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Alumino Thermic weldingAdvantages of SKV weldingPrinciples of Thermit Weldingand its FormulaThermic reaction:Process of AT weldingReference documents forQuick thermit welding withshort pre-heat (SKV process)Thermit Welding Equipmentand AccessoriesMouldsThermit PortionInspection of Rails beforeWeldingPreparation of Rail EndsGap between Rail EndsPreliminary Work Prior toWeldingAlignment of Rail Ends BeforeWeldingFixing of MouldsLutingPreheatingMaintenance of CrucibleExecuting of Welding.Block Period & Train PassingTimeMarking of JointsHeat Affected Zone (HAZ)Frequency of In-servicePaintingAcceptance Tests on WeldsPrecautions to be takenDuring SKV WeldingParameters for different gapsof A.T. Welding TechniquesAlumino Thermit Welding -Do’s & Don’tsLATEST DEVELOPMENTS INAT WELDING

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Alumino Thermic welding

Alumino thermic welding is a process thatcauses fusion of metals by heating them withsuperheated molten metal from an aluminothermic reaction between a metal oxide andaluminium.The alumino thermic process is extensivelybeing used world over for joining the ends ofthe rails.On Indian Railways Alumino thermic weldingwith short pre-heating process called SKVwelding is used for welding of rails of differentchemistry and sections.

Advantages of SKV welding

It is possible to do it at site under fieldconstraints with reasonable quality.It is used to weld flash butt panels of 3 rail/ 10rail/ 20 rail panels into longpanels.Most suitable for taking up repair work offractures and isolated welding.No pressure application is required and needsnormal surface preparation compared to othertypes of weldings.

Principles of Thermit Welding and its Formula

Thermic reaction:

Alumino thermic process is based on chemical reaction of iron oxide withaluminium. The reaction is ‘exothermic’ and is associated with heat* generation.After exothermic reaction lasting for few seconds, approximately equal volumes of

molten steel and liquid Al203 are separated at a temperature of about 24000C.

Al203 (slag), being lighter, floats on top of the molten metal.

Ferro-manganese is added to the mixture together with pieces of mild steel tocontrol exothermic reaction to match wear resistance of thermit steel to that of the

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various grades of rail steel to be welded.

Fe203 + 2Al = Al203 + 2Fe (25000C, 43.2 K Joules).

Process of AT welding

RDSO has issued a ‘Manual for Fusion Welding of Rails by the Alumino- ThermicProcess’.The alumino thermic process is to apply it for joining two pieces of rail, end to end,by casting molten ‘steel’ into a refractory mould that has been placed around thespacing between the two rails.The ends of the rail must be straight and the correct welding gap established.The rails must be properly aligned with faces free of rust, dirt & grease.The rails must then be preheated sufficiently to provide conditions for completefusion between molten steel and the base metal of rails to be welded.Prefabricated moulds are fixed and joints are filled with luting sand.The thermit reaction is carried out in a conical metallic shell lined with magnesite,called ‘crucible’, prior to tapping into the moulds.The weld must then be cooled prior to allowing any traffic hydraulic rail tensor ifused during the welding.

Reference documents for Quick thermitwelding with short pre-heat (SKV process)

The thermit welding with short pre-heat (SKV), despite all the improvements, stillrequires great care by the welders and supervisors during execution.For executing good quality welds, following documents should be referred to:

Indian Railway Standard Specification for fusion welding of rails by Alumino-thermic process (IRS-T-19-1994).Manual for fusion welding of rail joints by the alumino thermic process (Printedin Sept.1998), read with C.S.No.1 to 5.Instructions issued from time to time for improving the quality of welds and tocontain weld fracture.

Thermit Welding Equipment and Accessories

S.No. Description Quantity

MassWelding

RepairWelding

Pre-Heating Equipment

A1 Air-Petrol pre-hearing

1. Pressure tanks with pressure gaugescomplete

2 Nos. 1 No.

2. Vaporisers (burner) complete 2 Nos. 1 No.

3. Nozzles prickers 4 Nos. 2 Nos.

4. Nozzle keys 1 No. 1 No.

5. Vaporiser standv 2 Nos. 1 No.

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6. Goose neck attachment to vaporiser 4 Nos. 2 Nos.

A2. Compressed air-petrol pre-heating

1. pressure gauges 2 Nos. 1 No.

2. Torch (burner) complete 2 Nos. 1 No.

3. Torch (burner) keys 1 No. 1 No.

4. Torch (burner) stand 2 Nos. 1 No.

5. Goose neck attachment to vaporiser 4 Nos. 2 Nos.

A3. Oxy-LPG pre-heating

1. Oxy-LPG torch (burner) 2 Nos. 1 No.

2. Oxygen cylinder with pressure gauge 2 Nos. 1 No.

3. LPG cylinder with pressure gauge 1 No. 1 No.

4. Torch (burner) stand 2 Nos. 1 No.

5. Connecting hose pipe 4 Nos. 2 Nos.

B Other Equipment

1. Crucible complete 2 Nos. 1 No.

2. Crucible caps 2 Nos. 1 No.

3. Crucible forks 2 Nos. 1 No.

4. Crucible stands 2 Nos. 1 No.

5. Crucible rings 2 Nos. 1 No.

6. Mould pressure (clamp) 2 Sets 1 Set

7. Cleaning rod round 2 Nos. 1 No.

8. Tapping rod 1 No. 1 No.

9. Straight edge 1m long 2 Nos. 1 No.

10. Straight edge 10cm long 2 Nos. 1 No.

11. Aluminium steel rod for thermal plugging 2 Nos. 2 Nos.

12. Leather washers for pump 4 Nos. 2 Nos.

13. Gap gauges and height gauge 2 Nos. 1 No.

14. Filler gauge 2 Nos. 1 No.

15. Tools for punching the marking 2 Sets. 1 Set.

16. Mould shoes 6 Pairs 2 Pairs

17. Stop Watches 1 No. 1 No.

18. Pyrometer/ thermal chalk for measurement ofrail temperature

1 No. 1 No.

19. Wooden wedges for rail alignment 24 Nos. 12 Nos.

20. First aid box filled with medicines,bandages,cotton etc.

1 No. 1 No.

21. Mirror 150 X 100 mm with handle 2 Nos. 1 No.

22. Tool box containing :



(i) Hot sets (chisels) (For emergency use only) 2 Nos. 2 Nos.

(ii) Funnel tin (for pouring petrol) 1 No. 1 No.

(iii) Adjustable spanner 1 No. 1 No.

(iv) Hammer 1 kg 1 No. 1 No.

(v) Sledge hammer double panel 5 kg 2 Nos. 2 Nos

(vi) Steel wire brush 1 No. 1 No.

(vii) Blue goggles 2 Pairs 1 Pair

(viii) Paint brush 50 mm 1 No. 1 No.

(ix) Slag container (bowl) 2 Nos. 1 No.

(x) Asbestos gloves 4 Pairs 2 Pairs

(xi) Hose clips 4 Nos. 4 Nos.

(xii) Pliers 1 No. 1 No.

(xiii) Rail file 350 x 40 x 6 mm (For emergencyuse only)

4 Nos. 2 Nos.

23. Weld trimmer 1 No. 1 No.

24. Insulation hood for control cooling (for 110UTS rail welding)

1 No. 1 No.

25. Rail profile guided grinding trolley 1 No. 1 No.

26. To ensure quality, protective clothing, shoes gear & leather glovesshall be provided

5. Storage, Preservation and Handling of Portions & Moulds • The portion being hygroscopic in nature, will have double packing, first in a polythenebag and then in a cloth bag. Damaged/torn polythene bag may result in moist/dampportion and should not be used. • Once portion absorbs moisture, the same cannot be removed even by drying asingredients react chemically. All such portions should not be used for welding. • Therefore suitable storage condition for portion & mould to avoid contact frommoisture is to be made. These should be stored in water tight stores kept 0.3m awayfrom wall and 0.5m above Ground to avoid ingress of moisture. • The ‘acceptance slip’ for the portion given by the RDSO shall be found inside thebag. RDSO’s seal should be available on top of the bag. The portion should conformto IRS-T-19-1994. • It should be ensured that the portion to be used must match the rail section, grade ofrail and the welding technique. • The portion should be poured into the crucible through fingers with a spraying actionand striking the crucible wall so that the bottom plugging remains undisturbed • After filling, the portion should be heaped at the center of crucible and a small recessmade at the top into which the igniter can be placed • Portion should not be mixed with any foreign material or any amount of additionalportion. • The crucible cap should then be placed in position and an igniter (sparkler) hookedon to the crucible cap ready for use.



• Particulars of portion contained in the acceptance slip such as Batch No., PortionNo., Date of Manufacture, etc. should be recorded in a register kept for this purpose. • Moulds shall be handled with due care to avoid any breakage. Shelf life of portions: • There is no specific shelf life for portions. It depends on the quality of packing andstorage conditions. • If packing is intact and there is no entry of moisture, the portion can be used evenafter a long time. However, if they need to be used beyond two years after the date ofmanufacturing, following procedure is to be adopted for permitting use of portions. (a) One random sample per batch of 300 or part there of may be drawn from theportions available in stores. (b) The sample shall be tested for reaction test. If reaction is normal, batchrepresented by the sample can be used without further tests. © In case the reaction is found to be quiet or boiling, a test joint should be made fromone more sample selected from the batch for conducting Aluminium content test andLoad deflection test. (d) The above tests should be conducted at Zonal CMT’s organization and / or theFlash Butt Welding Plant. If values obtained in the above tests are within the specifiedvalues as given in Para 4.1.3 and 4.2.3.1 of IRS: T-19-94, the batch represented bythe sample can be used, otherwise batch should be rejected. (e) Rejected portions are to be disposed-off by igniting five portions at a time in a pitaway from the store.

Moulds

• Only prefabricated moulds supplied by the portion manufacturer shall be used forwelding. • Moulds are made by mixing high silica sand to IS: 1987 with sodium silicate to therequired consistency, followed by passage of carbon dioxide gas. • These prefabricated moulds shall have adequate permeability for escape of mouldgases and adequate reinforcement to avoid mould crushing during transportation andwelding. • Before mounting on the rail ends to be welded, each pair of moulds shall beexamined for defects, dampness, cracks, blocked vents, etc., and defective mouldsdiscarded. • The prefabricated moulds shall be handled with care, as they are fragile and liable tobreakage.

Thermit Portion

• Portion is a mixture of different materials when melted forms the material of type railsteel designed for doing one weld. • The ‘portion’ used for welding shall conform to the technical requirements asmentioned in IRS : T-19-1994. • The suitability of the ‘ Portion ‘ for the welding process in respect of the type andsection of rails to be welded shall be ensured before commencing welding. • Different main ingredients used in manufacture of AT portion are o Mill scales o Aluminum o Ferro-manganese



o Steel chips o Silicon carbide o Ferro vanadium o Flour spar • The proportion and quantity of the same depends upon the type of rail section andtype of welding and is the trade secrete of the manufacturing company. • Only RDSO certified/passed portions should be used for welding. • In India, though many labour contracting firms are approved by RDSO for executingAT welding with portion and technique developed by Thermit Portion Plant, N. Railway,Luknow, only 4 firms are approved for manufacturing of portions and execution ofwelding. They are • India Thermit Corporation Ltd., Kanpur. • Harshad Thermit Industries, Raipur. • Sagar Electrical and General Industries, Hyderabad. • Raybon Metals Private Limited, Bilaspur.

Inspection of Rails before Welding

• It should be ensured that the end bends of rails are within +0.5mm, -0mm in verticaland +/_ 0.5mm in lateral direction with 1m straight edge. • The new rails/ Old rails to be welded shall conform to the tolerances specified inTable 1 and Table 2 of “Manual for thermit welding” • Old rails : o Rails older than 50 years should not be welded. o Rails should be free from corrosion, excessive scabbing, wheel burns, andcorrugations. o Lateral wear on rail head should not be greater than 6mm. o The ends should be cropped to eliminate fish bolt holes. o If fish bolt holes are not present, the ends should preferably be cropped for aminimum of distance150mm. o Rails should be cut using sawing/ abrasive rail cutter only. o Rails should be got tested with USFD. o Rails should be match-marked to match the rail ends for welding.

Preparation of Rail Ends

• The rail end face and adjacent sides at foot (top and bottom), web and head up to50mm shall be thoroughly cleaned using kerosene oil and brushing with wire brush toremove all dirt, grease and rust before welding. • Any burrs at the rail ends shall be removed by chiseling or grinding. • Normally, no alumino-thermic welded joint shall be located closer than 4m from anyother welded or fish plated joint.



