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CHAPTER – 3 INSTALLATION AND MAINTENANCE OF WELDED RAILS ********************* PART – ‘A’ ALUMINO-THERMIT WELDING OF RAILS 301 General – Thermit welding process is used...
CHAPTER – 3 INSTALLATION AND MAINTENANCE OF WELDED RAILS ********************* PART – ‘A’ ALUMINO-THERMIT WELDING OF RAILS 301 General – Thermit welding process is used for carrying out welding of rails at site. 302 Alumino Thermit Welding of Rails – On Indian Railways Alumino-Thermic welding with short pre-heating process by using high silica sand mould (carbon dioxide dried) is being followed at present for welding rails of different chemistry and sections. Short pre-heating is done by air-petrol fuel mixture, Oxy- LPG and compressed air petrol fuel mixture. 303 Selection of rails to be welded – For both new as well as second hand rails, before welding it should be ensured that the end bends of the rails are within +0.5 mm, -0 mm in vertical and + 0.5 mm in lateral direction when checked with one metre straight edge as shown in Fig. 3.1(a), (b) and (c) in Annexure - 3/1. Further, in case of welding of new rails as well as repair/maintenance welding, fish boltholes are to be eliminated as far as possible to make the weld amenable for USFD testing for lack of fusion. (1) New rails: New rails to be welded shall conform to the tolerances stipulated in the specification IRS-T-12 (Indian Railway Specification for Flat Bottom Rails). (2) Second hand rails: For conversion of existing single rails/short welded panels into SWP/LWR/CWR or during secondary rail renewal, old serviceable rails may be welded subject to the following conditions: (a) Obsolete rail sections and rails older than 50 years shall normally not be welded. Specific approval of the CTE may, however, be obtained in special cases. (b) The Chief Track Engineer shall satisfy himself that second hand rails have a substantial rail life to make it a safe and economical proposal. (c) Rails shall be free from corrosion or excessive wear. The height of rail and width of railhead shall not be less than the values as indicated below. Normal height Minimum Width of Minimum width of head of old Rail of new rail height of old head of new rail (as measured at the gauge section (mm) rail (mm) rail (mm) corner) (mm) 60 kg/m 172 163 72 66 52 kg/m 156 150 67 61 The limit of lateral wear in the rail head as mentioned in table above may be followed subject to uniform gauge without any abrupt change. (d) Rails shall be tested before welding with Ultrasonic Flaw Detector apart from visual inspection, so that rails having cracks and internal flaws are not welded. In order to achieve satisfactory running on welded rail panels, rails with excessive scabbing, wheel burns, corrugations and wear of rail seats are not to be welded. The rail flange bottom is to be visually inspected to ensure freedom from defects like dent, notch, corrosion, etc. (e) Even where cracks/flaws are not detected during visual/USFD examination before welding, the ends of second hand rails should be suitably cropped so as to eliminate fish bolt holes. (f) The rail ends shall be cut by sawing or using abrasive disc cutter and not by flame cutting. Page 77 of 417 (g) Second hand rails shall be match-marked before releasing from track to enable matching of the rail ends at the time of welding. Kinks, if any, in the rails shall be removed before welding. (h) The rolling marks on the web of rails shall be checked before welding to ensure that generally rails of different Grades of rails are not welded together. However, in unavoidable circumstances, where rails of Grade 710 (72 UTS) 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. (i) The rail ends to be welded shall be checked and aligned both in horizontal and vertical planes to the dimensional limits given in Fig 3.2 Annexure - 3/1 304 Portion for welding-The portion used for welding shall conform to the technical requirements as mentioned in “Indian Railway Standard Specification for Fusion Welding of Rails by Alumino – Thermic Process”. The suitability of the ‘portion’ for the welding process in respect of the type and section of rails to be welded shall be ensured before commencing welding. Thermit welding portions and consumables to be used for welding shall be from RDSO approved sources only. Separate portion and moulds shall be used for execution of combination welds for 60 kg / 52 kg rails from RDSO approved vendors only. Welding Parameters viz. preheating time, preheating pressure, mould waiting time etc., as approved by the RDSO for the particular source and particular welding technique shall be ensured, while executing the AT weld at site. (1) Shelf life of portion: No specific shelf life has been indicated for AT welding portions. The life of portions would depend on the quality of packing and storage condition. AT welding portion is sensitive to moisture. Once the portion absorbs moisture, the same cannot be removed even by drying as chemical reaction takes place in the ingredients. Such portion should not be used for welding. Portions should be used in rotation i.e. first in-first out. (2) Notwithstanding aforesaid, in (1) above, the following procedure may be adopted for permitting use of portions beyond two years after the date of manufacturing: (a) One sample per supplied batch shall be taken. (b) The sample shall be tested for reaction test. If the reaction is normal, the batch represented by the sample 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) Weld Metal Chemistry Test (ii) Load deflection test: These tests should be conducted at Zonal CMTs organisation and/or the Flash Butt Welding Plant. If the values obtained in above tests are within the specified values as given in “Indian Railway Standard Specification for Fusion Welding of Rails by Alumino – Thermic Process” , the batch 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 pit away from the store. 305 Storage and transportation of Portions:- The manufacturer of portion shall provide guidelines containing best safety practices with every package for guidance of the user covering various aspects in safe handling, storage, transportation and disposal of Thermit Materials. Tubes of igniters should be stored in a locked steel cupboard, or other secure steel container. On no account must these be stored in the same building as the portions. Page 78 of 417 AT Portion should not be transported in passenger coaches. The package containing igniters should be kept in tin cases/steel containers. For detailed guidelines on storage and transportation, AT Welding Manual may be referred. 306 Equipment, staff and Traffic block for welding:- (1) The list of one set of AT welding equipment by short pre-heating process is given in Annexure - 3/2. (2) The composition of Thermit welding team is given in Annexure - 3/3. (3) A minimum traffic block of 70-75 minute duration, depending upon the type of preheating technique adopted, should be obtained for complete operation of welding and to ensure good quality of AT weld. (4) The traffic can be allowed only after 30 minutes have elapsed after welding of the joint. Suitable speed restriction shall be imposed until the grinding operation is completed. 307 Execution of Welding and other precautions:- (1) Alumino Thermic Welding of rails may be carried out in accordance with the detailed procedure laid down in the ‘Manual for Fusion Welding of Rails by Alumino Thermic Process’. A Thermit welding done in-situ shall be joggled fish plated with two clamps and supported on wooden blocks of length 300-450 mm until tested as good by USFD. (2) Joggled fishplates with far end bolts shall be provided on AT welds, which have undertaken traffic equal to or more than 50% of stipulated fatigue life (GMT) of the rail. (3) Joggled fishplate with clamps or two far end bolts on good AT welds shall be provided on banks having height 5 m or more. (4) Joggled fish plate with clamps or two far end bolts on good AT welds shall be provided on bridges (having length of waterway as 100 m or more) and on its approaches upto 100 m length. (5) Joggled fishplate with clamps or two far end bolts on good AT welds shall be provided on curves of 3° or sharper. 308 Tolerances on finished welds: - All the finished joints shall be checked to ensure that the joint geometry is within the following tolerances: (Back to Para 311(2)) (1) Vertical alignment: Variation not more than +1.0 mm, − 0.0 mm measured at the end of one metre straight edge. (2) Lateral alignment: Variation not more than ± 0.5 mm measured at centre of one-metre straight edge. (3) Finishing of top surface: + 0.4 mm, − 0.0 mm measured at the end of 10 cm straight edge. (4) Head finishing on sides: ± 0.3 mm over gauge side of the rail head measured at the centre of 10 cm straight edge. Note: In specific cases for joint geometry in case of old rails, dispensations may be permitted by Chief Track Engineer. The method of checking the geometry of welded joints is illustrated in Fig. 3.3 of Annexure - 3/1. 