At 1:00a.m, on 11 th Dec, the first hot tighteningbolt and sampling were carried out one hour rightafter dosing. And under this low pressure, the boiler was boiledwith NaOH & Na 3 PO 4 for 30 hours until 7:00 a.m.on 12 th December. It cost 3 hours to increase the pressure to 2.7MPa. The pressure of steam drum is unstable and lowdue to the need to use 0.6MPa steam to purge thepipeline for several times until the target below isclean. That’s why it cost 30 hours beforeincreasing the pressure