p way bulletin dec03

8/16/2019 P Way Bulletin Dec03

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FROM THE DESK OF THE EXECUTIVE EDITOR

(i)

The December 2003 issue of Permanent Way Bulletin features two

articles. The first article, authored by Shri R. K. Gupta is about composite

sleepers. These sleepers are environment friendly, made of waste plastics

and can be used in place of wooden sleepers, on bridges and turnouts.

The author has discussed its composition, advantages, testing criteria and

in-service performance over year, during trial.

The second article by Shri Deva Singh, on Ultra Sonic Flaw Detection

of rails. The author has discussed its reliability and various possible

sources of error. He has also pointed out certain discrepancies in the

USFD Manual, requiring clarification/correction.

The issue also incorporates the Correction Slip no. 87 to the IRPWM -

1986.

It is hoped that both the articles and correction slip will be useful to

Permanent Way Engineers.

The readers are requested to send the articles on various topics related

to Permanent Way, for publication in this bulletin, by e-mail.

With best wishes,

- EXECUTIVE EDITOR


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PERMANENT WAY BULLETIN

C O N T E N T S

Published by

The Director,

Indian Railways

Institute of Civil Engineering,

Pune - 411 001.

Volume 30, Number 3 December 2003

(iii)

TECHNICAL PAPERS

1. COMPOSITE SLEEPERS : AN ENVIRONMENT FRIENDLYALTERNATE SLEEPER FOR TRACK AND BRIDGES

by Rama Kant Gupta 1

2. DIAGNOSTIC OF ULTRASONIC FLAW DETECTIONOF RAILS /WELDS - A REVIEW

by B. Deva Singh 18

The views expressed by the authors of Technical Papers are not necessarily the viewsof IRICEN.


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Permanent Way Bulletin Vol. 30, No. 3, December 2003

6

S.No. Sleeper Life cycle cost Initial cost of the

Without traffic With traffic sleeperblock cost block cost

1 Bridge timber 10725/- 20376/- 466/-

2 Steel channel 19386/- 24744/- 10333/-

3 FRP 20733/- 20733/- 20176/-

Keeping in view the cost component, it was tried to search another alternative.In this process, an MOU was signed with the following two firms, who haveshown their interest in development of alternate composite sleepers inassociation with their foreign collaborators:

1. M/s Patil Group of Industries, Hyderabad, having association with M/sTietek/USA.

2. M/s Micron, Delhi, having association with M/s Polywood/USA.

1.0 Composite sleepers as an Eco-friendly product:

Thermo-plastic based composite sleepers are eco-friendly and can becategorized as the GREEN PRODUCT. It is eco-friendly in the sense that itensures reuse of the waste plastic in a better way by ensuring its usage insuch a fashion, otherwise trees are required to be cut to have required numberof wooden sleepers/turnout sleepers or bridge timbers. The main constituentsof composite sleepers are: used HDPE, plastics, polystyrene, polyethylene,PVC and so on. All are falling in the general category of plastic, which hasbecome part and parcel of life in every field. Furthermore, its application isincreasing day by day. Main problem with this material is that these are non

bio-degradable. As such, these used plastic waste are posing environmentalhazard to the society. Environmentalists are having serious concern about itsusage as well as disposal of such products. Non-use of plastic is not possibledue to its deep rooted link in the human life. As such, alternative about itsdisposal/reuse are required and now a days, it is the serious matter of concernworld over.

In any city, plastic is one of the major solid wastes as a non bio-degradablecomponent. For its proper disposal, scientists had taken the project for itseffective reuse. Fortunately, one of its usages in the form of railway sleepers

has come up. By reuse of the plastic, the land pollution, which otherwise wasincreasing by non-proper disposal of the same will certainly be reduced. Its useas railway sleepers will ensure comparatively less cutting of trees for the worldover railways. This will further result less destruction to the forests, whichultimately will ensure more consumption of carbon dioxide and simultaneouslymore release of oxygen by the forests to the atmosphere. As such, it is a boonto the society.

