Emergency Diesel Generator Preventive Maintenance

August 3, 2017 | Author: tsousi | Category: Diesel Engine, Turbocharger, Cylinder (Engine), Piston, Fuel Injection
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Emergency Diesel Generator Preventive Maintenance


LESSON 1 Terminal Objective ........................................................................................................................ 3 Improper Lube Oil Addition to EDG............................................................................................. 4 Diesel Generator Over-speed Trip And Damage........................................................................... 6 Broken Rocker Arm Damages Turbocharger ................................................................................ 7 Timing Chain Cover Removal ....................................................................................................... 8 Recent Industry Events ................................................................................................................... 9 LESSON 2 Terminal Objective ...................................................................................................................... 14 Check Air Start Timing................................................................................................................ 15 Check Fuel Nozzle Lift Pressure on Test Stand .......................................................................... 16 Engine Internal Inspection ............................................................................................................ 17 Inspect Rocker Arm Assemblies without Disassembly ................................................................ 17 Adjust Tappets .............................................................................................................................. 17 Foundation Fastener Torque Check .............................................................................................. 18 Measure Main Bearing Clearance................................................................................................. 18 Measure Connecting Rod Bearing Clearance............................................................................... 19 Measure Main Thrust Bearing Clearance ..................................................................................... 19 Check Camshaft Timing .............................................................................................................. 20 Perform Auxiliary Drive Inspections............................................................................................ 20 Clean and Inspect The Turbocharger............................................................................................ 21 Power Cylinder Maintenance..………………………………………………………………………………. 21


COURSE TERMINAL OBJECTIVE Given a maintenance task on the Emergency Diesel, the maintenance mechanic will describe how the maintenance is correctly performed as demonstrated by a score of at least 80% on the end of course exam.

LESSON 1 TERMINAL OBJECTIVE Given situations which have occurred in the past on the Emergency Diesel Generators, the mechanical student will identify the means to prevent the future occurrence as demonstrated by passing the final written examination with a minimum grade of 80%.

LESSON 1 ENABLING OBJECTIVES EO1 State the precautions to ensure proper lube oil addition to the Emergency Diesel Generator. EO2 Identify the potential for damage when performing maintenance on or near EDG control system components. EO3 State the importance of identifying and correcting a defect because of the potential for secondary damage upon failure. EO4 Identify the potential problem involved in removing the timing chain cover in the EDG. EO5 Discuss Recent Industry Events


IMPROPER LUBE OIL ADDITION TO EDG EVENT DESCRIPTION On January 17, 1980, the Kewaunee Nuclear Power Plant experienced a partial loss of offsite power which resulted in a turbine trip, reactor trip, and one emergency diesel engine driven generator (diesel-generator or D/G) supplying power to one engineered safeguards bus. Offsite power continued to supply the other engineered safeguards bus. During the day before, on 01/16/80, this diesel-generator had successfully completed a 24-hour loaded test run, but had a low lube oil alarm condition with oil level 1/2-inch low. The D/G was fully operational in this condition. Before oil could be added on 1/17/80, the D/G was required for emergency power following the failure of the reserve auxiliary transformer. The normal oil fill location could not be used while the D/G was operating. The D/G Tech Manual (TM) indicated that oil could be added with the engine running, but did not describe the method to be used. Lube oil was added by pumping it into the engine through a pipe that was assumed to be a lube oil line. This line was color coded in the TM and painted with the lube oil system color code. Three barrels of oil were added via this line while the D/G was operating. After transferring the emergency bus to off-site power through the tertiary auxiliary transformer, the D/G was shut down and two more barrels of oil were added through this line without increasing the sump level. Two more barrels of oil were then added through a different addition point and the level was restored to normal. The following day a factory representative determined that the first five barrels of oil had been added to the engine air box through a mismarked (should have been color coded as an air line) drain connection. Four and a half barrels of oil were drained out after which the diesel-generator was satisfactorily test operated. It is believed that the diesel engine could have been damaged had an engine start been attempted while the five barrels of oil were in the air box. The emergency electrical power could have been lost if the oil had damaged it enough to shut down the diesel.


CAUSES Procedures for adding oil to the operating diesel engine were not available. The personnel performing the addition were not familiar with, nor trained on, adding oil to a running engine. The personnel performing the addition did not know how to verify that oil had been properly added. ADDITIONAL CONCERN-LUBE OIL SUPPLY This event brought to light an additional problem, which may be generic. During the previous day's test run of the diesel-generator, lube oil consumption was approximately 3 gal/hr. The diesel engines are model 999-20 manufactured by the Electro-Motive Division of General Motors Corporation. These diesel engines use a 2-stroke cycle and lube oil consumption is normally higher than for the 4-stroke cycle diesel engine. Vendor representatives and NRC consultants indicate that lube oil consumption rate varies with engine condition and load. Further, the 3 gal/hr. consumption rate is considered to be in the normal range. During the loss of power event, the licensee had three barrels (165 gallons) of lube oil available onsite. The licensee's Technical Specifications require a seven day supply of fuel oil for one diesel-generator be available onsite. To meet the intent of the Technical Specification, a seven day supply of lube oil should also be available onsite. The operation of both diesels could have been impossible due to the lack of available oil. CORRECTIVE ACTIONS Verify the existence and adequacy of procedures or instructions for adding lubricating oil to safety related equipment. This should include the following: Whether or not how and where lube oil can be added while the equipment is in operation. Particular assurance that the wrong kind of oil is not inadvertently added to the lubricating oil system, and that the expected rise in level occurs for each unit of lube oil added. These operating procedures or instructions should be available locally in the area of the equipment. Verify that personnel are trained in such approved procedures and demonstrate an ability for using these procedures to add oil while the D/G is operating and that they understand how to verify that the proper amount of oil has been added. Verify that the color-coded or otherwise marked lines associated with the diesel-generator are correct and that the line or point for adding lube oil has been clearly identified. Determine the lube oil usage rate for each diesel engine under full load conditions including the rates considered to be excessive. Provide adequate inventory of lubricating oil of the proper grade consistent with the highest usage emergency diesel-generator(s) operating for the time period specified in the plant Technical Specifications for fuel oil supply. When lube oil consumption rates become excessive, provisions should be included for overhaul of the diesel engine.


