Power Sector Western Region
Technology Day
11th May 2009
Power Sector Western Region
TECHNOLOGICAL TOOLS
Power Sector Western Region
Use of Electrical Torque wrench for Tightening
Boiler Structure Bolts
At 1 x 500 MW Khaperkheda
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 4
Cycle time reduction in tightening boiler structure bolts
Background At boiler erection site thousands of BOLTED JOINTS are to be tightened
MANUALLY using DE Spanners for snug tightening & Torque tightening by trip torque type long handle torque spanner.
The process of bolting arrangement consumes enormous time for achieving desired results, including uniform tightening & ensuring a designed torque value.
This process was identified for taking up Improvement project because of the following
being repetitive in nature
time consuming
labour intensive
having substantial amount of preparatory work to be done before the starting actual process (set up time)
high level of risk involved (some locations for actual work place are above 80 meter above ground level & are to be performed on temporarily erected scaffoldings
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 5
Objective Reduction in time taken for complete bolting arrangement
necessary for a 500 MW Boiler erection (at Khaperkheda site about 40, 000 no. M24 Bolts of lengths 70 – 160 mm are used)
Ensuring designed tightness of bolting arrangement without further need of cross checking by Quality representative
Safer working conditions for Operator
Cycle time reduction in tightening boiler structure bolts
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 6
Evaluation of alternatives
1. Pneumatic torque wrench
Benefits
Available with leading hand tool manufacturers like Bosch, Ingersoll Rand & others.
Widely used in manufacturing plants (automotive assembly lines) where high turnover per day is the hour of need (but here the Operator has a fixed place & jobs move to his operating area one after another).
These wrenches are comparatively lighter.
Drawbacks for us
Difficulties in ensuring dry air to the wrench in all weather conditions
Maintaining desired air pressure at a long distance through a compressor
Requirement of supports since length of air pipes may extend up to 100 meters
Thus making the whole arrangement very clumsy & big.
Cycle time reduction in tightening boiler structure bolts
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 7
Evaluation of alternatives
2. Hydraulic torque wrench
Benefits
Available with leading hand tool manufacturers
Widely used in manufacturing plants
Drawbacks for us
Need sophisticated hydraulic equipment (difficult to maintain)
Require very good quality pressure hoses to feed optimum liquid pressure to the wrench limiting factors
Practically impossible to provide such facilities at sites
Cycle time reduction in tightening boiler structure bolts
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 8
Evaluation of alternatives
3. Electrically operated torque wrench
Benefits
Such wrenches are popular in assembly lines especially where job sizes are bigger & operator has to move around the job
Available with leading hand tool manufacturers
Electrical cables are much smaller, lighter & easily maneuverable
Operate at 1 phase ac supply abundantly available at all areas of sites
Cycle time reduction in tightening boiler structure bolts
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 9
Electrically operated torque wrench (contd..)
Results of Field Trial
M/s Tristar Industrial Tools Pvt limited was a source located for making a demo at Khaperkheda
Trial was successfully done on 10th April 2009 at a height of about 10 meters on Column number 19.
Time taken to fully tighten bolted joint by ETW was about 15 seconds as against 3 to 4 minutes by a handle type Trip Torque Wrench
Substantial saving in operation time for the activity
Saving in manual effort by Operator
Positive assurance of Quality of bolted joint.
Cycle time reduction in tightening boiler structure bolts
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 10
Electric wrench for tightening boiler structure bolts
Technische Daten DEA – Technical data DEA
PLARAD – GERMANY MakePLARAD – GERMANY MakeTechnische Daten DEA – Technical data DEA
Our selectionOur selection Type DEA 12 TLX Torque 200 – 1220 NM Weight 6,8 kgType DEA 12 TLX Torque 200 – 1220 NM Weight 6,8 kg
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 11
Electric wrench tightening of boiler structure bolts
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 12
Electric wrench tightening of boiler structure bolts
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 13
Expected Benefits
Tangible Saving in Time - On average saving of about 3 minutes per bolt
Saving in manpower cost
No need for Quality representative to ensure desired objective of proper tightness
Additional helper to hold spanner and a trip torque wrench, not required.
Intangible Safety of Operating Personnel (Operators & others assisting him)
from any Accidental fall due to Slipping
Slipping / Falling of the job from temporary scaffolding
Better safety of personnel on ground from falling of long torque wrench etc.
Cycle time reduction in tightening boiler structure bolts
Power Sector Western Region
Measurement of Face Run- out of IP & LP Rotors by improvised technique at site
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 15
Measurement of Face Run- out of IP & LP Rotors
Normal Practice
Normal practice of measurement of face run-outs of IP & LP Turbine Rotors is
To place them on saddle supports and rotate them (There is only an arc of contact between the saddle and the rotor).
A pin is made and inserted in one of the coupling holes.
A wire rope is wound around the rotor with the pin at one end and the crane hook of the EOT at the other.
Lifting action of the crane hook causes rotation of the rotor.
To aid in rotation of the rotor, copper sheets are placed in between the saddle and the rotor and, grease is smeared to reduce friction during rotation.
Contd…
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 16
Measurement of Face Run- out of IP & LP Rotors
Normal Practice (Contd..)
The normal method has few problems associated with it
1. It is not possible to restrict axial movement of the rotor in order to avoid overshooting the range of the dial gauge.
2. Area of contact being very small, it requires extreme care and control while operating the EOT, lest it should cause an irreparable accident and lead to loss to both men and material.
3. It has often been noticed that there is quite an error between the measurement made at shop and those made at site leading to avoidable loss of time in correspondence, summoning experts from MUs, etc.
4. It gives the feeling of using a very primitive and un-reliable method of measurement.
5. Overall, it is never like measuring the run-outs by anchoring the rotor on a lathe to take the measurements and that’s exactly the cause of the error.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 17
Measurement of Face Run- out of IP & LP Rotors
Suggested New Method
A simple device is made at site using the following material
Shaft of 40mm Ø x 1000mm long 1 no.
