Flushing Recommendations for Turbine Lube Oil Systems with Motor Driven Main Oil Pumps

DWG Number GEK116944

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G E K 1169 116944 44b b R evised, Nov 2018

G E Powe Power

Flushing Recommendations for Turbine Lube Oil Systems with Motor Driven Main Oil Pumps This GEK supersedes: GEK81515

These instructions do not purport to cover all details or variations in equipment nor to provide for every possible contingency to be met in connection with installation, operation or maintenance. Should further information be desired or should particular problems arise which are not covered sufficiently for the purchaser's purposes the matter should be referred to General Electric Company. © General Electric Company, 2011. GE Proprietary Information. All Rights Reserved.

GE Proprietary Information - Class II (Internal) US EAR - NLR

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Flus hing R ecommenda ecommendations tions for Turbine Lube Oil S ys tems tems with Motor Motor Dri ven Main Main Oil Pumps

TABLE OF CONTENTS I.

INTRODUCTION .........................................................................................................................................4 A. General Information .................................................................................................................................4 B. Oil Flushing Procedure .............................................................................................................................4 C. Turbine Oil Systems .................................................................................................................................5 D. Oil System Drawings ................................................................................................................................6 E. Equipment Supplied to the Site ................................................................................................................6 F. Pipe Storage ..............................................................................................................................................6 G. Piping Installation ................................. ................ .................................. ................................... ................................... ................................... .................................... ..............................6 ............6 H. Safety ........................................................................................................................................................7 I. Responsibilities of Parties ........................................................................................................................7 II. PREPARATION FOR FLUSHING - LUBE OIL SYSTEM ....................................................................9 A. General Preparations ................................... ................. ................................... .................................. ................................... ................................... ................................... .........................9 .......9 B. Turbine Lube Oil ......................................................................................................................................9 C. Turbine Bearings ......................................................................................................................................9 D. Supplementary Flushing Skid .................................................................................................................14 E. Lube Oil Tank/Skid ................................................................................................................................15 F. Oil Purifier ..............................................................................................................................................16 G. Lube Oil Coolers ....................................................................................................................................16 H. Lube Oil Filters .......................................................................................................................................17 I. Lube Oil Pumps ......................................................................................................................................17 J. Oil Tank Level Protection ......................................................................................................................17 K. Turning Gear...........................................................................................................................................17 L. Oil Transfer Tank ...................................................................................................................................17 M. Vibrating Piping .....................................................................................................................................18 N. Air Injection ................................. ................ .................................. ................................... ................................... ................................... .................................... ................................... ...................18 ..18 O. Lift Pump Piping ....................................................................................................................................18 III. PREPARATION FOR FLUSHING – HYDRAULIC/CONTROL HYDRAULIC/CONTROL OIL SYSTEM (GT SYSTEMS ONLY) ..............................................................................................................................19 IV. PREPARATION FOR FLUSHING – GENERATORS ..........................................................................19 A. Oil Flushing Generators ..........................................................................................................................19 B. Air Cooled Generators ............................................................................................................................19 C. Hydrogen Cooled Generators .................................................................................................................20 D. Hydrogen Seal Oil System .....................................................................................................................20 V. FLUSHING HARDWARE .................................. ................. ................................... ................................... ................................... ................................... ..................................2 .................21 1 A. Scope of Supply ......................................................................................................................................21 B. Bearing Jumpers .....................................................................................................................................21 C. Screens and Strainers ..............................................................................................................................22 D. Electrical Work .......................................................................................................................................23 E. Startup Spares and Consumable Materials .............................................................................................23 VI. FLUSHING THE LUBE OIL SYSTEM ...................................................................................................24 A. Flushing the Lube Oil System ................................................................................................................24 B. Filling the Oil Tank ................................................................................................................................24 C. Coarse Flush ...........................................................................................................................................24 D. Sequential Flush .....................................................................................................................................26
















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J. Securing the Flush ..................................................................................................................................30 K. Termination ............................................................................................................................................31 L. Acceptance Criteria ................................................................................................................................31 VII. REFERENCES ............................................................................................................................................33