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Indian Railways have mostly switched over from wooden sleepers to PRCsleepers but in some other countries, wooden sleepers are still beingpredominantly used. As per report of Rutgers University/USA, US rail road onannual basis replace 10 to 15 million wooden sleepers. Even if on theconservative side, we are taking 15 million wooden sleepers to be replaced onannual basis by two neighbouring American countries i.e. Canada and USA, itslength would be about 38600 Kms, which is approximately equal to

circumference of the Earth. If its cubical content is calculated, that is coming to16,00,000 Cubic meters. Considering total requirement of world over railways,one can get some idea about quantity of timbers required for use of the sameas railway sleepers, which will only be achieved by deforestation of huge areaon the Earth.

3.0 Composition of the composite sleepers:

Composition of such sleepers are mainly high-density polyethylene (HDPE)based. Different manufacturers have patented their products based on differentcompositions. As such, each material combination followed by different

manufacturers will have different properties from one another just like woodtaken from different species of trees have different properties. Brief ideas aboutcombination of some of the known manufacturers are given below:

1. Tietek Sleepers – Composition of this sleeper is given below –

Recycled HDPE 55%Crumbed rubber 12.5%Glass reinforcement 12.5%Fillers 20% (calcium carbonate, Mica etc.)

In addition to that, some other patented items are also there, which arethe trade secret of the manufacturer.

2. Polywood sleepers – Its composition is of mainly two items i.e.Polystyrene (PS) and High Density Polyethylene (HDPE). Its percentageis in the ratio of approximately 35% PS to 65% HDPE. In addition tothat, some other patented items are also there, which are the tradesecret of the manufacturer.

4.0 Advantages of composite sleepers:

There are so many advantages of composite sleepers. Some of them are listedbelow:

1. Composite sleepers being made of non bio-degradable material, its life isexpected to be more than that of wooden sleepers. Life of wooden

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sleepers is normally 10 to 25 years depending upon its variety, quality ofwood, traffic density and its location of use. As compared to this, life ofcomposite sleepers is assessed to be around 40 to 50 years.

2. All types of flexibilities, which is available with wooden sleepers likenotching, grooving, repairing of the spike killed area, adging, drillingholes etc are all available with composite sleepers. As such, it is one of

the best replacements of wooden sleeper.

3. Property of the wooden sleeper is not uniform due to presence of knotand other defects available in the timbers. Cost of the wooden sleeperalso increases which is disproportional with respect to increase in size.As compared to this, unit cost as well as property of composite sleepersis uniform in respect to shape and size (including length).

4. No toxic treatment is involved in composite sleepers like use of creosotein case of wooden sleepers.

It is worthwhile to point out that in USA where environmentalists are verymuch conscious about proper disposal of toxic materials, are facingproblems regarding disposal of creosote treated wooden sleepers.

5. The constituent material of the composite sleepers are thermo-plasticbased. As such, its recycling is possible.

6. Composite sleepers consume the waste plastic which otherwise isposing its disposal problem. As such, it is fantastic case of reuse ofwaste resources.

7. More use of composite sleepers will ensure less destruction to theforests.

5.0 Test criteria for passing of the thermo-plastic based composite sleepers:

Indian Railways have developed certain test criteria to ascertain the desiredmechanical properties and accordingly passing of such sleepers. The testcriteria are –

1. Static Load Test

2. Impact Load Test

3. Dynamic fatigue test

Furthermore, some other tests like resistance to ultra violet rays, fire resistanceand other tests which has not been standardized till on date for Indian

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Railways, was left to the suppliers of such materials to submit such reports.Details of the procedure about the various tests are given as below:

5.1 Static Load Test – This test is carried out to assess the adequacy of designas per details given below –

1. Load - 50t on each rail seat

2. Loading area - As per size of the bearing plate to be provided.3. Rate of loading - 5t/min.4. Number of samples- 3

5.1.1 Acceptance criteria – No visible cracks should be developed on the outersurface of the sleepers on holding the 50t load for 5 minutes.

