CORROSION IN RAIL TRANSITCORROSION IN RAIL TRANSITCORROSION IN RAIL TRANSITCORROSION IN RAIL TRANSITCORROSION IN RAIL TRANSITCORROSION IN RAIL TRANSITCORROSION IN RAIL TRANSITCORROSION IN RAIL TRANSIT

Possible methods of PreventionPossible methods of PreventionPossible methods of PreventionPossible methods of PreventionPossible methods of PreventionPossible methods of PreventionPossible methods of PreventionPossible methods of Prevention

K.L.V.S.VISWANADHAMB.Tech, DCE, DCOM;PGDCA

SSE (P.WAY)

Rail Rail Rail Rail –––– Corrosion Corrosion Corrosion Corrosion –––– Causes Causes Causes Causes ---- TypesTypesTypesTypes

�RAILRAILRAILRAIL ---- Is the fundamental component of Rail Transit System

�EXPECTATIONEXPECTATIONEXPECTATIONEXPECTATION- To function reliably and continuously over decades.

�WhatWhatWhatWhat isisisis thethethethe problem?problem?problem?problem?

• Saline atmosphere in salt-laden coastal areas deteriorating the life of the rail dueto corrosion.to corrosion.

• Corrosion of rails causes huge economic loss because of frequentreplacements.

• As per analysis of IIT/Kanpur, average annual loss due to premature railreplacements is about Rs.440 cr.

• Rail failures due to corrosion effects safety of trains and disturb normal traffic.

• Rails laid near coastal regions are more prone for atmospheric corrosion andwarranting more frequent replacement than rails in dry climate.

�WhatWhatWhatWhat isisisis CorrosionCorrosionCorrosionCorrosion????

� In simple terms, Disintegration of a metal due to an electrochemical reactionwith its neighboring environment.

�HowHowHowHow itititit formsformsformsforms

� Substance disintegrates into atoms by chemical reactions with water andoxygen in the environment, resulting into an electron loss of the material.

� If an electrical circuit is completed, the metal atoms become positively� If an electrical circuit is completed, the metal atoms become positivelycharged ions, causing pitting or the development of a crack.

� Rate of pitting corrosion is more in portions where welding operations havecaused micro structural transformation.

� Localized corrosion may initiate fatigue that can intensify by action withcorrosive agents like sea water.

� Strength of iron reduces due to the oxidation of its atoms, called rusting, bywhich oxides are formed.

�EVILEVILEVILEVIL EFFECTSEFFECTSEFFECTSEFFECTS OFOFOFOF CORROSIONCORROSIONCORROSIONCORROSION::::

� Loss of mechanical Strength� Damage to the dimensional integrity� Distortion to physical properties of the component.

�GENERALGENERALGENERALGENERAL TYPESTYPESTYPESTYPES OFOFOFOF CORROSIONCORROSIONCORROSIONCORROSION ONONONON RAILRAILRAILRAIL TRASITTRASITTRASITTRASIT SYSTEMSYSTEMSYSTEMSYSTEM::::

� (i) Atmospheric corrosion and� (ii) Localized corrosion.

Atmospheric CorrosionAtmospheric CorrosionAtmospheric CorrosionAtmospheric Corrosiono Rust is formed when iron compounds corrode in the presence of oxygen and water

which are available in atmosphere. This corrosion is the result of the oxidationreaction when iron metal returns to a more stable state.

o Rust is formed on the rail table, more predominantly on the rail flange and in the railweb.

o Rail corrosion, particularly at the base of the rail, is a serious problem in rail transitsystems. Rail base corrosion compromises the integrity of the rail and could result incatastrophic failures.

The average rate of deterioration of rail foot in absence of application of anyo The average rate of deterioration of rail foot in absence of application of anyprotective measures is around 1mm per year. This may be much more in corrosionprone areas.

o The deposition of salts such as alkaline salts, chlorines and sulfates on rails createsa very detrimental effect on the reliability of the rails, because the salts formelectrolytes promoting oxygen to react with the rails, thereby accelerates corrosion.

o Places of salt Deposition noticed at; top of the slide chairs in P&C area, lugs of steelsleepers, bearing plates of wooden sleepers and very prominently near pit lines andcoach maintenance lines. Most of these locations are usually humid and wherethere is consistent contact between the rail and ground.