LIST OF FIGURES Figure 1. Bearing Feed – Feed – Temporary Temporary piping ........................................................................................................... 10 Figure 2. Flushing Box ........................................................................................................................................... 12 Figure 3. Site installation of Flushing Box ............................................................................................................. 13 Figure 4. Typical Supplementary Flushing Pump Connection ............................................................................... 15

LIST OF TABLES Table 1. Cleanliness Level Particle Count ..............................................................................................................32 Table 2. NAS versus ISO ........................................................................................................................................32
















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I. INTRODUCTION A. General Information

This document was written to provide guidelines and recommendations for flushing steam turbines, gas turbine and generator lube and seal oil systems motor driven main lube oil pumps. This GEK should not be referenced for older units utilizing shaft driven main pumps. It is neither practicable practicable nor economical to utilize a step-by-step procedure written to cover every configuration of turbine-generator set being constructed under a wide variety of site conditions. It is the responsibility of the General Electric Technical Representative to evaluate such things as condition of the piping system, installation schedule, financial aspects of the customer and his agents, and assist in planning an oil flush that will result in a clean system. A long costly oil flush can be avoided if a program is set up early to assure the following criteria are met: 1. Piping is properly protected upon receipt at the site. 2. Piping is stored in a clean, dry environment, and not allowed to deteriorate prior to installation. 3. Piping is handled and installed in a manner that minimizes entry of foreign material. 4. Piping is adequately oil flushed. 5. Cleanliness of system maintained until initial operation. 6. Cover all pump openings 7. Cover each work area when work stops 8. Take caution when working with insulation and ensure that oil system is closed prior to installing insulation. Allow sufficient time for the flush itself after all provisions for flushing have been made. Flushing time will vary depending on the size and complexity of the turbine system being considered. It is not uncommon for the flush itself, not including set-up and return to operation, to require a minimum of 180 hours or more. However some flushes have been significantly longer. B. Oil Flushing Procedure

General Electric Company practices and recommendations should be reviewed with the owner and his agents prior to preparing the turbine generator set for oil flush. At this time, the owner may elect to outline in writing details of the intended flushing operation. The written procedure is recommended as it will serve to outline and communicate conduct of the flush, requirements, and responsibilities of all parties involved. involved. Details Details should should include: 1. Scheduling and manpower requirements. 2. Safety considerations; fire hazards, electrical equipment “tag out” procedures, etc. 3. Setup, flushing sequence, flushing and securing procedures. 4. Oil sampling and testing, sampling frequency, reports, and sample data logs by location, time,
















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C. Turbine Oil Systems

Lube oil is supplied to the entire turbine generator set, seal oil is supplied to the generator when the unit is hydrogen cooled, lift oil is supplied from separate pumps as required and lube oil is used for control functions such as gas valve control, turbine tripping, etc. when the unit is a simple cycle gas turbine. This oil will be supplied from the lift oil pumps. Hydraulic (control) oil for steam turbine is provided from a separate oil supply. Lube oil feed piping in the GE scope of supply is stainless steel, drain lines are carbon steel unless stainless is purchased as an option. The lube oil tank is located in the plant near the turbine by the plant designer who will also design and supply the interconnect feed and drain piping from the tank to the turbine. See the turbine operator manual for more detailed information prior to oil flushing or operating the system. Steam Turbine Lube Oil Components

