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• Time of issue:2023-02-14 16:31
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(Summary description)1.Main boiler details: Maker:   MITSUBISHI MARINE BOILER CO.,LTD Type:    MB Design pressure:  7.65MPa    Class:  LR 2.Boiler sketch 3.No.2 main boiler statement 3.1 One tube in 5th pass leaks. 3.2 One tube in 3rd pass is in bad condition. 3.Repair scope: 4.1Replacement of successive 4 panel coil elements (sacrifice 3 panels as access) including the plugged coil in the pass 5 and the successive 4 panel coil elements including the corroded tube in the pass 3 of superheater (shown as the following sketch marked with blue square box). Material: 2.25%Cr-1%Mo steel Tube size: Φ38.1 5Repaired on site:  The replacement of the 4panels tube coil in the pass 5 and 4 panels in the pass 3 of the superheater  5.1Isolate and drain the main boiler. 5.2 Remove the cover under the superheater headers after remove the cladding and insulation sheet. 5.3 Remove the superheater corridor refractory in way of repair. 5.4 Cut the 4 panel coils in the pass 5(No.5, No.6, No.7&No.8 panel counted from front side）and pass 3（No.4, No.5, No.6 & No.7 coil counted from front side）out of boiler. 5.5 Remove the tube stubs out of superheater headers. 5.6 Dye check the tube holes in headers to make sure defect free after grinding. 5.7 Install and fix the new panel in position (the tube end is 2~4mm above the tube plate). 5.8 Heat the superheater headers to 150~200℃ 5.9 Weld the tube ends to super heater headers by coded welders. 5.10 Dye check the new weld to make sure defect free after cool down and polish. 5.11 Hydraulic test the boiler witnessed by attendant surveyor and client. 5.12 Build up new superheater corridor refractory. 5.13 Box up the boiler in order. Replacement of the control desuperheater  No.1 & No.2 main boiler furnace refractory repair   Touch up with refractory the furnace floor around the screen tubes for both boilers.