309 Record of joint geometry:- (1) In case of welding by outsourced agency, the details of geometry of each joint shall be jointly signed by the firm’s and Railway’s representative and kept as record. (2) In case of welding by outsourced agency, any joint found not conforming to the above stipulations should be cut and re-welded, free of cost, by the firm. Page 79 of 417 (3) JE/SSE/P.Way shall maintain ‘Thermit Weld Register’ as per proforma given in Annexure - 3/4 & shall make entries in TMS. (4) The welded joints shall be serially numbered in a kilometre. (5) The Repair welds/additional welds done at a later date may be given continuing weld number in that kilometre. For example, the last Thermit weld number in a particular kilometre was 88 and subsequently a Thermit weld has been executed, it shall be numbered 89, irrespective of its location in that kilometre. (6) Each joint shall have a distinctive mark indicating month, year of welding, agency and welder/supervisor identification code number (as appearing on his competency certificate) at non-gauge face side of AT weld on head as detailed in AT welding Manual. 310 Painting of Thermit welds:- (1) Painting of weld collar should be done on all welds to protect them against corrosion immediately after the welding. (2) In service painting (maintenance painting) of Thermit welds should be carried as per following frequency: (a) Once in four years in areas not prone to corrosion. (b) Every year at locations prone to corrosion as defined in Para 612 (1). (c) The frequency may be increased depending on the site conditions. (d) On condition basis at locations which are prone to severe corrosion (areas of severe corrosion to be decided by Chief Track Engineer). (3) The procedure for painting of weld collar for Thermit welded rail joints to protect against normal corrosion and severe corrosion is outlined in AT Welding Manual. 311 Acceptance tests:- (1) Visual inspection: All the welded joints shall be cleaned and examined carefully to detect any visible defect like cracks, blow holes, shrinkage, mismatch, surface finish (smooth surface finish required) etc. Any joint, which shows visible defect, shall be declared defective. The bottom of the joint shall be checked by feeling with fingers as well as inspected with the help of a mirror for presence of ‘fins’ at the parting line of the mould. If fin is observed in any joint, the joint shall be declared defective. (2) Dimensional check: All finished joints shall be checked for dimensional tolerances, which should be within the tolerances as specified in Para 308 above. (3) Ultrasonic flaw detection test: All the welded joints shall be ultrasonically tested as per the provisions of 'Manual for Ultrasonic testing of rails and welds' as early as possible in any case not later than 30 days and record maintained as per Annexure - 3/5. The cumulative number of AT welds found defective in ultrasonic testing and in other criteria shall be limited as per clause 7.3.1 of AT welding Manual. For upgraded AT welding techniques approved in terms of Part E of IRS: T-19, cumulative number of failed AT welds in ultrasonic testing and in other criteria shall be limited as per clause 7.3.1.1 of AT welding Manual. Subsequent USFD testing of AT welds shall be done as per the provisions given in “Manual for Ultrasonic Testing of Rails and welds”. Page 80 of 417 PART – ‘B’ FLASH-BUTT WELDING OF RAILS 312 General: - Flash butt welding uses the principle of softening of interface by electric current and then butting the rail ends under pressure for welding. In Indian Railways, flash butt welding is done by Stationary flash butt welding plant or by mobile flash butt welding plant. Weld Parameters for different rail sections/chemistry have been prescribed by manufacturers and are unique to the particular welding plant. These shall be approved by RDSO in accordance with Para 5.6 of “Manual for flash butt welding of rails”. Should any change in these Parameters be considered necessary, it shall be approved by RDSO. The welding operators are also to be certified by prescribed authority. 313 Rail Welding by Stationary Flash Butt Welding plant:- These are used in rail manufacturing plants and in Flash Butt welding Depots of Indian Railways. It is necessary to get requisite approval from RDSO for the QAP and welding Parameters for the rail section and plant being used. Competency certificate to welding operators shall be granted by Chief Track Engineer. 314 Rail Welding by Mobile flash butt welding plant:- (1) Flash butt welding of new or second hand rails shall be carried out as per detailed procedure given in “Manual for Flash Butt Welding of Rails”, which gives the details of type and suitability of rails to be welded, pre-welding inspection, preparation of rail ends, procedure of execution of welding, finishing of welded joints, acceptance tests etc. (2) Quality Assurance Program for mobile flash butt welding shall be got approved from RDSO as detailed in Annexure - X of Manual for Flash Butt Welding of Rails. After having obtained approval of QAP from RDSO, approval for field welding shall be granted after execution of 30 welds on track (carried out in two shifts), if they satisfy the weld acceptance criteria defined in Para 5.6.4.1, 5.6.4.4, 5.6.4.5, 5.6.4.6, 5.6.4.7, 5.6.4.8 and 5.6.4.10 of Manual for Flash Butt Welding of Rails, (visual, dimension, ultrasonic, hardness, transverse testing, macro and micro examination). In case of Flash butt welding work of Zonal Railway, this shall be carried out in presence of Engineer in-charge and the approval shall be granted by Chief Track Engineer/ Chief Engineer Construction. The welding operators are also to be certified by prescribed authority. 315 Suitability of rails for welding:- For suitability of old/new rails for flash butt welding, “Manual for Flash Butt welding of Rails" should be referred. 316 Acceptance Tests:- (1) Visual Inspection: All welds and rails shall be inspected visually for welding, trimming, clamping or profile finish imperfections, such as tears, cavities, cracks, damage and thermal damage, in particular, in the electrical contact areas. (a) There shall be no sign of tearing, chisel mark or cavity in weld metal due to trimming and upset shall not be raised more than 3 mm and there shall be no depression in accordance with Annexure - IV-A & B of Manual for Flash Butt Welding of Rails, as applicable. (b) Step across the weld: All the welds shall be measured in as welded condition to determine step across the weld. No step shall be permitted except as provided in Para 3.3.3 and 3.3.4 of Manual for Flash Butt Welding of Rails. (2) Dimensional Check: Finished weld samples shall be checked for weld geometry and shall conform to tolerance laid down as per following. Page 81 of 417 Finishing Tolerances for Welds with New Rails Sl. Parameter Value No. At the centre of a 1 m straight edge 1 Vertical misalignment +0.3mm - 0.0 mm 2 Lateral misalignment ± 0.3 mm at the centre of a 1 m straight edge Side of rail head should be finished to 3 Head finishing (in width) ± 0.25 mm on gauge side at the centre of 10 cm straight edge At the centre of 10 cm straight edge 4 Finishing of top table surface + 0.2 mm - 0.0 mm Web zone (under side of head web, + 3.0 mm of the parent contour 5 top of base, both fillet each side) - 0.0 mm Upper sides, under surfaces and edges of rail foot shall be ground smooth. The edges of foot should be rounded and bottom of rail foot ground smooth without any minus 6 tolerances to ensure proper seating on sleepers, unhindered movement of welded panels on end unloading rakes, avoid damage to elastic rail pads and eliminate stress riser. Finishing Tolerances for Welds with Old Rails Sl. Parameter Value No. 1 Vertical misalignment ± 0.5 mm at the centre of a 1 m straight edge 2 Lateral misalignment ±0.5 mm at the centre of a 1 m straight edge ± 0.3 mm on the gauge side at the centre of a 3 Head finishing (on sides) 10 cm straight edge ± 0.2 mm at the centre of a 10 cm straight 4 Head finishing (on top table) edge Web zone (under side of head, 5 web, top of base and both fillets on + 3.0 mm ,-0.0 mm of parent contour each side) Upper sides, under surfaces and edges of rail foot shall be ground smooth. The edges of foot should be rounded and bottom of rail foot ground smooth without any 6 minus tolerances to ensure proper seating on sleepers, unhindered movement of welded panels on end unloading rakes, avoid damage to elastic rail pads and eliminate stress riser. Note: The above tolerances are finished tolerances of welds inclusive of tolerances of rail. (3) Ultrasonic test: All Flash Butt welds shall be subjected to ultrasonic testing for detecting presence of internal defects in the weld. This test shall be done manually with USFD machine by trained personnel as per the procedure laid down in “Manual for Ultrasonic testing of rails and Welds”. Welds having defects shall be rejected. Results shall be maintained as per proforma given in Annexure - 3/5 and entries made in TMS. Defective joint shall be distinctly marked and shall be cut & removed before the panel is laid in the track. (4) Lab tests: Hardness test, Transverse load test, Macro examination and Micro examination shall be conducted as per procedure and frequency prescribed in the “Manual for Flash Butt Welding of Rails”. Note: In case a sample joint does not comply with the requirements of the test, two more sample joints will be made and tested. If both the sample joints meet the requirements of the tests, welding may continue. In case of failure of any of the retest joints, RDSO should be consulted for investigation and fixing revised welding Parameters for the F.B welding plant. Page 82 of 417 Annexure - 3/1 (Para 303, 308) Page 83 of 417 Annexure - 3/1 (Para 303, 308) Page 84 of 417 Annexure - 3/1 (Para 303, 308) Page 85 of 417 Annexure - 3/2 (Para 306) List of