DIESEL GENERATOR OVERSPEED TRIP AND DAMAGE EVENT DESCRIPTION--SER 86-18 Grand Gulf Unit 1 Following maintenance on the governor which included removal of hydraulic fluid from the actuator system, (Woodward Model EGB-35), the engine oversped due to trapped air in the hydraulic actuator circuit of the governor. CAUSE Air was not vented from the system following the refilling the governor with oil. Procedure guidance was inadequate for the venting. RESULTS AND POTENTIAL DAMAGE The engine reached an estimated 620 RPM during the transient. Normal operating speed is 450 RPM and overspeed trip is 537. Overspeed happened so rapidly that the reaction time of the fuel racks and the trip throttle valve (4-6 sec) was insufficient to prevent damage. As a result, numerous engine components including connecting rod bushings, rod bearings, main bearings and the engine base were damaged. The potential for damage included personnel injury or death, and loss of emergency power if the overspeed had occurred during an actual emergency condition.


CRDR 2530393 Damaged Fuel Oil Return Line. Event Overview On 6/20/02, the 1B EDG was taken out of service for maintenance. A review of the schedule frag, revealed that several maintenance groups worked in the area of the 1L jerk pump. Following the maintenance activity, the EDG successfully passed a post-maintenance surveillance test (ST). The failure was discovered on 6/21/02 by an Area Operator (AO). Initially, the fitting was discovered to be cracked and then failed completely when touched by the AO. Cause: Therefore, it is readily apparent that the failure was induced during the maintenance activity when someone stepped on the fuel line and cracked the fitting. The vibration resulting from the post maintenance ST probably exacerbated the crack which then broke completely when touched by the AO. Results--potential results •

Potential personnel injury from slip hazard caused by leaking fuel oil.

Potential for fire.

Potential health hazards (i.e. inhalation, eye irritation, and oil acne).

BROKEN ROCKER ARM DAMAGES TURBOCHARGER EVENT DESCRIPTION On January 4, 1989, a Unit 3 ‘A’ EDG tripped during routine testing due to a broken rocker arm. Subsequent inspection revealed the rocker arm break had paint in the initiating crack, indicating the initial crack existed prior to being received at PVNGS. After repair, on January 9, the diesel tripped again, this time on vibration. It was restarted (with Cooper-Bessemer's blessing) and tripped again. It was discovered that the turbocharger was in various pieces, with fractured vanes and other pieces broken off due to the damage done by the vanes. Note: Restarting a diesel after it has tripped, to perform troubleshooting, has the potential of causing additional damage to engine components. CAUSE Cause of the rocker arm damage was manufacturer defect. A thorough inspection of the turbocharger indicated the failure was a sudden failure, not due to wear or fatigue from a long period of time. Cause of the turbocharger damage was actually the broken rocker arm! 7

The rocker arm failure caused airflow oscillations when air was pushed back into the intake instead of the exhaust. These oscillations created high and low flow conditions in the turbocharger compressor, creating the conditions for "surge" and "stall". These conditions in a radial flow compressor are periodic flow reversals which can be very violent in nature. The "surge" condition not only reduces capacity, but also can damage the compressor. The pulsations from the damaged cylinder created strong enough flow oscillations to bend and break the compressor vanes and damage the compressor. In addition to turbocharger damage the connecting rod was bent from compressing the gases in the cylinder. The NRC was concerned that the connecting rod was not checked for damage.

TIMING CHAIN TENSIONER COVER REMOVAL EVENT DESCRIPTION--South Texas Project From Dec 10, 1987 through June 30, 1988, the diesel generator was being tested for startup. Timing chain oil supply hoses were replaced and hose clips had been added by removing both timing chain covers. It was noticed that start times for the diesel were slower than normal and slower than the others. The vendor found the timing was off and adjusted the timing by 2 LINKS. The start times came in spec, but were still slow. During a subsequent test, water was observed coming out of the test cocks in cylinders 2L and 7L. These cylinder heads were removed and found to be cracked, allowing jacket water into the cylinder. Further testing was halted until all the cylinders could be checked. 18 OF THE 20 CYLINDER HEADS WERE FOUND TO BE CRACKED. Cause: The cause of the timing being out of spec was the removal of the timing chain covers. The cause of the cracking was determined to be the 19 hours of run time with the timing out of spec. The fuel was being injected early. This early injection increased compression pressures and temperatures. This heat of combustion was concentrated at the top of the cylinder for too long, too soon, and too hot. The area overheated and cracked the head. RESOLUTION: DO NOT REMOVE THE TIMING CHAIN COVERS WITHOUT RETIMING THE ENGINE--Or, DO NOT remove them at all! 8