Gap between Rail Ends

• The two rail ends to be welded shall be held in position with a uniform vertical gap of25mm+/-1mm for normal welding and a wide gap of 50±1/75±1 mm for repairingfractured/defective welds. • The uniformity and verticality of the gap shall be measured by a gauge prior towelding. • The gap is measured at four corners of rail section. • The permissible tolerance in squareness of joint is 0.6mm. In LWR/CWR territory,hydraulic / mechanical rail tensor of suitable and approved design should be used formaintaining correct rail gap during welding.

Preliminary Work Prior to Welding

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• Internal stresses will develop during in-situ welding as all the sleepers and rails arefastened tightly and will not allow to expand freely on rising of temperature. Thestresses reduce, if the length of unsupported rail is more during welding. • Therefore in case of in-situ welding rail fastenings for at least five sleeperson either side of the proposed weld shall be removed. • Sleepers adjacent to the joint to be welded shall be shifted to obtain a clear workingspace of 250mm on either side to accommodate moulds, clamps,preheatingequipment, etc., • When the welding work is carried out on cess, full rail length shall be leveled bysupporting on at least ten wooden blocks on either side. • The rails shall then beproperly aligned in horizontal and vertical direction and held in position.

Alignment of Rail Ends Before Welding

• Lateral alignment: The two rail ends, after alignment shall be within ± 0.5 mm whenchecked with a 1.0 m straight edge at rail ends. Any difference in the widths of railheads shall always be fully kept on the non gauge side, correctly aligning the rail endson the gauge face. • Vertical alignment : The joint shall be kept higher by 3 to 4 mm for 72 UTS rails and 2to 2.4 mm for higher UTS rails when measured at the end of 1 m straight edge ( as acompensation against sagging caused by differential shrinkage on cooling). This shallbe achieved by wedges applied on the rail supporting blocks on both sides of the joint.

• Gap between rail ends may be rechecked after completion of alignment. Datummarks shall be made on foot of both rails as well as on joint sleepers in order toobserve any longitudinal movement of rails. If excessive longitudinal movement occursduring pre-heating and produces a welding gap outside the prescribed limits, thewelding of joint shall be temporarily abandoned and joint allowed to cool.

Fixing of Moulds

• It shall be ensured that the center of the rail gap coincides with the center line of the




mould to avoid cross joint. • The mould jackets/shoes hold the pre-fabricated mould in a snug fit condition bytightening with adequate pressure. Excessive pressure may cause breakage of mouldand dropping of sand inside the mould cavity. • It is essential for the moulds to fit flush to each other across the bottom of the railflange which can be checked by feeling with fingers across the junction of the twohalves of the moulds and by looking down the riser aperture. • The moulds should touch the bottom of rail foot to ensure proper size of collar at thebottom. • After fixing the moulds, the gap between mould and the rail shall be packed firmlywith luting sand to prevent leakage of liquid weld metal. • To protect the rail table from metal splashes during reaction, the adjacent rail surfaceon either side of the moulds shall be covered with metal cover or smeared with lutingsand up to 15cm on either side of the moulds.

Luting

• It is the process of sealing the gaps of moulds. The material used is called lutingsand. • After fixing of the mould shoes, luting of the junction of the mould should be done,starting from the underside of the rail foot and continuing on both sides towards thehead of the rail. • Luting sand with minimum moisture content (6%) supplied for this purpose onlyshould be used. • To avoid any sand particle dropping into the mould, a luting cover may be placedover mould aperture. • Improper luting may result in leakage of weld metal. It may lead to formation of a ‘fin’at the underside of flange which may lead to development of half moon crack underrepetitive loading and may cause failure of the weld.




Preheating

Process of pre heating • Pre-heating is done to remove moisture from surface ofrails using torches. • The rail ends shall be uniformly pre-heated throughout the rail section with speciallydesigned air petrol/ compressed air petrol/oxygen-LPG burner. • The burner shall be properly adjusted during preheating to ensure that the head, weband foot of both the rail ends are heated uniformly to the desired rail temperature. • The pre-heating shall be done from the top of the mould box for stipulated period for

welding technique adopted, so as to achieve a temperature of around 600±200C.Higher temperature will cause metallurgical transformation and therefore should beavoided. • Presently, on Indian Railways air-petrol mixture, compressed air petrol mixture andOxy-LPG are being used requiring about 10- 12min, 4-6 min & 1-2 min. • The pre-heating torches should not be bent or damaged or their holes blocked. • Positioning of the pre-heating torch in the mould box must be carefully adjustedbecause it affects the quality of pre-heating. • Recommended pressure should be ensured while pre-heating • Proper pre-heating of the rail ends consists of fulfilling three requirements namely: 14.1 Minimum pre-heat time ii) Achieving proper and the uniform colour of the rail ends. iii) Observation of the entire preheating process to ensure that rail end(s) is not meltedand there is no breakage of the mould. In the event a portion of the rail head or railface of either rail end is melted, the weld must not be executed. • Rail ends and moulds must heat evenly. Uneven heat can cause internal cracking ofthe weld due to uneven cooling. • During the preheating process, a fairly usual occurrence may be the breakage of themould. This is where a piece of the mould may break off and fall into the weld cavity.In the event this happens, welding should be stopped, the mould should be removed &

Per weld consumption of luting sand is 3.5 to 4.0 kg




disposed off properly and new mould installed. 14.2 Pre heating equipment

Air Petrol BurnerCompressed Air petrol blowerOxy-LPG heating system

14.3 Preheating time & pressure • Preheating time: Preheating time would be about 10 to 12 minutes and 2 to 2.5minutes for air-petrol and oxy-LPG preheating techniques respectively. • Preheating Pressure:7±0.70 kg/cm2 in welding process using air petrol burner Incase of pre heating by oxy – LPG process, pressure for oxygen and LPG cylindersshall be adjusted in the range of 7.0 – 8.0 kg/ cm2 and 2.0-2.5 kg/ cm2 respectively.While preheating with oxy LPG burner, LPG supply should be opened first,ignited andthereafter oxygen supply should be opened. While closing, oxygen supply should bestopped first followed by LPG supply. • Control over heating time: By stop watch or by temperature measuring deviceslike optical pyrometer, contact type pyrometer or temperature indicating crayons maybe used for measuring rail end temperature.

Maintenance of Crucible

• The crucible lines with refractory material should be preheated from inside to removemoisture with the preheating torch before making the first weld. • Preheating should be done from top to bottom. • Failure to properly dry the crucible may cause. o a defective AT weld that is full of porosity. o danger of hot steel splashing forcefully out of the crucible causing serious personalinjury. • Slag should be cleared from the crucible side walls after each weld. Slag shall becleaned from the crucible after each reaction, if necessary. During cleaning, care shallbe taken not to damage the refractory crucible lining. • The lining shall be examined regularly and patch repairing , or relining as necessary




shall be carried out. • The pouring gate with thimble is designed to have a precise diameter, specific for theprocess. While cleansing it with a thimble drift, care should be taken not to damagethe orifice of the thimble. Thimbles with enlarged orifice should be replaced. • Proper seating of the thimble is very important. Improper seating of the thimble orapplication of the plugging material may. o cause premature tapping of the molten weld metal, due to a bypass of the thimble orin the event the thimble being cracked. o prevent the molten weld metal from tapping into the moulds. • The crucible should be placed on the crucible fork fixed to swivel stand on auniversal mounting. The crucible should be located in a proper position such that thetapping hole is central to the pouring gate of the mould and at a height of 50mm fromthe top of the pouring gate. Inaccuracies in these are likely to result in turbulent flow ofmolten metal. • The tap hole in the crucible should then be covered with a closing pin, the head ofwhich should be covered with asbestos pulp and alumina slag. This heat seal enablesthe welder to tap the molten metal at the precise time he desires. • After adjustment of the crucible to obtain correct pouring position, the crucible shouldbe swung clear of the moulds for charging.

Executing of Welding.

16.1 Ignition and reaction • After the pre-heating, the preheating torch isremoved and the dried sand core placed in the central pouring apparatus of themould. • The crucible is then swung into position centrally above the sand core, care beingtaken not to disturb the tapping pin. • The crucible cap is removed. The portion in the crucible is then ignited using sparklerby placing the igniter slowly and firmly into the center of portion & crucible capreplaced. • After the reaction subsides, about 5 seconds should be allowed for separation of theslag from the metal. • The molten metal is then tapped into the mould by pushing up the closing pin’sshank with the tool provided for the purpose. The crucible should not move duringtapping and no turbulence should occur while pouring. • In case of occurrence of boiling or vigorous reaction, because of moisture content inthe portion or crucible, the metal should be tapped outside and not in the mould. • Off center pours will cause defective welds due to slag inclusion. • Welding staff shall wear welding gloves and welding goggles. • During the initial violent phase of the reaction, all welding staff must stand clear. 16.2 Tapping time • Tapping time is defined as the total time, from the time the portion is ignited, till themolten weld metal begins to pour into the mould cavity. Tapping time is very importantfor the final weld quality. • Premature tapping can cause a high aluminium content in the weld metal withpossibility of slag inclusion too. • Delayed tapping, on the other hand, causes loss of heat from the molten metal withthe risk of lack of fusion. • The optimum tapping time is 20-23 sec which is Reaction time + Waiting time( For



slag to rise on molten metal). 16.3 Mould waiting time • It is the time the molten metal shall be allowed to cool and solidify after pouring withmould intact for the stipulated time. • It depends upon the rail section and ambient temperature. • The mould waiting time is generally 4-6 minutes for 25 mm gap joints and 12minutes for 75 mm gap joints. • The mould shoes shall be removed just prior to completion of mould waiting time.

16.4 Chipping of weld metal • On completion of pouring, the crucible is lifted off and slag bowls removed from themould shoes. • After the mould waiting time has elapsed, the trimming should be done by using weldtrimmer of suitable and approved design without knocking out the mould. • In the eventuality of sudden failure of weld trimmer, manual chipping may be resortedto. • In case of welding of old rails, if it is not possible to use weld trimmer due to flow ofmetal at rail head, manual chipping should be done. • During the trimming operation, it shall be ensured that the wedges used in aligningare in their proper places without loosening, and they are not removed for a t least 20minutes after stripping. • With the use of hydraulic weld trimmer, mould from the top and sides is removedleaving at least 1mm excess metal on the rail table for removal during final grinding. • The runner and riser must not be removed until cold, and that too only by knockingtowards the rail.




HYDRAULIC WELD TRIMMER

16.5Importance of risers • The side holes of the moulds are called risers. Slag comes out from this. • The risers are basically designed to allow slower rate of cooling of the weld metal toform Pearlitic structure ( fine grained with high fractured toughness) • Lower UTS rails are less susceptible to heat than higher UTS rails, hence for thesame welding type, lower UTS rails form a better joint 16.6 Grinding • Finish grinding of rail top and sides should be carried out by profile grinders. • Use of hand files should not be resorted to. • Grinding should commence only after removing the wedge kept for joint alignmentand putting back the fastenings. • Final grinding should be done to the original profile of the rail as per the dimensionaltolerances prescribed in the Manual on Fusion Welding of Rails. The accuracy ofgrinding shall be checked by using 10 cm straight edge. • While grinding, only light pressure should be applied and grinding wheel should bemoved to and fro to avoid local over heating. • The best finish grinding on the running surface of the rail head can be achieved when





the weld has completely cooled to ambient temperature. • No welding shall be carried out if it is raining. In case, the rains start while the joint isunder execution, immediate arrangements to adequately cover the site shall be made.

PROFILE GRINDING

Block Period & Train Passing Time

17.1 Block period • Minimum block period required for doing SKV weld is 75 mints. 17.2 Train passing time: • The first train should be allowed to pass on the newly welded joint only after 30minutes have elapsed since pouring of weld metal. Necessary speed restriction shall





be observed until the grinding operation is over. 17.3 Precautions for newly welded joints: • Before the passage of traffic, the wedges used for aligning should be removed andjoint sleepers which were shifted to obtain the clear gap of 250mm on either side shallbe re-shifted to the original location and repacked. • The newly weld need to be tested by USFD at the earliest • Till tested as good by USFD, the weld done in situ shall be joggle fish plated with twoclamps. • Painting of weld collar should be done on all welds to protect them against corrosionimmediately after the welding.

Marking of Joints

• Each joint shall have a distinctive mark indicating month, year, agency, welder’s codeand weld number of the welded joint. • This should be done by punching on an aluminium strip of suitable thickness anddimension of 30 X 100 mm which should be fixed to the web of the rail with epoxyadhesive at approximately 300 mm from the joint. • The welded joints shall be serially numbered in a kilometer. • Repair welds/additional welds done at a later date may be given continuing weldnumber in that kilometer. For example, the last thermit weld umber in a particularkilometer was 88 and subsequently a thermit weld has been executed, it shall benumbered 89, irrespective of its location in that kilometer. • PWI shall maintain ‘Thermit Weld Register’ as per program given in Annexure 5 ofThermit welding manual. • No punch marking should be done on the rail.

