Page 235 - Water Standards
P. 235

sure or exfoliation, etc. Babbitt bearing liners shall have no flaws such as
                    dense pores, fissures, hard spots and exfoliation. The liner roughness shall be
                    less than 0   8μm.
                   —Trial assembly of the rubber liner and cylindrical liner with the shaft shall be
                    done and the total gap shall meet the design requirements. Both the difference
                    between maximum and minimum gap at each end and the difference between the
                    upper and lower end gap at the same azumath shall be no larger than 10% of the
                    actual measured average total gap.
                   —When the cylindrical liner meets the two requirements above, it shall not be
                    scraped any more. Determine whether the segmented bearing liner shall be
                    scraped according to the design requirements. When the bearing liner has been
                    scraped, there shall be uniform contact in the liner surface and there shall be at
                    least one contact point per square centimeter. Each segment  s non⁃contact area
                    shall be no larger than 5% of its area and the total non⁃contact area shall be no
                    larger than 15% of the total bearing liner area.
                   —There shall be close contact between the weight resisting cushion and the back
                    cushion seat of the bearing liner, and between the weight resisting screw nut
                    and screw nut seat  
                 2) Bearing liner installation shall meet the following requirements:
                   —The bearing liner shall be installed under the condition that the generator unit
                    shaft and thrust pad have been well adjusted to meet load⁃carrying
                    requirements, and that the turbine sealing ring gap and the generator air gap
                    meet the relevant requirements.
                   —During bearing liner installation, the gap shall be adjusted according to the
                    main shaft center position and the value and position of the barring gear  s throw.
                    The total installation gap shall meet the design requirements. However, for
                    generator units with only two guide bearings, the gap can be adjusted without
                    considering the throw.
                   —The allowable error of the segmented guide bearing liner gap shall be no larger
                    than ±0   02mm. The allowable error of the cylindrical guide bearing liner gap
                    shall be ±20% of the distributed gap value and the liner surface shall be verti⁃
                    cal  
                 3) Bearing installation shall meet the following requirements:
                   —The bearing sump / tank which contains thin oil shall have no oil leakage. A
                    kerosene penetration test should be done according to the requirements of Item
                    15 of Article 4   2   2 in this specification.
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