Sleeper deflection at rail seat for FRP sleeper was kept as 3mm. In case ofcomposite sleeper other than FRP, deflection is likely to be more. Minimum tothe extent possible deflection is preferable. Deflection measurement andobservation of the cracks under rail seat shall be done at the interval of 5t load

e.g. at 5t, 10t, 15t….

5.2 Impact Load Test – Impact load test is required to assess the shockabsorption capacity of the sleeper, which the sleeper is about to bear duringthe train running as well as during derailment. The test scheme envisagesdropping of wheel on sleeper placed at 30o slope to horizontal plane atfollowing two locations:

i. 294mm away from centre line of rail toward centre.ii. 200mm away from sleeper end.

Wheel drop details are:

Weight of wheel - 500kg.Height of drop - 75cm.No. of drops - 2 at the same location.

5.2.1 Acceptance criteria – Only recess should form. No crack should appear onthe surface of the sleeper.

5.3 Dynamic Fatigue Test – This test is carried out to assess the structural

integrity of the product and to ensure absence of any void and other inherentmanufacturing defects (particularly for FRP sleepers) like dry patches, resin richareas, delamination inside the composite sleeper etc. Details about the test aregiven as below:

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Load:

Vertical - 4 to 20t on each rail seat.Horizontal - 40% of the vertical load.No. of cycles - 2 millionFrequency - 5HzNo. of samples - 3

5.3.1 Acceptance criteria – The sleeper should not develop any cracks on thesurface of the sleeper, which is of shear, flexural or torsional rupture (due tolocal buckling) in nature. Hairline localised cracks may be permissible providedthere is no reduction in the load carrying capacity of the sleeper. Sleeperdeflection at rail seat in case of FRP sleeper was prescribed as 3mm. In caseof composite sleeper, the same should be nearer to this.

6.0 Performance of the composite sleepers – Performance of sleepers in labtest as well as field test, which is known to RDSO till now is discussed asbelow:

6.1 Lab Test – Both the products have been lab tested in India as well as abroad.Basic properties required as per AREMA as well as Chicago Transit Authorityis given in Anenxure - 1, alongwith the respective values achieved againstthose parameters by the manufacturers of Tietek and Polywood sleepers.AREMA had introduced Part V in their Code in the name of EngineeredComposite Tie in 2003. Similarly, Chicago Transit Authority specified forcomposite plastic railroad tie bearing no. CTA 1117-020 of 2002. As such,these specifications are also of the recent origin. Without any reference, RDSOhad prepared test criteria about testing of such sleepers. The test criteria has

already been discussed in Para 5 above. Result achieved about such sleeperstested in India will be discussed first, followed by the test results conductedabroad.

6.1.1 Performance under static load test – Under this test, load of 50t is requiredto be applied at each of the rail seat and observations to be recorded. Sleepershould not fail in this regard.

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Performance of Tietek as well as Polywood sleepers is given as below:

S.No. Applied load in kN Average deflection Average deflection ofof Tietek sleeper Polywood sleeper

(in mm) (in mm)

1 0 0 0

2 50 1.62 1.91

3 100 2.45 3.03

4 150 3.28 3.89

5 200 4.15 4.57

6 250 4.98 5.43

7 300 5.80 6.19

8 350 6.82 7.04

9 400 8.20 8.06

10 450 9.73 9.17

11 500 11.83 10.2812 0 4.29 1.62

(Load released) (Residual deflection (Residual deflection)

Performances of both the sleepers are almost identical as far as deflection/ compression is concerned. After removal of the load, recoupment of thedeflection/compression was better in case of Polywood sleepers than that ofTietek sleepers.

6.1.2 Fatigue Test - Under this, sleepers are subjected to 2 million cycles ofdynamic loading, which is varying from 4 to 20t vertical and 1.6 to 8t horizontal

i.e. 40% of the vertical load. Both of these sleepers were tested at IIT/Madras.Both of the sleepers passed the test criteria and results are almost identical.