Ball Bearings with Plummer block for above shaft 2 nos.
Supports to anchor the Plummer blocks 2 nos.
Cross arm 1 no.
Dial Gauges for mounting to X-arm 2 nos.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 18
Measurement of Face Run- out of IP & LP Rotors
Brg with Plummer Block
Cross Arm
Shaft Support provided by UnitExternal Support for anchoring the Plummer Block
Dial Pointers
Dia 40 Shaft
Fixture developed and used
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 19
Measurement of Face Run- out of IP & LP Rotors
Advantages User friendly and costs only Rs.5000/- to make.
Does not require too much of a precision in machining the shaft.
Does away with repeated rotation of the rotor for every reading.
Reduces the risk of the rotor toppling during rotation by EOT crane.
Compares well with the values attained at works on a lathe.
Stator lifting by Strand Jack Method at 1x250MW Unit#8 TATA Stator lifting by Strand Jack Method at 1x250MW Unit#8 TATA TrombayTrombay
This was the 1st time the Generator Stator has been lifted by Strand Jack Method in PS-WR. Also, this is the 1st for 250MW Stators in the whole of BHEL. Picture shows Stator lifted off the Blocks.
Stator lifting by Strand Jack Method at 1x250MW Unit#8 TATA Stator lifting by Strand Jack Method at 1x250MW Unit#8 TATA Trombay….ContdTrombay….Contd
Stator lifting in progress
Stator lifting by Strand Jack Method at 1x250MW Unit#8 TATA Stator lifting by Strand Jack Method at 1x250MW Unit#8 TATA Trombay….ContdTrombay….Contd
Stator lifted and being moved inside the A-Row of TG Building
Stator lifting by Strand Jack Method at 1x250MW Unit#8 TATA Stator lifting by Strand Jack Method at 1x250MW Unit#8 TATA Trombay….ContdTrombay….Contd
Stator lifted above the bottom of TG Deck and ready to be moved inside for placement.
Stator lifting by Strand Jack Method at 1x250MW Unit#8 TATA Stator lifting by Strand Jack Method at 1x250MW Unit#8 TATA Trombay….ContdTrombay….Contd
Picture shows the Strand Jack Hydraulic Control System
Stator lifting by Strand Jack Method at 1x250MW Unit#8 TATA Stator lifting by Strand Jack Method at 1x250MW Unit#8 TATA Trombay….ContdTrombay….Contd
Picture shows stator in position
The entire operation was completed in 4 hrs from the start.
Power Sector Western Region
PORTABLE INDUCTION HEATING MACHINE
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 27
INDUCTION HEATING MACHINEConventionally, we at BHEL Power Sector Sites have been using the Induction Heating Machines of EDN Bangalore make. There are certain disadvantages of using this equipment listed below:
1. Too bulky and comes in two parts – one the Induction Heating Equipment proper and the other, the operator’s panel. Weighs a few tonnes.
2. Due to its bulk, moving the machine to different areas of work is an arduous task. Each shift of the machine is a 1 ½ days activity.
3. Often, it has been seen that when the machine is moved from one location to the other is has not been in use for a few months, the next re-start is faced with quite a few problems. The reason is not known.
4. Getting spares on time for the equipment is a big issue. This results in machines with minor repairs and requiring spares quarantined.
5. Overall the machine is not user-friendly
6. Costs around Rs. 75 Lakhs per machine
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 28
Induction Heating Machine -….Contd
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 29
Induction Heating Machine -….Contd Alternatively, there are machines available in the market and being
used by our competitors that is a vast improvement on the EDN Make machine and has the following advantages:
1. Very small and easily portable, thus rendering easy movement of the machines to various locations without loss of vital erection cycle time. Requires only a 2-3 hrs for shifting and re-connecting. The entire machine is as compact as welding transformer and is single modular. Weighs approx. 105Kgs.
2. The connections are very simple and does not need expertise.
3. Though imported, has a presence in the Indian market for the last 3 years and has been used to weld pipes of 94mm thick at Sipat. The machine can be used to thicknesses in excess of 100mm pipes as well. The size of MS Pipe for the proposed 660MW Unit with Full Flow is Φ660 x 102mm.
4. Costs only Rs.30 Lakhs. For every one machine of EDN Make, one can two of this kind.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 30
Induction Heating Machine -….Contd
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 31
Induction Heating Machine -….Contd
660 MW 800 MW
System Material Size Material Size
MS - Half Flow
P91 OD 508 x 80 P91 ID 370 x 66
MS – Full Flow
P91 OD 660 x 102 P91 ID 480 x 90
HP Bypass – U/S
P91 OD 355.6 x 52 P91 OD 355.6 x 54
HRH – Half Flow
P91 OD 711 x 40 P91 OD 813 x 49
HRH – Full Flow
P91 OD 864x48 P91 OD 1016 x 58
LP Bypass – U/S & D/S
P91 OD 711 x 40 / OD 1219 x10 (SA691 2 ¼ Cr)
P91 OD 864 x 50 / OD 965 x 35
Power Sector Western Region
Induction Heating for Opening & Tightening Casing fasteners of Steam Turbine
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 33
Induction Heating for opening & tightening Casing of Steam Turbine
Introduction Casing of steam turbines are tightened together by using
threaded fasteners of M48 to M140 size .
These fasteners referred commonly as studs and cap nuts have to be tightened firmly to withstand the high internal pressure and temperature.
During the tightening process, specified value of elongation has to be achieved so that during working at high temperature, the nuts will not slacken .
A recommended practice for tightening these fasteners is heat tightening.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 34
Induction Heating for opening & tightening Casing of Steam Turbine
Commonly used devices for heating the fasteners
Electric heaters - which include heater elements, cables, power source /transformer of high capacity etc.
