The code requires you to measure the flue gas temperature after the last heat recovery device (economizer or air heater). However, if air infiltration occurs downstream, PTC 4.1 provides a complex correction to back-calculate the temperature at the air heater exit. Most engineers skip this; the best engineers follow Appendix F to the letter.
Run the test for a minimum of 4 hours (for coal) or 2 hours (for oil/gas). Record at 15-minute intervals: Asme Ptc 4.1.pdf
A frequent search mistake involves overlooking the versioning. ASME PTC 4.1 was technically withdrawn and superseded by ASME PTC 4-2013 (Fired Steam Generators). However, the "4.1" methodology remains the industry standard for acceptance testing in older plants. The code requires you to measure the flue
Why do people still download the legacy .pdf? Warning: If you find a free "ASME PTC 4
Warning: If you find a free "ASME PTC 4.1.pdf" on a file-sharing site, check the revision date. The legitimate last reaffirmation of 4.1 was often 2004. If your PDF shows a 2019 date, it is likely a counterfeit or a third-party commentary, not the official code.