NAVY - MIL-T-24270B

THERMOWELLS FOR THERMOMETERS AND ELECTRICAL TEMPERATURE SENSORS GENERAL SPECIFICATION FOR

active

Organization:	NAVY
Publication Date:	2 September 1983
Status:	active
Page Count:	11

scope:

This specification covers wells (thermowells) for use with thermometers and electrical temperature sensors. Older military specifications may still refer to electrical temperature sensors as electrical temperature elements (thermocouple, temperature elements and resistance temperature elements).

Thermowells shall be of the following physical designs to receive the sensors of mechanical thermometers or electrical temperature sensors (see 6.2.1). A military part number system shall identify each variation of thermowell design in accordance with the following: Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: Commander, Naval Sea Systems Command, SEA 55Z3, Department of the Navy, Washington, DC 20362 by using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter.

Thermowell designs shall be in accordance with the applicable specification sheet number as follows:

Design symbol Design (specification sheet no.) 1 MIL-T-24270/1 2 MIL-T-24270/2 3 MIL-T-24270/3 4 MIL-T-24270/4 7 MIL-T-24270/7 12 MIL-T-24270/12 13 MIL-T-24270/13 18 MIL-T-24270/18 21 MIL-T-24270/21 22 MIL-T-24270/22 25 MIL-T-24270/25

Thermowells shall have an internal bore dimension suitable for mechanical thermometers or electrical temperature sensors as follows:

Symbol Sensor type Sensor details M Mechanical MIL-I-17244 and MIL-T-19646 E Electrical MIL-T-24388

Mechanical thermometers shall be either bimetallic (MIL-I-17244) or filled system (MIL-T-19646). Electrical temperature sensors shall be either thermocouples or resistance temperature sensors (MIL-T-24388).

Thermowell insertion length shall be one of the following:

Symbol Insertion length (inches) 2 2 3.5 3-½ (electrical sensor only) 5.5 5-½ (mechanical sensor only) L As required to fit the application

Thermowells shall be made of materials as follows:

Symbol Material CNR Copper-Nickel (90-10) CUNI Copper-Nickel (70-30) CRES Corrosion Resisting Steel NICU Nickel-Copper ALBR Aluminum Bronze CSA Steel

intended Use:

The thermowells are intended for use with thermometers and electrical temperature sensors as described in 6.1.1 through 6.1.3.

Thermowell designs are intended for use as... View More

The thermowells are intended for use with thermometers and electrical temperature sensors as described in 6.1.1 through 6.1.3.

Thermowell designs are intended for use as follows.

Insertion Specification length Method of sheet no. (inches) mounting Application¹/ 1 2 ¾ inch For mounting thermowells in tee NPS socket fitting, 2 to 4 inches pipe size with branch connection ¾ inch NPS socket for socket welding or brazing the thermowell. 2 2 ¾ inch For mounting in tee fitting, NPS socket 2 to 4 inches piping size with ¾ inch NPS socket size on branch connection, for socket welding or brazing the thermowell. (See footnote on next page). Insertion Specification length Method of sheet no. (inches) mounting Application¹/ 3 4 ¾ inch For mounting in ¾ inch NPS socket NPS socket boss on piping above 4 inches size. 4 4 ¾ inch For mounting in ¾ inch NPS socket NPS socket boss on piping above 4 inches size. 7 "M" 5-½ 1 inch NPS Main steam piping 1500 lb/in², "E" 3-½ pilot boss or 1000°F (538°C) maximum, 5 inches integrally pipe size and larger, steam reinforced velocity not to exceed 180 ft/sec insert butt for 5-½ inches (M) or 450 ft/sec welding pipe for 3-½ inches (E) insertion fitting type length. Well material CRES. boss 12 2 1-⅛ o.d. Air conditioning and refrigerant socket systems. 13 4 1-⅛ o.d. Air conditioning and refrigerant socket systems. 18 L ("M" only) Pilot boss or Thermowell for mechanical ther- double sup- integrally mometers where steam velocities port inser- reinforced exceed 180 ft/see. tion length insert butt depends on welding pipe pipe size fitting type boss 21 2 Threaded boss, For mounting thermowells in boss 1-5/16-12UN-2B of material not suitable for size, O-ring welding or brazing. 22 4 seal in accordance with MS16142 25 N/A N/A Extension neck adapter.

"M" design is for thermometers in accordance with MIL-I-17244 or MIL-I-19646. "E" design is for electrical sensors in accordance with MIL-T-24388. Thermometer and electrical temperature sensor selection for specific thermowells are in accordance with the following:

MIL-T-24270 Thermowell MIL-I-17244 MIL-T-19646 MIL-T-24388 ^1/ specification insertion stem length Adjustable Probe compressed sheet no. length (inches) (inches) union length l,2,12,21 2 2 (sensitive Sensing bulb 2-11/16 portion 1-½ 1-½ inches inches long long maximum maximum) 3,4,13,22 4 4 (sensitive Sensing bulb 4-11/16 portion 3 3 inches long inches long maximum maximum) 7 "M" 5-½ Not applicable Sensing bulb 4-19/32 "E" 3-½ Not applicable 3-½ inches long maximum 18 "M" only Not applicable Sensing bulb Not applicable (to fit 3 inches long piping) maximum

See 3.2.

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