Heat Affected Zone (HAZ)

• It is the length of rail affected by fusion from center line of weld. • For normal SKV welding of 25mm+/-1mm, The fusion Zone is 45mm and the HAZ is55mm. • For Wide gap welding Fusion zone = gap/2 +32mm and HAZ = Gap/2 +42mm. • No holes should be within HAZ. • Fixing of Responsibility for failure of weld is based on the HAZ. Normally a failureoccurred with in 100mm from center line of weld is considered as weld failure. And theone beyond 100mm is considered as rail failure.

Frequency of In-service Painting

• Once in 4 years in areas not prone to corrosion. • Once in a year in corrosion areas. • On conditional basis in areas prone to severe corrosion.

Acceptance Tests on Welds

21.1 Visual inspection • All the welded joints shall be examined carefully to detect any visible defect like



cracks, blow holes, etc. Any joint, which shows any visible defect should be rejected. 21.2 Dimensional check: • All finished joints shall be checked for dimensional tolerances which should be withinthe tolerances. (i) Vertical alignment : Variation not more that +1.0 mm, -0 mm measured at the end ofone metre straight edge. (ii) Lateral alignment : Variation not more that +0.5 mm measured at center of onemetre straight edge. (iii) Finishing of top surface : +0.4mm, -0mm measured at the end of 10cm straightedge. (iv) Head finishing on sides : +0.3mm over gauge side of the rail head measured at thecenter of 10cm straight edge. 21.3 Ultrasonic flaw detection test : • All the fusion welded joints shall be ultrasonically tested and accepted by thepurchaser or his representative as per the ‘Procedure for ultrasonic testing of thermitwelded rail. • Subsequently USFD testing of A.T. welds shall be done as per the provisions givenin Manual for Ultrasonic Testing of Rails and Welds (1998). 21.4 Rewelding of defective joints • The details of geometry of each joint shall be jointly signed by the firm’s andRailway’s representative and kept as record. Any joint found not conforming to theabove stipulations shall be cut and rewelded, free of cost, by the firm. • Where one bad joint is required to be replaced by two new joints, the entire cost ofboth the joints hall be borne by the firm 21.5 Sample testing of joints • One out of every 100 joints welded shall be selected at random and should be gottested within one month of welding for its hardness, transverse load/deflection testsand porosity. • If the sample test joint fails to satisfy any of the requirements of specification twomore randomly selected joints from the same lot of 100 joints shall be subjected toretests and both the joints should clear the tests. • If this report is also not satisfactory, further welding of joints shall be suspended untilthe firm’s welding technique has been examined certified by RDSO. 21.6 Guarantee • Rail joints welded by a firm shall be guaranteed against failure for a period of twoyears and if fails within the guarantee period shall be rewelded free of cost by the firm. • In case of failure of sample test joint, the period of guarantee for 100 jointsrepresented by the sample joint shall be extended for a further period of one year • The welded joints with the extended period of guarantee shall be marked ‘X’ withyellow paint on the outer side of the web of the rail near the joint 21.7 Other requirements • Welding shall be supervised by trained welding supervisor and carried out by trainedwelder having valid competency certificate from RDSO/TPP/NR,Lucknow • A welding supervisor shall supervise not more than two welding teams deployedwithin 50m distance at a time. • A copy of the thermit welding manual shall be available with each PWI and at eachwelding site ==== A.T.Welding – Defects, Causes & Remedial Measures ====

• The major types of defects which can cause weld failure because of improper weld



execution are given under.

SNo

Location Reason Remarks

1. Longitudinalcrack in railweb

Cutting of wearresistant graderails by flamecutting.

Flame cutting of rail ends is prohibiteddue to likelihood of cracking in web.

2. Lack offusion in railfoot

Flame cutting ofrail ends

When producing the welding gap, neverflame cut rail ends

3. Cold spot –lack offusion.

Gap between railends too wide-rail ends outsidethe collarformation.

Maintain the welding gap between railends specified in the approvedparameters of the technique. Neverattempt to weld a gap, which is toowide, with standard mould.

4. Cold spot –lack offusion andassociatedlocalporosity.

Mould fittedvertically but offcentre to the webgap.

Take care to centralize the mould to thegap. Never try to fit both mould halvessimultaneously.

5. Lack offusion onfoot of onerail end.

Mould fittedcenter to the gapbut inclined tothe vertical.

Take care to fit mould both vertical andcentral to the weld gap. Do not inclinemould to the vertical.

6. Gross lackof fusion onrail end.

Standard mouldfitted to rails ofdissimilar depth.

Do not try to weld worn to new rail, orrails dissimilar depth with standardmould.

7. Porosity inthe thermitsteel

Luting sand toowet.

Luting sand must be moist but not toowet. Never use wet luting sand.

8. Sandinclusion inthe rail footand sandburn markstransverselyacross therail head.

Dropping ofluting sand intothe mould.

Take care when sealing the mould withsand. It must not be allowed to dropinto the mould.

9. Grossporositythroughoutthe wholeweldsection.

Use of dampcrucible isdetrimental tothermit reactionand results ingross porosity of

Carefully dry out the crucible liningusing the preheating burner.



weld metal.

10. Grossporositythroughoutthe wholeweldsection.

Use of dampportion.

Moisture present in portion reacts withaluminium and in its characteristic, thereby affecting the thermit reaction andresultant steel. This change cannot bereversed by drying out. It is essentialonly to use dry thermit portions. Neveruse portions, which have been dampedand dried out.

11. Grossinclusion ofslag in therail head.

Pouring withoutthe plug in theposition.

After preheating, fit the sand core withthe riser aperture of the mould andpress down lightly.

12. Gross slaginclusion inrail head onone side.

Pouring offcentre to theplug.

Ensure that the crucible is positionedcentrally over the sand core and thecrucible does not move during thethermit reaction. Never allow the thermitsteel to pour directly into either pouringgate.

13. Fracturethroughweld centre.

Immediateimposition oftensile forces onweld metal causeinternal tearing ofweld metal whichleads to totaltransversefracture.

During solidification and immediatelyafter thermit weld should not besubjected to tensile force.

14. Cracking ofweld aftercooling atrail ends.

Failure to use thecorrect thermitportion andwelds. Procedureas approved forspecific railsection/railchemistry.

Always check the chemistry and type ofrail to be welded and use correct type ofportion and adopt correct weldingparameters at the time of welding of railjoints.

Precautions to be taken During SKV Welding

While carrying out welding at site, the following precautions shall be observed: (i) It should be ensured that the portion being used matches with type and chemistry ofrail. (ii) Rail ends should be square. (iii) Alignment of rail ends should be perfect as checked by straight edge. (iv) Rail ends should be properly cleaned with kerosene oil and wire brushes. (v) Stop watch should be provided to the welding supervisor at each welding site.



(vi) Pressure in the tanks/cylinder should be properly maintained during preheating. (vii) Correct gap between rail ends at head, web and foot shall be ensured. (viii) Correct preheating time for rail ends shall be ensured. (ix) Tightness of clips fitted with hose connections to compressor tank and burner shallbe checked before commencing preheating. (x) Nozzles of burners shall be cleaned periodically to avoid back – fire. (xi) Thecompressor tank shall be kept at least 2 to 3 m away from the burner to prevent firehazard. (xii) The tapping shall be done within the time specified for that particular technique.Welding parameters for techniques presently being used are available at Item No. 24below. For special type of welding i.e. 75mm gap, combination joint, etc. the time ofreaction and tapping shall be as stipulated by RDSO for that particular weldingtechnique. (xiii) Arrangements for giving first aid shall be available at site. (xiv) Welders should be provided with gloves and coloured glasses. (xv) Boiling portion shall be out tapped. (xvi) No moist portion/torned portion bag shall be used for welding. (xvii) Dampness in moulds can lead to Porosity and early fatigue failure of welds. (xviii)Only those contractual agencies which have clearance from the RDSO/RailwayBoard can execute welding work. Supply of portions must be from sources approvedby RDSO/Railway Board. (xix) Many weld failures show evidence of badly cut rail ends. The evenness andverticality of a rail cut depends solely upon the skill of the welder. With portable disc cutters, very little skill is required to produce good cut.

Parameters for different gaps of A.T. WeldingTechniques

24.1. Dimensional Tolerances for finished AT Welds

Alumino Thermit Welding - Do’s & Don’ts

25.1 Do’s

Welding is to be done only in adequate traffic block.For doing cess welding, rail should be supported on a minimum of 10 woodenblocks duly pegging the rail for better alignment. Welding is to be done either insituor on the cess, but not on the ballast shoulders.Battered / hogged rails are to be end cropped before welding.Rail ends should be cut true to square.The rail ends should be cleaned with K.oil before welding to remove dust, greaseparticles.Fittings for a minimum of 5 sleepers on either side are to be removed for alignmentand levelling.Welding gaps should be as specified for that type of welding. (25mm/50mm/75mm)Rails are to be properly aligned before taking up welding.Moulds utilized for welding should not be cracked or wet.Dry moulds should be fixed centrally on the joint.Mould shoe should match with dry moulds.



Rail ends are to be pre-heated uniformlyCrucible should be charged with magnesite powder at regular intervals of 8-10 weldjoints.The crucible should be free of moisture and charging should be

done periodically.

The height between the crucible and dry mould should be approximately 50mm,Gauges of the pressure tanks should be functional to develop proper pressure asspecifiedAdequate tank pressure should be maintained.Stipulated pre heating time is to be ensured.Ensure that weld portion bags are intact and portions are not contaminated.The shell life of portions is 2 years, beyond which portions should be tested forreaction before utilization.Portions should be thoroughly mixed for uniformly in a steel Pan

before pouring in the crucible.

Cap should be placed on the crucible when the reaction is in progress.Tapping should be done centrally in the mould, so that the discharge falls centrallyon the cake.Chipping of weld should be done after maintaining cooling time of 4-6 minutes for a25mm gap welding and 12 minutes for 75mm gap welding.The first train should be passed with restricted speed only after 30 minutes ofwelding duly grinding the weld, fish plating andsupporting the rail on wedges.It should be ensured that chisel marks are not made on the finished welds.Finishing of weld to be done within 24 hours after welding.On completion of the welding, particulars of welding like date of welding, type ofwelding, welder’s code etc.,are to be printed on aluminium strip glued to web of rail.Anti corrosive painting should be done for a length of 10 cm oneither side of weld.

25.2 Don’ts * Do not do welding in inadequate traffic block.

Welding should not be done in rain or rapidly cooling temperature.Unqualified welders should not be employed for welding.Gas cut rails should not be used for welding.Do not use untested rails for welding.The distance between two welds should not be less than 4 mts.Welding old rails, should not be done without end cropping.72 UTS portions should not be utilized for 90 UTS rails.Rail ends should not be welded without cleaning with K.oil and wire brush.No bolt hole should be within 40mm from the rail end.Worn out and damaged tools, equipment should not be used for welding.Location where portions are stocked should not be damp/wet.Weld portions and luting sand should not be utilized after expiry date.Damaged dry moulds should not be used for welding.Damaged and loose portions should not be utilized.Portions should not be tampered with.



Luting sand should not be mixed with ordinary local sand in case of shortage.Wedges under the rail should not be removed for a minimum of 20 minutes afterchipping.Portions should not be utilized without proper mixing prior to welding.Rail tensor should not be used for distressing before weld cools down.The first train should not be allowed over the welds before 30 minutes after themolten steel poured in to mouldSpeed restriction should not be relaxed till grinding of weld is completed.