�TYPESTYPESTYPESTYPES::::

� Stray Current Corrosion

� Crevice Corrosion

STRAY CURRENT CORROSIONSTRAY CURRENT CORROSIONSTRAY CURRENT CORROSIONSTRAY CURRENT CORROSION

� Stray current corrosion is related to design than material facet.

Localized CorrosionLocalized CorrosionLocalized CorrosionLocalized Corrosion

� Stray current corrosion is related to design than material facet.

� A constant leak of current of one ampere can corrode up to 20 pounds of ironper year.

� An electric system where the return current can be as high as 750 A or higher,can result in damages of the rail of up to 15,000 lb or 7.5 tons of iron per year.

� Stray currents can be eliminated by properly insulating the rails from the ground.

� Careful designing and proper installation considerably reduces corrosion due to

return current.

o The form of corrosion below and around the metal liner can commonly referred as“crevice corrosion”.

o Localized corrosion in the form of corrosion pits and thinning of rail foot under theliner contact area are matter of serious concern.

o EndEndEndEnd resultresultresultresult isisisis prematureprematureprematurepremature failurefailurefailurefailure ofofofof thethethethe rails,rails,rails,rails, whichwhichwhichwhich isisisis aaaa greatgreatgreatgreat safetysafetysafetysafety apprehensionapprehensionapprehensionapprehension becausebecausebecausebecause thisthisthisthis isisisisaaaa majormajormajormajor causecausecausecause ofofofof railrailrailrail failurefailurefailurefailure....

o This is mainly due to collection of moisture from the atmosphere and discharge fromthe open lavatories of the coaches.

CREVICE CORROSIONCREVICE CORROSIONCREVICE CORROSIONCREVICE CORROSION

o It is a localized form of attack, where there is a breakdown of the surface passivelayer, in crevices or on shielded areas beneath surface deposits.

oCrevice corrosion is more prominent in environments near sea coasts. The drawbackis, this corrosion is not easily visible to the naked eye unless we remove the linersand examine.

oMostly the pit formation and crevice corrosion is observed on the gauge face side ofthe rails. Arrangement of the discharge pipe of the toilets provided in the trains is amain cause. The sullage water and the night soil will be highly saline in nature andentrapped near rail and liner contact area and at weld collars thus accelerates thecorrosion and forming of corrosion pits.

�LONGLONGLONGLONG TERMTERMTERMTERM SOLUTIONSSOLUTIONSSOLUTIONSSOLUTIONS::::

� No instantaneous way out to get rid of the rail corrosion.� Alternative is,

� Adopt anticorrosive metal.� Constriction..... Rare in nature and proved to be either costly or weak in strength.

� Viable solution is� Adopt corrosion resistant Alloy.� Elements like Cu, Cr, Ni, Mo, P, Si etc., will improve the sustainability against

corrosion.

Combat on General CorrosionCombat on General CorrosionCombat on General CorrosionCombat on General Corrosion

� Iron pillar at Qutub Minar is a great example of corrosion resistant ferrous.Increased phosphorous content made it possible.

TRIALSTRIALSTRIALSTRIALS CONDUCTEDCONDUCTEDCONDUCTEDCONDUCTED

� SAILSAILSAILSAIL developeddevelopeddevelopeddeveloped CuCuCuCu----MoMoMoMo steelsteelsteelsteel ((((0000....69696969CCCC----0000....24242424CuCuCuCu----0000....18181818Mo)Mo)Mo)Mo) onononon trialtrialtrialtrial.... TheseTheseTheseThese railsrailsrailsrails shownshownshownshownpromisingpromisingpromisingpromising resultsresultsresultsresults duringduringduringduring fieldfieldfieldfield trials,trials,trials,trials, butbutbutbut thethethethe highhighhighhigh costcostcostcost ofofofof molybdenummolybdenummolybdenummolybdenum hashashashas becamebecamebecamebecameaaaa hurdlehurdlehurdlehurdle inininin commercialcommercialcommercialcommercial productionproductionproductionproduction....

