4.4　Casing，Bearing Pedestals and Sliding Pin System

4.4.1　During transport and storage of casing，the equipment bottom shall be protected with padding material，and they should be placed steadily at a flat surface to prevent deformation，protection shall be provided for machined surfaces and bolts against damage and rusting.

4.4.2　The inspection and records before installation of casing shall comply with the following provisions:

1　The anti-corrosive coating shall be removed before appearance check；the outer surface shall be free of crack，slag inclusion，double skin，overlap，porosity，casting sand or damage.Machined surfaces such as joint surfaces，sliding load bearing surfaces，flanges and cylinder grooves shall be clean and smooth，free of rust or dirt；the inside of steam chamber shall be cleaned thoroughly to make sure that there is no attachment.

2　For casings in sections to be assembled，the dislocation of horizontal joining sections and the deviation of concentricity of vertical sections shall conform to the ex-works records.

3　Inspection of casing joint surfaces shall conform to the provisions in Table 4.4.2，those unqualified shall be trimmed or be treated by manufacturer，and final records shall be made.

4　Slots at the intersection of vertical and horizontal joint of the casing with intruded coating shall be kept clean and through.

5　On both inner and outer side of casing，sealing surfaces of pipe flanges with working pressure of 1.96MPa and over and of governing valve flanges shall be inspected with color coating method，for contact in a complete ring，with its width no less than 2/3 of the width of the sealing surface.

6　The groove of casing exhaust section for connection with condenser or exhaust expansion joint shall conform to the specification in welding procedures.The sealing surface shall be flat in case of coupling.

7　A gap over 0.50mm shall be provided between the tightening bolt and bolt hole on the casing horizontal joint surface，to accommodate bolt expansion，and the gap between the casing claw connection bolts and bolt holes shall be able to accommodate casing expansion.

8　The location and diameter of casing drain holes shall conform to requirements on drawing，and the drain holes and pipes shall be well through.

9　Casing shall have complete plugs，which shall be reliably tightened and sealed.Excessive process openings shall be fitted with plugs and sealed by welding，and the plugs and welding material shall match that of the casing.

10　Hydrostatic test shall be performed for the steam chamber of the casing flange heating device.The test pressure shall be 1.25 times of the design pressure，no leakage shall occur when the pressure is held for 5min；or an oil penetration test can be performed，for which no oil leakage within 24 hours.

4.4.3　Casing bolts and nuts shall be inspected as specified below:

1　Bolts，nuts and threaded holes of casing shall be smooth without burr，the fitting of bolts and nuts shall be neither too tight or too loose，the bolts and nuts for HP and IP casings shall be marked with steel stamp and they must not be exchanged.

2　The materials of parts such as bolts and nuts of casings shall be inspected as per 3.1.9 of this part.

3　External thread with damage shall be ground with a triangle oilstone after trimming.Inner thread of threaded holes shall be repaired with dedicated taps.

4　For bolts requiring hot tightening，the joint surfaces between nuts，washers and casing shall be checked with color method and they shall be in good contact.

5　After inspection and repair of threads，they shall be coated with lubricant required by manufacturer for protection，to prevent collision or rusting.

6　The threaded part of casing bolts shall be fully screwed into the casing flange，with thread below the flange plane，the perpendicularity of threaded bolts with flange plane shall be checked and shall meet the requirements of manufacturer.

7　After the nut is tightened，the bolt end shall protrude from the nut by 2-3 pitches of thread.After cold tightening of cover nut，it shall be confirmed that there is a gap of 2 or more threads at the top of its bolt.Fitting of bolts with taper shall be performed as required by manufacturer.

4.4.4　Inspection of sliding pin system shall comply with the following provisions:

1　The sliding matching surfaces of sliding pin，pin slot and anchor plates shall be free of damage and burr，and the fitting with equipment shall comply with the requirements of manufacturer.

2　The corresponding dimensions of sliding pin and pin slot shall be measured at three points in the sliding direction with internal and external micrometers，the difference in dimensions measured at the three points must not exceed 0.03mm，and the gap shall comply with the requirements of drawings of manufacturer.After fitting of sliding pin and slot，a check should be made with a feeler gauge again for confirmation.

3　Sliding pin shall be securely fixed，and a tightening force should be provided when inlaying it directly，there shall be provision against loosening when fixed with bolts，and the bolt end shall be below the sliding pin surface.The transversal pins on the inner and outer cylinder horizontal joint shall be positioned after determining the axial position.