Recent Industry Events ZION STATION CYLINDER LINER FAILURE Background: 1/27/97 a through wall crack (ZION Station 2A EDG ) 1-L cylinder LINER allowed JW water to enter cylinder space. Upon startup of a Surveillance test, water entered into cylinder 1-L. The water caused a hydraulic lock within the cylinder and resulted in the failure of the piston. The piston actually was found to have a defective crown thickness (less than design). The EDG (C-B KSV 16) operated for ~ 32 minutes before being shut down. OPS noted high crankcase pressures. Cause: The liner failure was the first on a C-B Nuclear EDG engine. The root cause of the liner failure was several factors: The most significant contributor was an increase in the clearance between the liner fit and the block. These larger clearances caused increased stress at the underside of the top portion of the liner where it forms into a 90 degree flange. Originally Zion had trouble and the liners were taken in and out regularly. The bottom of the liners were cleaned with files and crocus cloth. The Zion liners were of the earliest C-B vintage liners, which were also susceptible to circumferential cracks. NO other C-B engines of the same vintage of Zion have cracks in their liners. I.e. Cooper-Station –Nebraska Power. Lessons Learned: Keep component parts dimensionally with in tolerance. Be careful of excessive cleaning of parts, even if it seems that the part dimension is not controlled. WATERFORD CRANKCASE OVERPRESSURIZATION (EXPLOSION) EVENT

Background: 10/10/95, During a 24 hour run of ISG testing following a refueling outage engine overhaul, the 5-L cylinder of the “A” EDG suffered an overpressurization. The engine had been running at 110% power as part of the 24 hour run requirement. During the refueling outage, 3 cylinders heads had been removed for maintenance inspections. Cylinder 5-L was one of the cylinders inspected. No unusual observations had been observed with the 5-L cylinder. Cylinders heads 4R and 5R had also been removed. Post Event inspections revealed extensive scoring of both the cylinder liner and piston. Chrome delamination was observed on the liner walls. Melted tin was noted on the liner and piston rings. The lower skirt had three longitudinal cracks. Cause: C-B EDG’s in nuclear service have had a history of piston and liner scuffing. The CBOG has categorized this scuffing as “tin transfer” phenomena. I.e. Tin from the piston skirts gets rubbed off into the pores of the chrome of the liner during fast engine starts. As the pores fill up a lack of lubrication develops between the piston and liner. Heat builds up and excessive wear 9

happens rapidly. Evidently combustion gasses reach the crankcase until the lube oil, in confined areas, gets vaporized. Once a hot spark ignites a highly vaporized pocket, an explosion ensues. Remedy: Engine Builder had already had a fix per a service bulletin for this problem. The Service Bulletin had utilities pull the power piston lower oil control ring and remove the piston end caps. This action results in more oil sprayed onto the liners via the piston pin. The service bulletin said owners could do the mod whenever it was convenient. I.e. when ever a head was being removed for any other reason. The effect on the plant of this event was to change the DG team philosophy (time table) of performing the piston modification. The plant had been performing the modification as per the Service Bulletin: whenever a piston or head had been removed for other reasons. PV had believed that the tin transfer phenomena was slow developing and could be found by engine analysis. Because the WATERFORD RCFA stated that tin transfer could happen rapidly, PV convinced management to perform the piston modification on one bank per engine per outage. This 3R7, the piston modification will have been completed on each engine on each Unit AIR START HEADER LOOSE BOLTING – UNIT “1A & 3B”; CRDR# 16-0030. Background: 1995 Time frame- Air start header bolts were found loose by an AO on 1A EDG. One bolt had fallen out and was on the floor. Other bolts were found loose on that engine. All other Unit’s engines were walked down for transportability. 3B was found to also have loose bolts. All bolts were immediately tightened to proper torque values. Cause: The RCF found that the required vendor torque for generic fasteners on the engine (i.e. fasteners with no specific torque found on a drawing) was too low. Mech Maint Engineering did a calculation to show that the torque was too low, even for cast iron. Remedy: Drawings were changed to reflect a higher torque value can be used on generic fasteners. PV lead the way in the CBOG on this issue as many other utilities had had similar problems, but were afraid to challenge the vendor. The vendor now agrees with PV and has issued a letter for other utilities to follow. FUEL PUMP PEDESTAL BOLT FAILURE – UNIT 1 “B”; Cylinder 6-L; (CRDR#160024) Background: Ever since start-up days, maintenance crews and engineers had noted that the 6-L fuel line had vibrated excessively. Attempts had been made by every system engineer to find the source of the vibration. Vibration surveys had been performed. In 1994-95 a new fuel line assembly was installed to prevent previous fuel line problems from recurring… i.e. fuel line cracks and fuel line “pull-out” in Unit 2 which caused a fire. A new fuel pump pedestal had been on order with the vendor, with the thinking that the lower machine surface was not parallel. However, in the mean time, the new fuel line mod was performed. The new fuel lines were much stiffer and the vibration seemed to disappear. However, the cause of the original problem did not. Eventually 2 of 4 bolts of the 6-L fuel pump pedestal broke where it mounts to the cam housing. Cause: The cause turned out to be that the upper bolt holes had never been bottom tapped. The bolts had been getting the proper torque over the years, however the joint was not getting proper clamping force since the bolts were bottoming out. The bolts eventually failed because of fatigue. Remedy/Lessons learned: Stay alert to problem solving. Many attempts were made to find the source of the vibration but nobody thought to look at the holes because the actual vibration was 10

away from the pedestal. Also adding stiffness to reduce vibration may not solve the problem!



