ASTM E839-23 PDF
Standard Test Methods for Sheathed Thermocouples and Sheathed Thermocouple Cable
Standard Test Methods for Sheathed Thermocouples and Sheathed Thermocouple Cable
- Статус документа:
- Действующий
- Формат:
- Электронный (PDF)
- Количество страниц:
- 18
- Дата публикации:
- 1 ноября 2023 г.
- Издание:
- E839
- ICS:
- 17.200.20
SIGNIFICANCE AND USE 5.1 This standard provides a description of test methods used in other ASTM specifications to establish certain acceptable methods for characterizing thermocouple assemblies and thermocouple cable. These test methods define how those characteristics shall be determined. 5.2 The usefulness and purpose of the included tests are given for the category of tests. 5.3 Warning—Users should be aware that certain characteristics of thermocouples might change with time and use. If a thermocouple’s designed shipping, storage, installation, or operating temperature has been exceeded, that thermocouple’s moisture seal may have been compromised and may no longer adequately prevent the deleterious intrusion of water vapor. Consequently, the thermocouple’s condition established by test at the time of manufacture may not apply later. In addition, inhomogeneities can develop in thermoelements because of exposure to higher temperatures, even in cases where maximum exposure temperatures have been lower than the suggested upper use temperature limits specified in Table 1 of Specification E608/E608M. For this reason, calibration of thermocouples destined for delivery to a customer is not recommended. Because the emf indication of any thermocouple depends upon the condition of the thermoelements along their entire length, as well as the temperature profile pattern in the region of any inhomogeneity, the emf output of a used thermocouple will be unique to its installation. Because temperature profiles in calibration equipment are unlikely to duplicate those of the installation, removal of a used thermocouple to a separate apparatus for calibration is not recommended. Instead, in situ calibration by comparison to a similar thermocouple known to be good is often recommended. SCOPE 1.1 This document lists methods for testing Mineral-Insulated, Metal-Sheathed (MIMS) thermocouple assemblies and thermocouple cable, but does not require that any of these tests be performed nor does it state criteria for acceptance. The acceptance criteria are given in other ASTM standard specifications that impose this testing for those thermocouples and cable. Examples from ASTM thermocouple specifications for acceptance criteria are given for many of the tests. These tabulated values are not necessarily those that would be required to meet these tests, but are included as examples only. 1.2 These tests are intended to support quality control and to evaluate the suitability of sheathed thermocouple cable or assemblies for specific applications. Some alternative test methods to obtain the same information are given, since in a given situation, an alternative test method may be more practical. Service conditions are widely variable, so it is unlikely that all the tests described will be appropriate for a given thermocouple application. A brief statement is made following each test description to indicate when it might be used. 1.3 The tests described herein include test methods to measure the following properties of sheathed thermocouple material and assemblies. 1.3.1 Insulation Properties: 1.3.1.1 Compaction—direct method, absorption method, and tension method. 1.3.1.2 Thickness. 1.3.1.3 Resistance—at room temperature and at elevated temperature. 1.3.2 Sheath Properties: 1.3.2.1 Integrity—two water test methods and mass spectrometer. 1.3.2.2 Dimensions—length, diameter, and roundness. 1.3.2.3 Wall thickness. 1.3.2.4 Surface—gross visual, finish, defect detection by dye penetrant, and cold-lap detection by tension test. 1.3.2.5 Metallurgical structure. 1.3.2.6 Ductility—bend test and tension test. 1.3.3 Thermoelement Properties: 1.3.3.1 Calibration. 1.3.3.2 Homogeneity. 1.3.3.3 Drift. 1.3.3.4 Thermoelement diameter, roundness, and surface appearance. 1.3.3.5 Thermoelement spacing. 1.3.3.6 Thermoelement ductility. 1.3.3.7 Metallurgical structure. 1.3.4 Thermocouple Assembly Properti...
Abstract
Overview
ASTM E839-23: Standard Test Methods for Sheathed Thermocouples and Sheathed Thermocouple Cable provides detailed test methods for evaluating Mineral-Insulated, Metal-Sheathed (MIMS) thermocouple assemblies and cables. Administered by ASTM Committee E20 on Temperature Measurement, this standard supports users, manufacturers, and quality professionals in assessing critical characteristics related to insulation, sheath integrity, thermoelement performance, and assembly properties. While ASTM E839-23 describes recommended test methods, the acceptance criteria for thermocouples and cables are specified in other relevant ASTM standards.
Key Topics
Insulation Properties
- Compaction: Methods including direct, absorption, and tension tests to evaluate insulation density and ensure thermoelements are locked in place, improving mechanical stability and heat transfer.
- Thickness: Verification of insulation thickness using metallographic examination or radiography, ensuring design specifications are met for performance and safety.
- Resistance: Measurement of insulation resistance at room and elevated temperatures to detect moisture or impurities that may affect thermocouple accuracy and service life.
Sheath Properties
- Integrity: Water tests and mass spectrometer analysis are employed to detect leaks that could allow moisture or gas intrusion, which compromise insulation and measurement reliability.
- Dimensions: Assessment of sheath length, diameter, and roundness for precise fit and compatibility with instrumentation requirements.
- Wall Thickness & Surface: Determination of sheath wall thickness and surface quality using visual, dye penetrant, and cold-lap detection methods.
- Metallurgical Structure & Ductility: Analysis to ensure sufficient durability and mechanical performance during installation and operation.
Thermoelement Properties
- Calibration and Homogeneity: Ensures temperature-electromotive force (emf) relationship is within standardized tolerances before initial use; notes that recalibration after service may not reflect installation-specific conditions.
- Drift and Ductility: Evaluates changes in thermoelement stability over time and mechanical flexibility.
- Diameter and Surface Evaluation: Measurement and inspection processes to verify conformance to design requirements.
Assembly Properties
- Electrical Properties: Tests for circuit continuity, loop resistance, and connector polarity to guarantee reliable operation.
- Radiographic Inspection: Non-destructive examination to identify internal faults in welds and assemblies.
- Thermal Response and Cycling: Evaluates thermal response times and resistance to temperature cycling, assuring suitability for dynamic process environments.
Applications
ASTM E839-23 is widely applied in quality control, specification compliance, and suitability assessment for sheathed thermocouples and thermocouple cable in critical industries such as:
- Industrial process control and automation
- Power generation and energy
- Aerospace and defense
- Chemical and petrochemical processing
- Laboratory and test measurement settings
The included test methods help manufacturers and users ensure that thermocouple products conform to applicable specifications and are suitable for intended service conditions, especially in high temperature and reliability-focused applications.
Related Standards
Organizations rely on ASTM E839-23 in conjunction with related ASTM and industry standards for comprehensive testing, specification, and terminology:
- ASTM E608/E608M - Mineral-Insulated, Metal-Sheathed Base Metal Thermocouples
- ASTM E585/E585M - Compacted Mineral-Insulated, Metal-Sheathed, Base Metal Thermocouple Cable
- ASTM E1129/E1129M, E1684 - Thermocouple connectors and miniature connectors
- ASTM E780 - Insulation resistance measurement at room temperature
- ASTM E220, E207 - Calibration and EMF test methods
- ASTM E165 - Liquid penetrant testing for defect detection
- ANSI B46.1 - Surface texture standards
Using ASTM E839-23 alongside these documents ensures a robust framework for thermocouple cable and assembly quality and reliability, supporting effective temperature measurement across demanding environments.
Технические детали
- Технический комитет
- E20 - Temperature Measurement
- SKU
- ASTM E839-23
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