Dear All,Whenever there is an issue with the Antiscale dosing pump / motor for Hot / Cold cells, MED is being shutdown, even for short duration to resolve the issue. This is being practiced, thinking that Antiscale flow will not be sufficient to avoid scale formation on the surface of the tubes. Due to this reason, MED units are being Shutdown & started many times, which has its own impact on the PHE leaks in many occasions. To avoid such MED Shutdowns for the requirement of short duration isolation of Antiscale system (one by one), the below mentioned Operation strategy is suggested, without any compromise on safe plant operation.A. Logic Forcing: MED Trip on Antiscale dosing pump needs to be forced, to avoid MED trip while carrying out maintenance work on antiscale dosing pumps.B. Operation Sequence for Maintenance on Antiscale dosing pump to cold cells: (As per OEM design only one pump installed)1. Reduce MED load to 60 % production.2. Observe that Maximum of cold cells temperature is 45 deg C. (Scale formation is not expected at this temperature in cold cells)3. Increase Antiscale flow to hot cell to a value of 7.2 L / hr to maintain 4.1 ppm of Antiscale in makeup water4. Stop & Isolate Antiscale dosing pump to cold cell for rectification of defect.5. Defect rectification by Maintenance team (Maximum duration 3 hr)6. Normalise and start Antiscale dosing pump to cold cell with a flow rate of 5.48 L / hr7. Decrease Antiscale flow to hot cell to a value of 4.22 L / hr C. Operation Sequence for Maintenance on Antiscale dosing pump to hot cells: (As per OEM design only one pump installed)1. Maintain MED load at 100 %2. Increase Antiscale flow to cold cell to a value of 13.3 L / hr to maintain 4.1 ppm of Antiscale in cold as well as hot cells make up water3. Stop & Isolate Antiscale dosing pump to hot cell for rectification of defect.4. Defect rectification by Maintenance team (Maximum duration 3 hr)5. Normalise and start Antiscale dosing pump to hot cell with a flow rate of 4.22 L / hr6. Decrease Antiscale flow to cold cell to a value of 5.48 L / hr D. Normal flow rates of Sea Water & Antiscale are given below for reference:1. Total Sea Water make up Flow: 4060 T / hr2. Hot cells Sea Water make up flow 2214 T/ hr3. Antiscale flow at Sea Water make up inlet (Cold + Hot cells) : 5.48 L / hr (1.7 ppm)4. Antiscale flow at cell 1 to 5 (Hot cells) (Additional 2.4 ppm) :4.22 L / hr (1.7 + 2.4 = 4.1 ppm)5. Antiscale Density: 1.26 T / M3Note: Antiscale flow to Cold and Hot cells is set as mentioned above as per OEM (SIDEM) recommendationThis procedure is not applicable for MED # 11, as the Optimization test is going on in this unit.