6.1.3 Impact/Derailment load test - Performance of the sleepers in impact/ derailment loading is given as below:

S.No. Type of sleeper Groove Size after wheel drop in mm

After 1st wheel drop After 2nd wheel drop

a. b. c. d. a. b. c. d.

1 Tietek sleeper 59 35 35 17 67 41 53 26

2 Wooden sleeper 61 41 50 21 81 57 193 28

3 Polywood sleeper 40 26 24 12 54 41 32 16

Note: Wheel drop hits the corner of the sleeper and

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a. Damaged length on the width portion.b. Damaged length on the depth portion.c. Width of damage in wheel drop.d. Depth of damage in wheel drop.

Wheels are dropped from the height of 75cms twice at the same location andat total 4 locations as shown in the figure. Average values of the results inrespect of a, b, c & d has also been given in the above table.

On perusal of the observations, it is clear that as compared to woodensleepers, Tietek sleepers as well as Polywood sleepers both performed better.Observations further reveal that with respect to derailment loading, Polywoodsleeper stands first, followed by Tietek sleepers and then after the bridgetimber i.e. wooden sleeper.

6.2 Ageing Test – Ageing is the phenomena, which determines the life of thesleepers. Being non bio-biodegradable in nature, composite sleepers are notaffected like wooden sleepers. However, it degrades in other fashion i.e.degradation due to ultraviolet rays. AREMA as well as Chicago TransitAuthority specifies that deterioration of material due to ultra-violet rays shouldnot be more than 0.003 inch/year (0.076mm/year).

Accelerated ageing test was got done from reputed testing labs by therespective manufacturers. Their results are given as below:

6.2.1 Tietek sleepers – As per the details submitted by M/s Tietek Inc, through M/sPatil Group, accelerate ageing test equivalent to 15 years of the exposure wasgot done on Tietek composite sleeper. Details are given below:

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S.No. Particulars Percentage retention of the strength

1. Tietek composite sleeper 75%

2. Soft wood sleeper (Oak) 50 to 60%

3. Hard-wood sleeper (Red Oak) 50 to 55%

The above figures show that deterioration rate of hardwood, as well as of the

soft wood is almost the same with a little bit better performance of softwood. Itseems to be somewhat controversial but the factual position as received, has

just been put up for sharing the result. Actually, performance of hardwood isbetter than the softwood. However, with respect to composite sleeper, retentionof 75% strength equivalent to 15 years exposure seems to be logical sincecomposite materials are non-biodegradable. It only degrades by ultra-violetrays.

6.2.2 Polywood sleepers: Accelerated weather test of the Polywood sleepers wasdone at University of Illinois/USA. Result as quoted by M/s Polywood which isequivalent to 20 years of the exposure, is given below:

S.No. Test Particulars Exposure OAK Polywoodcondition Sleeper Sleeper

1 Tie plate compressive Before Exposure 3,200 psi 2600 psimodulus After exposure 1,000 psi 3100 psi

2 Face hardness Before Exposure 3,600 lb. 6,300 lb.After exposure 1,000 lb. 7,800 lb.

3 Spike Insertion Force Before Exposure 11,000 lb. 7,200 lb.After exposure 3,900 lb. 6,900 lb.

4 Spike lateral Resistance Before Exposure 3,500 lb. 1,700 lb.After exposure 2,500 lb. 6,900 lb.

5 Spike Withdrawal Force Before Exposure 8,500 lb 2,600 lb.After exposure 1,900 lb 3,400 lb.

6 % Surface area loss from Before Exposure 0.9 % 0.0%checks/splits. After exposure 4.5% 0.0%

Accelerated weather test was got done as per provisions of AREMA containedin Document No. TD 96-010 dated April 1996.

On perusal of the above table, it reveals that except in spike insertion force

criteria, in all other respects, performance of Polywood sleeper improved overage. This is a very unusual phenomenon. Further detailed explanation is notavailable in the report prepared by Rutgers University of USA, which includedthe test report of Illinois University/USA. It is worthwhile to point out thatPolywood sleeper was developed at Centre for Advance Materials of RutgersUniversity, New Jersey, USA.