� FurtherFurtherFurtherFurther trialstrialstrialstrials –––– AlloysAlloysAlloysAlloys likelikelikelike CuCuCuCu andandandand CrCrCrCr,,,, CuCuCuCu andandandand MnMnMnMn,,,, Cu,Cu,Cu,Cu, CrCrCrCr andandandand NiNiNiNi etcetcetcetc....,,,, whichwhichwhichwhichareareareare cheapercheapercheapercheaper andandandand abundantabundantabundantabundant.... FieldFieldFieldField trialstrialstrialstrials havehavehavehave shownshownshownshown lowerlowerlowerlower rustingrustingrustingrusting inininin thethethethe casecasecasecase ofofofof NiNiNiNi----CrCrCrCr----CuCuCuCu railrailrailrail steelssteelssteelssteels.... OnceOnceOnceOnce thethethethe symbiosissymbiosissymbiosissymbiosis ofofofof thesethesethesethese metalsmetalsmetalsmetals isisisis provedprovedprovedproved satisfactory,satisfactory,satisfactory,satisfactory, generalgeneralgeneralgeneralcorrosioncorrosioncorrosioncorrosion cancancancan bebebebe getgetgetget ridridridrid ofofofof totototo certaincertaincertaincertain extentextentextentextent....

Condition of Alloy steels after 6 months exposure to Salt fog.Condition of Alloy steels after 6 months exposure to Salt fog.Condition of Alloy steels after 6 months exposure to Salt fog.Condition of Alloy steels after 6 months exposure to Salt fog.

� Galvanization� Coatings of zinc achieve corrosion prevention of the protected metal by the formation of

a physical obstruction, and by functioning as an anode if this obstruction is destroyed.� Constraint : Costly affair to put in long stretches. Perhaps,Perhaps,Perhaps,Perhaps, useuseuseuse ofofofof galvanizedgalvanizedgalvanizedgalvanized railsrailsrailsrailsinininin highlyhighlyhighlyhighly corrosioncorrosioncorrosioncorrosion proneproneproneprone locationslocationslocationslocations suchsuchsuchsuch asasasas platformplatformplatformplatform lines,lines,lines,lines, tunnelstunnelstunnelstunnels andandandandcuttingscuttingscuttingscuttings inininin thethethethe approachesapproachesapproachesapproaches ofofofof majormajormajormajor citiescitiescitiescities andandandand metrosmetrosmetrosmetros maymaymaymay helphelphelphelp totototo somesomesomesome extentextentextentextent....

� Application of anticorrosive paints, oil, grease etc :� Can minimise formation of rust by exclusion of air and water from the surface of rails.

�SHORTSHORTSHORTSHORT TERMTERMTERMTERM SOLUTIONSSOLUTIONSSOLUTIONSSOLUTIONS::::

�INITIATION BY SOUTH CENTRAIL RAILWAYINITIATION BY SOUTH CENTRAIL RAILWAYINITIATION BY SOUTH CENTRAIL RAILWAYINITIATION BY SOUTH CENTRAIL RAILWAY

� Guidelines for anti-corrosion treatment of rails, welds and other P.Way fittings throughESO 59

� Instructions on Corrosion of Rail foot due to Liner Bite and Protection through ESO 60.� Drives to curb corrosion

� Painting of Rails in corrosion prone areas� Greasing of ERCs� Sealing of Liner Contact Area� Shifting of Liner Contact Area� Use of Galvanized Liners

�INITIATION BY SOUTH CENTRAIL RAILWAYINITIATION BY SOUTH CENTRAIL RAILWAYINITIATION BY SOUTH CENTRAIL RAILWAYINITIATION BY SOUTH CENTRAIL RAILWAY

� Brings various corrosion control measures in a unified circular.

� Gives a solution to combat against General and Localized corrosions.

�EssenceEssenceEssenceEssence ofofofof thethethethe StandingStandingStandingStanding OrderOrderOrderOrder ::::

Salient Features of Engg. Standing Order No: Salient Features of Engg. Standing Order No: Salient Features of Engg. Standing Order No: Salient Features of Engg. Standing Order No: 59595959

EssenceEssenceEssenceEssence ofofofof thethethethe StandingStandingStandingStanding OrderOrderOrderOrder ::::

� Identification of corrosion prone sections, in addition to already identified locations,based on the practical experience of S.C.Railway and circulation of the list todivisions for taking various preventive measures.

� Highlighting the problem of corrosion and formation of corrosion pits near linercontact area on rails and the preventive measures.

