By now, most heat treaters should have had some time to read the new revision of AMS2750. The changes are extensive and, since it is considered a complete rewrite, there are no change bars to indicate specific changes.
AMS2750F and Nadcap requirements (both checklists and the pyrometry reference guide) amount to 70% of all Nadcap Heat Treat Audit findings. This trend has been consistent for over a decade now. This can be attributed to a lack of comprehension of the specification, internal execution and inadequate internal auditing systems at the supplier level as well as the prime level. Conrad Kacsik is committed to improving the comprehension of AMS2750F within the industry. We believe that this is the first step in creating a successful Pyrometry Compliance System for our customers.
There are two main changes within AMS2750F regarding instrumentation: 1) readability and 2) digital furnace instruments.
In the new revision of AMS2750F, selection of correction factors is now defined. When performing a SAT or TUS at a temperature which does not correspond to a tested value on the thermocouple calibration report, AMS2750F permits the selection of a correction nearest the temperature in use or linear interpolation.
In the new revision of AMS2750F, standard error limit requirements have been removed from Table 1. The error of ±4°F or ±0.75% is no longer permitted.
AMS2750F has added specific items that must be present on thermocouple certifications. These include, but are not limited to:
AMS2750F now addresses the assembly of the hot junction portion of thermocouples. It states that hot junctions may be made by twisting and/or welding or a combination of those, although no addition of filler metal may be used.
AMS2750F now presents a different definition of expendable versus nonexpendable thermocouples. As a thermocouple supplier, we feel it is important to keep our clients informed as to the details of these changes.
Our goal is to keep our clients up to date on the new changes to AMS2750. In today’s blog post, I’m discussing how AMS2750F now permits Type M and Type C thermocouples. It is important to understand the use and limitations of thermocouples prior to use.
When AMS2750 went from revision D to revision E, one of the changes was that ASTM E29 was required for rounding significant digits. Rounding using ASTM E29 is not your old spreadsheet version of rounding—more discretion is required.
