lecture 8 final

CE-363

Lecture 8: Wears and Failures in

Rails

Dr. Ankit Gupta, Assistant Professor

Department of Civil Engineering

National Institute of Technology Hamirpur

Lecture Outline

Wear in rails

Classification of wear

Effects of rail wear

Permissible limits

Remedial measures

Rails – Wear

Definition

This is one of the prominent defects of

the rails

The surface of the rail, either on the top

of rail head or side of rail head or at the

end of the rail head, gets removed

Rails – Wear

Major Reasons

Abnormally heavy loads

Fast train speeds

Concentrated stresses exceeding elastic

limit

Gap at joints

Slipping, skidding or striking of wheel

flanges on curves

Rails – Wear: Classification

On the basis of location

On the basis of position of wear

Rails – Wear: Classification

Based on location

On sharp curves – due to centrifugal

force

On steep gradients – due to extra effort

On approaches to stations – due to

braking or acceleration

In tunnels and coastal areas – due to

humidity and weather effect

On weak foundations – due to heavy

loads

Rails – Wear: Based on Position

Rails – Wear: Type

Based on Position – Top of rail head

Flow of metal

Recurring impact of heavy axle load

Abrasive / corrosive condition

Skidding / burning of head

Improper super elevation / centrifugal

force

Rails – Wear: Type

Based on Position – Top of rail head

Slipping of wheels on curves

Fluctuation in track

Adzing of sleepers

Engine Burns

Flow of Metal

Rails – Wear: Type

Based on Position – Side of rail head

Rigidity of wheel base

Slipping /skidding of wheels on curves

Greater thrust on inner rail (speed lesser than equilibrium speed)

Rail Head Side Wear

Flaking

Shelling

Rails – Wear: Type

Based on Position – End of rail head

Loose fish plate, fish bolts

Heavy loads at high speed

Wide joint opening

Difference in rail height at joint

Bad condition of vehicle springs

Poor maintenance of track

Rails – Wear

Rail Failures

Category Description of Fracture

A Cracks in the head of the rail

B Solitary cracks in the web or flange of the rail

C Transverse (parallel to rail cross- section) cracks

D Horizontal cracks in the web

E Pieces of head, web and flange broken off at the rail end

F Portion of rail broken off

G Breaks through sections of rail

Rail Failures

Category Description of Fracture

H Cracks and breaks through welds

J Portions absent from railhead

K Piece of rail broken away though web and head/flange

U

Category A

Vertical crack through

crown at rail head end

Vertical crack on

running face of rail

Category A

Horizontal crack on side

of head of rail at end

Horizontal crack on

side of rail head

Category B

Crack at junction of head

and web

Crack in body of web

Category B

Crack at junction of

flange and web

Crack in flange

Category C

Transverse Crack at rail

head

Transverse Crack at

bond

Category C

Transverse Crack

at bond

Transverse

Crack at flange

Category C

Vertical Crack at

end

Category D

Crack in web at end Crack in web along

holes

Category E

Broken Rail

Category F

Broken Rail

Category G

Horizontal Split Head

Split Web

Transverse Defects

Vertical Split Head

Head / Web Separation

Crushed Head

Bolt Hole Crack

Rails – Wear: Permissible Limits

Depends up on weight of rail (or weight of

axle)

Limited to 5% of rail weight

Wear of 25% of the section of head is also

allowable

Rails – Wear: Prevention

Better maintenance of track

Reducing number of joints

Use of heavier and higher UTS rail sections

Use of bearing plates (adzing of sleepers)

Lubricating gauge face

Using check rails on sharp curves

Track renewal

Rails – Wear: Prevention

Interchanging inner and outer rails

Using special alloy steel

Regular maintenance of rail joints

Welding or dehogging of battered ends

Maintenance of correct gauge

Application of heavy mineral oil in case of

corrosion of rail metal under adverse

atmospheric conditions