Model HRG


Refractory Drilling System

The Delta Controls Model HRG Refractory Drilling System protects the thermocouple’s clearance into the vessel by drilling straight, centered, and perpendicular holes. Using the HRG ensures successful installation of the Delta Controls Model HTP, HTX, and HTS thermocouples which require close tolerances in the borehole through the refractory.

The HRG guide is mounted on the vessel nozzle flange and keeps the drill bit on the centerline of the nozzle during drilling. The water swivel adapter and flow control valve deliver the proper amount of water to facilitate the drilling without introducing excessive water to the vessel interior. The final result is a straight hole that is properly positioned to accept the refractory thermowell and the thermocouple.

This precision hole permits proper insertion of the Model HRW outer protective thermowell and provides proper clearances for refractory movement.


  • Refractory drilling system for use with Delta Controls thermocouples and pyrometers
  • Produces concentric refractory hole drilling
  • Drill guide is rigidly mounted on the vessel nozzle flange
  • Diamond cutting fragments are embedded in a ceramometallic matrix
  • Flushing promotes rapid cutting and straight drilling
  • Water-cooled bit lengthens life


  • Flange Size: ANSI 4 in Class 150 to 6 in Class 300 DIN 90 to 175 mm
  • Nozzle Inside Diameter: ≥ 3.44 in (≥ 87 mm)
  • Nozzle Height and Refractory Thickness: ≤ 22 in (560 mm) (option EXD if longer)
  • Refractory Thickness: ≤ 22 in (560 mm)
  • Hole Size: 2.20 in (56 mm)
  • Drill Bit: Diamond core type, requires water flushing
  • Water Swivel: 0.625 - 11 TPI to 0.5 in tri-shaft drill drive shaft, 0.75 in - 11 NH Female Hose connector, flow control valve, quarter turn hose coupling
  • Drill Bit Extension (Length as Required): 12 in (300 mm), ≥ 24 in (600mm)

Required Ordering Information

  • Detailed model number
  • Documentation & testing packages (if required, refer to Additional Resources in the product catalog)

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Additional Information


Refractory Drilling System

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