Page 191 - Water Standards
P. 191
Table 3 9 5-2 Allowable form production error of spiral
cases and tailwater tube Unit: mm
No. Item Spiral case Tailwater tube
1 Form length and width ±5 ±5
2 Height between adjacent board surfaces 3 2
3 Local unevenness 5 3
4 Face slab crack 2 2
Note: Local unevenness means the deviation of a curved form from the design dimensions;
the error is checked by a 2m straight ruler for a flat form.
2 The equipping of the main items of machinery for concrete
transportation and pouring, as well as the productivity they may
reach, shall be decided according to the powerhouse characteristics,
such as complex structures shape, if there are many embedded parts
and much auxiliary work, etc.
3 The temperature control measures of the lower part concrete
shall meet the requirements in Articles 2 7 23, 2 7 24 and 3 3 6 of
this specification.
4 When the air temperature suddenly drops during the construc⁃
tion of the lower part concrete, the protection of the exposed surfaces
of the poured concrete structures shall be strengthened, and the
poured holes shall be closed off during the low temperature season.
3 9 7 Upper part concrete construction shall meet the following re⁃
quirements:
1 Upper part structures shall be finished before the crane opera⁃
tion.
2 An erection bay should be constructed in advance of the unit
bay, and the external crane should be used to hoist the crane into
place before capping the building, so as to create conditions for the
testing and pre⁃assembly of the components of the turbine⁃generators.
3 The parts related to the first stage power generation shall be
1 8 4