Event Description On 4-20-96 the Unit 2 "B" EDG was being run as part of a Post Maintenance ST (31 ST9DG01). As part of the ST, the engine was being run for two purposes: (1) to break in piston rings that were changed on 11 cylinders during the outage, and (2) an Engine Analysis for assessment of engine condition. While performing the Engine Analysis, engineering and maintenance personnel noted that the 1-R cylinder was not firing. Further investigation revealed that the fuel linkage to the 1-R high-pressure pump was frozen. Adjacent cylinders fuel linkage was normal, thus indicating that 1-R fuel pump had probably seized. The control room was notified and the engine was shut down. An Action Plan was formulated between engineering and the planner for troubleshooting and recovery. Details Of Component Failure The high-pressure fuel pump of the Cooper-Bessemer KSV engine is typical for direct injected engines running on diesel fuel. It consists of a plunger and barrel assembly, all of which are mounted in a pump body. The pump plunger and barrel control the timing and amount of fuel delivered to the fuel injector. The plunger is indirectly connected to the governor via linkage, fuel racks, and control levers. The plunger's stroke is produced by its fuel cam. The rotational position of the plunger controls the timing and the amount of fuel injected by covering and uncovering inlet and by-pass ports in the barrel. The plunger and barrel are precision parts and their tolerances are manufactured to the "millionths" of an inch. Therefore, "any minute nick, scratch or speck of dust may lead to decreased output or a pump failure." (Direct quote from the VTM) The 1-R cylinder high-pressure fuel pump seized in the full fuel position. The fuel rack was discovered frozen at ~33mm. This is the rack position when the engine is at full load (5500 kW). During fuel pump removal, it was noted that the fuel pump follower was clear of the cam follower. This meant that the pump plunger had seized in the full "up position". The fact that the plunger seized in the "up" position was fortunate for maintenance recovery. By seizing in the up position, no extra side loads were imposed on the follower and thus the cam. Therefore, the cam was found to be in excellent condition. High Pressure Fuel Pump Failure History The engine vendor was contacted on 4/21/96. There were reports that there had been fuel pump failures similar to the plant fuel pump failure. Common Wealth Edison had a rash of fuel pump seizures similar to this failure in the mid to late 1980's. However, these failures were due to cleaning and blasting grit found in the pump internals. The blasting grit was part of the manufacturer’s cleaning process but was not removed/flushed out prior to pump assembly. i.e. the manufacturer was not properly cleaning the grit out of the pump and his QA program was not catching the problem. Quality control steps have since been implemented in the early 1990's to correct this problem. Commonwealth fuel pump failures were different than the plant failure in that they were happening to "new" pumps within the few hours of operation. The 1-R fuel pump had run for at least 5 years with no apparent problems until this 12

outage. South Texas Project had fuel pump problems in the 1992-1994 time frame, however their pump problems were due to installation errors. Also, their failures were due to hold down bolt failures and not due to pump plunger seizures. Palo Verde, in 1992, had a fuel pump "crosshead" seizure on 1 "B" 10-R cylinder. This failure was also different than the 2 "B" 1-R pump failure because the 10-R pump failure occurred on the fuel pump "crosshead" (i.e. the pump drive mechanism). The 1992 crosshead seizure was due a LO supply orifice being plugged by debris from the LO crossover line.

CAUSE The 1-R fuel pump seizure was most likely caused by debris entering the fuel pump headers when they were removed from the engine and placed outside of the engine space in the environment i.e. out of the building. Debris in the form of sand, dirt or dust entered either the supply or return header through a loose FME device. After the engine was started, the debris had worked its way to the supply port of the 1-R fuel pump and eventually entered the space between the plunger and barrel. Minute pieces of sand (silica) or dust has the right size and hardness characteristics to cause the scoring and seizure marks found on the plunger. Although the above is not a definite cause of this event, the recovery Action Plan developed before the engine was restarted will prevent a re-occurrence of this event. The Action Plan prevents the possibility of debris entering the fuel pump by providing a flush of the fuel system before the system is activated and the engine is started. The plan also requires that the engine fuel filters be changed to assure they are of the 5-micron type. These WRs had already been out in the field. TRANSPORTABILITY/ OPERABILITY: This event is not transportable to other engines that are in an Operable Condition since the failure occurred during a maintenance activity. The normal scheduled maintenance retest (part of the ST) discovered the failed component. Even if the event had occurred on an Operable Engine, the engine vendor has a letter stating that the engine can perform all of its intended safety functions with "one cylinder not firing". Therefore, the engine still could have been declared Operable with the seized fuel pump.