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Based on the test report, it can be concluded that Polywood sleeper may beone of the excellent composite sleepers of the future. However, details aboutthe mechanism of improving the performance of Polywood sleeper with respectto ageing are under correspondence with the manufacturers to ascertain howthe properties are getting improved in due course of time.

6.3 Other related test results: Other related test results as per AREMA standard

as well as Chicago Transit Authority has been shown in Annexure I. Perusal ofthe Annexure reveals that:

i. Polywood sleepers are lighter than the Tietek sleepers.ii. Coefficient of thermal expansion of Polywood sleepers is more

favourable than that of Tietek sleepers.iii. Screw spike withdrawal result of Polywood sleeper is also better

than that of Tietek sleepers.iv. Modulus of elasticity in compression of Tietek sleeper is better

than that of Polywood sleepers.

6.3.1 About rubber content: Tietek sleeper is containing rubber also, while thePolywood sleeper doesn’t. AREMA standard is silent about specifying any suchcontent. It shows that rubber content is acceptable to AREMA standard. But theChicago Transit Authority standard limits rubber contents to maximum 3%.Tietek sleeper as per the composition received through Patil Group is having12.5% of rubber content. Why Chicago Transit Authority is limiting the rubbercontent of 3% needs to be ascertained for getting the desired quality ofcomposite sleeper for Indian Railways.

6.4 Field Performance: M/s Patil Group with the proposal of Tietek sleeper

approached first. Hence, after successful Lab tests, Tietek Sleepers wereprovided on the two bridges as per the details given below:

S.No. Bridge No. Division/Railway Date of laying

1 894A Moradabad/Northern Railway 26.12.02

2 42 HWH/Eastern Railway 29.04.03

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PHOTOGRAPH OF TIETEK SLEEPER PROVIDEDON BRIDGE NO. 42 OF HOWRAH DIVISION

M/s Micron with the proposal of Polywood sleepers approached later on. Theirsleepers have also been successfully lab tested and in many of the parameters, it

was found better than that of Tietek sleepers. These sleepers are yet to be providedon some of the bridges for field tests.

PHOTOGRAPH OF POLYWOOD SLEEPER PROVIDED ONONE OF THE TURNOUT OF US RAIL ROAD.

Report reveals that both types of composite sleepers have already been

provided in large numbers on US rail roads and performing well.

Report further revels that Polywood sleepers have also been provided forpoints and crossing. Even with the composition of Polywood Inc., 3 bridges asper details given below have been constructed –

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i. One bridge of 25ft span was constructed in 1999 for Jeep andPedestrian at Fort Leonard Wood in Missouri/USA.

ii. Another bridge of 30ft span was constructed in 2000 on naturetrail along Hudson river in New Baltimore/USA.

iii. Third bridge having span of 40ft was constructed in 2002 onMullica River in USA.

6.4.1 Performance about gauge retention: On Moradabad Division, the sleeperswere provided during the extreme cold. It was inspected by the author of thispaper during the extreme hot period i.e. in June 2003. While laying thesleepers, –3mm gauge was maintained. At the time of inspection, gauge wasfound to be +4mm. As such, there is variation of gauge of 7mm from extremecold to extreme hot weather conditions. Considering extreme cold to extremehot temperature variation of about 40oC and taking coefficient of thermalexpansion as 7.5X10-5 as conveyed by the manufacturers, variation in length iscoming to 5mm on gauge length i.e. 1673mm.

