Endurance test. also named as life test, is a method to check whether the brass ball valves can reach the requirements of using times. The test effected through automatic equipment, by opening and closing the brass ball valves. Here below we will explain how the test is carried out.
1. Principle
The manual actuator of the valve shall withstand a series of operating cycles as specified in Table below:
2. Test installation
An automatic test rig that ensures that the closing torque remains constant and is not effected by the influence of the moment of inertia of the equipment during test.
Equipment related forces that act horizontally or vertically onto the headwork and might result in abnormal wear ought to be eliminated. A frictionless connection to the operating spindle shall be ensured.
3. Test
3.1 Conditions
Apply a closing torque according to Table 7. With the ball valve in the closed position adjust the static pressure to between 0,2 MPa and 0,4 MPa (2 bar and 4 bar). With the ball valve in the open position adjust the flow rate to between 0,066 l/s and 0,1 l/s (4 l/min and 6 l/min) by a regulation valve downstream of the valve under test.
3.2 Procedure
1) Open the valve completely and mount the valve to the test rig;
2) close the valve with a speed of the ball 5 rev./min. and stop the movement without submitting the stops to a torque exceeding the appropriate value given in Table below;
3) hold the valve 5 s in closed position;
4) open the valve with a speed and torque as given in point 2;
5) hold the valve 5 s in open position;
6) repeat the procedure given in points 1 to 5 for 50 % of the number of cycles given in above table;
7) store the valve for one week at ambient temperature in open position;
8) mount the valve in closed position to the test rig and apply water of 65 °C;
9) repeat the procedure given in points 1 to 5 for 50 % of the number of cycles given in Table 14 at a water temperature of 65 °C;
10) store the valve for one week at ambient temperature in closed position;
11) the valve shall comply with 3.3.
3.3 Acceptance criteria
1) If leakage or malfunction occurs test shall be stopped;
2) 1 week after concluding the tests, stored in open position at ambient temperature, the valve shall comply with the leak tightness test and operating torque test.