Gas heaters. This is relatively simpler method which uses the specially fabricated bolt heating devices - Gas Torches with special nozzles, and oxy-acetylene cylinders , compressed air supply etc.
Main disadvantages of the above two methods
Long time taken for the operation
Due to the slower rate of heating, effectiveness of these methods is less and some other problems such as seizure of the threads also occur quite frequently.
Apart from this, the arrangements required are also complex and time wasted in maintenance / repairs of the equipment in case of defects is quite considerable.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 35
Induction Heating for opening & tightening Casing of Steam Turbine
Induction heating method for threaded fasteners
Induction heating method is being used in other site applications such as preheating of joints for special welding of alloy steel pipe lines in thermal power stations.
This method is very quick and effective means for heating.
By using some modified gadgets, it was found suitable for loosening and tightening of the big size threaded fasteners of steam turbines, valves etc.
SAS Nagpur decided to use the induction heating method for loosening and tightening of threaded fasteners.
This method has resulted in saving valuable time for dismantling and assembly of steam turbines during overhauls. The method is simple and highly effective.
With the use of induction heating method, the problem of seizure of threads necessitating cutting and gouging of the nuts and studs, in LMW design, has been minimized.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 36
Induction Heating for opening & tightening Casing of Steam Turbine
Comparison of time required for bolt opening
210 MW /500 MW KWU Electric/ Gas Heating Induction Heating
HP inner casing 6 hrs 3 hrs
IP Outer casing 10 hrs 7 hrs
IP inner casing 14 hrs 8 hrs
Time saved for overhauling is 3 days .
For a 210 MW set this translates into a gain of 5.04 million units perday i.e approx. Rs. 2 crore per day
For 500 mw set, 12 million units per day i.e.approx. Rs.4.8 crore perday
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 37
LASER ALIGNMENT KITLASER ALIGNMENT KIT
OBJECTIVETo carry out various alignment works in Turbine erection With high precision. At a reduced cycle time.
WORKS CARRIED OUT Catenary of pedestals Centering of bores of Diaphragms, Pedestals, Shaft Seals etc. Alignment of Rotors.
CATENARY OF PEDESTALS
Accuracy of 10 Microns achievable.Source equipments to be placed at extreme pedestals.Mobile equipment placed in intermediate pedestals.Laser is passed thro mobile equipment and adjustments carried out as per requirement.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 38
LASER ALIGNMENT KITLASER ALIGNMENT KIT
Centering of Bores of diaphragms,pedestals,shaft seals etc
Source Laser device fixed in one extreme end pedestalReceiver end device fixed in other extreme pedestal.Special fixtures used for centering of intermediate pedestals.Online adjustment possible.
Alignment of RotorsCan cater to Coupling Dia from 100 mm to 1200 mm.Alignment Device fixed on couplings to be alignedTotal misalignment is indicated by just 60 degree rotation of Rotors.Misalignment values as well as correction required indicated in display.
Salient AdvantagesSaving in Cycle time.Accuracy of Measurement.Indication of correction factors.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 39
LASER ALIGNMENT KITLASER ALIGNMENT KIT
CONCLUSION
The Laser Alignment kit is a useful equipment that is State of the Art in Technology and can be used very effectively in Turbine activities at high precision and reduced cycle time, as has been proved in Kudankulam site.Hence extensive use of this equipment has to be practiced.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 40
ORBITAL WELDINGORBITAL WELDING
Purpose – To provide leak proof joint between Tube to tube sheet in Condenser in addition to Forced expansion
Process – GTAW without filler wire addition
SIGNIFICANT ASPECTS
Material-Titanium
Large Qty of welding
Welding in position & at site
Material supply by Russians
TITANIUM TUBES
Grade : ASTM B 338 Gr2
Tube Sheet : 35 + 5 mm thick
Material : ASTM A516Gr 70 + ASTM B 265 Gr 1 CLAD
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 41
ORBITAL WELDINGORBITAL WELDING
Why Titanium is used?
Provides excellent resistance to general and localized attack under most oxidizing, neutral and inhibited reducing conditions in aqueous environments.
Corrosion Resistance due to stable, protective strongly adherent oxide film which forms instantly when a fresh surface is exposed to air moisture.
This film is transparent and not deducted by visual means.
Titanium resist corrosion by sea water to temperature as high as 260 0 C.
Even exposed to sea water for many years at a depth of over a mile shows no measurable corrosion.
Provides over 25 years of trouble free sea water service for chemical refinery de-salination and nuclear industries
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 42
ORBITAL WELDINGORBITAL WELDING
Has the ability to resist erosion by high velocity sea water
The presence of abrasive particles such as sand has only a small effect on the corrosion resistance of Titanium
Production began in the late 1950s
Most widely used titanium is commercial pure (99.5 % Ti)
Manufacturing Process
Ingot →slab → Hot strip → cold strip → Slitting → Forming → TIG Welding → Stress relieving → Eddy Current & Ultrasonic testing
Tensile, flare, flattening & reverse flattening
Visual InspectionCleanliness, ID, OD, Surface condition, end condition and marking.