Equipment for Alumino – Thermic Welding of Rail Joints by Short Preheating Process per Welding Team Quantity Life in Sl. terms of Description Mass Repair No. No. of welding welding joints A. PRE-HEATING EQUIPMENT A1. Air- Petrol Pre-heating 1. Pressure tanks with pressure gauges complete 2 Nos. 1 No. 500 2. Vaporisers (burner) complete 2 Nos. 1No. 500 3. Nozzle prickers 4 Nos. 2 Nos. 50 4. Nozzle keys 1 No. 1 No. 500 5. Vaporiser stand 2 Nos. 1 No. 1000 6. Goose neck attachment to vaporiser 4 Nos. 2 Nos. 50 A2. Compressed Air-Petrol Pre-heating Periodical maintenance 1. Suitable compressor system with pressure gauges 2 Nos. 1 No. half yearly 500 2. Torch (Burner) complete 2 Nos. 1 No. 300 3. Torch (burner) keys 1 No. 1 No. 500 4. Torch (burner) stand 2 Nos. 1 No. 1000 5 Goose neck attachment to vaporiser 4 Nos. 2 Nos. 50 A3. Oxy- LPG Pre-heating 1. Oxy- LPG torch (burner) 2 Nos. 1 No. 150-200 2. Oxygen cylinder with pressure gauge 2 Nos. 1 No. 100 3. LPG cylinder with pressure gauge 2 Nos. 1 No. 100 4. Torch (burner) stand 2 Nos. 1 No. 500 5. Connecting Hose pipe 4 Nos. 2 Nos. 75-100 B. OTHER EQUIPMENT 1. Crucible complete- Crucible shell & Crucible lining 2 Nos. 1 No. 500 & 50 2. Crucible caps 2 Nos. 1 No. 50 3. Crucible forks 2 Nos. 1 No. 500 4. Crucible stands 2 Nos. 1 No. 1000 5. Crucible rings 2 Nos. 1 No. 500 6. Mould pressure (clamp) 2 sets 1set 1000 7. Cleaning rod round 2 Nos. 1 No. 500 8. Tapping rod 1 No. 1 No. 1000 9 Straight edge 1 m long 2 Nos. 1 No. -- 10. Straight edge 10 cm. 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. 100 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 100 17. Stop watch 1 No. 1 No. -- Pyrometer/Thermal chalk for measurement of rail 18. 1 No. 1 No. -- temperature 19. Wooden wedges for rail alignment 24 Nos. 12 Nos. -- First aid box filled with medicines bandages, cotton 20. 1 No. 1 No. -- etc. 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. -- Page 86 of 417 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 50mm 1 No. 1 No. -- ix) Slag container (bowl) 2 Nos. 1 No. 500 x) Asbestos gloves 4 Pairs. 2 Pairs. 500 xi) Hose clips 4 Nos. 4 Nos. -- xii) Pliers 1 No. 1 No. -- xiii) Rail file 350 × 40 × 6 mm (For Emergency use only) 4 Nos. 2 Nos. -- 23. Weld trimmer(Cutter) 1 No. 1 No. 100 Insulation hood for control cooling(for 110 UTS rail 24. 1 No. 1 No. -- welding) 25. Rail profile guided grinding trolley (Grinding wheel). 1 No. 1 No. 50 26. To ensure quality, protective clothing, shoes gear & Leather gloves. Note: 1. For crucible lining, Magnesite powder and sodium silicate should always be available. 2. Expected life of the equipment has been given as guide lines for initiating action for procurement by zonal railways depending upon their requirement. The expected life of various equipment may vary depending upon site conditions and its use. 3. The items for which, expected life has not been given, they should be replaced on condition basis. 4. Tools and equipment viz. Pre-heating arrangement, Crucible and Mould used for A.T welding shall be as per the Approved A.T welding technique of a particular firm by RDSO. Also, critical process timing viz. Preheating time, tapping time, mould waiting time, time for passage of First train on AT weld etc. shall be followed as per the approved AT welding technique. Page 87 of 417 Annexure - 3/3 (Para 306) Composition of Thermit Welding Team (Compressor Tank- Wise) Sl. No. Designation Numbers 1 Welder Grade I/Grade II 1 2 Welder Grade III/Skilled Artisan 2 3 Helper Khalasi/Khalasi 5 4 Trackman As per work load Note: The composition of welding team has been framed taking into account that trimming and grinding operation would be done by weld trimmer and rail profile grinder. Annexure - 3/4 (Para 309) Proforma for Thermit Weld Register Sl. Date of Location details Rail Bolt hole distance No welding Block Stn. Cess / Situ Km TP U/D L / R Section UTS (mm) 1 2 3 4 5 Portion details Welding details Agency Batch Portion Date of Agency Process Supervisor Welder code code No. No. Manufacturing code code 6 7 Weld Block Average rail If rail tensor is Date of Dimensional tolerances USFD testing No. time temperature used for finish on finished joint after welding From To during creation of gap grinding welding for welding, On 1m On 10cm Date Result whether (Pass/ equalization of Lateral Vertical Top Side Failed) forces done (Yes/No) 8 9 10 11 12 13 14 In service failure Test joint Replacement Weld Reference Sign. of Date of sending details date Weld1 Weld 2 JE/SSE test joint with removed S. No. Date S. No. Date P.Way reference Welding Date Type 15 16 17 18 19 Test joint results Chainage Reference Date of Hardness (BHN) Transverse load Porosity Date of of weld point for receipt of % marking ‘X’ Chainage results Rail Weld HAZ Load Deflection for with (mm) extended reference guarantee Remarks 20 21 22 Page 88 of 417 Annexure - 3/5 (Para 311, 316) Ultrasonic Testing of Welded Joints 1. Date/Month/year 2. Details of Weld (Joint No, Km / Chainage / LR / RR / UP / DN / Line No etc.) 3. Name of Operator 4. USFD testing Machine used (make, model, serial number) 5. Rail section & chemistry 6. Day / Night shift 7. Result of testing 8. If defective, details of flaw Defective zone Head/Web/Foot 9. Probe wise USFD peak pattern. 10. Remarks 11. Signature Summary (at the end of the month) No. of joints welded during the month (Rail section-wise) No. of joints tested (Rail section-wise) No. of joints found defective (Rail section-wise) Page 89 of 417 PART – ‘C’ SHORT WELDED RAILS 317 General – SWR shall be laid generally on stable and efficiently drained formation. 100 mm extra width of shoulder ballast over and above the standard ballast section on tangent track shall be provided on outside of curves upto 875 metre radius. In case of sharper curves, the extra width shall be 150 mm. In case of 60 kg/m Rails, LWR profile shall be adopted. 318 Condition of Laying – (1) Alignment – SWR on PSC sleepers shall not be laid on curves sharper than 440 metre radius. Existing SWR laid on sharper curves may, however, be allowed to continue if there is no difficulty experienced in maintaining these lengths. Chief Track Engineer’s approval should be taken in such cases. (2) Junction with insulated joints and points and crossings – SWR butting against insulated joints, heel of crossing and stock rail joints, shall be anchored for a length of 39 metre on the approach effectively to arrest creep in either direction. (3) Regarding laying of SWR in Level Crossings and Bridges refer Para 918 and Para 226. 319 Laying of Short Welded Rails – The gaps to be provided for SWR at the time of laying shall be in accordance with Table 1 depending on the installation temperature (ti) and the Zone in which the rails are laid. (Back to Para 226 (3) (c), 320(5), 715) TABLE 1 Initial Laying Gaps for SWR for Various Installation Temperatures For Zone I and II Rail temperature at the time of Initial laying gaps (in mm) installation (ti) For 39 m panels For 26 m rolled rails tm- 17.5°C to tm- 12.6°C 12 10 tm- 12.5°C to tm- 7.6°C 10 9 tm- 7.5°C to tm- 2.6°C 8 7 tm- 2.5°C to tm+ 2.5°C 6 6 tm+ 2.6°C to tm+ 7.5°C 4 5 tm+ 7.6°C to tm+ 12.5°C 2 3 For Zone III and IV tm- 22.5°C to tm- 17.6°C 12 10 tm- 17.5°C to tm- 12.6°C 10 9 tm- 12.5°C to tm- 7.6°C 8 7 tm- 7.5°C to tm- 2.5°C 6 6 tm- 2.4°C to tm+ 2.5°C 4 5 tm+ 2.6°C to tm+ 7.5°C 2 3 Note: If the laying has to be done outside the temperature range given in table above, or whichever joint gaps could not be provided as per the table, readjustment of gap shall be carried out within two days of laying before the track consolidates. Along with the gap adjustment, any re- spacing of sleepers, if required, must be carried out. 320 Gap Survey and Adjustment of Gap – (Back to Para 226 (3), 620) (1) General – Gap survey and rectification of gaps is to be carried out, in stretches where track develops excessive creep, jammed joints, sun kinks, misalignment, wide gaps, battered and hogged joints, fractures at joints and bending of bolts etc. In SWR, the gap survey and adjustment should normally be done before the end of February once a year (i.e. before onset of summer). Page 90 of 417 (2) Gap survey – (Back to Para 322(3)(c)) (a) The gap survey shall be conducted on a clear and sunny day in the cool hours of the day in rising rail temperature trend. (b) The length over which gap survey is to be done should, wherever possible, be divided into suitable sub-sections, each bounded by fixed points such as level crossings, points and crossings etc. The survey should be completed during as short a time as possible, by employing adequate number of parties so that the rail temperature is not likely to vary appreciably. (c) The joint gaps shall be measured by taper gauge in mm (shown below) and the readings entered in the proforma as shown in Annexure - 3/6. Fig. 3.4 (3) Recommended range of value of gaps – The recommended range of value of gaps (in mm) during service for various ranges of rail temperature is indicated in the Table- 2 given below: Table – 2 For Zone I and II Rail Temperature During Gap Permissible Values of gaps (in mm) Survey For 39 m panels For 26 m rolled rails tm - 17.5°C to tm - 12.6°C 11-14 8-13 tm - 12.5°C to tm - 7.6°C 9-13 6-11 tm - 7.5°C to tm - 2.5°C 7-11 5-10 tm - 2.4°C to tm + 2.5°C 5-9 3-8 tm + 2.6°C to tm + 7.5°C 3-7 2-7 tm + 7.6°C to tm + 12.5°C 1-5 1-5 For Zone III and IV tm - 12.5°C to tm - 7.6°C 11-14 8-13 tm - 7.5°C to tm - 2.6°C 9-13 6-11 tm - 2.5°C