4　The sliding pin shall slide freely after trial fitting.When there are two sliding pins on the same soleplate at the same straight line，the measured value of transversal relative displacement shall be taken as the gap value.

5　The load bearing surface and sliding surface of sliding pin shall be checked with color coating method and they shall be in good contact.The locating dowels of sliding pins shall be smooth and free of burr，in tight fitting with the pin holes without offset inside the pin holes.

6　After tightening the link bolts of casing，bearing pedestals and soleplate，there shall be a gap of 0.04mm-0.08mm at the gasket.

7　The grease holes and ducts on the bearing pedestals sliding surface shall be clean and through，the pipes around and beneath the bearing pedestals must not restrict the expansion，and when sliding block structure is adopted for the sliding surface，the sliding block screw shall be removed after lapping as required by manufacturer.

4.4.5　For the shim thickness of casing push-pull device，after locating of casing，a fitting gap of 0.02mm-0.03mm shall be reserved for the measured gap value at the corners between the push-pull device and casing，and there shall be no jamming when the shim is fitted.

4.4.6　In case of excessive large sliding pin gap，patch weld or ion spray plating is permissible over the whole contact surface of sliding pin，and the patch weld or ion spray plating metal hardness shall not be lower than that of base metal.The sliding pin gap must not be adjusted with extrusion method.

4.4.7　During the works，protection shall be provided for casing joint surfaces，no hard metal parts shall be put on the joint surface，and it is not permissible to step on it with spiked shoes or knock it with a hand hammer or other hard metal object.

4.4.8　Casing assembling shall comply with the following provisions:

1　Before casing assembling，trial fitting without coating shall be performed，and the joint surfaces shall comply with the provisions in 4.4.2 of this part.

2　The sealing coating materials for casings can be selected with reference to Appendix B if there is no specific requirement from manufacturer.

3　For the assembled casing，the nuts for vertical joint surfaces shall be confirmed as being locked and spot welded before the casing is put in place，and in sealing weld of joint surfaces，provisions against deformation in welding shall be made.

4.4.9　Welding assembling of large LP outer cylinder without soleplate support shall comply with the following provisions:

1　The LP inner cylinder guide rod and push-pull device which cannot be mounted after locating of casing have been mounted in place in advance.

2　To position the front and rear end plates of casing，reliable temporary supports shall be provided，and the side plates on both sides can be aligned only after proper adjustment of the centers and elevations of front and rear end plates.

3　Spot welding of parts of casing can be done only after a recheck of centerlines and diagonal lines of all parts of casing to confirm their deviation is in line with drawing requirements.

4　Welding deformation shall be controlled during welding of casing.

5　After assembling and welding of casing，the permissible deviation of exhaust port diagonal lines and end plate parallelism is 10mm.

4.4.10　Inspection of turbine bearing pedestals shall comply with the following provisions:

1　The oil chamber and circuit of bearing pedestals shall be clean and through，paint dissolvable in turbine oil must not be used on inner surface，and oil-resistant paint shall not peel up.

2　After tightening the bolts on bearing pedestals horizontal joint surfaces，there shall be no gap at the joint surfaces when checked with a 0.05mm feeler gauge.

3　The joint surfaces around the pressurized oil holes shall be checked with color coating method，and the contact shall be continuous without interruption.

4　The bearing pedestals inlet and outlet oil pipe flanges shall comply with the provisions in 6.1.4 hereof，and the threaded holes on flange must not penetrate through the wall.

5　Oil filling test shall be performed for bearing pedestals oil chamber，and before oil filling，the inside and outside of bearing pedestals shall be cleaned，the oil filling level shall be no lower than the outlet upper edge of oil return pipe，and there shall be no leakage 24h after oil filling.

6　Provisions against oil permeation shall be made for I&C instrument wiring penetrating the bearing pedestals shell.

4.4.11　Installation of casing and bearing pedestals shall comply with the following provisions:

1　The longitudinal and transversal centerlines of casing and bearing pedestals shall comply with design requirements.

2　Before the casing is brought to place，the pipes and parts between the casing and foundation shall be installed in advance.

3　For a bearing pedestals with oil pipe beneath it，NDT shall be performed for the pipe weld seam before placing of bearing pedestals；after placing of bearing pedestals，the gap between the oil pipe vertical section and sleeve shall be able to accommodate the expansion of the unit.