Tube to tube sheet joiningContact Rolling (0 to 5 % wall thinning for a length of 10 mm)
Orbital Welding – For highly reliable leak tightness
Forced Rolling (8 to 10 % wall thinning for a length of 25mm)
Physical TestingORBITAL WELDINGORBITAL WELDING
PROCESS FLOW CHARTFront / Rear end tube sheet cleaning – wire brush mounted in portable drilling machine
followed by acetone
Visual inspection
Titanium tube insertion
Initial cleaning before contact rolling
Initial contact rolling up to 10mm
Sh 1 of 3
End facing of tube & tube sheet up to 0.05 mm
Welding
Visual inspection
Rectification of repair work
Final expansion 8 to 10 % by lubricating SAE 40 oil
Excess length trimming in the rear side
PROCESS FLOW CHART CONTD… Sh 2 of 3
Tube tightness test by MAUS Gun G-150
Dye Penetrant testing
Final cleaning by acetone
PROCESS FLOW CHART CONTD… Sh 3 of 3
TUBETUBE SPECIFICATIONSPECIFICATION
TUBE INSERTION AT KODAMKULAMTUBE INSERTION AT KODAMKULAM
FRONIUS MODEL - FPA 2000 (AUSTRIAN MAKE)
PROGRAMABLE ORBITAL WELDING MACHINES
AFTERAFTER TUBE INSERTIONTUBE INSERTION
TUBETUBE SHEET PROTECTIONSHEET PROTECTION
Welding parameters for FRONIUS MODEL - FPA 2000
Process : GTAW (Automatic )
No of weld passes 1Argon Gas flow rate 4 to 6 ltr /min
Pre Gas time T10 30 Sec Post Gas time T11 30 Sec Pre Fusion current I21 90A Pre fusion current time T21 0.1Sec Pulse current I22 90A Time of pulse current T22 100msec
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 53
USE OF HYDRAULIC OPERATED TORQUE CONTROLLED BOLT USE OF HYDRAULIC OPERATED TORQUE CONTROLLED BOLT TIGHTNING KITTIGHTNING KIT
OBJECTIVETo adopt a safe ‘State of the Art’ methodology in bolt stretching of coupling bolts of TG Couplings.
GENERAL COUPLINNGS IN TGHP Tubine to IP TurbineIP Turbine to LP TurbineLP Turbine to Generator Shaft
REQUIREMENTThe coupling bolts which are like pins, having a clearance of 0.03mm diametrically, have to be stretched up to 0.55 mm ,depending on the bolt dimensions to ensure uniform tightening .
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 54
USE OF HYDRAULIC OPERATED TORQUE CONTROLLED BOLT USE OF HYDRAULIC OPERATED TORQUE CONTROLLED BOLT TIGHTNING KITTIGHTNING KIT
Prevalent practiceNut of the Coupling bolt is tightened by a box spannerLeverage applied on end of the spanner by EOT crane through slings.Differential expansion monitored by Dial Gauge positioned at bolt ends.
Sources of ErrorDial gauge at the nut end has to be fitted with a long extension rod,which may lead to error in reading.Disturbances in the nut also can lead to erratic readings.
Safety element
The whole stretching operation dependent on skill of the Fitter and EOT Crane operatorFine movements in EOT Crane not possibleDanger of slipping/shearing always present.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 55
USE OF HYDRAULIC OPERATED TORQUE CONTROLLED BOLT USE OF HYDRAULIC OPERATED TORQUE CONTROLLED BOLT TIGHTNING KITTIGHTNING KIT
RECOMMENDATIONHydraulically operated Torque controlled Bolt tightening kit can be used.Manufacturing Unit to specify Torque tightening values of individual couplings.
ADVANTAGESNo error in reading.Uniformity in bolt stretchingSafe for the working personnelSafe for the equipment
Power Sector Western Region
IMPROVED PROCESSES
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 57
ALL-VOLATILE & OXYGENATED TREATMENTALL-VOLATILE & OXYGENATED TREATMENT
`
AVT : The basic idea of AVT is to minimize corrosion & erosion corrosion in the low temperature region by using deaerated high purity water with elevated PH. The actual PH range depend on cycle metallurgy In absence of Oxygen, the primary reaction of iron dissolution is inhibited by increasing PH. The solubility of ferrous hydrazine rises with increase in temperature and then decreases with steep drop to the solubility of magnetite between 200 – 250 0C. This results in undesirable magnetite deposit in this temperature range.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 58
ALL-VOLATILE & OXYGENATED TREATMENTALL-VOLATILE & OXYGENATED TREATMENT
`
To maintain the solubility of ferrous hydroxide in feed water below or equal to that of magnetite at 250 0C and to exclude the possibility of over saturation, a minimum PH of 9.6 should be maintained. A PH of 10 would be even better. Hydrazine acts both as a O2 scavenger & corrosion inhibitor by formation of ferrous oxide hydrate.
OXYGENATED TREATMENT :This process uses oxygenated high purity water to minimize corrosion & erosion corrosion in the feed water train. Oxygen, Hydrazine peroxide, air are used as oxidants
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 59
ALL-VOLATILE & OXYGENATED TREATMENTALL-VOLATILE & OXYGENATED TREATMENT
`
Oxygen level should be 30-50 ppb for drum units and 30-150 ppb for Once Through Units. Ph level shall be 9-9.6 at Drum units and 8-8.5 for Once Through Units In oxygenated system, p rotective layer consists of Magnetite(FE3O4) and Hematite(FE2O3) layers For temperature ranges upto 250 0C the addition of oxygen allows the formation of oxide protective layer which have a very low corrosion product release rate in the following water
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 60
ALL-VOLATILE & OXYGENATED TREATMENTALL-VOLATILE & OXYGENATED TREATMENT
AL L VOLATILE TREATMENT (AVT)
• Ferrous or mixed feedwater train
• Cation conductivity 0.2-0.4 μS/cm
• pH 8.8 – 9.6 (Dependent on feedwater metallurgy)
Fe 10ppb N2H4 ( >3x02)
O2 <5ppb NH3 ( 0. 15-2 . 3 ppm)
Fe <2 ppb O2 ( >30 ppb ) O2 ( >30 ppb )
NH3 ( 20 -70 ppb )
OXYGENATED TREATMENT (OT)All ferrous feedwater train Cation conductivity < 0. 15 μS /cmpH 8.0 – 8.5
HP Heaters
Boiler BFP DA LP Heaters
CP CEP Condenser
HP Heaters
BFP
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 61
LP BYPASS SYSTEMLP BYPASS SYSTEM LP BYPASS SYSTEM
MODIFICATION CARRIED OUT IN OLD LPBP SYSTEM
In case of Turbine trip, direct command will be issued to LP Bypass valves for opening upto 45% for 3 secs.
