Page 264 - Water Standards
P. 264
2 ) Horizontal pipe bending and the horizontal deviation
should not be larger than 0 15% and no larger than
20mm. The stand pipe verticality deviation should not be
larger than 0 2% and no larger than 15mm.
3) Rack pipes shall be in the same plane and the deviation no
larger than 5mm. The deviation of the distance between
pipes shall be between 0mm and +5mm.
4) The gradient of gravity water drain pipe and oil drain pipes
shall be in accordance with the direction of liquid flow and
it shall be between 0 2% and 0 3%.
7 The material of the flange sealing gaskets shall be in accord⁃
ance with the working medium and pressure requirements
8 Before the oil, water, gas and speed governing pipes are
used, the pipes shall be treated, washed and checked according to
the design requirements and relevant standards.
9 For an embedded pressure pipeline and its accessories, tight⁃
ness pressure test shall be done according to the requirements of
Item14 of Article 4 2 2 in this specification before the concrete place⁃
ment.
10 After the installation of air, water and oil pipe systems and
accessories, tests shall be done by pumping the air, water and oil
into the pipes. The pressure shall be raised to the rated working pres⁃
sure gradually during the tests. There shall be no leakage.
4 2 12 Installation of butterfly valves, ball valves and expansion
joints shall meet the following requirements:
1 Butterfly valve installation shall meet the following require⁃
ments:
1) For penstocks or spiral cases upstream or downstream of
the butterfly valves, the length outside of the concrete
wall shall be long enough to ensure sufficient working
2 5 7