The main oil tank contains the following lube oil system components. This list is typical, not exhaustive. 1. Lube oil reservoir, with drain provisions, connections for purchaser’s oil conditioning equipment (optional) and level transmitter with high and low level alarm signals to the turbine control system. Turbines shipped prior to 2000 were designed with either level transmitters or level switches. 2. Two lube oil coolers (100% cooling capacity each). Systems are either supplied with shell and tube or plate and frame type coolers. 3. Two full capacity, vertical AC motor driven centrifugal oil pumps with inlet strainers. 4. One DC motor driven emergency vertical centrifugal oil pump with inlet strainer and a GE supplied DC motor starter. A second DC motor driven emergency vertical centrifugal pump with inlet strainer will be supplied on units that require a seal oil supply. 5. Bearing pressure regulating valve. 6. Motor-driven vapor extractor and lube oil mist separator mounted on the reservoir. 7. Isolation valve, (for hydrogen cooled generators), to provide oil to generator shaft seals to maintain hydrogen gas pressure during shutdown when bearing oil is off. 8. Instrument cabinet mounted on the reservoir which contains pressure switches, pump test solenoids, gauges, and electrical terminals. All electrical connections to the tank are made in the console except for motor connections, oil tank heater, and motor/heater connections Note that oil tanks may either be designed with heaters in the reservoir or in the oil purifier, depending on environmental conditions. 9. Duplex lube oil filters with 12 micron filter elements with differential pressure gage and transmitters for high differential pressure alarm. 10. Oil purifier unit consisting of a self-contained motor driven pump and coalescing elements and separator for water removal. The oil purifier has a 30 KW heater, temperature controller, and
















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Gas Turbine Lube Oil Components

For a complete list of GT lube oil system components, including hydraulic/control oil, reference MLI A125 and the Gas Turbine project specific BOM for specific components and flushing hardware. The generator hydrogen shaft sealing system is supplied by oil, piped to the seal oil control unit from the main lube oil system. The seal oil control unit contains differential pressure regulator, flow meter, float trap, alarm pressure switches, gauges, and filters (if applicable, separate filters only used on a vacuum seal oil system). The air side seal-oil and generator bearing oil drains to the bearing drain enlargement through a loop seal and back to the main oil reservoir. The hydrogen side seal-oil, drains from the two seal drain enlargements through the float trap to the bearing drain enlargement. D. Oil System Drawings

The details of the steam turbine, gas turbine and generator lube and seal oil systems supplied with turbine generator sets are represented by information in the turbine operator’s manual and by detailed drawings issued to the customer and issued to PNET under job specific project folders. GE Customer Engineering should be contacted for the latest revision project specific drawings prior to beginning flush preparation. preparation. E. Equipment Supplied to the Site

Oil system equipment in the GE scope of supply typically includes the oil skid, DC motor starter, loose piping, and and oil flush / startup spares spares such as as an extra extra set of filters, filters, etc. etc. Oil piping, piping, base mounted mounted or piping piping shipped separately, has been previously cleaned to some extent during pipe fabrication but is considered to be dirty since sinc e it has not been flushed as a system in the “installed” condition. The oil tank as supplied has been flushed and performance tested at the factory and can be considered to be relatively clean. Interconnect lube oil piping from the lube oil tank to the turbine is generally supplied by others. For gas turbine specific equipment that may or may not be supplied by GE, reference the gas turbine BOM and MLI A125 F. Pipe Storage

Material shipped to site will be in accordance with the turbine and generator oil piping drawings, which in many cases will include some piping that is supplied by others, i.e. Architect Engineer. Piping will arrive on site previously cleaned, and protected internally, with the exterior painted, and ends capped. Depending on size and configuration, the piping will ship boxed, loose, or as part of a containerized shipment. Dry indoor storage is recommended since the protective coat will only stand a limited amount of moisture exposure. Protective caps should be replaced where lost, damaged in transit, or removed for inspection. Under no circumstance should piping be left uncapped and exposed to atmosphere or dragged on the ground during handling. G. Piping Installation Lube Oil Piping Installation

Even though the lube oil piping will be flushed after installation, it should be kept as clean as possible and erected in an appropriate manner since it is far easier to keep dirt out of the system than to remove it by flushing. Even Even piping that that appears relatively relatively clean clean visually visually will in fact fact contain a significant amount amount of


