It is expected that within this 3 secs., the spray valves will open and the spray water pressure will be achieved.
However, if the spray water pressure has not reached a value of 5 kg/cm2 within 3.5 secs., or the condenser wall temperature has become more than 90 0C, the LP Bypass trip command will be issued
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 62
LP BYPASS SYSTEMLP BYPASS SYSTEM
The sensing of pressure is done by installation of additional pressure transmitters at the downstream of spray water valves
The modification was implemented first in Vindhyachal U#10 and two occasions since the modification, the turbine has tripped and LP Bypass valves opened within 5 secs thereby saving the boiler trip
LBPB SYSTEM FOR NEW 250 MW SETS
To address this issue, now BHEL, Hwr has gone for a new High Pressure LP Bypass system which has much better response time. Such system have been supplied at 1 x 250 MW Parli, 1 x 250 MW Paras, 4 x 250 MW JPL and 2 x 250 MW Bhilai sites.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 63
LP BYPASS SYSTEMLP BYPASS SYSTEM
The logic provided for the operation of the LB Bypass valves are similar to that of the older low pressure LPBP valves. However, the following are the new features of High Pressure LPBP valves
The LPBP valves on sensing increase HRH Pressure, automatically opens without looking for adequate water pressure
For the water injection spray control valves, two curves have been implemented, one for control and the other for protection based on down stream pressure of LPBP valves.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 64
LP BYPASS SYSTEMLP BYPASS SYSTEM If the actual water injection flow is less than flow
corresponding the protection flow, then the LPBP valves closes on water injection flow protection.
The following problems have been noticed in the new system
As per the water injection curve, a continuous water flow is required to the system which is unnecessary and wasteful.
The spray water flow element and flow transmitter is showing 0 reading upto 50% of spray control valve opening.
The problem has been taken up with BHEL, Haridwar
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 65
LP BYPASS SYSTEMLP BYPASS SYSTEM
Conclusions :
The new High Pressure system is working satisfactorily and therefore, the boiler tripping due to reheater protection in the new system has been avoided in the recently commissioned units.
By implementing the modification in the old units as done at NTPC Vindhyachal U#9, 10, the problem of the old units can also be resolved.
Power Sector Western Region
BEST PRACTICES
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 67
CARD BOARD BLASTING OF LUB OIL AND CONTROL OIL LINES OF STEAM TURBINES
GENERAL PRACTICE
Only mechanical cleaning is done before start of oil flushing for lub oil and control oil system of steam turbines.
BEST PRACTICE
Exhaustive card board blasting along with mechanical cleaning is carried out for all the control and lub oil system before start of oil flushing.
This practice is being followed in almost all the sites now.
ADVANTAGES
Effective cleaning and time reduction.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 68
USE OF PORTABLE CENTRIFUGE DURING LUB OIL FLUSHING OF ROTARY MACHINES
GENERAL PRACTICE
Generally oil flushing were carried out at ambient temperature without any centrifuging arrangement for rotary machines such as BFP, ID Fans, FD Fans and Mills.
BEST PRACTICE
Oil flushing is carried out with portable oil centrifuge having in-built heating arrangement .
ADVANTAGES
Effective cleaning and time cycle reduction.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 69
CHEMICAL CLEANING OF PRE BOILER SYSTEM WITH CEP
GENERAL PRACTICE
Carried out by using temporary pumps, tanks and piping along with boiler acid cleaning setup
BEST PRACTICE
Existing CEP and Hotwell are used for the purpose of circulation in the entire system
ADVANTAGE
Effective cleaning of the entire system with minimum number of temporary loops
Cost and time cycle reduction
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 70
USE OF DEAERATOR AS MIXING TANK FOR PRE-BOILER FLUSHING
GENERAL PRACTICE
Mixing tanks and associated pipings are arranged for carrying out the pre boiler flushing activities.
BEST PRACTICE
For industrial sets, Deaerator itself is used as mixing tank for carrying out chemical cleaning of pre-Boiler system.
This results in cost and time cycle reduction.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 71
CHEMICAL CLEANING OF BOILER (WW, SH) AND MS LINES IN INDUSTRIAL PROJECTSGENERAL PRACTICE
Stages are : Alkali boilout, Acid cleaning and passivation
BEST PRACTICE
Alkali flushing, Citric acid cleaning, passivation of the entire system
ADVANTAGE
Chemical cleaning activities can be completed even before Boiler light up
Since both SH and MS lines are acid cleaned & steam blowing cycle is considerably reduced
Cost and time cycle reduction
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 72
CHEMICAL CLEANING OF HSD AND NAPHTHA LINES IN CCPP
GENERAL PRACTICE
Cleaned by card board blasting
BEST PRACTICE
Citric acid cleaning with passivation
ADVANTAGE
Where the length of HSD and Naphtha lines is more than 500 meters cardboard blasting shall not be very effective. Hence, citric acid cleaning is a most effective way of ensuring cleanliness of the entire piping
Time cycle reduction and trouble free operation
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 73
USE OF THERMIC FLUID HEATER FOR COMMISSIONING ACTIVITIES IN GREEN FIELD PROJECTS
GENERAL PRACTICE
Auxiliary boiler is used for generation of steam for pre-commissioning activities like flushing of Boiler Feed Line, Condensate Lines, Drip Lines etc.
BEST PRACTICE
Thermic fluid heater is used in green field projects in place of auxiliary boiler for carrying out chemical cleaning activities.
This results in cost and time saving.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 74
ACID CLEANING WITH EDTA
GENERAL PRACTICE
Generally HCL is used for acid cleaning of main boiler.
