ASME PTC 25-2008 pdf download

ASME PTC 25-2008 pdf download.Pressure Relief Devices AN AM E R I C AN N ATI O N AL S TAN D AR D ASME PTC 25-2008 (Revision of ASME PTC 25-2001) Performance Test Codes.
3-7.2 Temperature Temperature-measuring instruments shall be cali- brated in accordance with ASME PTC 19.3, Temperature Measurement. Instruments of the types listed in para. 4-2.2(a), except bimetallic thermometers, shall be cali- brated against at least one temperature within a 90-day period preceding the test or series of tests. Bimetallic thermometers shall be calibrated before and after each test or series of tests. Calibration of other means of indicating or recording temperature shall be agreed upon by the interested parties. 3-7.3 Lift Indicators and Recorders Since these instruments are usually subjected to some shock in the course of tests under this Code, their accu- racy shall be checked before and after each test or series of tests. 3-7.4 Weighing Scales Scales used in test procedures for weighted conden- sate orgravimetric methods shallhave a minimum value of the indicating element equal to or less than 0.25% of the expected load. Weighing scales used in tests con- ducted under this Code shall be calibrated at sufficient points to ensure their accuracy within their range of intended usage at least once within a 90-day period preceding a test or series of tests. 3-7.5 Steam Calorimeters Methods of calibrating steam calorimeters are given in ASME PTC 19.11, Water and Steam in the Power Cycle. The calorimeters shall be calibrated separately with steam at the time oftheir installation and at regular intervals not exceeding 6 months. Further calibrations shall be carried out if results indicate an obvious error in their readings or if their installation is altered.
3-9 FLOW RESISTANCE TEST RIGS The calibration of any type of test rig (see para. 4-9.1) shall include the actual piping and all fittings down- stream of the test vessel (Fig. 3-9-1). Calibration shall be conducted upon completion of the initial installation or construction and prior to the performance of any formal test and be repeated at least once every 5 years. Records of calibration shall be maintained and available for review by the interested parties. Modifications to the equipment shall be evaluated for the effect they have on the test rig, and new calibrations shall be performed if deemed necessary. The calibration shall be conducted per paras. 3-9.1 and 3-9.2. 3-9.1 Measured Flow Resistance Withno testdevice installed, conductthree flow resist- ance tests at the smallest, intermediate, and highest test pressures compatible with the test rig. The measured flow resistance, K Ri , for each test shall be 0 ± 0.075. 3-9.2 Pressure Tap Profile Comparison With no test device installed, conduct a flow test at an intermediate test pressure. (a) With the data from the flow test, calculate the average friction factor for the length of pipe between taps A-B and C-D. (b) Using the Lapple and Levenspiel model of the adiabatic ideal-gas integration of the mechanical energy (or momentum) balance for adiabatic flow from an ideal nozzle on a large reservoir, through an equivalent length of pipe, to a second large reservoir (or to the atmo- sphere), calculate the equivalent pipe length to tap A using the measured flow rate, the average friction factor from step (a), and the measured pressure at tap A. (c) Subtract the actual pipe length from the test rig entrance to tap A from the equivalent pipe length from step (b) to determine a nozzle equivalent length. (d) Repeat steps (b) and (c) for taps B through D.
3-12 MEASUREMENT UNCERTAINTY A post-test uncertainty analysis shall be performed to determine that the limits of uncertainty of the final flow measurement specified in Section 1 were met. A pretest determination may be performed to determine that the limits of uncertainty of the final flow measure- ment specified in Section 1 can be met by the specified instrumentand procedures. A guide for such determina- tion is given in ASME PTC 19.1. These determinations shall be documented by the laboratory and available for review.