LATEST DEVELOPMENTS IN AT WELDING

AT WELDING WITH THREE PIECE MOULDSCOMPRESSED AIR PETROL PREHEATING SYSTEMCOMBINATION JOINT & DIFFERENT GRADE RAILSWIDE GAP (50mm, 75mm) WELDINGONE SHOT CRUCIBLESELF TAPPING THIMBLE

Circulars

Copy of SC Rly Headquarters letter No.W.T-5/P/Vol.XIII, Date: 20-8-2009 JOINT ENGINEERING AND OPERATING CIRCULAR Sub: Traffic Block for removal of cautions due to Rail / Weld failures and cutting ofrails. Instructions have already been issued by Engineering Department regarding carryoutrepair of rail fractures and weld failures including the cutting of rails under Traffic Blockonly. To minimize the traffic block requirements, it has also been instructed to replacehacksaw blades by Abrasive Disc Cutters on priority and with due urgency. With aview to streamline the procedure for removal of cautions due to rail / weld failures, thefollowing further instructions are issued regarding the management of traffic blocks forimmediate compliance. 1. The work of repair of rail fractures and weld failures including the cutting of railsshall be carried out under traffic block only. No deviations are permitted under anycircumstances. 2. The removal of caution due to rail /weld failures will normally require two cuts an twowelds after inserting the rail of suitable length (not less than 4 meters). 3. The traffic block requirement involving two cuts and two welds shall be 100 minuteswhere the rail cutting is done by Abrasive Disc Cutters. In case the rail cutting is doneby hacksaw blades, the block requirement shall be 120 minutes. 4. When situation warrants due to more cautions on account of rail / weld failures,Abrasive Disc Cutters, from SEs/P.Way of adjacent sections shall be pooled up anddeployed, to complete the work early. 5. Wherever Abrasive Disc Cutters have been deployed, traffic block of 100 minutesonly shall be demanded and granted for repair of fractures involving 2 cuts and 2welds. Divisions shall make efforts to procure and deploy abrasive rail cutters in allsections. 6. On other sections, where rail cutting is to be done by Hacksaw Blade, traffic block of120 minutes shall be demanded and granted for repair of fractures involving 2 cutsand 2 welds. 7. In case of non-availability of continuous block of 120 minutes duration, the same



may split in two parts i.e., a block of 30 minutes followed by another bock of 90minutes duration. In case of split block f (30+90) minutes, due regard shall be given tothe prevailing temperature at the time of second block, so that the gaps available atthe time of welding during the second block are close to 25 mm. A close coordinationbetween the officials of Engineering and Operating Departments should be ensured incase of split block situation. 8. Block requirement for works involving one cut and one weld shall be suitablyreduced. The fundamental requirements being 70 minutes block for a single weld only,90 minutes block for two contiguous welds, 5 minutes for a single cut by Abrasive DiscCutters, about 20 minutes for rail cutting by hacksaw blade, etc. 9. There instructions should be quickly percolated to all the officers and inspectors ofOperating and Engineering Departments in control offices as well as in the field.

Sd/- (Rakesh Saksena) Sd/- (Pradeep Kumar) Chief Operating Manager Principal Chief Engineer.

Copy of SC Rly Headquarters lr. No.W.T-5/P/Vol.XIII, dated 20.8.2009 addressed toAll Sr.DEN/Co-ordinations of S.C.Railway Sub: Repairs to rail / weld failures and cutting of rails on running lines. Instructions exist vide para -15.08, Chapter XV of G&SR-2008 and also Rly. Board lr.No.98/CE-II/INSPN.5 dt.7/15.8.98 that track works leading to discontinuity in tracksuch as causal renewal of rails, temporary / permanent repairs of rail /weld failuresshall be undertaken under traffic block only. It has come to notice that the work of railcutting prior to rail renewal is being undertaken in between the train gaps with bannerflag and caution order protection without ensuring traffic block, which is an unsafepractice. At times, such situations have resulted into derailments also. It is pointed outthat the work of cutting of rails is an integral part of rail renewal activity and istherefore required to be executed under clear block protection. To avoid such unsafe situation, following instructions are issued on the subject matterfor strict compliance in the field with immediate effect. 1. Cutting of running rail on running lines should be undertaken under Traffic Blockonly. No deviations are permitted under any circumstances. 2. The work of repair of rail fractures and weld failures including the cutting of runningrail shall be carried out under traffic block only. 3. To minimize the traffic block requirements, for works involving rail cutting, hacksawblades are replaced by the Abrasive Disc Cutters, on priority and with due urgency. 4. Gas cutting shall not be carried out on running rails. In case it is essential to resortto gas cutting due to emergency, the gas cut rail shall be treated as IMR rail and samewill be removed within 24 hours at first opportunity. Till such time necessary speedrestriction shall be imposed duly posting a watchman. 5. In case of rail cutting by Abrasive Disc Cutters, traffic block of 100 minutes shall bedemanded for repair of fractures involving 2 cuts and 2 welds. 6. In case of rail cutting by Hacksaw Blades, traffic block of 120 minutes shall bedemanded for repair of fractures involving 2 cuts and 2 welds. 7. In case of non-availability of continuous block of 120 minutes duration, the samemay be split in two parts, a block of 30 minutes for cutting followed by another block of90 minutes duration for welding. 8. Block requirement for works involving one cut and one weld shall be suitably



reduced. This issues with the approval of PCE.

Sd/- (S.P.SAHU) Chief Track Engineer South Central Railway

Forwarded vide lr. No.501/I/7/Vol.VIII Dt.02.1.08 Copy of Headquarters lr. No.W.413/GENL/RWF/XXIV, dated15.6.2009 addressed toSr.DEN/Co-ordinations of S.C.Railway Sub: Rail / Weld failures – Dent / Notch marks. Recently one Rail fracture had taken place at km.211/30-32 Dn. line between BTTR-SVPM and GDR-BZA section on 8.6.2009. This was reported as Weld failure. Onexamination of the broken pieces, a deep Dent Mark was noticed on the rail foot closeto the SKV weld which was the origin for causing the Rail fracture. 2. On earlier occasion also one more Rail breakage had taken place on 5.12.2008 atkm.251/5-3 up line between MCI-MMZ of KZJ-BPQ section for which the cause offailure was also due to dent / cut mark at rail foot. Such type of Dent/Notch marks onUTS rails are serious cause of concerned resulting into Rail fracture. Such Dent/cutsare caused due to mishandling of rails during unloading or laying. 3. In order to avoid such unsafe situations, it is advised to carryout thorough inspectionof rails in the section and take action to identify and attend such locations.Sr.DEN/DEN of the section should be advised to take this matter seriously and takenecessary remedial action. Simultaneously, staff at all levels need to be counselingregarding proper handling of rails. Action taken in this regard may be advised to undersigned.

Sd/- (S.P.SAHU) Chief Track Engineer

Copy of Headquarters letter No.509/P/AT Welders & Welding, dated 29.10.2008 addressed to All Sr.DEN/Co-ordinations of S.C.Railway. Sub: Standard Register for recording rail / weld fractures – reg. Ref: CTE’s InspectionNotes No.35/2008 vide letter No.W.246/CTE/04/Vol.III, dt.20.10.08. A standard printed register for recording rail / weld fractures (for use of SSE/SE/P.Wayof open line) containing 15 columns for recording various details was issued toDivision earlier. CTE vide Para-7 of the above referred Inspection Notes has observed that theRegister do not have columns for noting down the name of agency, name of welderetc., which are required to monitor performance of the same. It was advised to re-design the proforma of the register incorporating these details. Divisions are advised tofurnish the desired revised format and the number of copies required for each division,to arrange from Hqrs. In the meanwhile, the details of welding agency and the name of welder may pleasebe recorded in the Column No.11 (type of welder) and Column No.12 (date of welding)along with the details for the printed item in the next line. Please acknowledge the receipt of this letter, with the details asked above.



Sd/- (J.N.GUPTA) Dy.CE/Tr.II

Copy of lr.No.B/W.413/GL/Joggled Fish Plates/P.Way-II, dated 14.11.07 addressed toAll ADENs & SSEs/SEs/P.Way on BZA Division. Sub: Precautions to be taken on Passenger intensive routes – Joggling of AT Welds –Reg. Ref: 1) CTE/SCs letter Nos. W.413/Joggling, dt.21.6.07, 10.8.07 and 13.9.7 2) This office letters of even No., dated 8.7.07 and20.9.07. Please refer to the letters cited under reference wherein it was advised that joggling ofAT welds has to be done at the following locations as per the extent instructions andthe same should be completed before 31.10.2007 without fail. 1) All AT welds in locations where the track has carried more than 50% of thestipulated GMT. 2) All AT welds in well fracture prone locations. 3) All AT welds on the outer rails of curves with curvature ½° and above. 4) All AT welds on major and important bridges and their approaches on either sideupto 100 Mtrs. 5) All AT welds on Track where the height of the bank is 4 M and above. Pleaseensure Joggled fish plating of all the AT welds in the above locations of your section iscompleted before 24.11.07 without fail and the compliance report should be submittedto this office to advise Hqrs. Office by 26.11.07. This has the approval of Sr.DEN/Co-ord/BZA.

Sd/- For Sr.DEN/Co-ord/BZA

Copy of Railway Boards Lr. No.Track/21/2002/0110/A T Policy, dt.11.8.2005addressed to PCEs of All Indian Railways. Sub: Quality control for welding of rails by SKV process. Board have decided that the following course of action be adopted in future weldingcontract. 1. Initial USFD testing should be conducted within a month’s time from the date ofwelding so that the welder with a bad workmanship can be identified and removedfrom the site. 2. In case of the defective weld exceeds 4% the certificate issued by RDSO should becancelled and welder will have to go through with the process of re-certification. Tillfresh certification is issued Welder should not be allowed to do any work on the track. 3. A penalty of Rs.500/- may be imposed for defective welds ranging from 2 to 4% anda penalty of Rs.1000/- of the defective weld is found more than 4%. 4. There should be a provision of joint checking with firm’s representative. During thecourse of joint checking, if the defective weld is less than 50% of what has beendetected earlier by PWI/USFD, explanation should be called from the PWI/USFD forthe discrepancy and suitable action be taken if the motive behind detecting the higher



number of defective welds is suspected. 5. A firm may be allowed to do the welding of defective weld by wider gap technology.This will reduce the wastage of rail and population of additional SKV weld at site. 6. Railway to maintain batch wise and welder wise data of each weld at site so thatany deficiency in a particular batch or portion or welder can be identified and suitableaction can be taken in consultation with RDSO. Numbering of SKV weld at site shouldbe done to co-relate a particular weld with a particular batch of portion and welder. 7. 1% sample joint testing as envisaged in the manual (Para 7.1 of Manual for FusionWelding of Rails By Alumino – Thermic Process ) shall be strictly followed by ZonalRailways. The instructions conveyed to the Railways vide this office letter of even number dated17.2.2003 stands withdrawn.

Sd/- (S.K.AGRAWAL) Executive Director Track (P) Railway Board

Copy of Railway Board’s letter No.Track/21/2004/0902/7, dated 08.02.08 addressed toPCEs of All Indian Railways. Sub: USFD testing of AT welds using digital AT weld testers. Digital Ultrasonic equipment for Aluminothermic Weld was developed by RDSO inassociation with trade for quite some time. These Ultrasonic Weld Testers are not onlyhandy but also can record data being a digital equipment. Moreover, PWI/USFD canhimself do the probing operation and view the signals on the monitor simultaneously.Therefore, the quality of testing improves drastically with its use. As on date, there are two RDSO approved vendors for the equipment, namelyM/s.Modsonics Instrument Manufacturing Company Pvt., Ltd., Ahemdabad and M/s.Parikh Industries, Mumbai. Railway Board has now decided that al ultrasonic testing ofAT welds henceforth would be carried out using RDSO approved digital ultrasonicequipment. Six months' time period has been fixed for the procurement of equipment /development of requisite infrastructure. Therefore, Railways are advised to takenecessary action in this regard and compliance report be sent to Board.

Sd/- (S.K.AGRAWAL) Executive Director Track (P) Railway Board.

Copy of Railway Board’s letter No.Track/21/99/0910/7, dated 30.5.07 addressed toPCEs of All Indian Railways. Sub: Precautions to be taken on Passenger intensive routes. Board (ME) desired that following precautions should be taken on the passengerintensive routes (Prority-1) and on CC+8+2T routes (Priority-2): 1. Joggle fish plating of the thermit welds (irrespective of age) on the outer rail of thecurves should be done on priority. The fist plating should be done using clampswithout drilling of holes. 2. Joggle fish plating of the thermit weld on the bridges along with its approaches upto



100 m should be done. 3. Each and every weld fracture is to be analyzed by sectional Sr.DEN/DEN. It shouldbe ascertained whether weld failure is sudden, due to some impact or it is due to aninherent defect leading to fatigue like, improper fusion or blow holes or presence of finetc., remedial action due to be identified and taken promptly.

Sd/- (S.K.AGRAWAL) Executive Director Track (P) Railway Board.