BEST PRACTICE
HCL is replaced by EDTA for all green field projects especially, where auxiliary steam is not available.
This is safe, environment friendly and reduces time cycle.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 75
PROVISION OF ADDITIONAL INTERSTAGE VALVES FORSTEAM BLOWING
GENERAL PRACTICE
Interstage valves are not used during steam blowing operations resulting in three to four days shut down for start of subsequent steam blowing operations.
BEST PRACTICE
Additional temporary valves are used at Main Steam HP Bypass lines, CRH Lines during steam blowing operations.
This has resulted in cycle time reduction.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 76
CONTINUOUS STEAM BLOWING IN CCPP
GENERAL PRACTICE
Puffing method is used due to limitation of fuel firing system
BEST PRACTICE
Continuous blowing method (30 minutes) is used in stages
ADVANTAGE
Effective cleaning and time cycle reduction
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 77
HIGHER STEAM BLOWING PARAMETERS
GENERAL PRACTICE
Steam blowing is carried out at 40 Kg / sq cm and 300 – 350 deg C
BEST PRACTICE
Steam blowing carried out at 50 Kg / sqcm and 370 – 400 deg C
ADVANTAGE
Effective cleaning due to higher disturbance factor at elevated parameters
Time cycle reduction
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 78
USE OF FRESH LUB OIL BOTH FOR FLUSHING AND REUSE IN ALL INDUSTRIAL SETS
GENERAL PRACTICE
Flushing oil is used for oil flushing operation, fresh oil is used for normal operation
BEST PRACTICE
After cleaning of entire lub oil system by cardboard blasting fresh oil is used both for flushing and normal use
ADVANTAGE
Cost and time cycle reduction
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 79
AIR LEAK TEST OF LUB OIL, CONTROL OIL, AND CONTROL FLUID SYSTEM
GENERAL PRACTICE
No separate test conducted before start of flushing resulting in leakage of oil / fluids
BEST PRACTICE
Entire system is pressure tested with compressed air at 5 to 6 Kg/sqcm before start of flushing operation
ADVANTAGE
Leakage of oil and control fluid is minimised
Cost and time cycle reduction
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 80
GENERATOR SEAL OIL FLUSHING
GENERAL PRACTICE
Seal oil flushing is done for the site erected pipes upto the inlet nozzle in the end shield
BEST PRACTICE
Pre-fabricated pipes from the end shield upto seal ring inlet are also included in the final stage of flushing.
ADVANTAGE
Avoids damage to Generator seal from the entrapped foreign material.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 81
HYDRAULIC TEST OF LUB OIL, CONTROL OIL AND SEAL OIL LINES
GENERAL PRACTICE
Jacking oil pumps were used for carrying out hydraulic test of lub oil, control oil and seal oil line after flushing.
BEST PRACTICE
AC seal oil pimp is used for the purpose of hydraulic test of the above system.
ADVANTAGE
Avoids damage to Jacking oil pumps.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 82
CONDENSER MASS FLUSHING
GENERAL PRACTICE
Cleaning of condenser is normally carried out during steam dumping operation
BEST PRACTICE
Condenser tubes are thoroughly flushed through high pressure jets (fire fighting water) before commissioning of CEP
ADVANTAGE
Duration of steam dumping operation reduced
Cost and time cycle reduction
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 83
CLEANING OF VACUUM PUMP SUCTION LINES
GENERAL PRACTICE
No structured cleaning is envisaged except draining the system through drain valves (NB50) during initial commissioning of vacuum pumps
BEST PRACTICE
Vacuum pumps suction lines are throughly cleaned through cardboard blasting before commissioning of vacuum pumps
ADVANTAGE
Smooth trouble free operation
Damage of vacuum pumps due to entry of foreign material is avoided
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 84
OLTC COMMISSIONINGGENERAL PRACTICE
OLTC is commissioned normally after attaining continuous operation of unit, i.e., CW system has been put into service for prolonged period
BEST PRACTICE
OLTC is commissioned either
Immediately after running of CW pump or
Before conductance of PG test after thorough cleaning of condenser tubes
ADVANTAGE
Collection efficiency of balls increase
Trouble free condenser operation
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 85
SELF CONTAINED BEARING COOLING ARRANGEMENT AT EPC PROJECT
GENERAL PRACTICE
Lub oil coolers for ID, FD and PA Fans are kept charged through the bearing cooling water system
BEST PRACTICE
In EPC project where due to certain circumstances there is a delay in commissioning of Cooling Water system a separate self contained cooling arrangement (Sintex tank, pumps and suitable hoses) to facilitate initial commissioning
ADVANTAGE
Trial operation of all major boiler auxiliaries can be completed by this method leading to time cycle reduction
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 86
PRE ERECTION CHECKING OF BUS-DUCTS
General Practice
Bus-ducts are cleaned and erected
Commissioning jobs taken up later
Best Practice
While at ground, check tightness of all electrical connections of heaters, thermostats etc
Check heaters healthiness and adjust thermostat tripping points easily now
Check drain pad holes before lifting so that any corrections, if required can now be done easily
Trial assembly of Bus-duct structure on ground before erection
Avoids difficulty in commissioning / troubleshooting
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 87
TURBINE X-CRITERIA
General Practice In X1 criteria for turbine rolling, main steam inlet temperature to
turbine has been used for criteria calculation. During any boiler trip and restart, X1 criteria gets fulfilled even though boiler outlet temperature is less. This leads to cold steam entering the turbine.
.
.Best Practice
Additional criteria X11 introduced using Temperature before HP bypass.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 88
ADDITIONAL TRIPPING DURING ATT
General Practice Tripping criteria during conductance of ATT does not include many
vital trip inputs
.
