depending on the material and wall thickness (3 to 10mm) of the heat sleeve.
4. Thermal response time: τ0.9 ≤ 30s (thin-walled sleeve) to 60s (thick-walled high-pressure sleeve), slightly longer than ordinary bimetallic thermometers (due to heat conduction delay of the sleeve).
5. Installation specifications:

   Insertion length of heat sleeve: 50 to 1500mm (customizable), insertion depth should be ≥ 10 times the diameter of the sleeve and exceed the centerline of the pipe.

   Environmental adaptability: Operating environment temperature -20℃ to 60℃, relative humidity ≤ 90%, vibration resistance level ≤ 2.5g.

• Petrochemical industry: Temperature monitoring of high-pressure crude oil pipelines, hydrogenation reactors, and catalytic cracking units, with resistance to high pressure and corrosive media such as hydrogen sulfide and acid-base solutions.
• Energy and power: Temperature measurement of high-pressure steam drums in boilers, high-pressure oil pipes in steam turbines, and auxiliary systems in nuclear power plants, with explosion-proof models suitable for flammable and explosive environments.
• Fine chemicals: Temperature monitoring of high-pressure polymerization reactors and storage tanks for corrosive solvents, with detachable heat sleeves for online maintenance without interrupting production.
• Oil and gas extraction: Temperature measurement of high-pressure oil and gas pipelines at wellheads and shallow downhole temperature measurement (short insertion length sleeves), with resistance to high pressure and wear from oil-gas mixtures.
• Pharmaceutical and food: Temperature display for high-pressure sterilizers and high-pressure autoclaves in food processing, with 316L stainless steel sleeves meeting hygiene standards.

The heat sleeve type bimetallic thermometer is the "heavily armored force" in industrial temperature measurement. By sacrificing a bit of response speed, it gains unparalleled safety, maintainability and environmental adaptability. In those critical measurement points where medium leakage is not allowed, frequent calibration of the instrument is required or the working conditions are extremely harsh, using a heat sleeve is not an option but a safety regulation and best practice that must be followed. It represents the ultimate pursuit of safety and reliability in industrial measurement.