ELUCIDATION AGAINST GENERAL CORROSION(i) PaintingPaintingPaintingPainting ofofofof NewNewNewNew railsrailsrailsrails andandandand inininin----serviceserviceserviceservice RailsRailsRailsRails::::

(a) For New Rails:o Paint before laying into the track.o Schematic painting shall be :

» Primer coat: Red Lead paint prepared by mixing 3.3kg dry pigment of red lead powderconfirms to IS type C 57-1989 with One litre boiled linseed oil confirming to IS 77/1966 to athickness of 80 microns.

» Second Coat: Ready mixed red oxide confirming to IS 123-1962 mixed with lamp black to athickness of 45 microns.

» Third Coat: Ready mixed red oxide confirming to IS 123-1962 to a thickness of 45 microns.

Red lead is effective in protecting the bear metal against the corrosion. As drying time of redlead is more, this scheme of painting is restricted to new rails on cess.

(b) For in-service Rails:» Primary Coat: Anticorrosive Bituminous black paint confirming to IS 9862-1981 to a thickness

of 100 microns.

» Secondary Coat: Anticorrosive Bituminous black paint confirming to IS 9862-1981 to athickness of 100 microns.

TheTheTheThe PaintingPaintingPaintingPainting ofofofof inininin----serviceserviceserviceservice railsrailsrailsrails shallshallshallshall bebebebe carriedcarriedcarriedcarried outoutoutout dependingdependingdependingdepending uponuponuponupon condition,condition,condition,condition, butbutbutbut notnotnotnotearlierearlierearlierearlier thanthanthanthan onceonceonceonce inininin twotwotwotwo yearsyearsyearsyears coveringcoveringcoveringcovering webwebwebweb andandandand toptoptoptop flangeflangeflangeflange onlyonlyonlyonly.... However,However,However,However, platformplatformplatformplatformlineslineslineslines ofofofof stationstationstationstation yards,yards,yards,yards, NonNonNonNon gaugegaugegaugegauge facefacefaceface sidesidesideside willwillwillwill alsoalsoalsoalso bebebebe paintedpaintedpaintedpainted.... ForForForFor locationslocationslocationslocations otherotherotherother thanthanthanthanplatformplatformplatformplatform lines,lines,lines,lines, onlyonlyonlyonly gaugegaugegaugegauge facefacefaceface sidesidesideside shallshallshallshall bebebebe paintedpaintedpaintedpainted....

Application of Anticorrosive Paint for in-service Rail

Revelation against CREVICE CorrosionLubrication of ERCs and Sealing of Liner Contact Area: Lubrication of ERCs and Sealing of Liner Contact Area: Lubrication of ERCs and Sealing of Liner Contact Area: Lubrication of ERCs and Sealing of Liner Contact Area: i. On corrosion prone areas - Once in a year.ii. On other areas - Once in 2 years.» ERC greasing shall be done for all 4 ERCs on the sleeper. » Sealing of liner contact area - In corrosion prone areas –

only on inside of the rail.» Grease graphite to the specification IS – 408 – 1981 Gr ‘O’

(Aluminum soap based).

Weld collar painting:Weld collar painting:Weld collar painting:Weld collar painting:� On identified corrosion prone areas - once a year.� Non-corrosive prone areas, once in two years. » Two coats of anti-corrosive bituminous black paint conforming to IS 9862- 1981, to a

thickness of 200 Microns.

Use of galvanized metal liners, galvanized plate screws and stretcher Use of galvanized metal liners, galvanized plate screws and stretcher Use of galvanized metal liners, galvanized plate screws and stretcher Use of galvanized metal liners, galvanized plate screws and stretcher bars in points and crossing areas.bars in points and crossing areas.bars in points and crossing areas.bars in points and crossing areas.

� Galvanized liners – In all identified corrosion prone areas.� Galvanized Plate screws and Stretcher bars - In all areas irrespective of

corrosion Proneness.

Galvanized Metal Liner vs MS Liner

Galvanized Plate Screw

�Speaks about Corrosion of Rail foot due to Liner Bite and Protection.

� Shifting of Liner Contact Area – Methodology to be adopted.