Office of the DRM/Works/SC No.CW.506.Tra ck/Grade/Genl. Date 25.5.2007 All ADENs / SC Division Sub: Performance of SKV Welders and Grading. A database has been developed at the Divisional office and Headquarters. CTE hasgiven instructions to assess the performance of the welders an grading should begiven to each welder working in your section. As ` ‘A’,’B’ or ‘C’. The welders whosegrade is ‘A & B’ only should be utilize in the field as welders. The other welders whoare graded as ‘C’ should be utilized for supporting the welder and after they gainconfidence, they are supposed to be upgraded. However, no welding should be donein the field who are not having valid compe6tency certificate and graded as ‘B’ or ‘C’. Sample proforma is enclosed to fallow and the details available are to be update andsubmitted to the undersigned along with the number of weldings done by the individualduring the year 2006 till date. Their performance results in terms of defective joints /failed joints shall b shown and considered for awarding gradations. The guidelinesgiven may be follows. Marks to be awarded: • For Technical knowledge - 35 Marks • For Skill in execution. - 35 Marks • For quality welding - 30 Marks (Based on defective/failed joints) ——- Total 100 Marks —– Grading A > or= 90 Marks B < 90 and > or = 75 Marks C < 75 Marks ——-

CORRECTION SLIP NO.1 ENGINEERING STANDING ORDER NO.3 of01.2.1999 Sub:-Guidelines for containing rail fractures/weld failures. In partial modification to the above Standing order, the following amendments aremade to the para mentioned below:- Existing para No.2.1. shall be read as under:= Thermit welding should preferably be done on cess. When the welding work is doneon the cess full rail length should be leveled by supporting on at least ten woodenblocks on either side, if done in site, it should be done under line block of adequate



duration. The rail fastenings for at least five sleepers on either side of the proposedweld shall be loosened to avoid internal contraction stress at the joint during cooling.The approximate time required for various operation for execution of SKV welding insitu under traffic block are indicated below:-

Sl.No Process involved Welding Time

52 Kg Section 60 Kg Section

1.

cleaning.|15-20 minutes |15-20 minutes|

2.

setting ,mould fixing & luting|10 minutes| 10 minutes|

3. Pre-heating 10 minutes 12minutes

4. Reaction time, removal of burner, tapping andremoval of crucible stand

3 minutes 3 minutes

5. Mould waiting time 5 minutes 6 minutes

6. Trimming of weld 3 minutes 3 minutes

7. First train passing time 30 minutes 30minutes

8. TOTAL 76-81MINUTES

79-84MNUTES

Hence, if welding is done in situ, it should be done under line block of minimum 75minutes for SKV welding process.

Sd/- (G.P. Mallikharjun) Principal Chief Engineer

USFD Testing of AT Welds ULTRASONIC TESTING OF ALUMINO-THERMIC WELDED RAIL JOINTS 1. SCOPE: Following types of testing for Alumino Thermic welds have beenprescribed. These are: (a) Testing of weld head/web, which gets covered during through periodic rail testingby SRT/DRT. The frequency of testing in this case is as per para 6.8.1.1 of USFDManual. As per this testing defects detected in weld heads are classified as IMRW andOBSW aide Annexure II. The action to be taken for such defective welds is as perpara 6.4 (b) Periodic testing of complete weld by hand probing of weld head/web and bottomflange using Oº 2MHz, 70º 2 MHz, 45º 2 MHz probe ( AT weld foot scanning for halfmoon shaped defect) and 70º 2 MHz ( 8 x 8 mm) probes. The frequency of testing inthis case is as per 6.8.2.1 of USFD Manual. As per this testing defects detected inwelds are classified as “ DFW “. The action to be taken for such defective welds is as



per Para 6.6 of USFD manual. © Besides this, welds are also tested after their execution using Oº 2 MHz, 70º 2 MHZ,45º 2 MHz probe( AT weld foot scanning for clustered defect/ micro porosities in webfoot region) and 45º 2MHz ( Tandem probe scanning for lack of fusion). This test istermed as Initial Acceptance Test. As per this testing, defects detected in welds areclassified as “ DFW “. The action to be taken for such defective welds is as per Para8.10 of USFD manual. 2. Equipment : Any RDSO approved model of ultrasonic equipment for Alumino-thermic welded rail joints as per RDSO specification No. M&C/NDT/129/2005 or itslatest version along with rig for tandem testing. 3. Probes : ( i) Normal/Oº , 2 MHz, 18mm Dia, Double crystal - 1 no. ( ii ) 45º, 2 MHz, 20 mm Dia. Or 20mmx 20 mm squarecrystal size, Single crystal - 3 nos ( iii ) 70º, 2 MHz, 20 mm Dia. Or 20mmx 20 mmsquare crystal size, Single crystal - 1 no. ( iv) 70º, 2 MHz, 8 mm x 8 mm crystal size,Single crystal - 1 no 4. Cable : Co-axial cable for each probe shall be used. The lengthshall not be more than 2 mtrs. 5. Couplant : Soft grease shall be used as couplant. 6.Testing procedure and Classification: Sl. No. Probe Calibr ation Sensitivity DefectClassification( DFW) Type of defect Detected Locatio n 1 Oº 2 MHz 300 mm 60% FSHon 3 mm Ø hole in head From head 40% or more ht.From web or foot >20% ht Todetect Porosity, Blow holes, Slag inclusion in Head&upto mid web of weld Head &Web 2 70º S/C 2MHZ 300 mm 60% FSH on 3 mm Ø hole in head From head 40% ormore ht To detect lack of Fusion, Porosity, Blow holes, Slag inclusion, Crack in Headof AT weld Head 3 70º S/C 2MHZ 300 mm 60% FSH on 3 mm Ø hole in the middle ofthe Flange of AT weld 40% or more ht To detect lack of fusion, Porosity, Blow holes,Slag inclusion in Flange of AT weld Foot 4 45º S/C 2 MHZ 500 mm 60% FSH onSimulated notch at Bottom of AT weld 20% or more ht To detect Halfmoon shapeddefect ay bottom of weld Foot 5 70º S/C 2 MHZ ( 8×8 300m m 60% FSH on Simulated20% or more ht To detect Halfmoon shaped defect ay bottom Foot mm) notch atBottom of AT weld of weld 6 45º/45º S/C 2 MHZ (Tande m Techni que) 500 mm 100%of FSH and increase the Gain by 10db 40% or more To detect vertical oriented defectssuch as lack of fusion in rail head, web and foot region below web. Head, Web & footbelow web 7. Defect Classification, marking and action taken: Classification Markingon both sides of web Action to be taken DFW + + With red paint For NEW Welds:These DFW welds shall be cropped, re-welded and tested again. For Service welds:These DEW welds on detection, SE/USFD/shall impose SR 30kmph or stricterimmediately. He should communicate to Sec Se about the flaw location who shallensure the following: ( i ) protection of DFW weld by jog. Fps using min.2 tightclamps/2 far end tight bolts one on each side, after which SR can be relaxed upto100/75 Kmph for Goods/Pass trains. ( ii ) In case protection of DFW weld has beendone using jog.FPs with clamps, the DFW weld shall be replaced with in 15 days.However, protection of DFW weld has a been done using jog.FPs with 2 far end tightbolts SR shall continue till weld is replaced which should not be later than 3 months.The DFW weld with SR may be continued in track if the track is to be renewed with in12 months. 8. Weld Testing Frequency ( SKV ) S.No Type of Weld Type of testingTesting Schedule Acceptance Test Immediately after welding First Periodic Test Oneyear Routes Having GMT Frequency

45 2 years30 < 45 3 years15 < 30 4 years



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1 SKV Further Tests based on route GMT 0 - 15 5 years 9. Note: ( i ) Due to unusualhigh weld failure or abnormal development in some sections, Chief Engineer mayorder testing of welds early, as per need. ( ii )The USFD testing can be dispensed within case of those welds which are more than 15 years old and protected by joggled fishplates with far end tight bolts. ( iii ) TWR should be planned after the welds havecarried 50% of the stipulated GMT of Rails.

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MANUAL FOR FUSION WELDING OF RAILS XHE ALUMINO

http://www.indianrailways.gov.in/railwayboard/uploads/codesmanual/FWRATP/Thermic%20Process_Data.htm[24-12-2013 12:25:49]

MANUAL FOR FUSION WELDING OF RAILS BY THE ALUMINO-THERMIC PROCESS

1. INTRODUCTION

1.1 This manual supercedes "Manual for welding of rail joints by the alumino-thermic process, April, 1987"

1.2 There have been many technological improvements in the ,process of Alumino-Thermic welding which havenecessitated revision of Manual issued in April- 1987. Same considerations also led to revision of IndianRailway Standared Specification for fusion welding of rails by alumino-thermic process which has now beenrevised and issued under the serial No. IRS T-19-1994.

1.3 On Indian Railways Alumino-Thermic welding with short pre-heating process by using high Silica sandmould (C02 dried) is being followed at present for welding rails of different chemistry and sections. Short pre-heating is mostly being done by Air-petrol fuel mixture. Oxy-LPG & Compressed Air petrol fuel mixture arebeing developed as these techniques take less time for pre-heating the rail ends to desired temperatureresulting in saving of block time with improved quality of joint.

1.4 A. T. welding is required to be done to convert flash butt welded panels into long panels and for repair offracture. Normally new single 'rails shall not be welded by A.T. welding.

1.5 Conventional AT welding process which utilised green sand mould has been banned on Indian Railways.Alumino- Thermic welding techniques with short pre-heat process have been standardised for 75R, 90R andhigher rail sections and not standardised for 60R rails. The welding of 60R rails will be done by .conventionalAT welding process using green sand mould, as the scope of such welding is very limited for which theprovisions laid down in "Manual for welding of Rail joints by the Alumino-Thermic Process, April 1987' willcontinue to be applicable.

2. SCOPE

2.1 This manual outlines the method of welding and the precaution and steps to be taken before, during andafter welding by short pre-heating process for .achieving, satisfactory weld.

3. SELECTION OF RAILS TO BE WELDED

3.1 For both new as well as second hand rails, before welding, it should be ensured that the end bends of therails are within + 0.5mm,-Omm in vertical and �0.5mm in lateral direction, when checked with 1 metrestraight edge as shown in Fig. 3.1(a), (b) & (c).

3.2 New rails - Rails to be welded shall conform to the tolerances stipulated in the relevant specification asstated in Table - 1 below:



3.3 Second hand rails - For conversion of existing single rails/ Short welded panels into SWP/LWR/CWR orduring secondary rail renewal, old serviceable rails may be welded subject to the following conditions:

i) Obsolete rail sections and rails, older than 50 years shall not, normally, be welded. Specific approval of theRailway Board may, however, be obtained in special cases.

ii) The Chief Track Engineer shall satisfy himself that second hand rails have a substantial rail life to make it asafe and economical proposal.

iii) Rails shall be free from corrosion or excessive wear. The height of rail and width of rail head shall not beless than the values as indicated in Table-2 :



The limit of lateral wear in the rail head as laid down in Table-2, viz. 6mm may be followed subject to uniformgauge without any abrupt change.

iv) Rails shall be tested before welding, with ultrasonic flaw detector apart from visual inspection, so that railshaving cracks and internal flaws are excluded from welding. In order to achieve satisfactory running on weldedrail panels, rails with excessive scabbing, wheel burns, corrugations and wear of rail seats shall not be used forwelding. The rail flange bottom shall be visually inspected to ensure freedom from defects like dent, notch,corrosion etc.

v) Even where cracks/flaws have not been detected during visual/ USFD examination before welding, the endsof second hand rails should be suitably cropped so as to eliminate fish bolt holes.

vi) The rail ends shall be cut by sawing or using abrasive disc cutter and not by flame cutting.

vii) Second hand rails shall be match - marked before releasing from track to enable matching of the rail endsat the time of welding. Kinks, if any, in the rails shall be removed before welding.

viii) The rolling marks on the web of rails shall be checked before welding to ensure that generally rails ofdifferent qualities are not welded together. However in unavoidable circumstances, where rails of Grade 710(72UTS) rail chemistry and that of Grade 880 (90 UTS) chemistry are to be welded, the portion of Grade 880(90 UTS) chemistry shall be utilised for welding.

xi) While using second hand rail panels for secondary renewal, released from LWR/CWR sections, the endsshould be cropped to eliminate fish bolt holes. If rail ends do not have bolt holes, the ends may be cropped toa distance of minimum 150mm for AT welds and 85mm for Flash Butt welds from the centre of welded joint toeliminate heat affected zone of welds. End cropping may be suitably' increased so as to ensure that rail endsare within the tolerances as specified in para 3.1.