to tm + 2.5°C 7-11 5-10 tm + 2.6°C to tm + 7.5°C 5-9 3-8 tm + 7.6°C to tm + 12.5°C 3-7 2-7 tm + 12.6°C to tm + 17.5°C 1-5 1-5 (4) Calculations for adjustment – The average of the measured gaps is worked out as shown in the proforma for gap survey (Annexure - 3/6). A comparison of the results of the gap measurements recorded and the permissible values of gap (concerned range for gap) given above will lead to one of the following cases: Case 1 – Average gap is within the recommended range, but some of the individual gaps fall outside the range. Case 2 – Average gap falls outside the recommended range. Case 3 – Average gap as well individual gaps fall within the range. (5) Action to be taken – The action to be taken is as follows – Case 1 – Rectification work should be restricted to correcting the individual gaps, Page 91 of 417 which falls outside the recommended range. Under no circumstances, adjustment shall be done by cutting a rail or introducing a longer rail. Case 2 – The joint gaps shall be systematically adjusted from one end to the other end of the sub-section. The rails shall be unfastened over convenient length, the gaps adjusted to the initial laying gaps as per Para 319 and rails fastened. In this case, introduction of a longer or shorter rail might be required. Case 3 – No action is to be taken (6) As far as possible, the day chosen for rectification should be a day on which the rail temperature is not likely to vary much during rectification period. Page 92 of 417 Annexure - 3/6 (Para 320) Page 93 of 417 321 Counteraction and Adjustment of Creep – (1) General – Rails have a tendency to move gradually in the direction of the dominant traffic. It is believed to be caused by the ‘ironing out’ of yielding track by the moving load, augmented by braking loads, and by the impact of the wheels on the running-on ends of the rails, particularly at times when they are in a state of expansion or contraction. Among the troubles caused by ‘creep’ are – (a) Sleepers getting out of square. (b) Distortion of gauge. (c) Loosening of joints. (d) Shearing and breaking of bolts and fishplates. (e) Buckling in extreme cases. (2) Causes for creep in track – The following are some of the avoidable causes to which creep is attributed: (a) Inadequate toe loads of the fastening and rails not secured properly to sleeper. (b) Inadequate ballast resistance to the movement of sleepers due to poor or insufficient ballast or other causes. (c) Inefficient or badly maintained rail joints. (d) Improper expansion gaps. (e) Damaged sleepers, uneven spacing of sleepers. (f) Lack of proper drainage. (g) Yielding formation. (h) Loose/uneven packing. (3) Precautions to reduce creep – (Back to Para 322 (3) (d)) The PSC sleepers with effective elastic fastenings are considered as creep resistant and therefore no other creep anchors are required. In case, excessive creep is observed on PSC sleeper road, the condition of elastic fastenings, sleepers and adequacy of ballast resistance should be examined. Action for replacement/ renewal of fittings, sleepers and providing adequate ballast resistance etc. should be taken as necessary. (4) Creep Record – Creep records should be maintained in the proforma given in Annexure - 3/7. Entries should be complete as regards kilometerage, section and length of rail, sleeper density. Periodical readings of creep should be recorded in TMS in the prescribed pro forma. Frequency of recording of creep should be specified by the Divisional Engineer taking into consideration the rate of creep. The Assistant Engineer should test check the record frequently, particularly sections which are prone to creep. (5) Creep indicator posts – (Back to Para 715) Creep indicator posts, square to the track should be erected on either side of the track on the cess at suitable intervals of not more than one km apart. These may be unserviceable rail posts with chisel mark square to the joints. The top of the post should be about 25 mm above the rail level and the amount of creep one way or the other measured with a fishing cord stretched over the chisel marks. (6) Permissible amount of creep – Creep in excess of 150 mm shall not be permitted. Page 94 of 417 (7) Adjustment of creep – Adjustments of creep should be carried out in the following manner: (a) It is a good practice to adjust creep before the commencement of summer. It is desirable to pull back the rails during the cool hours of the day. (b) Careful measurement of expansion gaps, as existing, should be done and appropriate length, which can be dealt with in one operation should be chosen. The total amount of gap in the length should be equal to the standard expansion gap required for the temperature at the time, multiplied by the number of joints in the length. (c) Work should start at the running-on end of the length, commonly just beyond the points and crossings or level crossings. The work of creep adjustments should be carried out under the protection of engineering signals by the JE/SSE/P.Way as envisaged in Para 806 (1) or under traffic block, on busy routes. (d) When the value of total gap existing is more than the standard expansion gap required for the temperature at the time of adjustment multiplied by the number of joints, it is necessary to provide closure rails. When closure rails are put in, a speed restriction of 30 Kmph should be imposed, which should be removed, when closure rail is changed. Page 95 of 417 Annexure - 3/7 (Para 321) Page 96 of 417 322 Buckling of Track (other than LWR) – (1) General – Buckling of track occurs when high compressive forces are created in the rails associated with inadequacy of lateral resistance in the track at the place. A special watch should be kept on the junction of two stretches of track, one liable to creep and the other held against creep. As one side of such a junction point is held firmly against creep, the movement of rails due to creep from the other side is resisted resulting in heavy compressive force being exerted, which will tend to buckle the track. Jammed rail joints at such junctions are therefore an indication of the track being subjected to undue strain. (2) Conditions, which induce Buckling – (a) The following conditions create high compressive forces in the rail: (i) Inadequate expansion gaps, (ii) Failure to counteract creep in time. (iii) Non-lubrication of rail joints, (b) The lateral resistance gets impaired due to inadequacy of ballast and due to carrying out of operations such as deep screening, lifting of track and slewing of track, without adequate precautions. (3) Precautions against Buckling – It should be seen that – (a) Operations, which impair the lateral resistance of track, are not carried out when rail temperatures are high. (b) The greasing of fishplates is done before the hot weather sets in. (c) The joint gap survey is done in the case of SWR and adjusted before the onset of hot weather as per Para 320(2). Similarly, in case of free rail track, joint gaps should be adjusted wherever necessary. (d) Adequate precautions are taken to reduce creep as detailed in Para 321(3). (e) Over tightening of fish bolts is avoided, but they should be reasonably tight. (f) Particular attention is also paid to stretches of track, one liable to creep and the other held against creep (refer Para above). Jammed joints at such junctions call for remedial measures. (g) Adequate shoulder ballast should be provided at all places. (4) Action on buckling of track – If a buckling does occur or appears imminent, the track should be protected immediately with hand signal flags and detonators as per the protection rules laid down. The buckled rails shall preferably be cut adequately apart not less than 6.5 metres. The track shall then be slewed to the correct alignment and cut rails of the required length shall be inserted to close the gaps making due provision for welding of joints on both rails. The cut rails shall then be connected by use of special fishplates and screw clamps and the line opened to traffic with speed restriction. It may not be possible to do any more until the temperature drops when the joints must be adjusted. Particular care must be taken to see that the factors, which contributed to the buckling i.e. jammed joints, seized fishplates or shortage of ballast, receive appropriate attention without delay. 