ISO 19879:2010 pdf free download – Metallic tube connections for fluid power and general use – – Test methods for hydraulic fluid power connections.
11 Overtightening test
11.1 Principle
Unless otherwise specified in the respective connector standard, six test samples for each size, three samples each of the tube nuts and the 90° swivel elbow (SWE) nut, shall be tested to confirm that tube and swivel nuts are capable of withstanding the overtightening qualification test when tested to the overtightening (overtorque) values or number of turns given in the respective connector standard.
11.2 Test equipment
Unless otherwise specified, an unplated threaded steel mandrel or mating connector test block with a minimum hardness of 40 HRC in accordance with ISO 6508 shall be used.
11.3 Procedure
Connectors shall be restrained during the test, and the wrench shall be located at the threaded end of the nut hex. The overtightening test shall be conducted in accordance with the requirements specified in Table 8.
11.4 Re-use of components
Parts that pass this test shall not be tested further, used for actual service or returned to stock.
12 Vibration test
12.1 Principle
Unless otherwise specified in the respective connector standard, six test assemblies as shown in 12.2 shall be tested to confirm that the connector is able to withstand the specified vibration without leakage or component failure. For flange assemblies of DN 51 and larger and connectors for tube OD sizes 50 mm and larger, the testing of three test assemblies shall be sufficient if the design has been verified through calculation or finite element analysis.
12.2.2 Prepare the test assembly as shown in Figure 7. The strain gauge shall be installed at the location specified in Figure 7. The minimum gauge length, L, shall be in accordance with Table 10.
12.2.3 Install the test assembly in a test fixture that provides either rotary or axial (planar) vibration, as shown in Figure 7.
12.2.4 Pressurize the test assembly to the working pressure of the tube.
12.2.5 Apply a bending load to the end of the tube opposite to the strain gauge until the combined axial stress is 25 % of the minimum yield strength of the tube.
NOTE The use of tubes with minimum yield strength greater than 235 MPa requires that the dynamic capability of the tube be taken into consideration when determining the stress level used in the test.
12.2.6 Submit the test assembly to vibration of 10 Hz to 50 Hz until failure or 10 000 000 cycles, whichever occurs first.
12.2.7 If failure occurs before the test sample reaches 10 000 000 cycles, record the number of cycles reached and type of failure.
12.3 Re-use of components
Parts that pass this test shall not be tested further, nor used for actual service or returned to stock.
13 Cyclic endurance (impulse) test with vibration
13.1 Principle
Unless otherwise specified in the respective connector standard, three assemblies in accordance with Figure 8 shall be tested to confirm that they pass, without leakage or component failure, a cyclic endurance test at 133 % of working pressure for 500 000 cycles, while simultaneously being subjected to vibration. For flange assemblies of DN 51 and larger and connectors for tube CD sizes 50 mm and larger, the testing of three test assemblies shall be sufficient if the design has been verified through calculation or finite element analysis.
13.2 Procedure
13.2.1 Conduct the cyclic endurance (impulse) test with vibration in accordance with the requirements of Table 11 and Figure 8.