4. EXECUTION OF JOINTS AT SITE

4.1 Technique for welding

Welding techniques approved provisionally or for regular adoption by Railway Board/RDSO should only beadopted for welding of rails. Present status of welding techniques, approved/ provisionally approved forextended field trials, of various A.T. portion manufacturing firms is given at Annexure- 1. (As on 31-12-97) :

4.1.1 Presently, only Four firms are approved for manufacturing of portion and execution of welding. Further,12 firms are approved only for executing A. T. welds with portion and technique developed by Thermit portionplant'/N. Rly./Lucknow (TPP). Apart from this departmental welders are also trained and certified by TPP for ATwelding of rails with the technique developed by them. Following course of action may be adopted for weldingof rails through approved portions manufacturers, labour contracting firms and by departmental welders:

i) Large scale welding

a) Approved portions manufacturing firms with their portions, consumables, equipments and RDSO certified



welders/welding supervisors.

b) Labour contracting firms with portions, consumables of TPP and welders/welding supervisors certified byRDSO.

c) Departmental welders certified by TPP with portions and consumables manufactured by TPP only.

ii) Casual welding

(a) Agencies as mentioned in para 4.1.1 (i) (a) & (b) above.

(b) TPP certified departmental welders for welds of 25mm gap using portion, consumables and preferablyequipment also of approved portions manufacturers as per the approved welding parameters as given inAnnexure - 1.

iii) AT. welding in case of Turn -key contracts: in case of turn-key contracts for gauge conversion, new lines,doubling, open line works, etc. in which A.T. welding also forms a small portion of work, suitable provisionsmay be kept in the contract conditions for executing welding by the agencies as mentioned in para 4.1.1. (1)(a).

4.2 Portion for welding:

4.2.1 The "portion" used for welding shall conform to the technical requirements as mentioned in IRST-19 -1994. The suitability of the "portion'' for the welding process in respect of the type and section of rails to bewelded shall be ensured before commencing welding. Only RDSO certified/passed portions should be used forwelding.

4.2.2 Shelf life of portion: No specific shelf life has been indicated for AT welding portions. Life of portionswould depend on the quality of packing and storage condition. AT portion is sensitive to moisture. Once theportion absorbs moisture, the same cannot be removed even by drying as the ingredients react chemically. Allsuch portion should not be used for welding.

If packing is intact and there is no entry of moisture , the portion can be used even after a long time.However, following procedure may be adopted for permitting use of portions beyond two years after the date ofmanufacturing:

(a) One random sample per batch of 300 or part there-of may be drawn from the portions available in stores.

(b) The sample shall be tested for reaction test. If the reaction is normal , the batch represented by thesample can be used without further tests.

c) In case the reaction is found to be quiet or boiling a test joint should be made from one more sample-selected from the batch. Following tests should be conducted on the test joints.

(i) Aluminium content test (from riser of the joint)

(ii) Load deflection test.

These tests should, be conducted at Zonal CMTs organisation and/or the Flash Butt Welding Plant. If the valuesobtained in above tests are within the specified values as given in para 4.1.3 and 4.2.3.1 of IRS T19-94, thebatch represented by the sample can be used otherwise batch should be rejected.

(d) The rejected portions are to be disposed-off by igniting five portions at a time in a pit away from the store.

4.3 Equipment and staff for welding

The list for one set of A. T. welding equipment by short preheating process is given in Annexure-2. Thecomposition of thermit welding team is given in Annexure-3.

4.4 Preparation of rail ends to be welded.

The rail end face and adjacent sides at foot (top & bottom) , web and head upto 50mm shall be thoroughlycleaned using kerosene oil and brushing with wire brush to remove all dirt, grease and rust before welding. Anyburrs at the rail ends shall be removed by chiselling or grinding.



4.4.1 Normally, no alumino-thermic welded joint shall be located closer than 4 metre from any other welded orfish plated joint.

4.5 Gap between rail ends

The two rail ends to be welded shall be held in position with a uniform and vertical gap as per gap specified inAnnexure-l. The uniformity and verticality of the gap shall be measured by a gauge prior to welding. In caseof wide gap 50�l/ 75�1 mm welding, for repairing fractured/ defective welds, it shall be ensured that the endfaces are vertical. In LWR/CWR territory, hydraulic/mechanical rail tensor of suitable & approved design shouldbe used for maintaining correct rail gap during welding.

4.6 Preliminary work prior to welding

4.6.1 In case of in-situ welding the rail' fastenings for at least five sleepers on either side of the proposedweld shall be loosened. The sleepers adjacent to the joint to be welded shall be shifted to obtain a clearworking space of 250 mm on either side to accommodate the moulds, clamps, preheating equipment, etc. Therails shall then be properly aligned, both horizontally and vertically.

4.6.2 When the welding work is carried out on cess, full rail" length shall be levelled by supporting on at leastten wooden blocks on either side. The rails shall be properly aligned in horizontal and vertical direction andheld in position.

4.7 Alignment of rail ends before welding

4.7.1 The rail ends to be welded shall be aligned in horizontal and vertical planes to the dimensional limitsindicated below:-

4.7.1.1 Lateral alignment: The two rail ends, after alignment shall be within �0.5 mm when checked with a1.0m straight edge at rail ends (Fig. 4.7.1.1(a) & (b)). Any difference in the widths of rail heads shall alwaysbe fully kept on the non-gauge side, correctly aligning the rail ends on the gauge face.

4.7.1.2 Vertical alignment: The joint shall be kept higher by 3 to, 4mm for 72 UTS rails and 2 to 2.4 mm forhigher UTS rails when measured at the end of 1m straight edge (as a compensation against sagging caused bydifferential shrinkage on cooling) (Fig.4.7.1.2) . This shall be achieved by wedges applied on the railsupporting, blocks on. both sides 0f the joint.

4.7.2 Gap between rail ends may be rechecked after completion of alignment. Datum marks shall be made onfoot of both rails as well as on joint sleepers in order to observe any longitudinal movement of rails. Ifexcessive longitudinal movement occurs during pre-heating and produces a welding gap outside the prescribedlimits, the welding of joint shall be temporarily abandoned and joint allowed to cool.

4.8 Fixing of mould

4.8.1 Only prefabricated moulds supplied by the portion manufacturer shall be used for welding. These are tobe made by mixing high silica sand to IS:1987 with sodium silicate to the required consistency, followed bypassage of CO2 gas. These prefabricated moulds shall have adequate permeability for escape of mould gasesand adequate reinforcement, to avoid mould crushing during transportation and welding.

4.8.2 Before mounting on the rail ends to be welded, each pair of moulds shall be examined for defects,dampness, cracks, blocked vents etc. and defective moulds discarded. The prefabricated moulds shall behandled withy care as they are fragile and liable to breakage.

4.8.3. During fixing the moulds, it shall be ensured that the centre. line of the rail gap coincides with thecentre line of the mould to avoid cross joint. The mould jackets/shoes holding the pre-fabricated mould in asnug fit condition, after fixing, shall be tightened by the application of adequate pressure. Excessive pressuremay cause breakage of mould and dropping of sand inside the mould cavity. Care shall be taken duringapplication of adequate pressure. It is essential for the moulds to fit flush to each other across ' the bottom ofthe rail flange which can be checked by feeling with fingers across the junction of the two halves of the mouldsand by looking down the riser aperture. The moulds should touch the bottom of rail foot to ensure proper sizeof collar at the bottom.

4.8.4 After fixing the moulds, the gap between mould and the rail shall be packed firmly with luting sand toprevent leakage. of liquid weld metal. To protect the rail top table from metal splashes during reaction, theadjacent rail surface on either side of the moulds shall be covered with metal cover or smeared with luting



sand upto 15cm on either side.

4.9 Preheating

4.9.1 After fixing and luting of the moulds, the rail ends shall be uniformly pre-heated throughout the railsection with specially designed air petrol/ compressed air petrol/ oxygen -LPG burner as the case may be. Theflame shall be properly adjusted to achieve the desired rail temperature . The pre-heating shall be done fromthe top of the mould box for stipulated period for welding technique adopted, so as to achieve a temperatureof around 600�20�C.

4.9.2 In welding process using air petrol burner, the compressor tank pressure during operation of the burnershall be maintained at 7 �0.70 Kg/cm2(100�10 lbs per sq. inch). In case of pre-heating by Oxy-LPG process,pressure for Oxygen and LPG cylinders shall be adjusted in the range of 7.0-8.0 Kg/cm2 and 2.0-2.5 Kg/cm2

respectively. While preheating with OXY-LPG burner LPG supply should be opened first and the gas ingited,thereafter Oxygen supply should be opened. While closing, Oxygen supply should be stopped first followed byLPG supply. The burner shall be properly adjusted during preheating to ensure that the head, web and foot ofboth the rail ends are heated uniformly.

4.9.3 Preheating time - Preheating time would be about 10 to 12 minutes and 2 to 2.5 minutes for Air-petroland Oxy-LPG preheating techniques respectively. The actual preheating time would depend upon the railsection and welding technique adopted as given in Annexure-I.

4.9.4 Special emphasis shall be given to the tank pressure efficiency of burner & flame condition for achievingrequired rail temperature within the stipulated time. From time to time or in case of any doubt with a view tomaintain proper quality control, temperature measuring devices like 'Optical pyrometer, Contact typepyrometer' or temperature indicating crayons may be used for measuring rail end temperature just aftercompletion of preheating i.e. after removal of burner.

4.10 Welding

4.10.1 The crucible lined with refractory material (magnesite/crushed alumina slag) and fitted with bottomstone and thimble shall be preheated before making the first weld of the day to ensure freedom from moisture.

4.10.2 Slag shall be cleaned from the crucible after each reaction, if necessary. During cleaning, care shall betaken not to damage the refractory crucible lining. The lining shall be examined regularly and patch repairing,or relining as necessary shall be carried out.

4.10.3 The crucible shall be positioned relative to the pouring gate with respect to its height from the mouldafter it has been placed on the stand mounted on the rail head. The tap hole in the crucible shall be sealedwith closing pin, asbestos powder and slag powder. The portion for the required technique, shall be thoroughlyhand mixed and poured into the crucible striking the crucible wall so that the bottom plugging remainsundisturbed. The portion shall be coned to the centre of the crucible and a sparkler be placed at the top. Thecrucible shall then be brought to the proper position over the mould in line with the pouring gate of the mouldwith a vertical distance of about 50mm between the tap hole and sand,, core /top of the pouring gate.

4.10.4 After preheating the rail joint , the sparkler shall be ignited & inserted in the portion at the centre topto start the reaction. The reaction shall not be vigorous or boiling. By the time the reaction is complete, theburner shall be removed quickly and the gap closed with a dried sand core in case of central pouring toprevent loss of heat and turbulence during flow of metal. The time period between removal of burner andtapping of metal should be as minimum as possible. After the reaction subsides, about 3 seconds shall beallowed for the separation of slag from the metal, which may be judged by looking into the crucible throughcolored glass to IS:5983. Thereafter, the molten steel shall be tapped into the mould by striking the closing pinwith a tapping rod. It shall be ensured that since the commencement of the reaction, thermit steel is tappedwithin the time limit as specified in Annexure-1 . Care shall be taken to ensure that the crucible does notmove from its position during tapping. When pouring is over, the crucible and swivel stand shall be removedand kept aside without disturbing the joint. If the reaction is found to be boiling, the metal shall be out-tapped. Vigorous reaction and loose closing of crucible may cause self tapping. In this case also, the metal shallbe out tapped. If, in any case, self tapped metal enters the mould, the joint shall be rejected, cut andrewelded. In cases of out tapping, the joint should be cooled to ambient temperature and .the process ofwelding restarted a fresh. However if temperature can be-measured, the rail end may be heated to an extentso as to achieve temperature of about 600�20�C and welding of joint may be completed.

4.10.5 After pouring, molten metal shall be allowed to cool and solidify with mould intact for the stipulatedtime (mould waiting time) depending upon the rail section and ambient temperature. In case of alloy steel



rails, full rail section upto 300 mm on either side of the joint shall be heated by using burner during thisperiod. The mould shoes shall be removed just prior to completion of mould waiting time. The mould waitingtime is generally 4 to 6 minutes for 25mm gap joints and 12 minutes for 75mm gap joints. After the mouldwaiting time has elapsed, the trimming should be done by using weld trimmer. of suitable & approved designwithout knocking out the mould. List of approved manufacturers of Rail profile weld grinder and Weld trimmer is given at Annexure-4. In the eventuality of sudden failure of weld trimmer , manual chipping may beresorted to. In case of welding of old rails , if it is not possible to use weld trimmer due to flow of metal at railhead, manual chipping should be done.

4.10.6 During the trimming operation, it shall be ensured that the wedges used in aligning are in their properplaces without loosening, and they are not removed for at least 20 minutes after stripping. The runner & risermust not be removed until cold, and that too only by knocking towards the rail.

4.10.7 No welding shall be carried out if it is raining. In I case, the rains start while the joint is underexecution, immediate arrangement to adequately cover the site shall be made.