323 Conversion of SWR into LWR – Wherever conditions permit, conversion of SWR into LWR should be considered. The following additional precautions should be observed when converting SWR into LWR – (1) The anticipated residual life of rails shall be at least10 years. Page 97 of 417 (2) The rails shall be tested ultrasonically and all defective rails replaced before conversion into LWR. (3) Rail ends which are hogged or battered or have a history of cracks in bolthole region, shall be cropped before conversion into LWR. 324 Maintenance of Short Welded Rails – (Back to Para 609) Regular maintenance operation – (1) Regular track maintenance operations like packing, lifting, aligning, local adjustment of curves, screening of ballast other than deep screening and scattered renewal of sleepers may be carried out without restriction when the rail temperature is below tm + 25°C in the case of zone I & II and tm + 20°C in the zone III and IV. However, on curves of less than 875 metre radius in Broad Gauge or yielding formation, the above temperature limit shall be restricted to tm + 15°C in the case of Zone I and II and t m +10°C in the case of Zone III and IV. (2) If the maintenance operations have to be undertaken at temperature higher than that mentioned above in Sub-Para (1) above, not more than 30 sleeper spaces in one continuous stretch shall be opened, leaving at least 30 fully boxed sleeper spaces between adjacent lengths which are opened out. Before the end of the day’s work, it shall be ensured that the ballast is boxed up. (3) As an additional precaution, during summer months, to be specified by the Chief Engineer, for attention to run down track, even if temperature is less than the temperature specified in Sub-Para (1) above, not more than 30 sleeper spaces in one continuous stretch shall be opened, leaving at least 30 fully boxed sleeper spaces between adjacent lengths which are opened out. Further, if joint gaps are not available at the time of opening of the track even when rail temperature are less than those specified in clause Sub-Para (1) above not more than 30 sleepers in one continuous stretch should be opened leaving at least 30 boxed sleeper spaces between adjacent length which are opened up. (4) Major lifting, major alignment of track, deep screening and renewal of sleepers in continuous length- Each of these operations shall be done under suitable precautions and normally when the rail temperature is below tm + 15°C in the case of Zone I and II, and tm + 10°C in the case of Zone III and IV. If it becomes necessary to undertake such works at rail temperature exceeding the above values, adequate speed restrictions shall be imposed. (5) Adequate number of joggled fishplates with special clamps shall be provided to the gangs for use in emergencies. (6) In the case of any fracture in the weld or in the rail, the portion of rail with fracture is cut, and removed for a length of not less than 5.5m to carry out the re-welding duly introducing a rail piece of equivalent length, also ensuring that no weld lies closer than 4 m from the fish- plated joint. Page 98 of 417 PART – ‘D’ LONG WELDED RAILS 325 Long Welded Rail (LWR) is a welded rail, the central part of which does not undergo any longitudinal movement due to temperature variations. A length of welded rail greater than 250m on Broad Gauge will normally function as LWR. 326 Permitted Locations for LWR/CWR: (1) General Considerations for laying LWR/CWR: (a) All new constructions/doublings/gauge conversions, permanent diversion shall be opened with LWR/CWR. (b) All CTR/TSR/TRR (Primary) shall provide for LWR/CWR, wherever permissible. (c) The existing rails on permitted locations may also be converted into LWR/CWR, provided they meet the requirements for Welding of Rail Joints by Alumino Thermic (SKV Process)/Flash Butt Process, as the case may be. (d) In yard lines, rail joints may be welded to form LWR if the condition of all the components of track is generally sound and without any deficiency, subject to such relaxation as may be approved by Chief Track Engineer, in each specific case. (2) Alignment: (a) LWR/CWR shall not be laid on curves sharper than 440 m radius. However, in temperature Zone-I, LWR/CWR may be laid on curves up to 350 m radius (5 o Curve) with following additional precautions: (i) Minimum track structure should be 52 kg/m rails on PSC sleeper 1540 sleeper density with 300 mm clean ballast cushion. (ii) Shoulder ballast for curves shaper than 440m radius should be increased to 600 mm on outside of curve and should be provided for 100m beyond the tangent point. (iii) Reference marks should be provided at every 50 m interval to record creep. (iv) Each curve of length greater than 250 m should preferably be provided with SEJ on either side. SEJ should be located in straight track at 100 m away from the tangent point. (b) LWR/CWR may be continued through reverse curves. Shoulder ballast of 600mm over a length of 100 m on both side of the common point of a reverse curve would be provided. In case there is a straight track between the reverse curves, this 100m would be considered from the center of the straight track. No such measure would be required if the length of straight track between the reverse curves is more than 50 m. (3) Gradient: The steepest permitted grade for LWR/CWR shall be 1 in 100. (4) Approvals & deviations: Installation of LWR/CWR, or change in its constitution at a later stage shall have the approval of the Chief Track Engineer in each case, on a detailed plan prepared in accordance with Para 336 (1) (c). However, for any deviation from this provision, approval of Principal Chief Engineer shall be obtained. (5) Track structure for LWR/CWR: (a) LWR/CWR shall be laid on stable formation having stipulated formation width and ballast cushion (below the bottom of the sleeper); and with approved PSC sleepers and its matching fastening system. Page 99 of 417 (b) The minimum rail section to be used shall be of 52 kg/m. (c) In a LWR/CWR, two different rail sections are not permitted. (d) In case of LWRs laid on concrete sleepers having different rail section on either side of SEJs, combination SEJ to RDSO Drg. No T-6782 (52kg / 60 Kg) shall be provided. Alternatively, two 3 rail panels (39 m), one of each rail section shall be provided with combination fish plated joint, between the two panels. (e) New rails used in LWR/CWR shall, as far as possible, be without fish-bolt holes. Joining of rail ends temporarily during installation of LWR/CWR shall be done by 1 m long fishplates with special screw clamps/joggled fish-plates having slotted grooves & bolted clamps as in Fig. 3.9, 3.10, 3.11, 3.12, 3.13 with speed restrictions indicated in Annexure - 3/8. (f) Bolt holes, if any, shall be chamfered. (6) Continuity of track structure: Wherever LWR/CWR is followed by fish-plated track/SWR, the same track structure as that of LWR/CWR shall be continued for at least three rail lengths (39 m) beyond SEJ. (7) Level Crossings: Level crossings situated in LWR/CWR territory shall not fall within the breathing lengths. (8) Points and Crossings: (a) In case, LWR is terminated near Points & Crossings, one three rail panel (39 m) shall be provided between stock rail joint (SRJ) and SEJ as well as between the crossing and SEJ. This length shall be provided with elastic fastenings with adequate toe load to arrest creep. (b) In case, LWR/CWR is taken through Points & Crossings, the provisions contained in RDSO report no. CT-48 shall be followed. 327 Provision of Glued Joints: All insulations for track circuiting in LWR/CWR shall be done by providing glued joints of G3(L) type. 328 Location of SEJ: The exact location of SEJ shall be fixed taking into account the location of various obligatory points such as level crossings, bridges, points and crossings, gradients, curves and insulated joints. The various designs of SEJs in use on Indian Railways are as per Para 225 (1) The conventional SEJ (RT-4160 and RT-4165) with straight tongue and stock shall not be located on curves sharper than 0.5° (3500 m radius). (2) The improved SEJs (RT-6902, RT-6914, RT-6922, RT-6930) may be located on curves up to 2°. SEJ beyond 2° and up to 4° shall be laid with approval of PCE in consultation with RDSO (3) The SEJ shall not be located on transition of curves. 329 Bridges with Ballasted Deck (without bearing): (Back to Para 226 (4)) LWR/CWR can be continued over bridges with ballasted deck without bearings like slabs, box culverts and arches. Page 100 of 417 330 Bridges with Ballasted Deck (with bearing): (Back to Para 226 (4)) Detailed calculations shall be done by the Design office of Chief Bridge Engineer / CAO(C) to ascertain the effect of LWR of such bridges and its effect on the Sub-structure of the bridge as per Para 2.8.1.2 of “Bridge Rules”. The LWR/CWR may be permitted on a case-to-case basis based on the above calculations. In case detailed calculations are not done, LWR may be permitted as per Para 331 below for bridges with un-ballasted deck. 331 Bridges with Un-Ballasted Deck: (Back to Para 226 (4), 630) LWR/CWR shall be continued over such bridges with overall length as specified in sub-Para (1) to (3) below: (1) Bridges provided with rail-free fastenings (single span not exceeding 30.5 metre and having sliding bearings on both ends) Overall length of the bridge should not exceed the maximum as provided in Table-1 with following stipulations: (a) Rail-free fastenings shall be provided throughout the length of the bridge between abutments. (b) SEJ of the LWR should be located such that bridge does not fall in the breathing length of the LWR. The approach track upto 50 m on both sides shall be well anchored by providing PRC sleepers with elastic rail clips with adequate toe load so as to arrest creep. (c) The ballast section of approach track upto 50 metre shall be heaped upto the foot of the rail on the shoulders and kept in well-compacted and consolidated condition during the months of extreme summer and winter. (2) Bridges provided with rail-free fastenings and partly box-anchored (with single span not exceeding 30.5 metre and having sliding bearings at both ends) Overall length of the bridge should not exceed the maximum as provided in Table-1 with following stipulations: (a) Central sleepers shall be anchored with anchoring arrangement (two each in end spans and one each in the middle spans) as per RDSO Drg. No. M-10920(1) (Fig 3.25) and the remaining sleepers shall be provided with rail-free fastenings. (b) The track structure in the approaches shall be laid and maintained to the