Thermometer Expansion Tube Fitting

The stainless steel thermometer expansion tube (also known as an enlarged thermowell jacket or instrumentation expansion fitting) is an essential component designed for process pipelines where the pipe diameter is too small to directly accommodate a standard temperature sensor or thermowell. By strategically enlarging the local line cross-section, this fitting allows bimetal thermometers, thermocouples, or RTD sensors to penetrate deep into the flow stream without restricting the fluid path or causing high pressure drop. Constructed from corrosion-resistant forged/machined stainless steel, it guarantees high mechanical integrity and reliable heat transfer for critical industrial processing lines.

Technical Specifications

• Product Type: Thermowell Expansion Tube / Thermometer Enlarged Sleeve

• Body Material: 304 Stainless Steel / 316L Stainless Steel (Corrosion-resistant grades)

• Instrument Connection Port: Threaded Female Boss (e.g., 1/2" NPT, 3/4" NPT, or G1/2")

• Process Connection Ends: Butt-Weld (BW) / Socket Weld (SW) pipe ends

• Main Tube Inner Diameter: Custom enlarged chamber sizing to prevent probe restriction

• Process Line Size Adaptability: Designed to weld onto DN15, DN20, or DN25 standard process lines

• Manufacturing Process: TIG welded and seamless mandrel expanded body

• Maximum Pressure Rating: Equivalent to standard schedule 40/80 pipe pressure limits

• Operating Temperature Range: -200°C to 600°C (-328°F to 1112°F) depending on alloy choice

• Surface Finish: Matte blasted / Pickled & Passivated / Polished (Sanitary specification available)

• Applicable Sensors: Bimetal thermometers, heavy-duty thermocouples, industrial RTDs

• Sensor Well Integration: Accommodates straight, tapered, or stepped sensor elements

• Flow Dynamic Optimization: Concentric reducers on both ends to minimize localized turbulence

• Wall Thickness: Schedule 40 or Schedule 80 heavy-wall options for severe wear environments

• Leak Integrity: 100% dye penetrant and radiographic weld inspection verified

• Applications: Oil refining, chemical processing, pharmaceutical, food and beverage, HVAC steam loops

• Media Compatibility: Water, steam, gases, hydrocarbons, and mildly corrosive process chemicals

• Mechanical Strength: Provides rigid support to protect temperature probes against high velocity fluid vortex shedding

• Material Certification: Full heat number traceability with EN 10204 3.1 certification

• Dimensional Conformance: Fabricated to match ASME B16.9 or DIN standards for butt-welding fittings