CORRECTIVE ACTIONS The required corrective actions to prevent re-occurrence have already been stated and they are: (1) Change the engine fuel filters to 5 microns and (2) ensure that a fuel system flush is performed if the engine fuel supply and return headers are removed from the engine for ease of maintenance. Mechanical Standards has modified the Model WO for Piston Modifications to add a "note" to this Work Instruction which says: "Perform a fuel system flush from the day tank through the supply headers before the engine is restarted if fuel headers are removed for maintenance


CRDR 2562611 Unit I “B” Diesel Governor Failure During U1R10, the speed-regulating governor on the 1B EDG was replaced with a governor that had been refurbished by Engine Systems Incorporated (ESI). Following replacement, the EDG was started in the test mode via 40OP-9DG02. The diesel achieved rated voltage and frequency. The governor was vented and verified to have a full range of control. The EDG was shutdown after running for approximately one hour. The EDG second start was performed with the engine in the emergency mode. The EDG achieved rated voltage and frequency, ran unloaded for approximately 30 minutes and then was shutdown. A third start was performed with the electrical control power breakers open (no power to the governor) and the EDG in the emergency mode. The EDG started and achieved rated voltage and frequency solely on the mechanical governor. The EDG was shutdown after approximately 30 minutes run time. EDG was started in emergency mode for the 24-hour run. The EDG achieved and stabilized at rated voltage and frequency. Approximately 35 seconds later, the EDG speed ramped from 600 to 700 rpm over a 1.5 second span and the engine tripped on overspeed. The cumulative run time on the new governor was 2 hours. The failed governor was transported to ESI for failure mode investigation. The investigation was witnessed by Palo Verde engineering personnel. When installed on the diesel generator, the governor is coupled to the engine via a beveled drive/pinion gear arrangement. This arrangement provides a rotational speed input to the governor. At ESI, the governor was placed upon a test stand, which simulates engine rotational input to the governor. The governor did not respond to any speed inputs. While providing a speed input, the governor cover was removed and it was noted that the flyweights were not rotating. Further testing of the governor was suspended and governor disassembly commenced. Disassembly revealed that the flyweight drive shaft had sheared. Disassembly also found that the idler gear had seized within the sub-governor base. The most probable cause of the governor failure was the presence of a foreign material, which passed between the idler gear and the sub-governor base. This caused the idler to seize and resulted in shearing of the drive shaft.


TERMINAL OBJECTIVE: At the completion of the instruction, the mechanic will, explain preventive maintenance on the Emergency Diesel Generator as demonstrated by passing the end of course exam with a score of 80% or better.

LESSON 2 ENABLING OBJECTIVES EO01 Explain the basic steps necessary to check Air Start System timing. EO02 Explain the basic steps necessary to remove and check Fuel Nozzle lift pressure. EO03 Explain the basic steps necessary to perform engine internal inspection. EO04 Explain the basic steps necessary to inspect Rocker Arm Assemblies without disassembly. EO05 Explain the basic steps necessary to adjust Main Valve Tappets. EO06 Explain the basic steps necessary to check Foundation Fastener torque. EO07 Explain the basic steps necessary to measure Main Bearing Clearance. EOO8 Explain the basic steps necessary to measure Connecting Rod Bearing clearances. EO09 Explain the basic steps necessary to measure the main thrust bearing clearance. EO10 Explain the basic steps necessary to check Camshaft timing. EO11 Explain the basic steps necessary to perform Cam/Auxiliary Drive Inspections. EO12 Explain the basic steps necessary to set up and to inspect the Turbocharger. EO13 Explain the basic process of performing power cylinder maintenance.



FLYWHEEL MARKINGS Two revolutions on the flywheel are one complete cycle on cylinders. Numbered marks on flywheel are for left side only at TDC. There are 72 degrees between left side cylinders. The right side cylinders are 45 degrees after the left side. Degrees are marked in one-degree increments 35 degrees before and after each left side TDC with one unmarked degree between marked 35 degrees.

NOTE: The flywheel does NOT have a mark on it between the two 35 numbers in the field, but you must remember to count as though there is a mark there

In firing order IL (#1 Left) TDC, 1OR (#10 Right) TDC is 45 degrees later (or 27 degrees before 6L TDC), 6L TDC, 5R TDC is 45 degrees later (or 27 degrees before 9L TDC), 9L TDC, etc... To find TDC on power stroke, check the inlet and exhaust valve push rods. They will be loose if the valves are closed; meaning the cylinder is TDC in the power stroke. If they are not loose, the valves are open and the cylinder is TDC in the exhaust stroke. If 1L is TDC power stroke, 10L is TDC exhaust stroke. The firing order is: 1L, 10R, 6L, 5R, 9L, 2R, 8L, 3R, 7L, 4R, 10L, 1R, 5L, 6R, 2L, 9R, 3L, 8R, 4L, 7R.