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The oil supply and drain lines are welded without backing rings using a butt-welding procedure. This eliminates dirt traps caused by backing rings. It is also required to use tig welding for the first pass when butt welding in order to keep weld splatter out of the piping, which is one of the hardest materials to remove through flushing. Lines 2 in. (50.8 mm) and smaller are generally socket welded by design. Lubrication Oil Piping Specification drawing 364A7196 provides details and recommendations for the design and installation of field erected lube oil piping. Hydraulic/Control Hydraulic/Control Oil Piping Installation (when GT multi-shaft or GT only)

See GT BOM and MLI A125 H. Safety

Safety precautions should be considered for equipment that is temporarily configured for oil flushing, in addition to personnel safety. Concerns include avoiding oil spills, protection against running equipment dry as a result of oil loss emptying the tank, fires resulting from hot work, and contaminating the system while parts of the machine are open during flushing. Post “No Burning and Welding” signs in appropriate areas and restrict traffic passageways where oil soaked areas may cause a hazard. Equipment “Tag -Out” procedures should be in effect for equipment that will be reconfigured several times during the flushing sequence. Equipment such as oil pumps should be bump checked for rotation, then current checked while valved for the maximum flow condition prior to turn over for flushing in order to ensure that the motors will not run in an over current condition later during the flush. See “Preparation for Flushing” section for more details. I. Responsibilities Responsibilities of Parties

Obtaining a clean oil system is an integral part of the installation of the turbine – turbine – generator, generator, and consequently, the basic responsibilities of the various parties are the same as they are throughout the installation. However, a brief discussion may clarify the responsibilities of the Purchaser and the General Electric Company as they apply to the cleaning and flushing operation in particular. The responsibilities of the parties involved as discussed here is typical. The project specific contract will determine the actual responsibilities for any given job. The contract shall be reviewed to determine appropriate project specific responsibilities. responsibilities. Purchaser
















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correctly performing these operations to the extent he has assumed responsibility for doing so from the construction forces. It is essential that these responsibilities be clearly understood by all involved individuals before any equipment is energized or operated. In most cases, the purchaser is responsible for furnishing the charge or charges of lubricating oil. He is, therefore, responsible for the oil being suitable for the intended purpose. In particular, the purchaser is responsible for the oil tank after the flush. There have been a number of cases when an oil flush has been satisfactorily completed and the system made ready for service, only to be contaminated by dirty oil pumped into the main oil tank by the purchaser. purchaser. The purchaser should monitor the tanks/trucks tanks/trucks for a potential source of contamination. contamination. It is often mutually advantageous advantageous for the cleaning and flushing of the purchaser’s oil storage, purification, purification, and transfer system to be carried out in conjunction with the cleaning and flushing of the turbine – generator generator oil system. However, in all cases the purchaser’s oil storage purification, a nd transfer system must be cleaned and flushed prior to cleaning and flushing the turbine – turbine – generator generator oil system. When the oil system cleaning operation has been completed, the tank filled with clean oil, and the system pronounced ready for service, it is t he purchaser’s responsibility to see that the system and the oil stay clean. The General Electric Company shall provide:

a.

Lube oil system that can be cleaned in a responsible manner consistent with the design requirements.

b.

Components that are clean and in good condition when delivered to the destination.

c.

Guidance and recommendations for cleaning the system. These are general recommendations based upon experience, tests, and knowledge of the design capabilities and limitations. They are to be used as guidelines in setting up the specific instructions by the purchaser for his particular unit. This bulletin is intended to fulfill this this obligation. obligation.

d.

Clarifications, explanations, and interpretations of the material contained in this bulletin leading to the establishment of a mutual understanding of the responsibilities involving the purchaser and the contractor. contractor. This subdivision of responsibilities should be clear and specific.

e.