Composite sleeper by nature is having more coefficient of thermal expansion as

compared to other sleepers like concrete, steel and wooden. Variation of 7mmin gauge from extreme cold to extreme hot was taken seriously by RailwayBoard. However, this is not the problematic area, if initial adjustment is beingdone at the time of laying the sleepers. Regarding this, some literature surveywas done. One of them is AREMA Part V of 2003. It very beautifully explainsthe thermal behaviour of composite sleepers. Relevant provisions of Pt. V ofAREMA of 2003 are reproduced below:

“Characteristics property of engineered polymer composites (EPC) ties is higher thermal expansion coefficient than wood, concrete, steel or engineered wood

product (EWP). Theoretically, this means that EPC ties could grow longer or shorter with changes in temperature as compared to the other tie materials for the same changes in the temperatures. However, field experience in a variety of locations and climates as shown that gauge is not affected to the degree predicted by direct calculations. The specification requirement for thermal expansion ensures that rail gauge will be maintained over a wide range of operating temperature.

While engineered polymer composite ties will undergo, at least, some dimensional changes due to change in temperature, it should be noted that these changes do not occur instantaneously with the change in ambient air

temperatures. The polymer matrix materials used in these ties are inherently poor heat conductors. While the surface of the tie may exhibit, a repeated change in temperature (e.g., when exposed to direct sunlight) the bulk of tie will not. Change in gauge will only not be seen as a result of changes in temperature over a single day-to-night cycle. However, over more long term seasonal changes in temperature, gauge dimensions will be affected –

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increasing as temperature gets higher and decreasing as the temperature gets lower as the bulk of the tie material has time to reach a thermal equilibrium at the new seasonal temperature.

If EPC Ties are installed at ambient temperatures below 4 0 C or above 38 0 C,gauge should be adjusted by 0.125” (3.2mm) (tighter at cold temperatures installations, greater at high temperatures) or otherwise recommended by the

manufacturer.

Since gauge adjustment exercise while laying the sleepers at bridge No. 894Awas not done, hence variation of gauge from –3mm to +4mm in view of theexplanation given in the AREMA Code is not a matter of concern.

6.4.2 Performance about-spike killing - While inspecting the sleepers provided atthe above-mentioned two bridges, one more problem i.e. spike killing wasreported on Bridge No. 42 on Howrah division of Eastern Railway but the samewas not reported on bridge No. 894A on Moradabad Division of Northern

Railway. Spike killing tendency reported on HWH division might be due tochange in material quantity. It is worthwhile to mention that the compositesleepers provided on different bridges were of different lot received at differenttime. To ensure that no spike killing tendency particularly at early stage,sleeper quality needs to be maintained by the manufacturer. In due course oftime, spike-killing problem may arise as we are facing with wooden sleepers.Regarding this, just as we have its solution in wooden sleeper by insertion ofwooden gulli, somewhat similar provision had been made in AREMA Code.Here Para 5.4.2.8 of the AREMA Code is worth mentioning which isreproduced blow:

“Tie plugs may be used in EPC ties, basically in the same fashion as they areused in sawn ties. The specification for wooden tie plugs are located in Article3.1.5. Polymer based plugging compounds (e.g. polyurethane) may also beused.

M/s Patil Group, representative of Tietek sleeper came with the idea that justlike plugging the wooden sleeper, Tietek Sleepers can also be plugged with thehelp of gulli made of the same material of which Tietek sleeper is composed.

It is expected that, if the provisions are working satisfactorily in foreigncountries, there is no doubt that the same will not give similar result here also.However, all such provisions needs to be tried on Indian Condition also forconfirmation.

6.4.3 Riding quality and compression: Till now, riding quality has been reported tobe good on bridges provided with such sleepers. Adverse compression hasalso not been reported.

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Conclusion

Literature survey, test results and performance of the sleeper abroad as well as in this country, revels that composite sleeper may be one of the alternative for bridge timber. It is also having potential in use of the same for non-standard turnout where it is not possible to standardize the PRC sleepers. Composite sleeper

will ensure use of plastic waste, which is creating otherwise environmental hazard in the form of land pollution as well as choking of the sewerage system. Furthermore, adoption of composite sleeper will ensure less destruction to the forests. In case of import of such sleepers to be used as bridge timber, cost of the same is likely to be between Rs. 7000 to Rs. 8000 per sleeper. In case, the same is manufactured in this country itself,cost of the same may come to around Rs.5000/sleeper. As such, it would be better that such sleepers to the requirement of Indian Railways may be got manufactured here itself.

