Defects in Rails

A.Corrosion and Rusting:-

Corrosion is caused not so much by dampness as by acid gases dissolved in the film of moisture which frequently coats on rails. Corrosion generally occurs in following locations:-

1. Platform lines where trains makes prolonged halts.

2. Siding where saline or corrosive goods dealt with.

3. Where the rails are affected by the dropping of engine ashes, such as at ash pits.

4. Near water columns due to insufficient drainage.

5. Tunnels and damp cuttings

6. Areas near the sea coast.

7. Industrial belts.

Corrosion is generally noticed on the web and the foot of the rail.

B. Wear on Rail Table:-

Normally this is of a very small order. The amount of wear increases with heavy traffic density as in suburban section though not proportionately.

C. Flattening of Rail table:-

This mostly occurs on the inner rail of a curve by high contact stresses combined

with horizontal forces. The vertical pressure may be due to heavy axle load, large

unsprung mass or under equilibrium speed on canted track.

D. Wear on Gauge Face:-

The outer rail of a curve has to withstand heavy pressure from the wheels which results in the running edge becoming worn or ‘side-cut’. Wear on gauge face is specially pronounced in case of suburban sections where multiple unit coaches are provided with laterally unsprung traction motors.

E. Hogging of Rails:-

A hogged rail is one with its end or ends bent in vertical direction. A hogged rail

end in the track is ascertained by unfishing the joints, removing the fastenings and then measuring the extent of hog at the rail end by placing a 1 metre long straight edge over the rail table, centrally over the joint.

F. Battering of Rail Ends:-

Battering of rail ends – Rail end batter occurs where the joint gaps are excessive. It is caused by the impact of wheels on end of a rail particularly if the fish-plates do not fit snugly. Rail end batter is measured as the difference in heights of the rail at its end and at a point 30 cm. away from the rail end as shown in the sketch as shown below

G . Wheel Burn:-

Wheel slipping occurs usually on adverse gradients or while starting on rising grades when considerable heat is generated and top of the rail is torn off in patches, causing depressions known as wheel burns, from which cracks may develop. This also occurs when train brakes are applied suddenly and wheels lock and slide. Wheel burns cause the wheels to hammer the rails and lead to difficulties in keeping the sleepers packed firmly and fastenings tight. Such rail should be kept under observation and changed, in case repair by welding is not feasible

H. Corrugation:-

Rail table develops ridges and hollows called corrugation and when vehicles pass

over these rails, a roaring sound ensues. Such rails are called “roaring rails”. In such locations, excessive vibrations are caused, due to which fastenings and packing tend to get loose, track needing frequent attention at these places.

Rail Failure

A rail is said to have failed if it has fractured in track or it is considered necessary to remove it from track on account of defects other than those due to accidental damages due to buckling, kinking, derailments, abnormal wheel burns etc.

Causes of Rail Failure

1. Manufacturing Defect:- These Defects are identified during the manufacturing of rail like composition of rail, piping, seams, laps, guide marks etc.

2. Rolling Stock:- These defects are found due to flat tyre, slipping of wheel and due to braking of trains.

3. Corrosion of Rails:- Corrosion is caused not so much by dampness as by acid gases dissolved in the film of moisture which frequently coats on rails. Corrosion is generally noticed on the web and the foot of the rail.

4. Bad Maintenance of Joints:-This defect is found due to improper packing and bad squaring of sleepers etc.

5. Welding Defect:-These Defects are usually found due to improper composition of Thermit Welding material or improper technique of welding.

6. Bad Maintenance of Track:-These are due to improper inspection of the track.

7. Derailment:- Cause of rail failure is due to trains getting down of track

Action to Be Taken in Case of Rail fracture/ Weld Failure

(1) It is of paramount importance that whenever a fracture of a rail/welded joint is noticed, immediate action is taken to restore the track, if necessary with restricted speed, with the least possible delay.

(2) The Mate/Keyman/Gangman, as soon as he notices the rail fracture/weld failure should first protect the track, while the repairs are being carried out. He should also send information to the P.W.I. and the Station Master of the nearest station. 

(3) If the fracture is with a gap of less than 30 mm. in the case of fish-plated/SWR track, the fractured portion should be supported on wooden block or by shifting the nearest sleepers on both sides. In the case of LWR the fractured rail should also be clamped.

(4) When the fracture gap is more than 30 mm, a closure of appropriate length should be used with a clamp.

(5) In cases where a small portion or piece of rail has come off or in the case of multiple fractures, the rail has to be changed.

(6) In the case of weld failure, joggled fish-plates and clamps should be used.

(7) After doing the emergency repairs the trains may be passed at 20 Kmph. by a

Mate/Key man, until the Permanent Way Official replaces the rail and restores full speed.

(8) If there is a spate of rail fractures, additional Key man’s patrol should be introduced in the early hours of the morning.