PHI SiSiC Radiant Tube “INEX”


Innovative New Twist On SiSiC Radiant Tube
Innovators in Composite Radiant Tube Technology

INEX specializes in Composite Radiant Tube (CRTs) used for indirect heat-treating processes. Our tube consist of Silicon Carbide (SiC) particles reinforcing a continuous Silicon (Si) metal-matrix formed using our patented melt-infiltration process. Introduces in 1988, these composite material completely eliminate common problems associated with metal alloy radiant tube that suffer from Creep (deformation, distortion & rupture), Carburization (embrittlement & corrosion), Thermal Shock, Melt-Through, Weld Failure and Oxidation to 2450 °F (1340 °c) Change to INEX and quit changing your radiant tube.

Standard Sizes of Radiant Tube

  • 2 3/8 inch O.D., 1/8 inch wall (60.3 mm, 3.2 mm)
  • 2 3/4 inch O.D., 1/8 inch wall (70 mm, 3.2 mm)
  • 3 1/4 inch O.D., 1/8 inch wall (82.5 mm, 3.2 mm)
  • 3 3/4 inch O.D., 1/8 inch wall (95.3 mm, 3.2 mm)
  • 4 1/2 inch O.D., 3/16 inch wall (114.3, 4.8 mm)
  • 5 1/8 inch O.D., 3/16 inch wall (130 mm, 4.8 mm)
  • 6 inch O.D. 13/64 wall (152.4 mm, 5mm)

Benefit of Using Internally-Finned SiSiC Radiant Tube

  • Higher Operating Temperatures up to 2450°F
  • Longer Tube Life
  • Reduction in Gas Consumption
  • Improved Recovery Rates
  • Increased Combustion Efficiency
  • Proven Savings

INEX conducted a year long test in a pusher furnace. Though this was considered a conservative test, the results showed a 10.4% metered fuel savings. The furnace was rated at 600,000 BTU’s per hour and was operated at high fire approximately 60% of the available time. A savings of over 300,000
cubic feet of gas resulted in an annual savings. With the cost of gas rising dramatically, plug in your own figures and see the savings an INEX Finned CRT can deliver to you!


Benefit of High Performance U-Tube Systems

  • Higher Heat Flux – Metal-alloy tubes are typically designed to radiat at 55 BTU/H/in2 (25 KW/m2), but INEX Tube excel at much higher  temperatures to 2450°F (1340°C) providing twice the heat flux output of 110 BTU/hr/in2 (50 KW/m2). Because INEX tubes can be fired so much hotter, they provide faster furnace ramp-up & recovery, reduced cycle time and tighter temperature control. With this in mind, consider a smaller INEX composite tube to replace a larger metal-alloy tube for both increased performance and purchase savings.
  • Longer Tube Life – Conventional metal-alloy tubes frequently fail due to creep, carburization, thermal shock, melt-through and oxidation. INEX composite radiant tubes eliminate these problems and out-live all other types. Lower your operating expense by reducing furnace downtime, tube replacement, and labor. 
  • Decreased Cycle Time – Higher radiant output means faster recovery to operating temperature than conventional metal-alloy tubes, insuring maximum furnace throughput and productivity.

Standard U-Tube Sizes

Tube Outside DiameterTube Inside DiameterCenterline
4-1/2” (114 mm)4-1/16” (104 mm)9″ (229 mm)
6″ (152 mm)5-1/2 ” (141 mm)9″ (229 mm)
6″ (152 mm)5-1/2 ” (141 mm)12″ (305 mm)


  • Atmospheric Annealing 
  • Carburizing 
  • Carbide Solution  Treating 
  • Neutral Hardening 
  • Carbo-Nitriding 
  • Stainless Steels


  • Endothermic, Lean & Rich
  • Carbon-Enriched Gases 
  • Ammonia-Enriched Gases 
  • Mixed 50/50 Endo-Ammonia
  • Exothermic
  • Nitrogen

For more information on the SiSiC Radiant Tube, or request for customized Radiant Tube, please contact us directly here!