Advice to the purchaser for the planning, organizing, and scheduling of the flushing operations in
















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II. PREPARATION FOR FLUSHING - LUBE OIL SYSTEM A. General Preparations

The turbine generator set is prepared for oil flush towards the end of the installation so the turbine oil system can be in operation to protect the unit. The piping should be checked to make sure that all welds have been completed and there are no open holes in the system. This includes plant piping and equipment that may be connected to the GE supplied equipment such as plant transfer tank. The area around the oil tank and open bearings should be inspected and tarps erected if it is judged that work activities around these areas will introduce debris into the system. Other plant work should be planned so as to not interfere with the flush which is generally conducted 24 hours a day. All standards, bearing housings, and the oil tank should be thoroughly cleaned before the flush. Bearing jumpers with shut off valves and inspection screens should be made and installed with temporary covers over open areas to prevent entry entry of foreign foreign material and minimize minimize oil splashing, splashing, leaks, leaks, and vapors. B. Turbine Lube Oil

Turbine oil recommended for use in the turbine generator set purchased is specified in the turbine operator’s manual. Turbine oil used for flushing and commercial operation is norma lly supplied by the plant owner, and or their agents unless otherwise otherwise specified by contract. Although Although the practice of reusing flush oil is strongly discouraged by engineering, it is recognized that this practice is occasionally utilized in the field. In the event that the site personnel, end user, and oil vendor all concur that reusing the oil is acceptable, it shall not be done without reconditioning. As such, turbine oil can be reused after the flush if properly filtered, free of contamination and if the oil has the correct chemical properties. Details regarding the supply and delivery, transfer, and storage of oil should be determined well in advance of the oil flush. C. Turbine Bearings

There are several ways that oil feed piping can be flushed at the turbine bearings. Each bearing feed line must be flushed and accepted separately by installing 100 mesh inspection screens at each bearing. Bearing jumpers with shut off valves and inspection screens are prepared to jumper each feed line to drain. Oil must never be flushed through a bearing with a rotor journal in place since dirty oil with debris can damage both the bearing and journal. However, care must be taken to thoroughly flush the entire run of feed piping as experience has shown that debris remaining in feed lines can a significant cause of problems.
















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For some units it is possible to install temporary piping with a valve and strainer basket at the orifice assembly cover adapter to drain into the pedestal. Temporary piping connected to the main turbine and generator bearing must be EQUAL TO OR LARGER in size than the FEED line before entry to the bearing. This piping should be immediately immediately increased to size at the bearing horizontal joint and contain as few fittings as possible. GATE shutoff valves MUST be used in the temporary feed. These measures will ensure to maximize the high flushing velocities required for an adequate flush. One hundred mesh strainers should be placed at the outlet from temporary piping at all bearings. Duplex strainers can also be used for ease of maintenance maintenance during flush. These will provide dirt collection points and CONTAMINATION MONITORS for each feed line. These strainers may be manufactured on site or purchased. If strainers are are made at at the site, the following rules rules must be followed followed to ensure ensure a low pressure pressure drop across them. From pressure drop considerations screen area must be at least 4 times that of the temporary piping discharging into the strainer. However, to provide plenty of dirt holding capacity there ought to be a least 150 in2 (0.097 m2) screen surface area. a.

The screening must be backed up (supported) by perforated plating having at least 60% open area.

b.

The screening material should be stainless steel so that it will resist rupture upon impact by foreign material.

c.

Strainers should be easily removed from the end of temporary piping and not so heavy that one cannot be handled easily by one man.

d.

The basket design should be such that the screening can be easily cleaned for purposes of monitoring the collected contamination.

e.

The screen should be on the sides of the strainer to reduce impingement damage. A more compact design for the crowded bearing standards will also result.

Undersize strainers will critically reduce bearing flushing velocity and prevent a successful flush. Contamination collected in each strainer basket at the bearings should be collected and used as a method of measuring the progress of the flush. The amount of contamination (e.g., weight) can be plotted against flushing hours for each bearing. This will give an indication of the state of cleanliness of each feed line. Even a visual comparison of such samples can be a good indicator of flush progress.


