5. OPERATIONS SUBSEQUENT TJ2 WELDING

5.1 Post; weld cooling

5.1.1 110 UTS alloy steel rail joints ( Chrome Manganese and Chrome Vanadium type ) are required to beslowly cooled immediately after trimming by fixing an insulation hood (fig.5.1) lined with asbestos, so as tocontrol the cooling rate of the weld zone. The hood must be kept around the joint for at least 20 minutes.

5.1.2 In case of welding of Head Hardend rails, the average hardness of the HAZ of the rail becomesconsiderably less than the parent rail hardness. This lower hardness is due to transformation of rail steeloccurring at cooling rate much lower than that achieved during the original head hardening operation. Such ahardness difference can lead to differential plastic deformation during wheel rail contact which may causelocalised cupping. Head Hardend rails, therefore, must be subjected to controlled quenching for a specific timeby the arrangement approved for the technique.

5.2 Post weld packing pf sleeper

Before the passage of traffic, the wedges used for aligning should be removed and joint sleepers which wereshifted to obtain the clear gap of 250mm on either side as per clause 4.6.1 shall be re-shifted to the originallocation and repacked. Packing of these resifted sleepers should be carried out gently and carefully.

5.3 Passing of traffic

The first train should be allowed to pass on the newly welded joint only after 30 minutes have elapsed sincepouring of weld metal. Necessary speed restriction shall be observed until the grinding operation is over.

5.4 Grinding

5.4.1 After the excess metal is trimmed off, the grinding of the remaining metal on the rail table and the sidesof the rail head shall be carried out only with rail profile guided grinding trolley of approved design. Use ofhand files should not be resorted to except in unavoidable circumstances. In the case of in-situ joints, thegrinding shall commence only after the sleeper fastenings are refixed, after the removal of wedges. The railtable shall first be ground down to original profile and checked by a 1 m straight edge. This should be followedby grinding of the sides of rail head. The accuracy of grinding shall be checked by using 10 cm straight edge.While grinding, only light pressure should be applied and grinding wheel should be moved to and fro to avoidlocal over heating.

5.4.2 Tolerances on finished welds.All the finished joints shall be checked to ensure that the joint geometry is within the following tolerances:

i) Vertical alignment: 'Variation not more than +1.0mm,-0 mm measured at the .end of one metre straight

ii) Lateral alignment: Variation^ not: more than �0.5mm measured at centre of one metre straight edge.

in) Finishing of top surface: + 0.4 mm,-0 mm measured at the end of. 10 cm straight edge.

iv) Head finishing on sides: �0.3mm over gauge side of the rail head measured at the centre of 10 cm straightedge.



Note: In specific tales, for joint geometry, in case of old rails, dispensations may be permitted by ChiefEngineer.

The method of checking the geometry of welded joints is illustrated with sketches in Fig. 5.4.2

5.5 Record of Joint Geometry

The details of geometry of each joint shall be jointly signed by the firm's and Railway's representative and keptas record. Any joint found not conforming to the above stipulations shall be cut and rewelded, free of dost, bythe firm.

5.6 MARKING

Each joint shall have a distinctive mark indicating: month, year, Agency, welder's code and weld number of thewelded joint in the following manner: joint in the following manner:

** ** *** *** ***

Month Last two digits ofyear. Agency Specific person

number Weld No.

This should be done by punching on an Aluminum strip of suitable thickness and dimension of 30 mm x 100mm which should be fixed to the web of the rail with epoxy adhesive at approximately 300 mm from the joint.The welded joints shall be serially numbered in - a kilometer. Repair welds/additional welds done at a later datemay be given continuing weld number in that kilometer. For example, the last thermit weld number in aparticular kilometer was 88 and subsequently a thermit weld has been executed, it shall be numbered 89,irrespective of its location in that kilometer. PWI shall maintain THERMIT WELD REGISTER as per proformagiven in Annexure - 5. No punch marking should, be done on the rail.

5.7 PAINTING OF THERMIT WELDS

5.7.1 Painting of weld collar should be done on all welds to protect them against corrosion immediately afterthe welding. The procedure of painting and specification of paint is outlined in Annexure-6 & Annexure -7.

5.7.2 In service painting ( maintenance painting) of thermit welds should be carried as per following frequency:

(i) Once in four years in areas not prone to corrosion.

(ii) Every year at locations prone to corrosion as defined in para 249 (i) of IRPWM. The frequency may beincreased depending on the site conditions.

(iii) On condition basis at locations which are prone to severe corrosion (areas of severe corrosion to bedecided by territorial Chief Engineer / CTE). ;

5.7.3 The procedure for painting of weld collar for thermit welded rail joints to protect against normalcorrosion and severe corrosion is outlined in Annexure-6 and Annexure-7 respectively.

6. ACCEPTANCE TESTS

6.1 Visual Inspection - All the welded joints shall be examined carefully to detect any visible defect likecracks, blow holes etc. Any joint, which shows any visible defect should be rejected.

6.2 Dimensional Check- All finished joints shall be checked for dimensional tolerances which should be withinthe tolerances as specified in para 5.4.2.

6.3 Ultrasonic Flaw Detection Test

All the fusion welded joints shall be ultrasonically tested and accepted by the purchaser or his representativeas per the "Procedure for ultrasonic testing of thermit welded rail joints given at Annexure-8. This testingshall be completed as early as possible but in any case before the contractor/welding team leaves the weldingsite,

6.4 Rewelding of Defective Joints



6.4.1 All the joints found to be defective as per acceptance tests as given in clause 6.1, 6.2, & 6.3 and/orjoints failed in guarantee period as specified in para 7.3 will be cut and rewelded by the firm free of cost usingtheir portions, equipments, labour & consumables.

6.4.2 Where one bad joint, is required to be replaced by two new joints, the entire cost of both the joints shallbe borne by the firm.

6.4.3 All the rewelded joints should meet the acceptance tests as indicated in Paras,-6.1 to 6.3

7. Sample Test Joint

7.1.1 One out of every 100 joints welded shall be selected at random by the purchaser or by the; inspectingofficer within one month of welding and subjected to Hardness, Transverse load/ deflection tests and Porosityas per clause 4.2 of IRST-19-1994 (reproduced partly as Annexure-9 for ready reference) and the joint shallcomply with the provisions laid down therein,

7.2 If the sample test joint fails to satisfy any of the requirements of specification IRST-19-1994, the Railwaywill be at liberty to suspend further welding. However, two more randomly selected joints from the same lot of100 joints shall be subjected to retests as per clause 4.2 of IRST-19-1994. Both the joints should clear all thetests. If this report is also not satisfactory further welding of joints shall be suspended until the firm's weldingtechnique has been examined and the same satisfies the requirements of clause 4 of IRST-19-1994, Theclearance for recommencement of welding shall be given by RDSO.

7.3 GUARANTEE

7.3.1 Rail joints welded by a firm shall be guaranteed against failure for a period of two years from the. dateof welding the joints in track or from the date such welded joints made in cess are inserted in the track. Anysuch welded joint which fails within the guarantee period shall be rewelded free of cost by firm as perstipulations of clause 6.4.

7.3.2 In case of failure of sample test joint (refer Clause 7) , the period of guarantee for 100 jointsrepresented by the sample joint shall be extended for a further period of one year. In case of failure of jointsor joints exhibiting signs of failure by cracking within extended period of guarantee, the joints shall berewelded free of cost by the supplier as per stipulations of Clause 6.4.

7.4 The welded joints with the extended period of guarantee shall be marked 'X' with Yellow paint on the outerside of the web of the rail near the joint in addition to the marking prescribed in clause 5.6. Such markedjoints shall be kept under careful observation by the purchaser.

8. OTHER REQUIREMENTS

8.1 Welding shall be supervised by trained welding Supervisor and carried out by trained welder having validcompetency certificate from RDSO/ TPP, NR, Lucknow in their possession.

8.2 A welding supervisor shall supervise not more than two welding teams deployed within 50m distance at atime.

8.3 A copy of the thermit welding Manual shall be available with each PWI and at each welding site.

9. PRECAUTIONS

While carrying out welding at site, the following precautions shall be observed:-

i) It should be ensured that the portion being used Matches with type and chemistry of rail,

ii) Rail ends should be square,

iii) Alignment of rail ends should be perfect as checked by straight edge,

iv) Rail ends should be properly cleaned with kerosene oil and wire brushes.

v) Stop watch should be provided to the welding supervisor at each welding site,

vi) Pressure in the tanks/cylinder should be properly maintained during pre-heating.



vii) Correct gap between rail ends at head, web and foot shall be ensured.

viii) Correct preheating time for rail ends shall be ensured.

ix) Tightness of clips fitted with hose connections to compressor tank and burner shall be checked beforecommencing preheating,

x) Nozzles of burners shall be cleaned periodically to avoid back-fire.

xi) The compressor tank shall be kept at least 2 to 3 metres away from the burner to prevent fire hazard.

xii) The tapping shall be done within the time specified for that particular technique. Welding parameters fortechniques presently being used are available at Annexure-1. For special type of welding i.e. 75mm gap,Combination joint etc. the time of reaction & tapping shall be as stipulated by RDSO for that particular weldingtechnique .

xiii) Arrangements for giving first aid shall be available at site.

xiv) Welders should be provided with gloves and coloured glasses.

xv) Boiling portion shall be out tapped.

xvi) No moist portion/torned portion bag shall be used for welding.

xvii) Dampness in moulds can lead to porosity and early fatigue failure of welds.

xviii) Only those contractual agencies as have clearance from the RDSO/Railway Board can execute weldingwork. Supply of portions must be from sources approved by RDSO/Railway Board.

xiv) Many weld failures show evidence of badly cut rail ends. The evenness and verticallity of a rail cut dependssolely upon the skill of the welder. With portable disk cutters, very little skill is required to produce good cut.

10. DEFECTS IN A.T. WELDING

The major types of defects which can cause weld failure because of improper weld execution are given atAnnexure -10.

Annexure - 1



ANNEXURE-2



ANNEXURE-3

COMPOSITION QE THERMIT WELDING TEAM (COMPRESSOR TANK-WISE)

Designation NumbersWelder Grade I/Grade II 1Welder Grade III/ Skilled Artisan 2Helper Khalasi/Khalasi 5Gangman As per work load

Note: The composition of welding team has been framed taking into account that trimming and grindingoperation would be done by Weld trimmer and Rail profile grinder.

ANNEXURE-4



ANNEXURE-5



ANNEXURE-6

PROCEDURE FOR PAINTING OF WELD COLLAR FOR THERMIT WELDED RAIL JOINTS TO PROTECTAGAINST NORMAL CORROSION

A. NEW WELDED JOINT

1. Surface preparation:-

1.1 Remove dust, loose rust and mill scale by wire brushing.

1.2 Scrub welded area with water to make it free from slag and other water soluble compounds. Make it dry.

2. Painting procedure;-

2.1 Apply one coat of ready mixed paint; brushing, bituminous, black, lead free, acid, alkali, water and chlorineresisting, conforming to IS:9862-81 on the welded area and 10 cms on either side.

2.2 After 8 hrs. drying, apply a second coat of the same paint.

2.3 Painting should be carried out by brush only.

B Maintenance Painting (For old painted joints)

1. Surface Preparation:-

1.1 Remove dust, dirt, and flaked paint from the welded joint by wire brushing.

1.2 Degrease the surface by. Petroleum hydrocarbon or any other suitable solvent, if oil or grease is present.Allow it to dry.

2. Painting procedure:-

2.1 Apply one coat of ready mixed paint; brushing, bituminous, Black, Lead free, Acid, alkali & chlorineresistant to IS:9862-81 or bituminous emulsion to IRS P-30-96 on welded area and 10 cms on either side.

2.2 If required, a second coat of the same paint may be applied after a minimum of 8 hours drying.

2.3 Painting should be carried out by brush.

3. The list of approved manufacturers for the above quality of paints is issued every year byDG/M&C/RDSO/LKO to Zonal Railways.

ANNEXURB-7

PROCEDURE FOR PAINTING OF WELD COLLAR FOR THERMIT WELDED RAIL JOINTS TO PROTECTAGAINST SEVERE CORROSION

A. NEW WELDED JOINT

1. Surface preparation:

1.1 Remove dust, loose rust and mill scale by wire brushing.

1.2 Scrub welded area with water to make it free from slag and other water soluble compounds. Make it dry.

2.0 Painting procedure-

2.1 Apply one coat of high build Epoxy paint (Two pack) conforming to RDSO specification No. M&C/PCN-111/88 on the welded area up to 10cms. on either side.

