Page 265 - Water Standards
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space for component assembly and welding.
                  2) When the butterfly valve has been installed, the center
                     line in the flow direction shall be determined according to
                     the actual centers of the spiral case and penstock. The de⁃
                     viation between the actual and design positions should not
                     be larger than 3mm. The position deviation ( be perpen⁃
                     dicular to the flow direction) should not be larger than
                     10mm. The butterfly valve  s horizontal and vertical devia⁃
                     tions shall be no larger than 1mm/ m measured after flange
                     welding. In case of butterfly valves of diameter larger than
                     4   0m, the deviation shall be no larger than 0   5mm/ m.
                  3) For convenience of moving the butterfly valve towards the
                     expansion joint when overhauling, enough distance shall
                     be left between the base bolts and bolt holes. The distance
                     shall be no less than the diameter of the rubber packing
                     between flanges.
                  4) The butterfly valve  s allowable assembly error shall meet
                     the requirements of Table 4   2   12-1  
                 Table 4   2   12-1  Allowable assembly error of butterfly valves
                                                             Unit: mm

             No           Item               Allowable error  Explanation
                                         Meet requirements of Item 10
                   Composite joints between the
             1                         of Article 4   2   2 in this specifi⁃  —
                 valve seat and foundation plate
                                       cation











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