standards as stated in (1) (b) & (c) above. (c) The girders shall be centralized with reference to the location strips on the bearing, before laying LWR/CWR. (d) The sliding bearings shall be inspected during the months of March and October each year and cleared of all foreign Materials. Lubrication of the bearings shall be done once in two years. TABLE - 1 Maximum Overall Length of Bridges Permitted on LWR/CWR (in m) Para – 331(1) & 331(2) Tempe Rail-free fastenings on bridges Rail-free fastenings on bridges and Rail rature as per Para 331(1) with PRC partly box-anchored as per Para 331(2) section zone sleepers on approaches and with PRC sleeper on approaches 60kg/m 30 77 I 52kg/m 45 90 60kg/m 11 42 II 52kg/m 27 58 60kg/m 11 23 III 52kg/m 27 43 60kg/m 11 23 IV 52kg/m 27 43 Page 101 of 417 (3) LWR/CWR may also be continued over a bridge with the provision of SEJ at the far end approach of the bridge using rail-free fastenings over the girder bridge (Fig. 3.5(b)). The length of the bridge in this case, however, will be restricted by the capacity of the SEJ to absorb expansion, contraction and creep, if any, of the rails. The length of the bridges with the above arrangement that can be permitted in various rail temperature zones for LWR/CWR with SEJs having maximum movement of 120 mm and 190 mm are as under: Rail temp Max. movement of Overall length of Initial gap to be provided at td zone SEJ used (mm) bridge (Para331(3) With PRC approach sleepers IV 55 m 7.0 cm III 70 m 7.0 cm 190 II 110 m 6.5 cm I 160 m 6.5 cm II 20 m 4.0 cm 120 I 50 m 4.0 cm Note: (i) SEJ is to be installed 15 metre away from the abutments. (ii) Improved SEJ with 2 gaps of 65 mm (max.) each (Drawing no. RDSO/T-6922 and RDSO/T-6930) may also be used for laying at far end approach of bridges in lieu of IRS design SEJ with 120 mm max gap. (4) Welded rails may be provided from pier to pier with rail-free fastenings and with SEJ on each pier. The rail shall be box-anchored on four sleepers at the fixed end of the girder if the girder is supported on rollers on one side and rockers on other side. In case of girder supported on sliding bearings on both sides, the central portion of the welded rails over each span shall be box-anchored on four sleepers. See Fig. 3.5 (a). (5) Welded rails may be provided over a single span bridge with rail free fastenings and SEJs with 190 mm gap at 30 m away from both abutments. The rail shall be box anchored on four sleepers at the fixed end of the bridge if bridge is supported on rollers on one side and rockers on other side. In case of bridge supported on sliding bearings on both sides, the central portion of the welded rails shall be box anchored on four sleepers. The approach track upto 50 m on both sides shall be well anchored by PRC sleepers with elastic rail clips with minimum toe load as specified. The installation temperature of such welded panels shall be equal to t m. The length of single span bridge permitted temperature zone-wise shall be as under: Temperature zone Maximum length of single span girder bridge IV 75 m III 87 m II 110 m I 146 m (6) Bridges on which LWR/CWR is not permitted/provided as per above shall be isolated by a minimum length of 30 metre of well anchored PSC sleeper track on either side. (7) In case of LWR is continued over bridges as per Sub Para (3) above, the measurement of gaps of stock rail / tongue rail tip of SEJ provided at bridge approach from the reference post shall be compared with the theoretical gaps as prescribed in Annexure - 3/9A. (8) In case welded rails are provided as per Sub Para (4) or (5) above, these shall not be entered in TMS as LWR and accordingly, measurement of gaps of at such SEJs of welded panels is not warranted. Page 102 of 417 Fig 3.5 Welded Rail on Bridge Back to Para 331(3) Page 103 of 417 332 Measurement of Rail Temperature: (1) Thermometer: The following are the types of approved thermometers for measuring rail temperature: (a) Embedded type: This is an ordinary thermometer inserted in a cavity formed in a piece of railhead, the cavity filled with mercury and sealed. The rail piece is exposed to the same conditions as the rail inside the track. This type of thermometer takes 25 to 30 minutes for attaining temperature of the rail. (b) Dial type: This is a bi-metallic type thermometer, which is provided with magnet for attaching it to the rail. The thermometer is attached on the shady side of the web. A steady recording of the rail temperature is reached within 8 minutes. (c) Continuous recording type: It consists of a graduated chart mounted on a disc, which gets rotated by a winding mechanism at a constant speed to complete one revolution in 24 hours or 7 days as applicable giving a continuous record of rail temperature. The sensing element is attached to the web of the rail and connected to the recording pen, through a capillary tube, which is filled with mercury. (d) Any other type of thermometer approved by RDSO/Chief Engineer. (2) Where a number of thermometers are used to measure the rail temperature at one place, as in case of laying of LWR, de-stressing etc. or during routine tools inspection at office of SSE/ P.Way, any of the thermometer showing erratic readings, appreciably different from the other adjoining thermometers, shall be considered as defective. 333 Temperature Measurements: (1) The existing SSE/P.Way (In-charge) shall record rail temperature using preferably a well-calibrated continuous recording type thermometer and data to be updated in TMS. (2) The maximum and minimum rail temperature for a continuous period of at least 5 years shall be ascertained and the mean rail temperature (tm) for the region arrived at. (3) These temperature records shall be analysed to assess the probable availability of time periods during different seasons of the year for track maintenance, de-stressing operations and requirements of hot/cold weather patrolling etc. (4) The rail thermometer shall also be available with each Gang and sectional JE/SSE/P.Way to enable the Gangs to work within the prescribed temperature ranges. 334 Temperature Records: (1) The maximum daily variation of rail temperature and the mean rail temperature (t m) for the section shall be ascertained from the temperature records available with the SSE/P.Way(In-charge) or as built up as per Para 333. (2) If rail temperature records of preceding five years are not available, the mean and range of rail temperatures shown in the ‘Map of India showing Rail Temperature Zones’ (Fig. 3.6 below), shall be adopted. Page 104 of 417 Fig. 3.6 (Back to Para 334 above) Page 105 of 417 335 Thermal Forces in LWR/CWR: (Back to Para 338) Temperature changes cause movement of the ends of LWR/CWR in the breathing lengths but the central portion of LWR/CWR does not expand/contract. This results in building up of thermal forces in the central portion. The thermal force (P) calculated by P= EAαt Where, P= Thermal force in the rail (kg) E= Modulus of elasticity of rail steel, (2.15 x 106 kg/cm2) A= Area of cross section of the rail (cm2) Rail Section Cross-sectional Area (cm2) 60 kg/m 76.86 52 kg/m 66.15 α= Coefficient of linear expansion of steel, (1.152 x 10-5/0C) t= Variation of rail temperature from td /to (°C) The Range of td or t0 shall be within the limits of rail temperature shown below: Temperature Zone Rail Section Range I, II, III All Sections tm to tm+ 50 C IV 52 kg/m & heavier tm+50 C to tm+100 C Usual breathing lengths on PSC sleepers for different temperature zones and sleeper density is shown in Annexure - 3/16. The level of maximum thermal stresses in LWR depends upon variation of Rail temperature from the stress free temperature. The thermal force diagram in LWR is shown as under (Fig 3.7): Fig. 3.7: Force Diagram in LWR / CWR Page 106 of 417 336 Laying of LWR / CWR (1) Survey: (a) A foot by foot survey of the sections where LWR/CWR is proposed to be laid shall be carried out in regard to the Locations over which LWR/CWR cannot be carried through on account of constraints such as bridges having substructure/superstructure in a distressed condition, curves, gradients, points and crossings, unstable formation etc. Such stretches of track shall be isolated from the remaining portion of LWR/CWR by provision of SEJs at either end. (b) Locations where following preliminary works are required to be carried out shall be identified for completion before laying of LWR/CWR: (i) Replacement of insulated joints by glued joints (ii) Realignment of curves (iii) Lifting or lowering of track to eliminate sags and humps (iv) Introduction and improvement of vertical curves (v) Stabilisation of troublesome formation (vi) Rehabilitation of weak bridges involving removal or lifting of rails or introduction of temporary arrangements. (vii) Deep screening of ballast along with lifting or lowering of track, if required. (c) A detailed plan shall be made showing the exact locations of SEJs and of various other features mentioned in Sub-Para (a) and (b) above. A sample of the detailed plan may be seen at Fig. 3.8. The plans may be prepared to a horizontal scale of 1:5000. (Back to Para 326(4)) (2) Materials Required: Following Materials are required for laying one LWR: (a) Four numbers of 4 metre or longer rail pieces of the same rail section as LWR (b) Two sets of SEJs with sleepers and fastenings (c) Adequate numbers of 1 metre long fishplates with special screw clamps/ joggled fishplates with slotted grooves & bolted clamps as in Fig. 3.9, 