BASIC PROCEDURE Verify Turning Gear is engaged. Verify cylinder cock indicator valves are open. Disconnect starting supply tubing to air distributor inlet. Left bank. Disconnect air supply tubing for a selected cylinder from air start distributor. Connect a temporary, regulated to ≤ 25 psig, air supply to air start distributor inlet. NOTE: Air should start escaping from port on distributor just as flywheel comes up to 5.0 +/-1.0 degrees ATC (After Top Center) on power stroke of selected cylinder. Rotate flywheel clockwise until it reaches 5 + 1 degree ATC for selected cylinder. If air escapes too soon, loosen the four bolts securing the body flange and rotate slightly counter-clockwise. If air escapes too late, loosen the four bolts securing the body flange and rotate slightly clockwise. Tighten the four bolts securing body flange. Disconnect the temporary air supply from distributor inlet. Connect air supply tubing to the cylinder and starting air supply tubing to distributor inlet. Perform the same steps for the right bank. 16

CHECK FUEL NOZZLE LIFT PRESSURE ON TEST STAND TEST STAND BASIC OPERATING PROCEDURE Never place hands in the path of the spray as the CAUTION: force will puncture the skin, possibly resulting in blood poisoning!! Fill Supply Cup with clean fuel oil. Open Gage Valve. Attach nozzle and connector to Discharge Block Fitting. Use the lower connection for pop tests. Use upper connection for leakage rate measurements. Install plug on connection not in use and tighten all connections. Install Pump Handle on Handle Shoe in base of Nozzle Tester and pump the unit for desired test. REMOVAL Remove Fuel Injector nozzle from cylinder. Remove hold down clamp. Remember to use Fuel Line Nut Wrench (part # LSV-44-H#4). Use special knocker tool to remove nozzle (part # LS-44-DD). Use special tool to remove nozzle copper gasket (part # LSV-44-1B). Using Test Stand perform tests on the nozzle. NOTE: Always use new, clean #2 diesel fuel oil in the test stand. Use the test stand pressure gage only when reading is desired. TEST FOR OPENING PRESSURE Pump handle slowly and note pressure when nozzle opens. Normal opening pressure is 3500 psi. New nozzles are set 200-300 psi higher, since after a short period of engine operation, the opening pressure will drop 200-300 psi. TEST FOR SPRAY CHARACTERISTICS Pump test handle about 20-25 strokes per minute. All holes in nozzle should be open and injecting same quantity of fuel. Spray pattern must be uniform. TEST FOR SEAT TIGHTNESS Pump rapidly then wipe end of nozzle with a clean dry cloth. Slowly raise pressure to within 100 psi of opening pressure. Hold this pressure for 10 seconds. If it drips while the test handle is being rapidly pumped the valve is leaking. If it drips while being held, the seat is leaking. NOZZLE VALVE CHATTER TEST Pop the nozzle valve. Movement of nozzle valve returning to its seat is accomplished by a sharp staccato noise. A good nozzle will make almost a "chirping" sound. Worn valve will make a “dull" sound. 17

Replace any nozzle that fails the test with a new nozzle then rebuild the failed nozzle and return it to the warehouse. If the spray pattern is unsatisfactory, the spray tip may require replacement. Also, if the pop pressure is too low, shims will have to be installed to increase the pop pressure. Assemble the fuel nozzle and reconnect it in reverse order. ENGINE INTERNAL INSPECTION Disconnect high pressure fuel lines from fuel injection nozzles to fuel injection pumps. Inspect all sealing areas for cracks. High pressure fuel lines must be marked such that they can be returned to their original location. Remove injector nozzles as previously discussed. With cylinder fuel injectors removed, borescopically inspect all cylinder internals for damage or cracks. Open the crankcase and inspect the following: CAUTION: THE CRANKCASE IS A CONFINED SPACE AND REQUIRES A CONFINED SPACE ENTRY PERMIT AND ASSOCIATED SAFETY PRECAUTIONS PRIOR TO ENTRY! Cylinder liners for scuffing and cracking. Expansion seal at the bottom of liner for dents, cracks or water leaks. Piston skirts for wear and cracking. Visually inspect all bolting for signs of fatigue and premature failure. INSPECT ROCKER ARM ASSEMBLIES WITHOUT DISASSEMBLY Visually inspect rocker arms for abnormal wear and damage. Measure rocker arm shaft thrust clearances between valve (intake and exhaust) rocker arms and bushings with feeler gages. Use of a dial indicator is also an acceptable practice at PVNGS to obtain measurements, but care must be taken to ensure accurate readings. Acceptance criteria is 0.008" to 0.010". If out of tolerance, initiate corrective action to adjust. ADJUST TAPPETS Rotate the crankshaft and position the piston for which the valve train components are to be measured on Top Dead Center (TDC) of the power stroke, the main valves will be closed. Install a dial indicator so that indicator tip rests on one of the intake valve spring retainers, then zero the indicator. Loosen tappet adjustment lock nut and slowly turn adjusting screw clockwise until indicator shows that valve has started to open. Allow the valve to remain in position (off its seat) for several minutes. If the valve remains off its seat, the lifter is collapsed, and final adjustment can be made. If valve seats itself during the waiting period, it must again be unseated with the adjusting screw and the waiting period repeated until the valve remains off its seat. After lifter is fully collapsed, back off adjusting screw until the dial indicator again reads "0" and then an additional 1-1/2 turns, and torque lock nut. Repeat these steps for all valves (inlet and exhaust). When performing this step, follow the 18

