With the pipe de-pressurized, drill a hole using a step drill. Deburr the inside meticulously. Some engineers use a ball mill or a carbide burr to ensure a sharp, flush edge.
But what exactly does "ASME PTC 19.2 fixed" refer to? Why do engineers specify this particular standard for fixed pressure measurement installations? And how does adhering to this code improve your plant’s heat rate and profitability?
Place the pressure transmitter (e.g., Rosemount 3051 or Yokogawa EJA) at a fixed elevation. For liquid service, the transmitter should be below the tap. For gas service, above the tap.
For , ASME PTC 19.2 remains the controlling document. The "fixed" installation is acceptable but auditors will expect to see the uncertainty budget. Real-World Case Study: The Importance of ASME PTC 19.2 Fixed A 500 MW combined-cycle power plant struggled with unexplained 1.5% variance in gas turbine output between spring and fall. The culprit? Fixed pressure taps on the compressor discharge.
Use a thread-o-let or weld-o-let. Back-purge with argon to prevent slag on the inside. After welding, ream the inside to remove any internal weld penetration.
| Standard | Focus | Fixed Tap Allowed? | | :--- | :--- | :--- | | | General pressure measurement for performance tests | Yes (primary focus) | | ASME PTC 6 | Steam turbine testing (refers back to PTC 19.2) | Yes, with additional requirements | | ISO 5167 | Differential pressure flow meters (orifice plates) | No (requires corner taps or flange taps) | | API 551 | Process measurement (not performance testing) | Yes, but less stringent |
