TWF11, TWF16

Summary

Product identification

TWF11 and TWF16 are metal or ceramic thermowells designed as accessories for high-temperature assemblies TAF11 and TAF16, respectively.

TWF11 applications:

• Steel treatment (annealing)
• Concrete furnaces
• Primaries

TWF16 applications:

• Cement production
• Steel treatment
• Incinerators
• Fluidized bed furnaces

Operating limits

Process temperature:

• TWF11: up to +1600 °C (+2912 °F)
• TWF16: up to +1700 °C (+3092 °F)

Process pressure:

Thermowells in high-temperature applications are generally designed for use in pressureless processes. Available process connections can be gastight up to 1 bar.

Material

Various materials are available for the thermowell construction, each with specific temperature limits and properties:

• Stainless Steels:

  • AISI 316L / 1.4404 / 1.4435: Max. 650 °C (1200 °F) for continuous use in air. Offers high corrosion resistance, particularly in chlorine-based and acidic, non-oxidizing atmospheres.
  • AISI 310 / 1.4841: Max. 1100 °C (2012 °F). Good resistance to oxidizing and reducing atmospheres.
  • AISI 304 / 1.4301: Max. 850 °C (1562 °F). Suitable for water and low-pollutant wastewater.
  • AISI 446 / ~1.4762 / ~1.4749: Max. 1100 °C (2012 °F). High resistance to reducing sulfurous gases and salts with low oxygen content.

• Nickel Alloys:

  • INCONEL® 600 / 2.4816: Max. 1100 °C (2012 °F). Excellent resistance to aggressive, oxidizing, and reducing atmospheres, chlorine gas, and chlorinated media. Not for sulfur-containing atmospheres.
  • INCONEL® 601 / 2.4851: Max. 1200 °C (2192 °F). Enhanced high-temperature corrosion resistance due to aluminum content.
  • INCOLOY® 800 HT / 1.4959: Max. 1100 °C (2012 °F). High creep rupture strength, good oxidation and carburization resistance. Suitable for sulfurous environments.
  • HASTELLOY® X / 2.4665: Max. 1150 °C (2102 °F). Very resistant to oxidizing and reducing atmospheres with good high-temperature strength.
  • Special nickel/cobalt alloy (NiCo): Max. 1200 °C (2192 °F). High resistance to sulfidation, chloride environments, oxidation, and hot corrosion.

• Ceramic Materials:

  • C610 (Al₂O₃-content approx. 60%): Max. 1500 °C (2732 °F). Economic, non-porous material, resistant to hydrogen fluoride and temperature shocks.
  • Sinterized silicon carbide (SiC): Max. 1650 °C (3000 °F). High thermal shock resistance, good thermal conductivity, hard and stable at high temperatures. Not for environments with chlorine and fluorine compounds.
  • Kanthal Super (MoSi₂ with glass phase): Max. 1700 °C (3092 °F). Not affected by thermal shock, very low porosity. Not for environments with chlorine and fluorine compounds or mechanical shock.
  • Special silicon nitride ceramic (SiN): Max. 1400 °C (2552 °F). Excellent wear and thermal shock resistance, no porosity. Not resistant to impacts.

Mechanical construction

• Thermowell Types: Metallic (machined from tubes or bars) or ceramic.
• Selection Criteria: Hardness, chemical resistance, maximum operating temperature, wear/abrasion resistance, brittleness, porosity, and creep resistance.
• Ceramic Thermowells: Often require an additional non-porous inner protection sheath if the outer sheath is porous. Sensitive to fast temperature changes and mechanical loads.
• Metal Thermowells: Generally higher mechanical resistance but lower temperature limits and less abrasion resistance.
• Sleeve and Process Connection: Metal sleeves connect ceramic thermowells to the terminal head and accommodate the process connection. Available with adjustable flange, stop flanges, or gas-tight compression fittings.

Weight examples:

• TWF11 (SiC or SiN, Ø Lg = 17 mm, Lg = 800 mm): 0.8 kg (1.8 lbs)
• TWF16 (SiN, Ø A = 26 mm, Lg = 800 mm): 1.4 kg (3.1 lbs)
• TWF16 (Kanthal AF, Lg = 1000 mm): 0.6 kg (1.3 lbs)
• TWF16 (NiCo, ¾" schedule 40s, Lg = 1000 mm): 1.9 kg (4.2 lbs)

Process connections:

• Adjustable flange: Max. temp. +350 °C (+662 °F), Material: Aluminum. Not gas-tight.
• Stop flange (DIN EN 50446): Max. temp. +400 °C (+752 °F), Material: Cast iron. Not gas-tight.
• Gas tight GCP assembly: Max. temp. +350 °C (+662 °F), Material: AISI 316Ti. Maximum process pressure ≤ 1 bar (14.5 psi).

Installation conditions

• Orientation: Vertical installation is preferred due to potential bending of metal tubes and brittleness of ceramic materials.
• Horizontal mounting: Recommended maximum immersion length is 1500 mm for diameters > 20 mm, and 1200 mm for diameters < 20 mm.
• Ceramic sheaths: Sensitive to fast temperature changes. Pre-heating is recommended before installation to prevent thermal shock. If pre-heating is not possible, installation rate must be reduced. Avoid mechanical shock during installation.

Certificates and approvals

• CE Mark: The device meets the legal requirements of EC directives.
• PED approval: Complies with paragraph 3.3 of the Pressure Equipment Directive (97/23/CE).

Ordering information

Detailed product structures for TWF11 and TWF16 are provided, outlining options for sheath material, diameter, length, sleeve dimensions, and process connections.

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Disclaimer: This extraction may miss figures, footnotes, or revisions. Contractual data must match the OEM PDF revision used on the project.

Official datasheet (PDF)

Lenntech datasheet mirror