engine firing order. FOUNDATION FASTENER TORQUE CHECK This ensures engine frame is secure and that engine alignment will not change. Check torque of 1 1/2" foundation fasteners. Minimum torque of 1455 ft-lbs, not to exceed 10% (1600.5 ft-lbs). If fasteners are not at this torque, tighten to proper torque. Check torque of 1 1/4" foundation fasteners. Minimum torque of 835 ft-lbs, not to exceed 10% (918.5 ft-lbs). If fasteners are not at this torque, tighten to proper torque. If fasteners are found at too low a torque value, web deflection may be checked. That determination will be made by the diesel engineer. Note: Allow at least 24 hours cooldown prior to performing foundation torque checks. Oil should be in the crankcase. PURPOSE: Ensures crankshaft and main bearings are in alignment. THE CRANKCASE IS A CONFINED SPACE. A CONFINED SPACE ENTRY PERMIT IS REQUIRED WITH APPLICABLE SAFETY PRECAUTIONS TO PREVENT PERSONNEL INJURY. Engage Turning gear and ensure Test Cocks are open. Ensure foundation torque check has been completed. Remove crankcase doors as necessary. Remove crankcase doors as necessary. Use a web deflection gage between the counterweights. At PVNGS, the crank webs have been center punched at the factory and measurements will always be taken at the crankshaft journal. Web deflection readings shall be taken at the 3, 6, and 9 o'clock positions, with the web deflection gage zeroed as high on the cycle as possible. MEASURE MAIN BEARING CLEARANCE Drain oil from base of engine and engage turning gear. Remove crankcase doors from each side at location to be checked. Rotate crankshaft until the crank web, adjacent to the bearing to be checked, is parallel with horizontal centerline of crankshaft. Place a magnetic base dial indicator on the main bearing cap or on the engine where the stem can be placed against crankshaft. CAUTION: Do not apply pressure on jack after dial indicator reading stops or damage to crankshaft may result. Ensure crankshaft is bottomed in bearing to be checked. Place a hydraulic jack and 6” H-beam on the crank web and butt end of jack against center frame rib. Set indicator on zero and apply sufficient pressure on crankshaft to assure crank is bottomed. If no indicator reading is observed, then shaft is seated. Remove the hydraulic jack and dial indicator. Span bottom of engine base with 6" H-beam across webs in the bottom of the crankcase. Place a hydraulic jack on the beam under the crank web. Install a dial indicator so it will contact the crankshaft and indicate upward movement. Ensure dial indicator is zeroed and carefully jack shaft up until dial indicator stops. 19

Note: We do not exceed 10,000 PSI on the pressure gage with the ram that we use to prevent crank or web damage. If the crankshaft stops moving before we reach 10,000 psi, we take our reading at that point. Crankshaft is now seated against upper bearing shell. Add the two readings together, this is running clearance. Bearings that exceed permissible maximum clearance (0.012") must be replaced as a set. MEASURE CONNECTING ROD BEARING CLEARANCE Drain oil from base of engine and engage turning gear. Rotate the crankshaft in the clockwise direction and position the "master" rod of the cylinder to be checked in any convenient position at the discretion of the WGS. The clearance can be taken in any order. Place a beam across webs in base or across door openings and place a hydraulic jack on it directly under connecting rod bearing cap. Place a dial indicator (with mag. base) on a crank web with its stem on the master rod bail so that it will indicate upward motion of the connecting rods, and zero the dial indicator. (Dial Indicator A) Locate a second indicator with its stem on the crank web and its base on a main bearing cap so that it will indicate upward motion of the crankshaft. (Dial Indicator B) Raise rod with jack until rod stops moving. Reading on dial indicator 'A', with its stem on the master rod bail, is bearing clearance. If dial indicator with its stem on crank web moves (Dial Indicator B), stop jacking immediately since the crankshaft is moving, and damage can result. This also indicates that all the clearance has been taken up at the other dial indicator. Bearing clearance is 0.008" - 0.014". If it is outside this range then contact diesel engineer.

MEASURE MAIN THRUST BEARING CLEARANCE Insert appropriate size of feeler gages between the forward thrust shoe and crankshaft. Check 180 degrees around the shoe and record the smallest clearance. Insert appropriate size of feeler gages between the aft thrust shoe and crankshaft. Check 180 degrees around the shoe and record the smallest clearance. Add the two measurements together to obtain the total thrust clearance. If total thrust exceeds minimum/maximum clearance allowed (0.010" to 0.024"), initiate corrective action as necessary.


CHECK CAMSHAFT TIMING Camshaft timing is checked for the following reasons: • • •

To ensure air intake valves are operated in proper timed sequence with the crankshaft To ensure exhaust valves are operated in proper timed sequence with the crankshaft and To ensure fuel is injected into the cylinders in proper timed sequence with the crankshaft

USING A PROTRACTOR Determine TDC on compression stroke for a selected cylinder. Lay a precision machinist bevel protractor across the valve spring keeper of one exhaust valve and one intake valve and center the bubble. Bubble should center at approximately 22.5 degrees on bevel protractor since this is the cylinder bank angle. While holding the bevel protractor in contact with both spring keepers, have the engine rotated in the normal direction of rotation, using the turning gear, until the bubble again centers. This should occur at 16 degrees Before Top Center (BTC) on the exhaust stroke. Acceptance criteria is ± 3 degrees. If the timing is off, initiate corrective action to have the timing chain tension checked and have the engine retimed. PERFORM CAM/AUXILIARY DRIVE INSPECTIONS Remove inspection cover on forward end of engine, and jacket water/ fuel pump drive cover. Inspect for damage, failures, cracks, or defects of all visible components. Check for damaged gears, roller bearings, and drive chain condition. Check vibration damper for dents. Check mounting for vibration damper, to ensure damper is secure. Replace inspection cover gaskets and cover. Remove camshaft housing covers left and right on the AFT end of the engine, to facilitate camshaft auxiliary drive inspections. Note: Ensure that speed probe shield is reinstalled immediately after removing cam drive cover to prevent damage to an unprotected speed probe. Visually inspect condition of the camshaft gears, note any unusual gear wear patterns. Inspect cam drive chain and check proper tension. Replace AFT end inspection cover gaskets and 21

covers. Remove camshaft bearing access covers as necessary on both sides of engine. Visually inspect camshaft, lobes, crossheads and crosshead bores for scoring, cracking or other defects. Replace camshaft bearing access cover gaskets and covers.

