AMS2750 is an aerospace heat treatment high-temperature measurement (Pyrometry) specification issued by SAE, which stipulates thermocouples, instruments, furnace classification, temperature uniformity test (TUS), system accuracy test (SAT) and their frequency and recording requirements. Furnaces are divided into several categories according to temperature uniformity (common Class 1 ±3 °C to Class 6 ±28 °C), and are divided into different instrument types according to the configuration of control, recording, and over-temperature thermocouples. It is also the basis for Nadcap heat treat audits and many aerospace specifications.
- Applicable: Aerospace heat treatment and other specifications citing it
- Furnace classification: Classified by temperature uniformity (common Class 1–6)
- Instrument type: classified by control/recording/over-temperature thermocouple configuration
- Thermocouples: Type, Calibration, Usage and Life Management
- TUS/SAT frequency varies with furnace type and instrument type
Scope of application
AMS2750 specifies high temperature measurement requirements for heat treatment equipment, covering:
- Sensor (thermocouple);
- Instrumentation (control, recording, test instruments);
- System Accuracy Test (SAT);
- Temperature Uniformity Test (TUS);
- Calibration, Recording and Documentation.
It is referenced in aerospace part heat treatment specifications such as the AMS2759 series and is an important basis for Nadcap heat treatment audits. Some automobile and energy companies also refer to its practices to improve temperature management.
Stove classification (common divisions)
| Category | Temperature uniformity (approx.) |
|---|---|
| Class 1 | ±3 °C（±5 °F） |
| Class 2 | ±6 °C（±10 °F） |
| Class 3 | ±8 °C（±15 °F） |
| Class 4 | ±10 °C（±20 °F） |
| Class 5 | ±14 °C（±25 °F） |
| Class 6 | ±28 °C（±50 °F） |
The stricter the category, the higher the requirements for TUS frequency and instrument accuracy. The specific values are subject to the current version.
Instrument type
The specification divides equipment into different instrument types (such as Type A, B, C, D, E, etc.) according to the configuration of thermocouples in the control area (control, recording, over-temperature protection, and whether there is load thermocouple recording). The more complete the configuration, the higher the type, and in some cases the TUS and SAT frequencies can be adjusted accordingly.
Thermocouple Management
- Type selection:Select K, N, S, R, B and other types according to the temperature range;
- calibration: Test thermocouples and sensors need to be calibrated according to regulations and traceable to national/international standards;
- Number of uses and lifespan: Reusable thermocouples have a limit on the number of times or duration of use. If the limit is exceeded, they need to be replaced;
- Record: Batch number, calibration certificate and usage record of each thermocouple.
Instrumentation requirements
- Accuracy and resolution requirements;
- Regular calibration;
- Recorder sampling frequency and recording completeness;
- Data integrity and tamper resistance of digital records.
Implementation suggestions
- Inventory all furnaces to determine required categories and instrument types;
- Prepare annual plans for thermocouples, instruments, TUS, and SAT;
- Establish an electronic ledger and automatically remind due items;
- Do a gap analysis against the latest version - the AMS2750 revision will change some frequency and tolerance requirements.
Frequently asked questions
Do you need to meet AMS2750 if you don’t make aviation parts?
It is not necessary, but its method system is complete and many companies use it as a best practice reference for temperature management.
Are the temperature requirements for the AMS2750 and CQI-9 the same?
The concept is similar (both require TUS, SAT and instrument management), but the specific classification, tolerances and frequency are different. Heat treatment plants serving multiple industries need to be managed uniformly or separately according to the strictest requirements.
What does a digital recorder need to meet?
It is necessary to ensure that the data is complete, readable, traceable, tamper-proof, and calibrated according to regulations. Specific terms are subject to specifications and customer requirements.