.Best Practice
Conditions like MFT, Turbine Bearing temperature VH, axial shift VH, vacuum low, cold gas temp trip, seal oil temp trip etc are added
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 89
COMMISSIONING OF ATRS, ATT & AUTOSYNCHRONIZER
General Practice
Normally, ATRS, ATT and Auto-synchroniser are getting commissioned as pending points and not as a part of normal plant commissioning.
So after the ‘pending point’ is cleared, customer is normally not using the system.
Best Practice
We are putting efforts for commissioning these system in the first rolling
synchronisation itself.
Recently at Bhilai and Tata Trombay, ATRS and Auto-synchroniser have been commissioned during first few start-ups.
At Tata Trombay, ATT is also commissioned.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 90
DC EOP AND SOP LATCH RELAY
General Practice Lub Oil pressure low switch starts DC EOP through max system
SLC latch relay contract..
.
Best Practice
SLC latch relay contract in DC EOP and SOP cabinet looped so that lub oil pressure low switch contact starts DC EOP and SOP directly, bypassing MAX system SLC ON.
This safeguards machine in the event of AC as well as failure of max system
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 91
AUTOSYNCHRONIZATION
General Practice As per circuit configuration, auto synchronizer after fulfilling its set
condition directly closes the Generator circuit breaker..
.Best Practice Additional contact of check synchronization relay wired up in auto
synchronization circuit. Here autosynchroniser setting are coordinated with setting of check synchronizing relay so that autosynchroniser and check synchronization relay operates at the same time.
This helps in safeguarding the machine during malfunctioning of autosynchronizer.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 92
AUTOSYNCHRONIZER TESTING
General Practice
As per normal practice, autosynchronizer is tested and its output command is verified within the panel terminals..
Best Practice
Autosynchronizer is tested in cold condition with supply of PT voltages through injection kit and actual Generator breaker closing (ensuring that isolators are open)
This helps in optimization of autosynchronizer setting more correctly and also total circuit gets checked.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 93
USE OF MULTIPLE FILTRATION MACHINES FOR TRANSFORMER DRYOUT
General Practice One Oil filtering machine (about 6 KL capacity) engaged for dryout
Best Practice More than one such machine put in parallel operation to optimally
utilise transformer drain header flow capacity
Advantage Cycle time reduced around 50%
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 94
TURBINE BEARING METAL TEMPERATURE CHECKING
General Practice
As per normal practice, cabling from bearing metal temperature JB to control room/Cold Junction Compensation(CJC) JB are checked after installation of thermocouple in bearings..
.Best Practice
Before installation of thermocouples in bearing, signal upto DCS checked by heating the thermocouple tag wise.
This ensures correctness of connection, readings and also ambiguity of polarity change is avoided.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 95
DAVR DUMMY LOAD TESTING
General Practice As per normal practice, the AVR/DAVR dummy load testing is
carried out at site with the help of 500W lamp or any available resistive load..
.Best Practice
Dummy load testing is carried out with same type of resistive load which is identical in ratio to that of factory testing. With this type of testing, exact and identical readings with factory can be ensured.
Customer as well as commissioning engineer gets better confidence on DAVR working.
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 96
PAINTING OF TRANSFORMERS AND BUS-DUCTS
General Practice
Painting works for busducts and transformers are attempted at very late stages
Becomes difficult because of shutdown requirement and thus opportunity may not be there
Best Practice
At least Station transformer and its busducts may be painted immediately after erection completion (before first charging). This transformer hardly goes into shutdown later
Better to paint the other transformers and busducts as well as soon as possible before charging
However, customer opinion / permission may be required since they may insist on painting only after all works are completed
Best Practices, TSX PSWR
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 97
SEQUENCE STARTUP OF HT DRIVES
General Practice All HT drives are generally started individually during first
commissioning of the drives This lead to a pending point as we do not get suitable opportunity to
commission the HT drives in sequence mode
Best Practice
All the HT drives to be started in sequence during first startup of the any HT drive
Best Practices, TSX PSWR
Power Sector Western Region
Process improvements Adopted During Overhaul by PSWR-SAS Nagpur
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 99
Introduction
Implementation of Best Practices during Overhauling
of T.G. has resulted into the following -
Overhauling cost reduction.
Reduce overhauling periods.
Improvement in quality.
Introduce latest technologies.
Improve customer satisfaction
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 100
Implementation of Best practices
Use of latest technology like induction heating for dismantling and assembly of turbine.
Unit de-synchronization at 480 ºC of HP shaft temp by decreasing the load before shut down..
Turbine oil pump stop at 125ºC (HPS temp).
Barring gear stop at 125ºC (HPS temp).
To initiate overhauling activities as soon as machine comes to barring gear.
Decoupling of Generator rotor from turbine rotor and put back turbine rotor in barring.
Start dismantling of generator and O/H activities thereafter.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 101
Review by Site and follow-up from HQ
Site reviews all activities minutely
Time taking processes, idle times between activities, delay in arranging spares and mobilization of experts from units etc are identified well in advance.
HQ also involves in reviewing processes and all important issues and HQ inputs are duly incorporated on activity planning at site.
Reduction in overhauling duration to the target schedule is attributed to meticulously planning and follow-up of critical activities, which is accomplished in a shortest duration.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 102
Strategic Planning List out the History of past problems
Pre-overhaul survey record.
Analyze Present running behavior.
Input from MOU’s and utilities.
Timely arrange experts service from MOU’s
Milestone based review.
Mobilization of resources 3 days before start of Overhaul.
Scheduling of sequential & parallel activities
Identification of idle time & to avoid them by detailed planning in advance
All the anticipated spares required for completion of the overhauling work arranged at T.G. Floor before start of the work.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 103
Generator work starts within 36 hrs of De-synchronization
0000 hrs : De-synchronization (HP shaft temp at 480 Deg.C)
17.5 hrs : Barring gear stop (HP shaft temp at 400 Deg C)
17.5 hrs. to 20.5 hrs:
AOP stop
Lub oil to brg. 5,6,7 blanked & brg. 4 minimized
LP-Gen coupling decoupling
Hand barring will continue during this period
20.5 hrs : B/G re-started
With this practice Generator rotor thread out work starts within 36 hrs of de-synchronization.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 104
Procedure for decoupling of LP-Generator in hot conditions
Turbine is on Turning Gear. JOP in service, AOP in service.
