Sub: - Leakage in Lube oil system.

Leakages in Lube oil system is a major area of concern for sheds; analysis of recent failures of lube oil system reveals need to strengthen and update existing maintenance practices.

Action to be taken:

1)           Dresser coupling:

Failure locations: 2-1/2" armor of pipe line in between lube oil strainer and lube oil regulating valve, 3" armor gasket of L/oil strainer to L/oil main header dresser and delivery pipe armor joint.

Action to be taken:

·                     New gaskets should be examined for signs of wear, nicks, cracks, splitting or laps. Only lab tested/certified gasket should be used.

·                     Smoothen the pipe down where the gaskets are to reside. Sand them down with emery paper, using 100-grit first to remove any abnormalities on the pipe, like burrs or casting impurities. Next, use 200-grit to finish sand and smooth down the pipe. coupling nut and retainer ring (if fitting has them) on to the end of each pipe so the nut threads are facing the end of the pipe

·                     Brush gasketting compound onto the pipe ends. This makes a positive seal between gasket and pipe and lubricates the pipe so the gaskets slide on easily. Slide a gasket onto each pipe so the bevelled end faces the end of the pipe. Make sure the gasket on either side of the pipe extends right to the end, then push the pipes into the dresser coupling.

·                     In pipe line joints, the space between two ends of the pipe  gap should be  measured and  both side pipe ends should be equally distant from centre of the dresser coupler .Mark with paint  and space the coupler evenly on pipes to be joined on the pipe .there should not be any displacement of the dresser coupler at the time of fitment and clamping  .

·              The middle ring and followers of the coupling should be true circular sections free from irregularities, flat spots or surface defect.

·              Alignment of pipe line & tightening of gasket should be done perfectly, The correct procedure of fitment should be explained to fitters.

2)           Gasket :

Failure locations : Lube oil Cooler, side cover gasket, lube oil delivery pipe gasket, Lube oil pump gasket burst, OST housing gasket, Filter drum gasket.

Action to be taken:

Condition of old gasket will yield valuable clue regarding poor surface condition, sharp edges, over tightening and premature perishing.  Causes of these should be attended before new gasket is fitted. Gasketting compound should be used for attending surface imperfections. Gasket must be visually examined and tightened uniformly.

Whenever two surfaces are to be joined either with or without gasket, proper lapping and colour matching of surface should be ensured. Surface condition should be checked and restored if required.

Non standard gasket or handmade gasket of improper gasket material should not be allowed. Only machine cut ready to use gasket of approved material should be used to arrest failure. Sheds should initiate special drive to weed out all non standard gaskets immediately.

3)      Pipe line failures:

Location of failure:

Leakages from lube oil pipe lines like lube oil cross over pipe, governor lube oil pipe, gauge line pipe, centrifuge to flexible hose, pipe connector thread crack.

Action to be taken:

Lay out:

The layout of pipe line should be laid in stream line fashion exactly similar to DLW manufactured/DMW RPP locos. There should not be any sharp bend or rubbing in pipe lines. T gauge should be used for ensuring correct gap and alignment for joining pipe. Single ferrule flare less tube (errmettro) fittings should be provided in lube oil line. ‘T’ gauge should be used to measure correct gap during fitment

Vibration:

Vibration monitoring of pipe lines must be done in every schedule. 10% rise in vibration reading from previous reading of same loco at identical condition and  location should be immediately investigated and due attention should be given.

For lube oil system components absolute reading of support vibration more than 90 mm/second will lead to fasteners, clamps or brackets breakages. Any change in type and intensify of sound is cause of alarm.  Engineer’s stethoscope should also be used for listening sound. The root cause of vibration should be identified and eliminated before releasing the loco.

Clamps and brackets should be renewed in M24 schedule by chipping out old welding.

To arrest rubbing of pipelines suitable rubber sleeve should be provided and sufficient air gap must be ensured between pipe line and nearby surface.

Failure due to heavy vibration in WDG3 locomotive should be modified as per RDSO’s IB. Additional member has to be welded to frame.

