Short Note on How to arrest the weld failure.

How to arrest the weld failure.

1. In case of welding of rail on cess, full rail length should be supported on at least ten wooden blocks either side of proposed weld and rails should be properly aligned spiked and held in position. Welding should be carried out on proper cess and not on the ballast shoulder.

2. In case of in-situ welding, rails fastenings of at five sleepers on either side of proposed weld should be loosened.

3. Ensure that rails are with nil battering & nil hogging at their ends.

4. Ensure that portions being used match with type and chemistry of rail i.e. weight & UTS.

5. Rail end should be cleaned with wire brush & k-oil.

6. Rail ends should be cut straight and square.

7. Gap should be as per welding technique being used.

8. Ensure correct alignment of rails prior to welding.

9. Ensure that prefabricated moulds are as per welding techniques, free from any moisture & cracks.

10. Pre-fabricated moulds should be dressed with respect to actual rail profile being welding prior to their fixing

11. Prefabricated mould should be centrally fixed and central lines of two halves of prefabricated moulds should be coinciding with each other. 12. Ensure that mould shoes are in proper shape.

13. Prefabricated mould should be gently inserted / adjusted in mould shoe.

14. Spatulea should be used for luting of the joint-gap ensure that premixed luting sand is not older than four months from its date of manufacture.

15. Ensure that no foreign elements are mixed in luting sand.

16. For proper and uniform preheating of both rail ends, vaporizers should be placed/set at proper height. Maximum height of gooseneck from rail top should be 40mm.

17. Ensure that crucible is properly dried/charged and respaired with magnasite prior to pouring o portions.

18. Enusre that thimble is dry and free from moisture and also thimble shape is round and of dia 18-20mm (25mm Technique)and 20-22mm(75mm Technique)

19. Maximum height of crucible from top of prefabricated mould should be 50mm.

20. Workability of pressure gauge fitted on petrol tank in case of pre-heating by petrol and gauge fitted on Oxygen & L.P.G. cylinder in case of preheating. With oxy-LPG mixture should be checked before carrying out of welding of rails.

21. Ensure that portion bags are properly sealed and intact at the time of opening for use.

22. 90 UTS portion should be used when welding of 72 UTS & 90 UTS rails is being done under unavoidable circumstances.

23. Portion being used should not be of more then two years old from the date of manufacturing provided packing is intact and there is no entry of moisture.

24. Portion should be stored in steel box at the site of welding.

25. Parameters of traffic block, preheating pressure and preheating should be adhered as stipulated for AT welding. Table 10.20 Traffic block and pre-heating time for different types of pre-heating

26. Portion should be thoroughly mixed in the pan before pouring it into the crucible for ignition

27. Ensure reaction time after ignition of portion, as 25±3 seconds and portion in the crucible should be covered by crucible cap after start of reaction.

28. Molten metal should be tapped on completion of reaction and after slag separation. 26. Bottom half of prefab mould and risers should be preserved at the time of demoulding to ensue controlled cooling.

29. Chipping of hot metal should be done after 4-6 minutes of pouring of molten metal into the gap for 25mm gap joint & 12 minutes for 75 mm gap joint.

30, In case of in-situ welding newly welded joint should be supported on wooden block joggle fish plated and first train should be passed with restricted speed after rough finishing of joint after 30 minutes of pouring molten metal.

31. Ensure final finishing of joint within 24 hours of its execution. 26. Ensue that there is no chisel mark on rail surface after final finishing.

32. Ensure that each weld bears distinctive mark indicating month, year, agency, welder’s code and weld number punched on an aluminium, stop and fixed to the weld with epoxy adhesive at 30mm from joint. No punch marking should be done on the rail and particulars of welds are recorded are per proforma. 26. Ensure that weld are stencilled with welder’s code and particulars of welds are recorded as per proforma circulated by Railway Board.

33. Repair to crucible shall be done using magnasite

34. Weld collar should be painted upto 10 cms on either side of weld by usmg correct procedure.

35. In case of emergency if joint is to be executed in failing temperature use tensor.