CLEAN AND INSPECT THE TURBOCHARGER Disconnect then remove the Overspeed Shutdown Valve. Visually inspect all exposed parts for the following: build up of dirt on the impeller or diffuser and evidence of oil carryover. Oil could possibly carryover from the intake oil filter (oil bath type). This would imply that the oil filter requires servicing. Freedom of movement (rotate rotor manually). Clean out any dirt found in impeller or diffuser. Using a dial indicator, measure thrust clearance. Install and reconnect the Overspeed Shutdown Valve. Let's look at "What is the worst thing that can happen and how can we prevent it?" or "What else could go wrong?" CRDR 2559704 OST Butterfly Valve Causes Diesel to Trip. Event Overview On 10/10/02 in Unit 1, DG 'A' was 22 hours into its 24-hour post-maintenance run. DG 'A' tripped at 5.8 MW load when the RO commenced raising load to 110% per 73ST-9DG01. Cause: Electrical engineer inspected the DG OST Butterfly and suspects the increased air flow from the increased load resulted in the valve leaving its limit switch; thereby giving the indications of an overspeed trip. EXPLAIN THE MAINTENANCE.







Dismantle Cylinder Heads. What could go wrong when removing the cylinder head? CRDR 2345330 Abnormal Level of Chrome and Iron metals found in Emergency Diesel oil samples just after the most recent outage for 2MDGBH01, 2MDGAH01, 3MDGBH01 Event Overview Following U2R8 the 2A diesel generator experienced a chrome and iron spike in the crankcase 22

spectrographic analysis of the oil sample. The oil sample on 5/20/99 indicated chrome at 12 ppm and iron at 10.5 ppm. The next sample indicated a slight increase in chrome and iron (13 and 12 ppm respectively). The third sample indicated another step increase in both chrome and iron (16 and 15 ppm respectively). Subsequent borescope inspection revealed the 3R liner to have excessive scoring in the upper regions of the cylinder liner. Engine analysis revealed that while the liner condition had degraded, critical cylinder operating parameters (combustion and compression pressures) were found to be normal. Excessive liner and ring wear event was not an engine failure; the engine was considered operable and could have performed its design safety function. Cause A CRDR documented two possible causes; 1) The pistons’ rings lined up allowing blowby, which removed the lubricating oil film and led to the scoring 2) Combined effects of dry liner, ring design and position of the 3R piston at the start of the firing sequence. The above causes do not appear to be likely causes of the current condition for the following reasons: While it is possible, it is highly unlikely that piston rings on 3 engines could line up in such a short period of time following an outage. After the U2R8 event, general tear down procedures were revised to include a requirement to coat liners with oil for any liner whose head was replaced. While again possible, it is highly unlikely that piston rings line up on one of the first or the first piston to fire during a start up. In light of the above, it is believed that the head replacement maintenance activity is the cause of high chrome and iron in the crankcase oil. During a head replacement activity, carbon build up at the interface of the liner and head breaks away. This carbon can slide down the liner and lodge between the piston and cylinder liner. Upon start up, the carbon gets caught by the ring and scores the chrome-plated liner. A review of past maintenance practices reveals why this is a relatively recent phenomenon. Prior to U2R8, head replacement was performed in conjunction with piston modifications. So when a head was replaced, the piston would be pulled out of the liner to have the bottom oil scraper ring removed. The end result was that the entire assembly would be reassembled in a clean condition. This is still an anomaly that has not been completely solved to date. Remove Cylinder Head Drain engine coolant. Remove fuel line from injection pump to fuel injector. Using tool LS-44DD (Nozzle puller) pull fuel nozzle out of head. Using tool LSV-44-1B, remove copper gasket from bottom of fuel nozzle mounting port. Remove breather and head cover from head. Disconnect the following: Fuel drain line and lube oil lines between head and fuel pump. Lubricating oil line from the head. Water outlet piping. Air starting pilot air line and main starting air header. Move piston to TDC on compression stroke. This 23

relieves valve spring tension on rocker arms. Remove oil line between rocker arm stands. Remove rocker assemblies and push rods. Notice that the solid push rod is used in the horizontal position and that the hollow push rod is used in the vertical position. Install two retaining tools (KSV-44-T) where pushrods were removed. This tool retains the crossheads in power head while it is being removed and prevents them from falling and causing damage. Remove cylinder head stud nuts and washers. Install head lifting tool KSV-44-D. Ensure the head lift rig bolts are tightened using GMJ prior to lifting the head. Using the crane and suitable rigging, slowly, raise head off cylinder block and studs and move it to a previously prepared location. Use a chain fall between hoist and cylinder head to facilitate handling. NOTE: Head must be lifted off at 22.5º angle so as not to damage water connections or studs.
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