Alignment: 

Misalignment of pipe line has been identified as major contributor of lube oil leakage.

Misalignment in lube oil pipe line should be thoroughly attended during pre-commissioning of POH and RB locos.

Primary focus and input to arrest leakages should be given during major schedule to avoid repeated attention on locomotives during trip schedules.

Alignment of Heavy schedule locos should be done by experienced technicians under supervision of section supervisor.

Poor thread condition and Over tightening:

Thread condition pipes and of adopter should be checked before fitment. Pipe lines laving worn out or damaged thread should be replaced. Tendency of stopping leakage by applying excessive thread tap should be avoided.

Whenever any leakage is observed in shed, staff simply over tightens the component and allows it in service. No over tightening should be permitted, if leakage is observed then component should be dismantled and cause of leakages e.g. damaged thread, surface or gasket should be attended.

Application of thread locking compound:

Thread locking compound must be applied to fill up the gap between male and female threads to increase strength of joints.

Marking on head and coupling: It is a good idea to make a line on head of fastener, coupling and pipe line to indicate condition of fasteners during fitment stage. A line should be drawn with paint on all pipe line joints to check alignment and gap in service, if any change in line is observed during service, joints need to be inspected and attended.

4)       Centrifugal lube oil cleaner:

Failure locations: Base crack and ‘O’ ring .

Action to be taken :

·      The side support of base should be welded properly

·      Cleaner body assembly “O” ring to be fitted properly.

·      Hose pipe to be changed in M-12

·      New bolts should be fitted in M₂₄ schedule and bolts should be fitted with thread locking compound.

·      Outlet to sump flexible hose should be converted into steel pipe.

·      Inlet flexible hose along with forged end fittings should be made stock item and replaced one round as old hoses are still in service.

5)      Lube oil cooler

Failure locations :  Tube crack

Action to be taken:

·      Hydraulic test of cooler in M-24.

·      Replacement of conventional cooler by PTLOC.

·      Radiator compartment vibration contributes max number of failure of lube oil cooler . Due to vibration, armour joints of lube oil cooler get disturbed on run. The clamp, holding the cooler and the pipelines should be attended properly during major sch and whenever new lube oil cooler fitted.

·      Monitor and arrest vibration in radiator compartment

·      The lube oil cooler rubber pads should  be replaced during overhauling of lube oil cooler, worn/perished pads cause vibration  in the system.

6)      Lube oil filter drum:

Failure Locations: L/oil drum welding cracked and ‘O ring perished.

Action to be taken:

·      Cover “O” ring to be fitted carefully duly checking sharp edges/sharp grooves of filter drum. The diameter of the O ring should be measured carefully and also compared with the filter drum groove.

·      Removed O ring should be carefully observed   for any sign of over tightness . If any sign of damage in O ring is observed, the root cause of damage( incorrect ring dia/incorrect groove depth/over tightening) should be identified and corrected before fitment of new ring symptom the cause to be find out .

·      All Lube oil filter drum wing nut should be tightened uniformally by modified torque wrench in diagonal fashion and no hammering should be done as it damages the stud threads (torquing value – 110 to 115 foot pounds).

·      Drum foundation base bolt to be checked for tightness

·      Lube oil filter drum foundation bolt retaining plate to be checked for welding crack

·      L/oil filter drum drain cock to be checked for condition of thread and seepage.

·      Capsule type filter drum should be made stock item and it should be changed in M₄₈ and above schedule.

7)       L/OIL pump:

Location: Lube oil seal and housing gasket.

Action to be taken:

Proper backlash must be measured at the time of fitment of lube oil pump assembly.

Ovality of pump bearing frame should be measured and housings found beyond the limit should be replaced. 

During overhauling and failure investigation all released items should be thoroughly examined for defects. Observations on defects and condition of components should be recorded and analysed jointly with lab to find out the root cause of such abnormalities. Correlation with service life, make, fitment faults, material quality etc. should be explored to ascertain the root cause in such cases.

Oil and water seals should be of RDSO approved source and manufacturing should be less than one year. Lab must check seal quality and certify before fitment. Proper setting of seals must be ensured.

