Q Bank for Civil Engineer LDCE Exam - Write short notes(10)

Q.No.26. Write short notes on: 

 1. Anti corrosive treatment of plate/rail screw, 

2. Protection of rail from liner biting. 

3. Renewal of rail on major bridges and their approaches. 

4. Handling of 90 UTS rails. 

Ans (i) Anti corrosive treatment of plate/rail screw It has been observed that the plate screws and rail screws provided on PSC sleepers on turnouts, SEJs, bridge guard rail and level crossings are getting corroded due to either aggressive environmental conditions or in stretches where passenger trains reach destinations in the early morning hours. This results in corrosion of screws and often shank of the screw is left inside sleeper and can not be taken out, due to corroded head. This renders sleepers totally useless. Due to excessive corrosion of plate/rail screws, maintenance has been badly affected as the thickness of screws gets reduced and in time they get jammed/loosened resulting in loosening grip with plates and sleepers become useless. Remedial Action To minimize the occurrence of this problem, as a preventive measure, lubrication of plate screws and rail screws should be done. Grease graphite used for this purpose shall be as per IS specification number IS:408 grade ‘O’.

 METHOD OF LUBRICATION

Prior survey shall be done to ascertain number of corroded screws. New screws shall be procured as per assessed numbers and provided in place of corroded ones after applying ‘O’- graphite grease/black oil. Plate/rail screws should be removed one by one from track. Then screw as well as dowel be properly cleaned for corroded material from the surface with the help of wire brush and then dipped in black oil uniformly both on the surface of plate/rail screw and dowel and fixed back head of plate/rail screw should also be either coated with hot bitumen to avoid corrosion. 

FREQUENCY – 

1. At new turnout/SEJ/bridge guard rail/level x-ing renewal site, the greasing of new plate/rail screws should be done while providing in the track. 

2. Once a year in areas not prone to corrosion. 

3. Once in six month in corrosion prone areas. 

RECORD - Each PWI should maintain a record of the location of greasing of plate/rail screws as per Performa given in Annexure- I. 

Record for lubrication if plate/rail screws –

Ans.  (ii)    Protection of rail from liner biting- 

Generally  in  yards  due  to  drainage  problem,  which  causes  dampness  conditions,   there  is  corrosion  mainly  in  the  rail  foot  area.  In  addition  in  stretches  where  passenger   trains run in the early morning hours, due to toilet droppings, there is reduction in the rail  foot  in  the  area  which  is  in  contact  with  the  liners.  The  remaining  section  of  the  rail  is   normally not affected in such cases. In case of rail corrosion at fastening location, the measurement of rail corrosion in  rail  foot  it  to  be  done  at  every  500mm  or  part  once  a  year.  The  format  for  this   measurement shall be as given below :- 

Rail corrosion at fastening location – 

1. To minimise the occurrence of this problem, as a preventive measure, at the time of initial provision as well at the time of periodic cleaning of central leg of elastic rail clips.

Graphite grease grade ‘O’ to IS:408 shall be applied on the underside of liners as well as moisture to the surface of the liner and rail foot, grease shall be applied along the boundary of liner to seal the liner boundary. In areas indentified to the prone to such corrosion. This treatment shall be done once a year and in other sections with concrete sleepers once in two years. 

2. In case of location identified to be prone to corrosion, shifting of rail from its position will result into stopping of further development of corrosion at same location and will result into increase in life. By shifting of rail from its posisition, the reduced foot section due to corrosion gets shifted away from the liner. Thus, its further reduction in foot thickness at same location due to corrosion gets eliminated and new location with normal thickness comes under the liner to accept further corrosion. Thus the reduction of foot thickness at one location gets stopped. This is to be done when the rail is relatively new and reduction in rail foot area is less i.e. reduction in rail foot is less then 1.5mm. This may be done by de-stressing. 

3. As this type of corrosion is observed more on gauge face side, changing/turning of rail will result into making the gauge face as non gauge face which will result into increase in life of rail as the reduction of foot thickness at same location will get stopped. 

 Ans4 (iii) RENEWAL OF RAIL ON MAJOR BRIDGES AND THEIR APPROACHES – Renewal of rails on major bridges and their approaches shall be done after passing of 50% of the stipulated GMT of rail as per the rail section. There should not be any fitted, corroded, wheel burnt rail on bridge or its approaches. Regular visual examination and pre winter USFD testing of rail/welds shall be carried out

invariably. New rails should not be unloaded on bridge itself to avoid any infringement to passing trains. Uniform rail section shall be maintained on bridge and its approaches upto 100m on either side. 

Ans (iv) HANDLING OF 90 UTS RAILS 

1. PROTECTION OF STRAIGHTNESS- Barely visible straightness deviations, for example, a deflection of 0.75mm over 1.5 meters span renders a rail unacceptable and require careful handling and

stacking therefore. 

AVOID- 1. Heavy static loading 

2. Sudden impact of dynamic loading 

3. Localised point on line contact loading in stacking. 

4. Excessive end drop and flange overlaps while lifting/moving. 

5. Criss – Cross stacking of rails of alternative layers at rightangle as far as possible. DO 

1. Keep rails horizontal and straight while lifting/moving. 

2. Stack rails of same length on firm level base of well drained platform, preferably of concrete.

3. Stack subsequent layers on uniformly placed spacers in vertical alignment with base supports.

4. Keep rail ends in vertical alignment 

5. Place rails of shorter length in upper layers. 

2. PROTECTION OF RAIL SURFACE- Surface notches of even less than 0.75mm in depth are liable to cause rail fracture in service. 

Therefore- AVOID

i. Impact abrasion of rails against separators in wagon. 

ii. Round link chain slings for securing the rails. DO 

i. Use conventional slings for lifting rails made of flat link chains. 

ii. Lifting of rails preferably with magnet lifting device. 

 3. PREVENTION OF METALLURGICAL DAMAGE These rails are thermally very sensitive and are likely to develop metallurgical defects, if exposed to localised heating, which produces very hard, brittle and cracked metallurgical structures which may lead to sudden failures. Therefore, AVOID i. Heating, flame cutting on or adjacent to rails. ii. Contact with electric area and molten metal splashes i.e. from loose cables or adjacent welding operations. 

DO Flame cutting when found essential after pre heating minimum of 10cm of rail length on either side of the cut to about 250-300 degree ̊C by uniform movement of heating torch. 

4. PROTECTION FROM CONTACT WITH INJURIOUS SUBSTANCES These rails can withstand normal degree of rusting but localised corrosion pitting may cause subsequent rail fractures. Therefore AVOID Contact with injurious substances which produce high corrosion of steel i.e. acids, alkalis, salts etc. DO Stack rails on well drained platform preferably of concrete. 

 5. SLINGING PRINCIPLES The single point aligning increases risk of excessive lending and surface damage to the rails the overhang beyond the outer lifting joint should not be greater than one half the distances between lifting points. Therefore, AVOID 

i. Single point slinging DO Use two point slinging for rail length upto 18m. Next four point slinging with 26 met. Rails. 

Recommended location of lifting points for various rail lengths are tabulated below –

Use of lifting beams fitted with slings would be necessary for handling rails in rail  rolling plants, ports and flash butt welding plants. 

6. SAFETY OF PERSONNEL   AVOID Standing under suspended loads. DO 

1. Use protective gloves and clothing’s to minimise the risk abrasion. 

2. Wear distinctive colures helmet and clothing for easy identification by crane and  machinery drivers to avoid accidents.