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1. For short piping sections where it can be positively determined without a doubt that the piping between the bearing bearing cavity feed flange flange and the bearing is clean, clean, a flanged jumper jumper can be attached to the pipe flange without flushing through the casing. Caution must be used if the casing connection inward is not flushed since machining chips and weld splatter has been known to hide in these areas where it cannot be observed and cannot be removed by air blowing alone. Generator bearing feed piping is presently presently flushed in this this manner. manner. 2. Some bearings are designed to be rolled partially out to access casing flushing provisions. These types of turbine bearings are designed with flushing ports. The bearing is rolled for the bearing flushing port to line up with the casing feed to jumper oil from the casing to drain without passing through the bore of the bearing. Most bearings of this design have split joints that are not horizontal. In this case, bearings and casing areas are stamped with markings such as “Flush” and are provided with information in the turbine operator manual regarding this feature. 3. The more difficult, or traditional way of flushing bearings is to either roll out the bearing and support the shaft or partially roll it out and fit a jumper pipe into the casing feed hole at the bearing fit. Many of the newer bearing designs don’t have enough room between the rotor and casing to do this. If this method is used, the jumper pipe is wrapped with shim stock to fit the bearing feed hole tightly, then a piece of wood is wedged between the pipe and the rotor to hold it in place against the oil pressure. Duct seal putty is then wrapped around the fit area to prevent oil from splashing around the shim wrap. 4. One can use permanently installed flushing boxes (see Figure 2) for ST bearing and piping flush. Permanently installed bypass and valving to ease in set-up and installation post flush. Open valve to bypass line, oil oil travels through through bypass and filter returns returns through flush box through through drain return back to tank. Once the feed lines have been filtered, the same system can be used to flush to the bearings by closing bypass. See See Figure Figure 3 for site installation installation or flushing box.
















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D. Supplementary Flushing Skid

In order to approach, as closely as possible, the high flow velocities required, an external supplementary flushing pump can be utilized. However, for the larger pipes in the system (main feed header and the larger branch lines) maximum velocity alone is not always high enough to rapidly remove all particles. Therefore, the intent during a lube oil flush should be to use all the available contamination releasing tools/methods (hydroblasting, pipe vibration, pipe hammering, air injection, etc.) to the maximum practical extent. A supplementary pump will increase the oil flushing velocity (the single most effective element in flushing dirt and debris). The suction of the pump should be connected at the blank flange (flushing connection) on the tank side, see Figure 4. The turbine lube oil pumps on the main lube oil skid are designed to provide a normal operating flow to the bearings. The two main pumps on the skid can be run simultaneously to increase velocity and the site can employ a sequential flush to increase velocity. However, the use of a supplementary flushing pump can accomplish the same end. The turbine oil pumps should not be run simultaneously simultaneously with the supplementary supplementary flushing flushing pump. The supplementary flushing pump should be sized to handle two to three times the rated flow of the unit. Oil pump pressure should not exceed 150 psig [ 1034.2 kpag] [10.5 kg/cm2 gauge]. The use of a supplementary flushing skid will help to reduce flushing time. Flushing and filtering skids for this purpose are available from several sources that specialize in these services. When using an external supplementary flushing pump, this should be made part of a skid that will include additional equipment important to the successful completion of the flush. Along with an external flushing pump, the skid shall include a heat exchanger (cooler) for maintaining the lube oil temperature in the acceptable range per this GEK. The cooler shall be sized for lube oil pressure per the deadhead of
















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Figure 4. Typical Supplementary Flushing Flushing Pump Connection E. Lube Oil Tank/Skid

The oil tank assembly is factory tested during manufacturing in which both the turbine lube, seal and hydraulic/control (for GT units) oil circuits are run and functionally checked for performance and operation. Pressure switches and devices are also bench tested when the tank is built however, none of the lube oil piping outside of the oil tank is included during testing. Even though the tank is cleaned prior
















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*100 mesh screen is the equivalent to 150 micron. F. Oil Purifier

Steam turbine oil systems are supplied with a standard lube oil purifier unit. The purifier is a coalescing and separator unit used for water removal. The oil purifier is a self-contained unit mounted on top of the oil tank with its own motor control for motor driven pump, heater, and temperature controller. It is not necessary to put the purifier in operation during the flush since moisture in the lube oil is mainly an issue associated with normal turbine operation. The lube oil purifier has been previously factory run with the oil tank and requires no special preparations to prepare for the flush. The system is usually put into service after the oil flush is complete. G. Lube Oil Coolers