D.P. testing of L/Oil pump housing, shaft, gears must be ensured by lab before fitment.

8)       Other maintenance practices:

Leakage checking: Leakages are best checked when loco is on load box test and run for some time. Lube oil and fuel oil leakage tendency is very high due to reduction in viscosity at elevated temperature. Crank case exhauster motor can be stopped for 30 seconds and lube oil leakages can be observed.

Training and acceptance level: Sectional staff and supervisors must be trained and counseled to ensure leak free locomotives. Significance of the objective must be understood by all of them.

Measurement of lube oil level:

·      Whenever loco touches the shed its incoming lube oil level & LOFR should be recorded.

·      Trend monitoring of LOC and lube to fuel oil ratio of the current trip with past records should be done before schedule attention to observe rise in trend if any.

·      Any abnormal drop of lube oil level or higher LOFR indicates the lube oil leakage in system. Loco should be thoroughly checked and leakage should be attended.

·      Lube oil level & LOFR should be monitor & prepared by lab and given to SSE/Running and ADME/Running for taking necessary action. It must be discussed during power meeting.

Maintaining correct Crank case vacuum:

·  Crank case vacuum to be checked in every schedule

·  Exhauster hose pipe to be checked for chocking

·  Exhauster drain pipe to be cleared in M-4

·  Old stock crankcase gasket should not be use as the gaskets are become hard and failed to 100% leak proof.

·      Crankcase door cover to be fitted & tightened properly .No oil leakage should be allowed.

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Annexure 

The Basic Working Principle of Dresser Couplings:

The Dresser coupling consists of one cylindrical middle ring, two follower rings, two resilient gaskets of special Dresser compound and a set of steel track head bolts. The middle ring has a conical flare at each end to receive the wedge portion of the gaskets. The follower rings confine the outer ends of the gaskets. As the nuts are tightened, the bolts draw the follower rings toward each other, compressing the gaskets in the spaces formed by follower rings, middle ring flares and, pipe surface thus producing a flexible, leak-proof seal on the pipe joint.

The Basic of gaskets:

Materials for gaskets can be divided into three main categories:

•Non-Metallic types    •Semi-Metallic types    •Metallic types

Non-Metallic gaskets are usually composite sheet materials are used with flat-face and raised-face flanges in low Pressure Class applications.

Semi-Metallic gaskets are composites of metal and non-metallic materials. The metal is intended to offer strength and resiliency, while the non-metallic portion provides conformability and sealability. Semi-metallic are designed for almost all operating conditions and high-temperature and pressure applications, and are used on raised face, male-and-female, and tongue-and-groove flanges.

Metallic gaskets are fabricated from one or a combination of metals to the desired shape and size. Often used metallic gaskets are ring-type-joint gaskets (RTJ). They are always applied to special, accompanying flanges which ensure good, reliable sealing with the correct choice of profiles and material.

Ring Type Joint gaskets are designed to seal by "initial line contact" or wedging action between the mating flange and the gasket.

Spiral Wound gaskets : The concept of spiral wound gasket construction was originated by Flexitallic in 1912, inaugurating the beginning of a new era in safe, effective sealing.

The necessity for a gasket to have the ability to recover cannot be over emphasized. The effects of pressure and temperature fluctuations, the temperature differential across the flange face, together with bolt stress relaxation and creep, demand a gasket with adequate flexibility and recovery to maintain a seal even under these varying service conditions.

