6.8　Sealing Oil System of Hydrogen-cooled Generator

6.8.1　Works for sealing oil system equipment and pipes shall comply with the relevant provisions in 6.1 and 6.7.

6.8.2　Inspection of gear sealing oil pumps shall comply with the following provisions:

1　The lubricating oil grooves at pump cover，pump casing end and bearing and gear central oil holes shall be correct and be well through.

2　Gears shall be in good contact，the tooth side clearance should be 0.15mm-0.30mm，but not greater than 0.50mm；the tooth tip clearance shall comply with design requirements.

3　The fitting of gear with shaft shall be tight without looseness.

4　The fitting of bearing pad with casing or end cover shall be tight without looseness，and shall have provision against rotation.

5　The bearing pad clearance is 1.2/1000-3/1000 of journal diameter，but must not be less than 0.10mm.

6　The radial clearance between casing and gear shall be no less than that of oil pump bearing，and should be 0.15mm-0.25mm.

7　The joint surfaces of oil pump casing and end cover shall be in good contact，and shall have no gap when checked with a 0.03mm feeler gauge after all bolts are tightened.

8　The total axial clearance at the pump cover and gear end is 0.10mm-0.25mm，and this clearance can be adjusted with the thickness of gaskets.

6.8.3　The circumference and end permissible deviation for gear oil pump and motor couplings centering is 0.10mm.

6.8.4　Inspection and installation of centrifugal sealing oil pump shall comply with the relevant provision in 9.1 to 9.3 of this part.

6.8.5　Inspection of screw type sealing oil pump shall comply with the following provisions:

1　The central oil hole of the driving screw shall be clean and through.

2　The internal clearance of screw pump shall comply with manufacturer requirements.

3　The mechanical seal at the end of pump shaft shall be in a sound condition.

4　The circumference and end permissible deviation for screw type oil pumps and motor coupling centering is 0.10mm.

6.8.6　The oil window shall be plexiglass and be clean and transparent，the joint surfaces shall be applied with oil-resistant packing and the threaded hole shall not penetrate through the housing.

6.8.7　The floating ball of floating ball controlling valve shall be free of leakage，when immersed in oil，the valve disc and seat of controlling valve shall be in good contact in coloring inspection.The controlling valve shall operate flexibly and correctly when assembled.

6.8.8　Leakage test of sealing oil cooler oil side shall be performed according to the provision in 6.7.9.Inspection and installation of compound corrugated plate oil cooler shall comply with the provision in 5.8.3 of this part，and oil-resistant packing shall be used between plates.

6.8.9　For gravity action oil-hydrogen differential pressure controlling valve，the piston operation shall be flexible，valve shall be installed vertically without slanting.The installation elevation should be 500mm higher than the sealing oil tanks.The sealing oil pressure guide tube leading to the bottom of piston shall be connected from the oil inlet close to the sealing pad，the guide tube shall have reduced resistance and be slightly sloped.

6.8.10　For the oil pressure balance valve in a double-flow ring sealing oil system，the piston operation shall be flexible，and valve be installed horizontal.The sealing oil guide tubes on hydrogen side and oil side shall be connected from the oil inlet close to the sealing pad，the two guide tubes shall be parallel，and with the identical bending angle，sloping and length.

6.8.11　The floating ball inside the oil sealing tank shall be securely fixed，the valve stem shall operate flexibly without blocking.It shall be in good sealing and free of leakage when closed.

6.8.12　There shall be free of missed weld between the diaphragm and tank body in the hydrogen and oil separating tank.The pipes shall extend into the tank by a length complying with manufacturer requirements.

6.8.13　Installation of sealing oil pipe，shall also comply with the following provisions in addition to relevant provisions in 6.1 and 6.7:

1　The sealing oil drain pipe shall have a sloping no less than 10/1000 in the drain direction，and the pipes shall be short and straight.

2　On the sealing oil return pipe directly to the turbine main oil tank，an oil sealing pipe shall be fitted upstream the main oil tank，at a height complying with design requirements.

3　The oil supply pipe shall be fitted with a local oil pressure gauge at the sealing pad seat.