Turbine lube oil systems are designed with either shell and tube or plate and frame type oil coolers. Flushing is performed with the lube oil coolers in the flushing circuit for both these designs, when not using a supplementary flushing skid. Each tank has two lube oil coolers, each sized for 100% capacity with lube oil filters downstream of the oil coolers by design. Remove one cooler bundle during the flush so that maximum flushing velocities may be obtained. The remaining cooler should have a source of hot and cold water for temperature cycling of the flushing oil. If using the plate and frame oil coolers on the skid, a 100 mesh temporary screen shall be placed upstream of the cooler oil side. The plate and frame coolers have smaller channels, which can trap debris. It is prudent to place to screens upstream of the coolers to prevent larger debris from entering the coolers. Flushing with the coolers and oil filter elements in place will not negatively impact the oil velocity required for flushing. If large debris is allowed to enter the cooler bundles, it cannot generally be


















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H. Lube Oil Filters

Steam turbine, gas turbine and generator oil systems are designed with 12-25 micron lube oil filters. There are no special actions required to prepare the lube oil filters for oil flush however, extra sets of filter elements are shipped as spares to restore the system after flushing is complete. This is assuming that a supplementary flushing skid is not utilized with separate filter housing and elements. The filter elements are generously sized to minimize plugging and are designed as a woven mesh and stainless steel matrix to be able to survive high differential pressures of approximately 100 psid without collapsing. The filter elements are designed without any bypass system but are set to alarm during normal operation on high differential pressure of 15 psid. They are rated, and are factory tested for maximum pump flow without downstream restriction. For these types of filters, flushing should be conducted with the filter elements in place. I. Lube Oil Pumps

The lube oil pumps have been previously tested at the oil system manufacturer for flow, pressure, and
















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M. Vibrating Piping

Vibrating and hammering the piping while circulating oil is very effective. It loosens dirt and weld beads and keeps the particles in suspension for the oil to carry it away. Any piping that has been modified on the job and all field welds and bends that can be reached with reasonable effort should be hammered with a hand held pneumatic hammer. Pneumatic vibrators that can be mounted directly to the welded joints of the piping are recommended. recommended. N. Air Injection

At certain pertinent points, connections should be made to facilitate the injection of dry air into the system. These should be approximately 1 in (25 mm) in size with check valves and shut – shut – off off valves and 2 connected to an air supply of approximately 100 psig [690 kPa(gauge)] [7.0 kg/cm (gauge)]. Air blasts of one minute duration at 15 minute intervals during as much of the flush as possible may be advantageous advantageous at the following locations: Oil feed lines to generator bearings
















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III. PREPARATION FOR FLUSHING – HYDRAULIC/CONTROL HYDRAULIC/CONTROL OIL SYSTEM (GT SYSTEMS ONLY)

For GT hydraulic control oil systems see GT MLI A125. IV. PREPARATION FOR FLUSHING – GENERATORS GENERATORS A. Oil Flushing Generators

When flushing a turbine generator set, the furthest feed lines away from the oil supply should be planned for cleaning and acceptance so as to flush debris down the line and not reintroduce material into lines that have been previously accepted as clean. Usually the generator bearings lie at these extremities however, one must look at the particular piping arrangement when determining the sequence of flush. Generators are presently flushed without flushing through the bearing cavities, by disconnecting the bearing and or hydrogen seal oil feed line flanges flanges at the casing. This assumes assumes that the connection flange inward has been thoroughly cleaned during manufacturing and will remain in that condition until put into service. These connections should be inspected for rust or other signs of problems that may have
















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3. A temporary oil drain receiver vessel can be made from either a drum cut in half or by using a large diameter pipe and fabricating flanged drain connection that bolts to existing drain line flange connections. Often it is necessary to re-orient these receptacles vertically to connect to horizontal drain flanges. These three jumpering methods are applicable to both bearing pedestal mounted air cooled generators and hydrogen cooled generators with end shield mounted bearings and hydrogen seals. C. Hydrogen Cooled Generators