Annexure

SN	Cause	Location	Remedial action
1	Lube oil leakage from compression fitting of gauge line with gauge	Nose compartment.	Fitting Adopter to be checked for any damage
2	L/oil leakage from L/oil gauge line of copper pipe line connecting to the lube oil pressure gauge has cracked		Annealing of copper pipes
3	Lube oil gauge copper pipe rubbing with booster gauge copper pipe near TG		Proper clamping
4	Governor engine oil pressure sensing pipe cracked near cone portion	Free end side	Annealing of copper pipes during M24(new material was fitted)
5	The Governor's engine lubes oil sensing copper pipe. A cut mark found near the T adopter to lube oil gauge line near Generator room partition wall		Proper bracketing& HP joint sheet application
6	Lube oil leakage from 2-1/2" armor of pipe line in between lube oil strainer and lube oil regulating valve.		Dresser gasket badly damaged
7	L/oil strainer head gasket burst		Gaskets from RDSO approved firms
8	3" armor gasket of L/oil strainer to L/oil main header dresser		dresser gasket badly damaged
9	L/oil regulating valve engine sump armor joint leakage	Comp. Compartment	Maximum vibration in compressor base as the base welding and base plate cracked
10	Lube oil by- pass valve gasket found unseated due to improper fitment.		Improper fitment of gasket.
11	Lube oil leakage from lube oil pump delivery pipe near lube oil regulating valve due to welding joint failed.		delivery pipe crack, (In M-24 all pipe D.P test for crack)
12	L/oil cooler to strainer Armor Gasket perished		clamp welding failure
13	L/Oil relief valve gasket burst		improper fitment
14	Paper gasket at lube oil pump face jointing area is torn out.		Gaskets from RDSO approved firms
15	Lube oil leakage from pump housing		pump housing was cracked and idler gear bush both side were worn out
16	L/Oil leakage from L/Oil pump delivery pipe to centrifuge hose.		Hose pipe replacement in M-12
17	L/OIL pump pipe flange joint gasket burst.		premature failure of gasket
18	L /Oil leakage from steel pipe dresser coupler.		Pipe alignment wrong
19	Lube oil cooler out let pipe flange gasket damage.	Radiator room	Gaskets from RDSO approved firms
20	Filter delivery pipe 3" armor joint near lube oil drum		Gasket over aged
21	Lube oil cooler side cover gasket.		Gasket over aged
22	Lube oil cooler body welding joint cracked		Hydraulic test in M-24
23	Oil leaked from armor joint causing heavy vibration and		Lube oil filter drum foundation bolt retaining plate welding broken
24	Lube oil filter drum ‘O’ ring came out from its original position		Lube oil filter drum 01 no. wing nut found loose
25	Lube oil leakage from filter drum drain cock.
26	Lube oil drain pipe	Eng. room	Drain pipe flange holding bolts loose.
27	Centrifugal cleaner 3" out let rubber hose to sump burst longitudinally.
28	Lube oil pre-lubrication pump inlet hose rubbing and damaged causing lube oil leakage		hose rubbing, Proper clamping of pipe
29	Pipe bracket gasket (HP joint sheet) of turbo L/oil filter got burst		Gaskets from RDSO approved firms
30	Lube oil leaking from OST upper housing.		Housing surface cleaning before applying gasket
31	L/oil leakage from copper pipe cone of main header.		Cone to be checked for proper seating
32	Main header to Aux header union nut L/oil leakage.		Proper tightening to be done
33	Lube oil leaked from main header to aux header T joint union nut. pipe cone (T connector end) loose		Short length pipe fitted
34	L/Oil leakage from L/H no. 6 cross pipe		Thread of adopter& use of Teflon
35	L/oil leakage from header to Turbo flexible hose.
36	The thread area of the centrifuge cleaner found maximum slag
37	Self centrifuge to flexible hose pipe connector (steel pipe) thread portion crack.	Eng  room	Bracket welding
38	Centrifugal L/Oil cleaner stud drop down.		The side support of the cleaner base found welding crack
39	Al base Turbo Filter casing cracked at centre bolt fixing bush
40	Centrifugal lube oil cleaner body assembly rubber ‘O’ ring worn out		over age
41	out let flexible pipe of centrifugal L/oil cleaner		Flexible pipe to be changed in M012
42	Oil comes from drain hose from CCM which was loose connected & bend.		Drain hose bending & straightness to be checked in each sch.
43	Lube oil leakage from the front cover near left side no. 6 bolt. A piece of front cover gasket (high pressure joint sheet) came out near L-6 bolt.		Surface to be cleaned carefully