3.10, 3.11 & 3.12. Note: Slotted fishplates as in Fig. 3.13 with fish-bolts may be used in exceptional cases. (d) Rail closures of suitable sizes (e) 1 metre and 10 cm straight edges (f) Callipers and feeler gauges (2 mm to 0.1 mm) (g) Rail cutting equipment (h) De-stressing equipment i.e. rollers, mechanical/hydraulic rail tensor, mallets and side rollers for curves, Fig. 3.14, & 3.15. (i) Alumino-thermic welding equipment and consumable Materials (j) Equipment for protection of track. Page 107 of 417 Fig 3.8 Proposal for laying LWR / CWR Back to Para 336 (1) (c) Page 108 of 417 Fig. 3.9 - 1 m LONG SLOTTED FISH PLATE FOR CLAMPED JOINTS /SUPPORT ARM Back to Para 326(5) (e), 336, 337, 349 Page 109 of 417 Fig. 3.10 SCREW CLAMP FOR FIXING 1 m LONG FISH PLATE Back to Para 326(5) (e), 336, 337, 349 Page 110 of 417 Fig. 3.11 M.S. CLAMP FOR FIXING 1 m LONG FISH PLATE Back to Para 326(5) (e), 336, 337, 349 Page 111 of 417 Fig. 3.12 DETAILS OF JOGGLED FISH PLATE WITH CLAMP / SUPPORT ARM Back to Para 326(5) (e), 336, 337, 349 Page 112 of 417 Fig. 3.13 SLOTTED FISH PLATE Back to Para 326(5) (e), 336 Page 113 of 417 Fig. 3.14 ROLLER Back to Para 336, 340 Page 114 of 417 Fig. 3.15 SIDE ROLLER / SUPPORT ARM Back to Para 336 Page 115 of 417 337 Welding of Rails to form LWR: (1) Rails shall normally be welded into sufficiently long panels of 10 to 20 rail lengths or more by flash butt welding, either in the welding depot or on cess or in-situ. The joints in between only shall be welded by Alumino-Thermic welding (SKV process)/flash butt welding (using mobile FBW plant). (2) Before laying long welded panels and/or before welding of rails, two complete sets of SEJs, one at either end of the proposed LWR/CWR shall be inserted at pre- determined locations with gaps in mean position as per Para 338 below. Closure rails of suitable length (refer Para 340 / 341) shall be provided at LWR side/sides of SEJs to facilitate adjustment of gaps during de-stressing operation. (3) Laying of welded panels and/or welding of joints at site can be done at any time of the year. However, after welding into sufficiently long panels of about 1 km or longer, de- stressing as per Para 340 / 341 shall be undertaken as soon as possible. (4) Under unavoidable circumstances where de-stressing could not be done soon after and not likely to be done within a reasonable period, a strict vigil shall be maintained on the prevailing rail temperatures, and if the rail temperature rises more than 20 °C above the rail temperature at which welding of rails/laying of welded panels was done temporary de-stressing shall be undertaken at a rail temperature of 10 °C below the maximum rail temperature likely to be attained until final de-stressing. If the rail temperature comes down appreciably, cold weather patrolling as per Para 1005(3) should be introduced. Final de-stressing shall be done after consolidation of track has been achieved. (5) Consolidation of track can be achieved by the following:- (Back to Para 117(4)(a)) (a) For Existing track where maintenance activity involving disturbance to ballast compaction (tamping operation) has been undertaken. (i) For the track structure consisting of concrete sleepers, passage of at least 50,000 gross tonnes of traffic or a period of two days whichever is later. (or) (ii) At least one round of stabilisation by Dynamic Track Stabiliser (DTS). (b) For newly laid track (CTR/TSR) or freshly deep screened Track Three rounds of packing, last two of which should be by on-track tamping machines (6) Temporary speed restriction as indicated in Annexure - 3/8 shall be imposed on the length of track where welded panels are joined by 1 m long fishplates with special screw clamps or joggled fishplates with slotted grooves & bolted clamps as in Fig. 3.9, 3.10, 3.11 & 3.12. 338 Gaps at SEJ: (Back to Para 341(10)) (1) (a) The thermal force in a LWR as shown in Para 335 is to be resisted by suitable track structure. Accordingly, the Gap at SEJ depends on following factors: (i) Longitudinal Ballast Resistance of sleepers (taken as 13.28 or 13.74 kg / cm / rail per sleeper for PSC sleeper of density 1540 or 1660 per km respectively, which is indicative and can vary as per site conditions) (ii) Area of rail section (iii) Modulus of Elasticity (E) for rail steel (iv) Coefficient of linear expansion (α) for rail steel (v) Difference between the De-stressing temperature and prevailing rail temperature of LWR (vi) Initial gap at SEJ at de-stressing temperature. Page 116 of 417 (b) Gaps at SEJ shall be adjusted at the time of de-stressing of LWR/ CWR as under: (Back to Para 340) Rail section laid Gap to be provided at ‘td’ 52 kg/m 40 mm 60 kg/m (c) For Gaps at different types of SEJ and its laying and measurement, Fig No 3.17, 3.18, 3.19, 3.20 may be referred to: (2) Hysteresis Curve: (a) In service, the change in gap at SEJ due to rail temperature variations is in the form of a Hysteresis Curve. Therefore, for any given rail temperature, the measured gap at the SEJ may fall within the range defined by the Hysteresis curve. A typical hysteresis curve for Zone – IV with 52 Kg/m rail on PSC sleeper with 1540 density is as under in Fig 3.16 below: Fig 3.16 (b) The gaps between the reference mark and tongue rail tip/stock rail corner, which is attached to the LWR/CWR side at various rail temperatures, shall not differ by more than ±10 mm from the theoretical range as shown in Annexure - 3/9. (c) Where fish-plated or SWR track is joined on one side of SEJ, the gap between the reference mark and tongue rail tip/stock rail corner on SWR/Fish plated track side shall not be measured. Page 117 of 417 Fig 3.17 Setting of Gap at SEJ (IRS Design) to Drawing nos. RDSO/T-412, RDSO/T-4160, RDSO/T-4165, RDSO/T-5478, RDSO/T-5586, RDSO/T- 5748, RDSO/T-6257, RDSO/T-6782 at De-stressing temperature (td) Back to Para 338 Page 118 of 417 Fig 3.18 Setting of Gap at Improved SEJ with double gap of max. 65mm each (DG 65 Design) to Drawing no. RDSO/T-6922 (60 Kg) & RDSO/T-6930 (52 Kg) (Applicable for both rails) at De-stressing temperature (td) Back to Para 338 Page 119 of 417 Fig 3.19 Setting of Gap at Improved SEJ with Single gap of max. 80mm (SG 80 Design) to Drawing no. RDSO/T-6902 (60 Kg) & RDSO/T-6914 (52 Kg) (Applicable for both rails) at De-stressing temperature (td) Back to Para 338 Page 120 of 417 Fig 3.20 Illustration for measurement of gap at SEJ for observation of movement of LWR/CWR Back to Para 338 Page 121 of 417 339 De-stressing Operation of LWR: The work of de-stressing shall be done during a traffic block under the personal supervision of JE/SSE/P.Way. De-stressing shall be done when rail temperature falls between the range provided for t d. If required temperature cannot be obtained in field, de-stressing can be done at a little lower temperature than the targeted stress-free temperature to with the use of rail tensors. 340 De-stressing without Rail Tensors: (Back to Para 337, 346, 351) In case rail temperature at the time of de-stressing is within the range specified for td, detailed procedure as given below may be adopted. (1) The LWR, if longer than manageable lengths that cannot be de-stressed at a time, then, the LWR shall be de-stressed in parts by tackling manageable lengths depending on the availability of Block, labour etc. (2) Remove impediments to free movement of rail such as rail anchors, guard rails, check rails etc. (3) A traffic block of adequate duration should be arranged at such a time that the rail temperature will be within the temperature range specified for t d during the fastening down operations of fittings. (4) Before the traffic block is actually taken, a speed restriction of 30 Kmph should be imposed and fastenings on alternate sleepers loosened. (5) When the traffic block is taken, a closure rail near the SEJ shall be cut and removed, the SEJs adjusted as per Para 338(1) (b) and fastened. (6) The remaining fastenings on both running rails shall be loosened/removed starting from the ends near the SEJs and proceeding towards the centre of LWR. The rail shall be lifted and placed on rollers Fig. 3.14 at every 15th sleeper to permit the rails to move freely. While de-stressing on curved track, provision of side rollers as per Para 341(6) (a) & (b) may be adopted. The rails shall be struck horizontally with wooden mallets to assist in their longitudinal movement. (7) The rollers shall then be removed, the rails lowered to correct alignment and fastenings tightened, starting from the middle of LWR and proceeding towards both ends simultaneously. The tightening of fastenings shall be completed within the temperature range for td. The actual range of temperature during the period of tightening shall be recorded by JE/SSE/P.Way along with the time and date. (8) Simultaneously with the tightening of fastening, arrangements for insertion of cut rails, 4 metre or longer, between the SEJ and LWR shall be started. The four gaps shall be measured individually and the rails of required length cut by saw keeping required gaps for AT welding. The cut rails shall then be placed in position, fastened to the sleepers and welded at each end. Fastenings for 20 m on each end of the LWR shall be removed before welding. 