API SPEC 6FC-2009 pdf download.Specification for Fire Test for Valves with Automatic Backseats.
3 Test Procedure 3.1 Stepwise Procedures (See Figure 4) 3.1.1 Open valve(s) (Item 5 and Item 6) at water source, and any necessary vent valves (Item 17) to flood the system and purge the air. The test valve may have to be placed in the partially open position in order to completely flood the valve body. 3.1.2 Close fill valve (Item 5) and test valve (Item 11), then close vent valves (Item 17). The piping system upstream of the test valve shall be completely water filled and the system downstream shall be drained. 3.1.3 Pressurize the system to the appropriate high test pressure from Table 1. Maintain this pressure during the burn and cooldown period. Momentary pressure losses are permissible, provided their cumulative recovery time is less than two minutes. Record the reading on the calibrated sight gauge (Item 4). Empty the graduated downstream container (Item 19). 3.1.4 Open fuel supply, establish a fire, and monitor the flame temperature. The average of two thermocouples (Item 14) must reach 1400 °F (761 °C) within two minutes. Maintain the average temperature between 1400 °F to 1800 °F (761 °C to 980 °C), with no reading less than 1300 °F (704 °C) for the remainder of the burn period. 3.1.5 The average temperature of the calorimeters (Item 13) shall reach 1200 °F (650 °C) within 15 minutes of fire ignition. For the remainder of the burn period, the calorimeters shall maintain a minimum average temperature of 1200 °F (650 °C); and none of the calorimeters shall have a temperature less than 1050 °F (565 °C). NOTE Impingement of water or steam from external leakage onto flame thermocouples or calorimeters can result in a substantial drop in the indicated temperature of the affected sensor(s), even if no actual drop in flame temperature has occurred. Such drops in indicated temperature(s) shall be noted in the test report. The test may continue with no downward adjustment of the burner controls provided that at least one flame thermocouple and one calorimeter are functioning.
3.1.7 At the end of the burn period (30 minutes), shut off the fuel. 3.1.8 Immediately determine the amount of water collected in calibrated container (Item 19) to establish total through valve seat leakage. Continue collecting water in the calibrated container (Item 19) for use in establishing the external leakage rate. If the test valve is of the upstream sealing type, the volume of water that is trapped between the upstream seat seal and the downstream seat seal, when the valve is closed, shall be determined before the test is started and identified in the test report. It is assumed that during the test this volume of water would move through the valve, past the downstream seat seal and be collected in the calibrated container. Since this volume has not actually leaked past the upstream seat seal, it may be deducted from the total volume measured in the downstream calibrated container when determining the through valve leakage. NOTE If the total volume collected downstream during the burn and/or cooldown is less than the body cavity volume, the through leakage can be assumed to have been zero. 3.1.9 Cool the valve (or allow to cool) to 212 °F (100 °C) or less. Record reading on sight gauge (Item 4), and calibrated container (Item 19). Cooling may, at the manufacturer’s option, be natural or forced. 3.1.10 The following low-pressure test is required only for API 6D valves with ratings of Class 600 and lower. Decrease the test pressure to the low test pressure value shown in Table 1. Measure the through valve and external leakage over a 5-minute period. 3.1.11 If the step in 3.1.10 was performed, increase pressure on test valve to the high test pressure value in Table 1. 3.1.12 Verify that backseating has occurred by monitoring for (and measuring) leakage at a test port above the backseat, for a period of 5 minutes. 3.1.13 Vent pressure. NOTE Venting pressure is a change made for safety reasons, and may be omitted at the manufacturer’s option, or for previously-qualified valve designs.