4　The elevation of casing and bearing pedestals split shall comply with design requirements，with permissible deviation 5mm，and the distance from soleplate bottom and foundation concrete surface should be 50mm-80mm.

5　During turbine operation，with the maximum thermal expansion produced，the sliding surfaces of casing and bearing pedestals must not extend out of soleplate edge，and shall have margin.

6　The transversal horizontality of casing and bearing pedestals shall be measured using a spirit level with a precision no less than 0.02mm/m，the measuring positions shall be at the front and rear gland seal cavities or bush cavities，and when necessary，a straight edge and tripod can be used in the measurement.

7　The transversal horizontal permissible deviation of casing and bearing pedestals is 0.20mm/m；the longitudinal horizontality should be close to the rotor design up-rising inclination at that position.When it is not possible to satisfy both casing horizontality and casing load distribution，priority shall be ensured for load distribution and confirmation from manufacturer shall be obtained.

8　During turbine installation，measures shall be taken to prevent dust or sundries from entering the bearing pedestals sliding surfaces and sliding surface oil grooves.

9　After installing and locating of casing and bearing pedestals，the foundation pad block joint surfaces shall be spot welded on both sides，and anchor bolts shall be tightened.

4.4.12　Casing load distribution shall be according to the requirements of manufacturer，and comply with the following provisions:

1　Arrange load distribution with a dynamometer:

1）The dynamometer shall be checked and calibrated before use.

2）For load distribution，the casing shall be in free state，no force shall be applied to the jack or temporary pad blocks，and the sliding pins shall be free of jamming.

3）The dynamometer must not be used overload in adjusting load distribution.Adjustment shall be made by homogeneous micro-lifting，which should not be greater than 0.10mm each time，and it shall be adjusted in one way and must not be allowed to fall back midway.When heavy pieces such as upper casing are lifted，temporary backing shall be made beneath the soleplate.

4）When permanent blocks are laid，the load variation of their adjacent dynamometer must not be greater than 980N，the load value measured by dynamometer shall comply with design requirements，the load difference at symmetric positions on both sides of casing centerline shall not exceed 5%of average load of both sides.

5）The end load value measured by the dynamometer and the corresponding horizontal up-rising inclination of casing and bearing pedestals shall be recorded.

2　In load distribution，good contact of the claw transversal pin bearing surface，sliding surface and soleplate sliding surface shall be checked，and the result of check with a 0.05mm feeler gauge shall agree with that in trial fitting.In special cases，it is permissible to add a full steel adjusting shim between the non-sliding contact surfaces of claw transversal pins，and its thickness shall be no less than 0.10mm.

3　For a casing supported with front claws and soleplates on both sides，the load distribution may normally be adjusted according to the casing horizontality and claw drooping arc，and the LP casing installation of a multi-cylinder unit can be adjusted in conjunction with the casing split horizontality.

4　When claw drooping arc is used in casing load distribution，the casing shall be closed，and the permissible deviation of left and right drooping arc is 0.10mm.

5　For units with load distribution using claw differential method，the adjustment shall be made at front and rear claws respectively in closed state according to the requirements of manufacturer.

6　The casing horizontal and up-rising inclination measurement positions shall comply with the requirements of manufacturer，and be marked on the records.

4.4.13　The installation of casing unloader shall comply with the requirements of manufacturer.

4.4.14　The installation of casing atmospheric relief diaphragm shall comply with the requirements of manufacturer.

4.4.15　The installation of casing expansion indicator shall be secure and reliable，and its indication range shall cover the maximum expansion of casing.Before first startup of turbine，the indicator indication shall be adjusted to zero in cold state and be marked.

4.4.16　Installation of a unit supplied with integrated HP and IP casings shall comply with the following provisions:

1　The turbine rotor shall be fixed axially and radially at both ends of casing using dedicated devices.

2　During locating of casing，it shall be ensured that no relative displacement will take place between the rotor and casing.

3　In shaft system alignment，the casing and rotor shall be adjusted synchronously，and the radial gap at the gland seals of both ends shall comply with the manufacturer requirements.

4　The minimum axial and radial gaps shall comply with manufacturer requirements.

5　The axial locating dimensions of rotor shall be adjusted as per manufacturer requirements and be recorded.