Loosening of pedestal cover bolts, removal of Vibration probes.
Close turning gear valve to reduce the speed. Simultaneously loosen and remove pedestal cover bolts.
When Turbine speed becomes zero. Stop AOP while JOP is continuously kept in service. Continue Hand Barring.
Remove pedestal 4 cover. Close Lubricating oil throttle valve to the minimum possible.
Simultaneously blank lub oil supply to bearing 5,6 and 7 by putting gasket in lub oil supply line. (parallel, by 3 gangs). Keep watch on bearing 1,2 and 3 metal temperature and simultaneously do hand barring.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 105
Put tin sheet/polythene to cover on bearing 4. Start EOP and continue hand Barring.
Loosen LP-Generator coupling bolts and decouple LP-generator by continuing hand barring.
Shift generator rotor away from turbine Stop EOP and Adjust brg. 4 lubricating oil throttle valve to normal. Put pedestal cover back and start EOP & barring gear.
Dismantling & prepare for rotor thread out.
At the time of rotor thread out, stop turning gear again and stop EOP. Remove pedestal 4 cover.
After thread out put pedestal 4 cover back. Turbine on Barring gear with AOP in service till HP shaft temp comes to 125 deg C .
Note: Jacking oil pump is throughout kept in service.
Procedure for decoupling of LP-Generator in hot conditions
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 106
PSWR’s Best records on TG overhauls
Overhauling of IP-LP Turbine & Generator including LP Turbine blades MPI have been carried out in record lowest time of 8½ days barring to barring. (13 days Bar to Bar) on year 2007 at 250MW U#2 Dahanu TPS.
Overhauling of LP Turbine & Generator have been carried out in record lowest time of 9 days barring to barring. (15 days Bar to Bar) on year 2005 at 250MW U#2 Dahanu TPS . This was achieved as an exceptional case to avoid power problem in Mumbai.
Overhauling of HP- LP Turbine & Generator including HP rotor replacement & HP/IP coupling hole reaming, LP free standing blades MPI & NFT along with bearings 1,2 & 4 replacement have been carried out in record lowest time of 13 days baring to barring. (18 days Bar to Bar) on year 2006 at 250MW U#1 Dahanu TPS.
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 107
Overhauling of IP-LP Turbine & Generator including LP Turbine blades MPI & NFT have been carried out in record lowest time of 12 days barring to barring. (17 days Bar to Bar) in year 2008 at 250MW U#2 Dahanu TPS.
Unit-3 HP Module overhauled in 14 days barring to barring (19days bar to bar) in year 2006 at 200MW U-3 KSTPS NTPC Korba.
Capital Overhauling of HP-IP-LP Turbine & Generator including HP rotor replacement & HP/IP coupling hole reaming, LP free standing blades MPI & NFT have been carried out in record lowest time of 35 days barring to barring in year 2008 at 500MW U#8 NTPC VSTPS Vindhyachal .
PSWR’s Best records on TG overhauls
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 108
Schedule comparisonSl.
No Capacity (MW)
Capital Overhauling TG SET (Barring to Barring)
Previous Best Record Present Record
1 500
(All three module + Gen)
36 Days Unit-6, NTPC,KSTPS Korba on year 1996
35 days Unit-, NTPC, VSTPS Vindhyachal on year 2008
2 250
(HP-LP&GEN)
30 Days Unit-U-2 REL, Dahanu TPS on year 2002
13 days Unit-U-2 REL, Dahanu TPS on year 2006
3 250
(IP-LP&GEN)
- 8½ days Unit-U-2 REL, Dahanu TPS on year 2007
4 200/210
(HP Module)
28 Days Unit-2 NTPC KSTPS on year 2001
15 Days Unit-3 NTPC KSTPS on year 2006
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 109
Conclusion
A benchmark on record minimum duration in KWU design TG set overhaul could be achieved.
It was the determination, commitment, monitoring and follow-up of associated activities that ascertained to achieve a challenging target.
Working out activities well in advance with subcontractor agencies/ partners and round the clock execution of job with new strategies helped to meet schedule deadlines.
Work can be started as soon as machine comes to Barring gear.
Cooling Down period can be saved relatively by 4 days during the Generator overhauling.
Power Sector Western Region
IMPROVED SITE FACILITIES
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 11109/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 111
Award of Enabling works and its construction takes considerable time, after receipt of confirm order. This delays posting of site staff and material management including posting of Construction Manager.
PSWR has decided to procure Porta Cabins with all amenities as replacement of Conventional Site office sheds.
This will be provided in all new sites like Satpura, Mauda, Chandrapur, Raigarh, Vindhyachal, Bela Ideal Energy including all forthcoming sites.
NIT has been floated and tender is likely to be finalized by end April 2009.
Porta Cabins - to overcome delay in site mobilisation
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 112
09/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 11309/04/23
Exploring Heights ..................... Setting Standards .................... Marching Towards ExcellencePower Sector Western Region 113
Advantages of Porta Cabins
1. Quick mobilization
2. Quick realization of mobilization advance from customer
3. Quick demobilization
4. Flexibility in use & can be installed as per the site condition
5. Environmental friendly due to cleanness & easy maintenance
6. Provide better facility to site staff
7. Light weight (Easy in handling and transportation)
8. Aesthetic look.
9. Durable and Termite proof
10. Seismic-resistant
11. Economical in long term because of repetition
12. Thermal Insulation
Porta Cabins - to overcome delay in site mobilisation