1. Main boiler details:

2. Boiler sketch

3. No.2 main boiler statement

Obvious deformation on the tubes panel from No.41 to No.61 counted from front side.

4. Repair scope:

4.1 Replacement of the successive 21 panel coil elements (from No.41 to No.61 counted from front side) in the pass 4 and pass 5 (shown as the following sketch marked with red square box).

Material: 2.25%Cr-1%Mo steel

Tube size: Φ38.1

The panel sketch	The panel replacement area

5. Repaired on site:

The replacement of the 21 panel tube coils in the pass 4 and 5 (from No.41 to No.61 counted from front side) of the superheater.

5.1 Isolate 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 21 panel coils in the pass 4 and pass 5（from No.41 to No.61 counted from front side）out of boiler.

5.5 Remove the old weld between tube ends and water headers by machinery, and then remove 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 Install the refractory support plates and casing plates at the bottom of boiler.

5.13 Build up new superheater corridor refractory.

5.14 Box up the boiler in order.