Depending on the generator model selected for the application, the hydrogen seal oil piping is either packaged packaged on the generator, generator, or shipped loose and field erected erected on site. site. Unlike air air cooled generators, generators, a two stage flush is required for all hydrogen cooled generators in order to keep debris out of the hydrogen seal and bearing drain enlargement tanks, where once debris enters, it is very hard to remove. Hydrogen cooled generators are prepared for coarse flushing of the hydrogen seal oil system with the two end shield mounted hydrogen seal tanks, float trap(s), and bearing drain enlargement tank jumpered
















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Generator Hydrogen Seal Oil System Components

Hydrogen cooled generators are designed with a hydrogen seal oil unit as part of the generator scope of supply. The seal oil unit contains the following components: 1. Hydrogen seal oil system that is supplied by oil piped to the hydrogen seal oil unit from the turbine lube oil system. The seal oil unit contains a differential pressure regulator, flow meter, float trap(s), alarm pressure switches, and gages. Depending on the generator selected, this equipment may either be mounted mounted on the generator generator package or field installed installed on the foundation. foundation. 2. The air side seal-oil and generator bearing oil drains to the bearing drain enlargement tank through a loop seal and back to the main oil reservoir. The hydrogen side seal-oil drains to the two seal drain enlargement tanks through the hydrogen float trap(s) to the bearing drain enlargement tank. 3. Most seal oil units presently being shipped have hydrogen seal oil filtration performed in the lube oil tank. Previous designs had separate hydrogen seal oil filters built into the seal oil unit.


















Rev B

G E K 116944b 116944b

Released 11/30/2018

Page 22 of 34


C. Screens and Strainers

Screens must be installed in each bearing feed line and all lines returning oil back to the tank. It is recommended that 100 mesh screens (150 micron equivalent) are used. The 100 mesh screen is expected to pass all particles with any dimension less than 150 microns. Particles greater than 250 microns will most likely be intercepted by the screens. The 12-25 micron filters that are part of the lube oil system will further reduce particle size below these levels. Each bearing feed line is monitored and accepted on
















Rev B

Released 11/30/2018

Page 23 of 34


G E K 116944b 116944b

Oil Transfer from Containers

Filtering or straining the oil from storage tanks to the main oil tank is a must. In many cases the oil storage facilities have unknown or questionable cleanliness levels. Temporary filters can be installed in between the the storage tanks and the main oil tanks, tanks, or use one one of the following: following: 1. Witch hats and flat screens work well when used to strain oil of unquestionable cleanliness level
















Rev B

G E K 116944b 116944b

Released 11/30/2018

Page 24 of 34


VI. FLUSHING THE LUBE OIL SYSTEM A. Flushing the Lube Oil System

It should be recognized that techniques recommended in this section are best applied with regard to the condition of the piping equipment, piping configuration, and the nature and type of material that must be cleaned up. For example, pipe vibrators provide maximum benefit in the removal of weld splatter and
















Rev B

Released 11/30/2018

Page 25 of 34


G E K 116944b 116944b

Flush of the Lift Pump Lines (if applicable)

During the coarse flush the lift pump lines should be flushed, as described in the following text. During later bearing feed line flushes the same techniques will be repeated but for longer periods. The location in the flush sequence of the lift line flush varies with different machines, since the location of the lift pads can vary. The lift pump pump piping should be flushed at a time which which will prevent the draining draining oil from flowing over previously flushed drain header piping.
















Rev B

G E K 116944b 116944b

Released 11/30/2018

Page 26 of 34


Flush Exciter Bearings and Hydrogen Seal Piping

The external supplementary flushing oil pump or main lube oil pump should be turned on. The temporary valves at the exciter bearings should be opened. Bearing caps or temporary covers should be in place at the generator bearings. Exciter Bearings





































































































Flushing Recommendations for Turbine Lube Oil Systems with Motor Driven Main Oil Pumps

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