InInInIn aaaa nutshellnutshellnutshellnutshell::::

» Average rate of corrosion at rail foot in absence of corrosion protective measures

Salient Features of Engg. Standing Order No: Salient Features of Engg. Standing Order No: Salient Features of Engg. Standing Order No: Salient Features of Engg. Standing Order No: 60606060

» Average rate of corrosion at rail foot in absence of corrosion protective measuresis @ 1mm/year.

» In severe corrosion prone areas, though protective measures adopted, within 3to4yrs., corrosion pit is being formed.

»Shifting of liner contact area is giving a promising result.

» Corrosion measurement and recording of corrosion

Guidelines for Shifting of Liner Contact Area:Guidelines for Shifting of Liner Contact Area:Guidelines for Shifting of Liner Contact Area:Guidelines for Shifting of Liner Contact Area:i) This operation shall be done at an interval of 5 years, or, before corrosion pit

depth at liner contact area reaches a limit of 1.5 mm, whichever is earlier.

ii) Next round of destressing shall again be carried out after next 5 years, or,before corrosion pit depth at liner contact area reaches a limit of 1.5 mm atshifted location, whichever is earlier.

During each process of destressing, it should be ensured that linercontact area is shifted away from the existing rail seat in the direction oftraffic in case of Double line, by a minimum of 150 mm, so that corrosion pit,if any, formed at sleeper seat gets shifted away and does not aggravatefurther.further.

iii) In any case, efforts should be made to ensure that corrosion at liner contactarea is not allowed to exceed a limit of 1.5 mm at any point of time.

iv) When a stage that there is no possibility of shifting is reached, and if rail stillhas residual life, operation of rail interchanging (left to right and vice-versa)shall be tried, so that corrosion pits are shifted to non-gauge face side.

v) Any destressing operation, whenever needed in areas not identified ascorrosion prone, same procedure shall be followed except that no time limit of5 years is to be observed.

Corrosion Measurement and Recording:Corrosion Measurement and Recording:Corrosion Measurement and Recording:Corrosion Measurement and Recording:

* Periodical measurement of corrosion pit both laterally and vertically shall be taken.

* Shall be done with the help of straight edge and filler gauge.

* Frequency- Once in a year on every 100 sleepers by removing ERCs & Liners

* Shall be measured on gauge face side.

* Record in a register maintained with every SSE (P.Way)* Record in a register maintained with every SSE (P.Way)

Date of testing

Location (KM/TP)

Sleeper No.

Corrosion depth on gauge face in mm. Remarks with

signatureLeft Right

Vertical Lateral Vertical Lateral

1 2 3 4 5 6 7 8

Advance Correction Slip No:124 to IRPWMAdvance Correction Slip No:124 to IRPWMAdvance Correction Slip No:124 to IRPWMAdvance Correction Slip No:124 to IRPWMParaParaParaPara 250250250250 ((((2222)))) PreventionPreventionPreventionPrevention ofofofof corrosioncorrosioncorrosioncorrosion::::

(a) Identification and measurement:

(i) Corrosion prone areas shall be identified by PCE based on reports of DENs.(ii) Measurement of pit corrosion shall be recorded in the register.

(iii) For new lines/GC projects, corrosion prone areas shall be identified byCAO(C) in consultation with PCE.

(b) Anticorrosive Painting:(i) Anticorrosive painting of new rails before laying in the track as per(i) Anticorrosive painting of new rails before laying in the track as per

procedure lay down.(ii) In-service rail painting with bituminous paint.(iii) Detailed procedure of surface preparation and procedure to be

adopted while applying anticorrosive paint.(iv) Periodicity of rail painting.

(c) Greasing and sealing of liner contact area

(d) Shifting of liner locations.

Updates Warranted Updates Warranted Updates Warranted Updates Warranted

1. Practically, Crevice corrosion is noticed on the gauge face side of

the rail in the facing direction of the toilet droppings from the

coaches. Modification to discharge pipe shall be done at the earliest

to get rid of this menace.

2. Though it is a little costly, use of2. Though it is a little costly, use of

galvanized rails in highly corrosion

exposed environments such as pit lines,

platform lines, cuttings in the approa-

ches of metropolitans etc., may reduce

corrosion formation.

SCR has taken initiative in this

regard and galvanizing rails in FBWP/MLY.

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THANKTHANKTHANKTHANK YOUYOUYOUYOUTHANKTHANKTHANKTHANK YOUYOUYOUYOU