Model HRM

Refractory Mandrel, For Use with HTP/HTX Thermocouple

The Delta Controls Model HRM Refractory Mandrel is designed to be installed on the thermocouple nozzle prior to installation of the refractory material. It creates a centered, accurate hole through the refractory lining, and the attached stop disc keeps refractory mortar out of the nozzle interior. The stop disc is required so that the HRW refractory well will be positioned correctly in relation to the mounting flange.

The HRM is used when core drilling is undesirable, such as when water (for drilling) may not be used.  Use of the HRM will require cutting and fitting the refractory firebrick around the mandrel pipe.

Model Numbering System

Model HRM Numbering System

Note: Smaller flange sizes down to ANSI 2″, 50mm pipe and those with a larger I.D. can be accommodated.

6″ flange size is recommended for best results.

Using the Refractory Mandrel

The HRM Mandrel is first mounted on the thermocouple nozzle.  The refractory is then installed around the mandrel pipe. Remove the mandrel before thermocouple installation.

Model HRM Creating a Refractory Mandrel by Casting


The tube is tapered and greased. This prevents the refractory from, adhering to the tube, making the HRM easier to remove. The resulting hole will not interfere with installation or operation of the HRW refractory well.

Final Result

The result produced must be a hole on the centerline of the mounting nozzle and concentric with it.

Model HRM Final Result


  • Results in a straight, centered, accurate hole through the refractory lining
  • Keeps excess refractory and mortar out of the nozzle during refractory installation
  • A 6” 150# size nozzle is recommended for best results


The Delta Controls thermocouple assembly must be installed on the center-line of, and concentric with, the mounting nozzle. The refractory lining can move in relation to the vessel shell. The refractory expands at rates different from the shell as the temperature varies. Refractory will also shift and deform as it ages.

The Delta Controls thermocouple requires a relatively large hole on the center-line of the mounting nozzle. This allows the insertion of a refractory well with a large internal hole. The thermocouple, which is attached to the nozzle flange, is suspended and free to move around inside the refractory well hole. This large hole must be straight, true, and on the center-line of the nozzle. Being located off the center-line or at an angle can allow the thermocouple element well to contact the refractory well and possibly become damaged.

Additional Information


Refractory Mandrel, For Use with HTP/HTX Thermocouple

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