B Maintenance Painting (For old Painted joints)

1. Surface Preparation:-



1.1 Remove dust, dirt, and flaked paint from the welded joint by wire brushing.

1.2 Degrease the surface by Petroleum hydrocarbon or any other suitable solvent, if oil or grease, is present.Allow it to dry.

2. Painting procedure:-

2.1 Apply one coat of high build Epoxy paint (Two pack) conforming to RDSO specification No. M&C/PCN-111/88 on the welded area up to 10cms. on either side.

3. RDSO specification No. M&C/PCN-111/88 has been circulated vide RDSO's letter No. M&C/PCN/II/TR/3dt.13/14-5-91.

NOTE:

1. The Epoxy based paint recommended is a two pack system with a pot life of around 5 hours. Hence prepareonly that much quantity of paint which can be consumed in less than 5 hours.

2. The paint should be procured along with the thinner recommended by the manufacturer of the paint. Noother thinnner i.e. kerosene oil etc. should be used.

3. The painting shall be carried out by brush only. Brush shall be cleaned, by the thinner after use.

4. The list of probable suppliers is given below as per Letter No. M&C/PCN/II/TR/3 dt. 13/14-5-91 :

i) M/s Asian Paints (India) Ltd., "Nirmal' 5th floor, Nariman Point, PB No. 1546, Bombay - 400 421.

ii) M/s Addison Paints & Chemicals Ltd., "Huzur Gardens', Sembium Madras - 600 011.

iii) M/s Goodlass Nerolac Paints (P) Ltd., Nerolac House , Ganpat Rao Kadaw Marg, Lower Parel, Bombay - 400013.

iv) M/s Shalimar Paints Limited, 13, Camac St. Calcutta - 700 071.

v) M/s Berger Paints India Ltd., 32, Chowringee Road, Calcutta - 700 071.

ANNRXURE-8

PROCEDURE FOR ULTRASONIC! TESTING OF ALUMINO THERMIC RAIL. JOINTS

1. Scope

This procedure covers the requirement of ultrasonic testing of alumino thermic (AT) welded rail jointsimmediately after execution of the weld.

2. General conditions of test

2.1 Surface preparation

After execution of the AT weld, the welded zone shall be dressed properly to facilitate placement of probes andto avoid incidence of spurious signals on the CRT. The rail table shall be dressed to obtain reasonably flat andsmooth surface. The flange and the web, up to a distance of 200mm on either side of the weld collar shall bethoroughly cleaned with a wire brush to ensure freedom from dust, dirt, surface unevenness etc.

2.2 Couplant

Water/oil/soft grease shall be used as couplant.

2.3 Sensitivity

The equipment Sensitivity shall be normal, 70� and 80� probes in accordance with the procedure laid down inpara 4. The sensitivity so adjusted shall be considered as normal gain setting and shall be utilised during ATWtesting. The sensitivity level shall not be altered during the course of testing.



3. Apparatus required

3.1 Equipment

Any model of RDSO approved rail tester shall be considered suitable for testing of AT welded rail joints.

3.2 Probes

During ultrasonic examination of AT welded joints, the following probes shall be utilised:

a) Normal (00) , 4 MHz Double crystal fitted in trolley

b) 70�, 2 MHz. ,, ,, ,, ,,

c) 80�, 1.25 MHz Single crystal for hand probing

3.3 Cable

One co-axial cable of suitable length for connecting 80� probe to flaw detector shall be used. The lengthshould not exceed more than 5m.

4. Sensitivity setting procedure

4.1 Calibration

The equipment shall be set for a depth range of 250mm by manipulating the depth control knob suitably. Eachmain scale division, therefore, shall correspond to 25mm.

4.2 Test Rail

The sensitivity of the ultrasonic equipment shall be set with the help of a standard AT welded rail piece of 1.5mlength having a simulated flaw at standard locations as shown in Fig. 1.

4.3 Alignment of probes

The alignment of normal and 70� probes fitted with the trolley may be checked by placing the rail tester onthe test rail using water/oil as a couplant and ensuring that the probes travel along the vertical axis of the rail.

4.4 Sensitivity setting for 70� probes

4.4.1 Place the trolley on the test rails shown in Fig. l. Keep the switches of all the probes in Off positions andturn the Potentiometer knobs of all the probes to 50% of their highest working range.

4.4.2 Switch on only 70� forward probe and move the equipment towards the drilled hole of 3mm dia. in railhead. When the probe is just in the reflecting range, a pulse corresponding to the hole shall appear on thescreen which during onward travelling shall show higher amplitude. The pulse shall appear moving from right toleft. The equipment should be progressively moved forward till maximum height of the pulse is obtained. Atthis location the height of the pulse shall be adjusted to 60% of full screen height by suitably manipulation ofthe gain knob.

4.4.3 The forward probe shall be switched off and the 70% backward probe shall now be switched on. In thiscase a flaw signal shall appear moving from left to right. The signal height in this position shall also beadjusted to 60% of full screen height. This can be accomplished through suitable manipulation of relevantpotentiometer.

4.4.4 The sensitivity setting for the normal probe has to be done while keeping all other probes in Offposition. Switch on only the normal probe and bring it above 3mm dia hole drilled in the head of the test rail.Manipulate the potentiometer control knob to obtain echo height of 60% of full screen height at 1.0 divisionhorizontal scale.

4.4.5 80� probe shall be connected to the socket available in the ultrasonic equipment. The selectors switchmay be set to single crystal mode. Move the probe towards the 3mm dia hole drilled at the middle of theflange through in the AT weld and manipulate knobs to Obtain a 60% full screen height on the CRT.



5. Criteria for-defect classification

5.1 Any flaw1 signal obtained by normal probe of 40% height or more from head location shall be treated as adefective AT welded joint and any flaw signal obtained from the normal probe either from the web or the footlocation shall also be a cause for rejection of the AT weld.

5.2 In the-case of lack of fusion, inclusions, blow holes etc. in the rail head, moving signal shall be obtainedwhile testing with 70� probe. The position of onset of the signal and its corresponding range on the horizontalscreen as well as their maximum amplitude shall be recorded. -.

A welded joint showing the moving signal of 40% or more of the full screen height shall be considered as adefective welded joint.

5.3 80� probe shall be placed on the flange at a distance of 180mm corresponding to position 'L' in Fig.2such that ultrasonic waves are directed towards the weld. The probe shall thereafter be moved slowly in azigzag pattern towards the weld. A welded joint showing a flaw echo of 40% vertical height or more with thestipulated gain setting shall be treated as a defective welded joint. Similar testing shall be carried out on "Cand 'U' region as shown in Fig.2. In these cases also the criteria for rejection shall remain the same.

6. The defective joints based on the criteria mentioned at clause 5 shall not be allowed to remain in serviceand shall be cropped, re-welded and tested again. This execution shall be done by the contractor free of cost.The re-welded joints shall be scanned ultrasonically again with the same set of acceptance criteria to ensurefreedom from any harmful defects.



ANNEXURE-9

EXTRACTS FROM T-19-1994

4.2 Mechanical and Metallurgical tests on test welds

4.2.1 Two new rail pieces of same section and grade, each approximately 750 mm long, shall be used to maketest weld joint. The welded joint shall be made as per the technique offered by the manufacturer. The rail tableand sides of rail head shall be finished to the geometrical tolerances specified in Clause 18.1.

4.2.2 Hardness test

Brinell hardness test shall be' carried out at the welded zone, heat affected zones and parent metal of the railsin ac-cordance with IS:1500, " Method for Brinell Hardness test for steel ". The test shall be done on the topsurface of the head of the test weld with a ball of 10 mm dia and a test load of 3000 kg maintained for 10sees. The average hardness number (of two readings) determined for the weld metal at locations shown as "A'in Fig. l shall be within +20 -0 HB of the hardness values of rail as shown in table 1. The average hardnessnumber (of two readings) on each heat affected zone at locations shown as B1 and C in Fig. l shall be within (-)20 HB for locations B and ( + )20 HB for locations C of the actual hardness of the parent rail.



Table-1

Type of rail 72 UTS rail 90 UTS rail UTC Cr-Mn or Cr-V alloy steel rail

Head Hard enedRail

Average Hardness(BHN) 230 265 310 365

4.2.3 Transverse breaking load test:

4.2.3.1 The test weld shall be supported on cylindrical or semi-cylindrical supports having a distance of onemetre between them from centre to centre. The weld shall be at the centre of the span and loaded in such amanner that the foot of the rail is in tension. The diameter of mandrel and the supports shall be between 30 to50mm. The load shall be gradually increased (rate of loading shall not exceed 2.5 t/sec) till rupture occurs.

The test weld shall withstand a minimum load and show corresponding minimum deflection as stipulated inTable-2 for different sections and types of rails.

TABLE-2



4.2.3.2 If the fracture does not occur through weld, a slice shall be cut transversely at the weld and etched inboiling 1:1 Hydrochloric acid for about 20 minutes to determine casting defects if any.

4.2.3.3 The fractured surface of the weld, or in case where macro-etching is done on transverse sectionthrough the joint, shall not show defects such as blow holes, porosity and inclusions etc. exceeding totalpermissible area of defect shown in Table-3. However, the size of any individual defect shall not exceed 2mmdiameter. The defects should not be interconnected and none of these shall extend upto the outer surface ofthe weld. There shall not be any lack of fusion. The fractured surface shall also not show the presence ofaccretions or mirror like structure and shall be crystalline in appearance.

TABLE-3

Area of permissible defects

Rail Section Permissible total area of defect (mm2)60 R 19.075 R 23.790 R 28.552 kg 33.460 kg 38.4

4.3 Retests

4.3.1 If the results of any of the tests referred to in clause 4.1 and 4.2 are found to be unsatisfactory, thebatch will stand rejected. However, retests can be carried out at the manufacturer's request. These retests shall



be carried out as per para 4.1 and 4.2 on twice the original sample size.

4.3.2 If the results of all the retest samples are satisfactory, the batch represented by the sample portionsshall be accepted. If any sample fails to meet the requirements of any of the tests, the batch shall be rejected.

ANNEXURE -10

MAJOR DEFECTS IN AT WELDING BECAUSE OF IMPROPER WELD EXECUTION



Figures 3.1 (a), (b) & (c)



Figure 4. 7.1.1 (a) , (b) & 4.7.1.2



Figure 5.1

Figure 5.4.2



SALIENT FEATURES 0F REVISED MANUAL FOR WELDING OF RAIL JOINTS

BY THE ALUMINO-THERMIC PROCESS (1999)

1. As Conventional method of Alumino-Thremic (AT) welding has been discontinueed on Indian Railways exceptfor 60R rails, accordingly the revised manual provides for only SKV AT welding. (Clause 1.5)

2. A para on Shelf life of portion1 has been included, which brings out the importance of proper packing andstorage of AT portions. Procedure to be adopted for use of portions beyond two years since the date ofmanufacture has also been laid down (Clause 4.2.2)

3. Detailed instructions on painting of weld collar immediately after welding and also its in-service paintinghave been laid down. In case of areas where severe corrosion is observed epoxy painting has been providedfor. (Clause 5.7)

4. Course of action to be adopted for welding of rails through approved portion manufacturer, labourcontracting firms and departmental welders, in case of large scale welding, casual welding and welding formingpart of turn-key projects have been outlined. (Clause 4.1.1)

5. In case of secondary rail renewal, AT welding by end cropping so as to eliminate both bolt holes has beenspecified. In case of use of rail panels released from LWR/CWR territory, cropping of rail ends so as toeliminate heat affected zone has been specified. (Clause 3.3(xi)).

6. Use of 880 grade portions for AT welding where grade 710 (72UTS) and Grade 880 (90UTS) rails formjunctions in unavoidable circumstances has been specified (Clause 3.3(viii))

7. The composition of welding team has been revised keeping in view introduction of SKV welding and use ofweld trimmer & rail profile grinder.(Annexure-3)

8. A list of defects giving causes and preventive action to be taken to avoid the same has been briefly outlined.(Annexure-10)

9. As only grade 880 rails are being produced, AT welding by flame cutting/ gas cutting of rails specially forwide gap welding has been deleted and only sawing or abrasive disc cutting has been provided. (Clause3.3(vi))

10. Welding parameters of AT welding techniques (As on 31.12.97) including welding techniques underdevelopment for various approved firms have been laid down. (Annexure-1)

11. Provision of fixing an Aluminium strip with distinctive weld number on the web of rail by epoxy basedadhesive has been laid down. (clause 5.6)

12. Guarantee period and other provisions wherever required as provided in IRST-19-1994 have been includedto update the manual in line with IRST-19-1994, (Clause 7.3)

11. List of approved manufacturers of Rail profile weld grinder and Weld trimmer has been-included.(Annexure-4)

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