Installation method and troubleshooting of steam pressure relief valves

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This post was last edited by shiwendong on 2017-4-8 at 11:52. Installation methods and troubleshooting of steam pressure regulators – Please keep adding better methods. Before installing a steam pressure regulator, it is necessary to flush and clean the pipeline system first. To prevent contaminants such as solder slag and scale from entering the valve and damaging its sealing surfaces, thereby affecting the proper operation of the steam pressure relief valve. The steam pressure relief valve should be installed in a location that facilitates operation and maintenance, and it must be installed upside down on horizontal pipes. Care must be taken to ensure that the flow direction of the medium in the pipeline is consistent with the direction indicated by the arrows on the ball valve, hydraulic control valve, and valve body; it must not be installed in the reverse direction. Steam medium valves must be installed in reverse, and the condenser that comes with them must be positioned above the actuator, so that the actuator can be filled with condensate, thereby serving as a protective layer for the diaphragm. Extend the service life. When installing and using a steam pressure reducing valve, the condenser should be filled with cold water, and the shut-off valve on the bypass pipe should be opened in order to remove any condensate and mixture of water and steam from the pipeline. This prevents damage to the pressure reducing valve due to the formation of water droplets when the valve opens. Once there are no abnormal conditions, slowly turn the adjustment screw clockwise to set the outlet pressure to the desired level (based on the gauge pressure after the valve). After making the adjustment, tighten the lock nut and attach the protective cover. A filter should be installed before the pressure reducing valve to prevent debris in the medium from entering the valve and affecting its performance. 　　　 There should be a section of straight pipe before and after the installed pressure reducing valve; the length of the straight pipe before the valve is approximately 600 millimeters, while the length of the straight pipe after the valve is about 100–200 millimeters. 　　　 Generally, pressure relief valves require that the pressure difference between the inlet and outlet be ≥0.2 Mpa. 　　　 Pressure relief valves are generally available in various sizes ranging from DN15 to DN400. The operating pressures before and after the valve are respectively <1 MPa and 0.1–0.5 MPa, with a pressure regulation error of ±5%–10%. 　　　 Troubleshooting of Steam Pressure Reducing Valves Unstable pressure behind the valve, which changes as the pressure in front of the valve varies ； Reason for occurrence ； 　　　 1. The valve core is stuck by foreign objects ； 　　　 2 ； The valve stem and push rod are stuck ； 　　　 3 ； Clogged inlet pipe　　　　　 Removal method ； 　　　 1 ； Disassemble and reassemble to remove foreign objects. 2. Adjust again ； 　　　 3. Unblocking 　　　 The pressure drop behind the valve does not decrease; it remains above the required value ； Reason for occurrence ； 　　　 1 ； 1. The spring stiffness is set too high. 2. The valve diameter is too large. 3. The pressure before the valve is too high, resulting in an excessive pressure reduction ratio. Solutions: 1. Replace the spring. 2. Use a valve with a smaller diameter. 3. If the pressure before the valve to the pressure after the valve is greater than 10:1, a two-stage pressure reduction should be applied. The pressure after the valve fails to increase and remains below the desired value ； Reason for occurrence ； 　　　 1 ； The spring stiffness is set too low. 2. The valve diameter is too small. 3. The pressure reduction ratio is too low. Solutions: 1. Replace the spring. 2. Use a valve with a larger diameter. 3. If the pressure before the valve is lower than 1.25 times the pressure after the valve, increase the pressure before the valve. If the pressure before the valve cannot be increased and remains below the required value, ； Reason for occurrence ； 　　　 1 ； The spring stiffness is set too low. 2. The valve spool is stuck by foreign objects ； 　　　 3 ； The valve stem and push rod are stuck ； 　　　 4 ； Damaged valve core or seat, excessive leakage; 5. Excessively large valve diameter – Methods for elimination ； 　　　 1 ； Replace the spring. 2. Disassemble and reassemble again. 3. Adjust again. 4. Re-grind or replace it. 5. Use a valve with a smaller diameter. The pressure drop before the valve does not decrease; it remains above the required value. Causes ； 　　　 1. The spring stiffness is set too high. 　　　 2. The valve diameter is too small. 　　　 3. The valve core, valve stem, push rod, etc. are stuck. 　　　 Solutions: 　　　 1. Replace the spring. 　　　 2. Use a valve with a larger diameter. 　　　 3. Eliminate the cause of sticking and adjust again. 　　　 Frequent fluctuations in pressure behind or in front of the valve 　　　 Causes: 　　　 1. The valve diameter is too large. 　　　 2. The volume of the actuator’s chamber is too small. 　　　 Solutions: 　　　 1. Choose an appropriate valve diameter. 　　　 2. Install a damper in the liquid inlet pipeline