341 De-stressing with Rail Tensors: (Back to Para 337, 346, 351) For de-stressing of LWR with the use of rail tensor, the following procedure shall be adopted: (1) The LWR, if longer than manageable lengths that can be de-stressed at a time, then, the LWR shall be de-stressed in parts by tackling manageable lengths depending on the availability of Block, labour and the capacity of the tensor available etc. (2) Remove impediments to free movement of rail such as rail anchors, guard rails, check rails etc. Page 122 of 417 (3) During the traffic block, create a gap of 1 m at location ‘B’ i.e. centre of the first segment of the LWR (Fig. 3.21). (4) Mark the anchor length A1 A2 and C1 C2 each equal to la at either end of the length A2 C2 to be de-stressed (Fig. 3.21 (a)). Note: The anchor length ‘la’ should be determined on the basis of the lowest value of tp at which the de-stressing is likely to be carried out. Anchor length shall be increased suitably based on the condition of the fastenings, rubber pads, liners or ballast (5) Erect marker pillars W0 W1 etc., on each of the length A2 B and C2B. Transfer the marks W0 onto the rail foot (Fig: 3.21 (a)). Note: The distances W0 W1, W1 W2 etc. shall be marked at about 100 m intervals, the distance from the previous pillars and the last pillar WB may be less than 100 metre. (6) when tP is less than the desired to (Fig. 3.21 (b)), de-stressing operation shall be carried out for the lengths A2 B and C2 B as described below:- (Back to Para 340(6)) (a) Unfasten and mount on rollers the portion from A2 C2. Note: Side rollers on the inside of curve shall also be used while undertaking de- stressing on curved track these should be spaced at every n th sleeper, Where, n = Radius of curve (R) x No. of sleepers per rail length 50 x (to-tp) (b) Outside supports shall be used in addition at the rate of one for every three inside supports. (c) Fix the rail tensor across the gap at ‘B’ and apply tension so as to obtain some movement at W0 to remove any kinks or misalignment and to minimize the friction in the rollers etc. Release the tension and note the movement Y 0 at W0. (d) Transfer marks W1, W2,....... onto the rail foot and note temperature tp. (e) Calculate the required movement at W1 = Yo + elongation of length W0 W1 (L) due to temperature difference (to - tp) = Y0+ Lα (to - t p) (f) Calculate the required movement at W2 = Movement at W1 + elongation of length W1W2 (L) due to temperature difference (to - tp). Similarly, calculate the required movements successively at each of the remaining points. (g) Mark the above calculated extensions with respect to the transferred marks referred at (d) above on the rail foot on the side away from the tensor. (h) Apply the tension by means of rail tensor till the mark of required extension comes opposite to the mark on the marker pillar W1. Fasten down the segment W0W1 (i) Then check at W2, bring the mark of required extension at this location opposite to the mark on the marker pillar W2, by adjusting the tensor either by reducing or increasing tension and fasten down the segment W1W2. Similarly, check the remaining marks, adjust the tension as required and fasten down each segment before proceeding to the next segment. Note: (i) Annexure - 3/11 gives the value of Lα (to - tp) for different values of L and (to - tp). (ii) Only one value of tp has to be taken at the time of marking W1, W2 etc. on the rail foot. The values of tp is not required to be taken thereafter. The variation of temperature, if any during the de-stressing operation shall automatically be taken care of by reducing or increasing the tensile force from the tensor, while coinciding the reference mark on rail with the corresponding mark on pillars. (iii) If for any reason, both the lengths A2B and C2B cannot be fastened down simultaneously, the final adjustment in pull and fastening down of the individual segments may be done in series, first from A2 to B and then, from C2 to B. Page 123 of 417 (j) After the fastening down of the last length A2B and C2B is completed, make a paint mark near free end of one rail at a distance of (X metre + 2 x 25 mm -1 mm), measured from the end of the other rail across the gap spanned by the rail tensor. (k) Remove the tensor, close the 1 m gap temporarily and allow traffic at restricted speed (Fig. 3.21 (c)). (7) During traffic block, cut the rail at the paint mark, insert a rail closure of length exactly equal to X metre and weld one end thereof (Fig. 3.21 (d)). If the gap at the other end is also 25 mm, it can be welded in the same block. Otherwise, fasten with special fishplates and clamps and allow traffic at restricted speed. In the latter case, during a subsequent block, when tp is not greater than to, release rail fastenings on either side to the required extent of about 50 to 75 m and pull the rails with rail tensor to get the desired gap of 25 mm (Fig. 3.21 (e)); refasten the rail and weld the joint. Release the tensor after a lapse of a minimum of 30 minutes after pouring of the weld metal. Note: - (i) X=4 metre or longer (ii) In case gap at the time of the second weld as above is less than the desired welding gap, additional cutting of rail shall NOT be done to create correct gap for welding. In such cases, the welding should be done below td and the requisite gap for welding shall be created by using rail tensor and equalization of forces as described below shall be done. (8) During a traffic block, when tp is less than td, equalize the forces in the rail by releasing the fastenings over a length of minimum 125 m on either side of location ‘B’ and tapping with wooden mallets etc. (Fig. 3.21 (f)). Fasten down the rail and allow traffic. (9) The above procedure should be repeated for the remaining segments, if the entire LWR is to be de-stressed. (10) During another traffic block, when tp is within the range of temperature specified for td, destress the end 125 metre from SEJ. Thereafter, weld the closure rail next to SEJ duly ensuring setting of the gaps at SEJ as per Para 338. Page 124 of 417 Fig 3.21 Destressing of LWR using Rail Tensor Back to Para 341 Page 125 of 417 342 Joining of LWRs: (Back to Para 346) Detailed procedure for joining of LWRs is as given below (Fig. 3.22 (a) to (f)):- (1) During traffic block, replace the existing SEJs between the LWRs with ordinary rails, of which there should be two temporary rails about 4 metre or longer for each of left and right sides. Leaving the temporary rails fish-plated, weld the other rails and traffic passed. Note: Where fluctuations of temperatures during the period of joining are likely to be small, only one temporary rail instead of two may suffice. (2) Provide W0 marker pillars for each of the LWRs at a distance of 100 m from the centre of temporary rails, to mark the ends of the breathing lengths. (3) Keep ready two rails of standard length. Measure their lengths ‘l’ correct to the nearest mm. (4) Transfer the marks W0 to the rail flange for both the LWRs. (5) During the traffic block when tp is less than desired t0,remove the fishplates and fish- bolts connecting the temporary rails to the breathing lengths, release the fastenings of LWRs between the W0 marks, mount the rails on rollers and note the movements Y0 and Y'0 at the marker pillars W0, for LWRs 1 and 2 respectively. Note: The movements of Y0 and Y'0 should be away from the ends of LWR, if the LWRs are in a state of correct de-stressing. (6) Note tp and mark the anchor length on either side as shown Fig. 3.22 (b). (7) Make a paint mark near the end of either of the LWRs at a distance of l + Lα(t0-tp) + Y0 + Y'0 + 2 x 25 -1 mm measured from the end of other LWR. Here L = 200 m, 25 mm is the allowance for each Thermit weld and 1 mm is the allowance for a saw cut. The value of L α (t0-tp) may be read from Annexure - 3/11. (8) Remove the rollers, fasten down the length ‘L’, cut the rail at the paint mark, remove the temporary rails, insert the rail of length ‘l’ and weld one end of it. If the gap at the other end is 25 mm, it can also be welded during the same block. If the required 25 mm gap is not available, fasten the rails with fishplates and clamps and allow traffic at restricted speed. (9) During the next traffic block (Fig. 3.22 (e)), weld the other joint if the gap is 25 mm. If the gap is more than 25 mm, release the rail fastenings on either side to the required extent and pull the rails with rail tensor to get the desired gap of 25 mm. Re-fasten and weld the rail. Release the tensor after the lapse of a minimum of 30 minutes after pouring of the weld metal. (10) During the block (Fig. 3.22 (f)), equalize the forces in the rail by releasing the fastenings over the portion marked ‘L’ and over the anchor lengths on either side and tapping with wooden mallets, etc. Fasten down the rail and restore traffic. Page 126 of 417 Fig 3.22 JOINING OF LWR (Back to Para 342) Page 127 of 417 343 Reference Marks: (1) Reference marks shall be fixed at each SEJ and at the centre of LWR/CWR, on the reference pillars erected for this purpose. (2) While the reference marks on the reference pillars shall be saw marks, corresponding marks on the running rails shall be paint marks on the non-gauge face of the rail. (3) In no case, a saw mark shall be made on the running rail. Reference marks are required to be fixed immediately after de-stressing of LWR/CWR and shall not be shifted or tampered with thereafter. (4) Additional reference marks in fixed portion and breathing length may be provided to know the behaviour of LWR/CWR. 344 Maintenance of LWR/CWR: An important prerequisite for proper functioning of LWR/CWR is its initial laying to a high standard and its subsequent maintenance by trained personnel possessin