**********

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Note : ‘‘__’’shows that the respective values are not known.


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APPENDIX

(Based on the report published by Center for Advanced Materials, Rutgers University, New Brunswick, New Jersey and the details submitted by M/s

Polywood, regarding use of product in bridges as well.)

As a part of reuse of the waste plastic, Prof. Thomas J Nosker and Research Scholar

Rich Renfree had taken this project. While finalizing of the optimum design, theychanged the composition of PS and HDPE to study its behavior. Every time, theytested the compressive strength Vs varying composition as well as compressivemodulus Vs varying composition. The results are plotted as below:

After analysis of the data and examination of the graphs, they found that HDPEand polystyrene are making immiscible mix. At the composition of about 35%PS to 65% HDPE, they found appreciable increase in the desired parameterand as such, this proportion was adopted. Microscopic level study reveals thatat this percentage, HDPE and PS bodings are interlocked to each others andas such, the same is giving best result. To achieve some more desirableproperties, some other additives are also added, which are the trade secrete.

After development of polywood plastic lumber, M/s Polywood tried to explore itsdiversified use. Most astonishing among them is use of the same in bridges, inthe form of “I” girder and decking components. Its further use in the form of

piling is also in process. Polywood plastic lumbers have been used on thefollowing bridges –

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1. In 1999 experiment was done in construction of 25ft span bridge forJeeps and pedestrians at Fort Leonard Wood in Missouri. Foundation ofthis bridge is made of steel piles.

2. Then after, in 2000, 30ft. bridge was built for Hikers on Nature Trailalong the Hudson River in New Baltimore, New York.

3. Report reveals that performance of the smaller bridge addedconfidence and in 2002, a 40ft. span bridge over river Mullica wasconstructed. Some photographs of the Mullica Bridge are given asbelow:

NOTE: HDPE stands for High Density Polyethylene. It is basically the materialused in mineral water bottles and some other similar products.

PS stands for Polystyrene. It is the foam type material, normally used infoamy type of tea and coffee cups as well as foam material used inPackaging.

“I” SECTION MADE OF POLYWOOD PLASTICLUMBERS FOR BRIDGES

MULLICA BRIDGE UNDER CONSTRUCTION

WITH POLYWOOD “I” SECTION

ANOTHER VIEW OF MULLICA BRIDGE UNDERCONSTRUCTION WITH POLYWOOD PLASTIC

LUMBERS.

COMPLETED VIEW OF MULLICA BRIDGE

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DIAGNOSTIC OF ULTRASONIC FLAW DETECTIONOF RAILS /WELDS -

A REVIEW

by

B. Deva Singh*

Ultrasonic testing of rails was introduced over Indian Railways during early1960’s. Since 42 years of its existence, number of testing procedure, specifications,guidelines and criteria have been issued from time to time depending on the need anddevelopment of technology. Mandatory provisions are made for ultrasonic testing ofvarious routes. An inspection may be deemed to have failed if it does not locate thedefects being sought, but will also be regarded a failure if it results in large number ofspurious defect deductions. The basic limitations are imposed by the technique itself.But the manner in which the technique is applied and the attitude of the operator will

also be significant in determining the overall reliability of testing.

It is to remember that a perfect technique badly applied may be less reliable than apoor technique applied consciously. A perfect inspection will find all the defects andgive rise to no false alarms.

The causes of unreliability in Ultrasonic flaw detection (USFD) are many. Butcan be related to a number of possible sources. They are

1. Defects:

(i) In this a dividing line is set up and features which exceeds this limit areclassified as defects when other features are ignored. The placement ofthis dividing line if it is low will result in higher apparent defect detectionrate but very few defects detected are failing.

(ii) Nature of Technique employed

(iii) Type of equipment used.

2. The operator:-. In ultrasonic testing the reliability depends purely on the

operator only, and the evaluation differs from operator to operator and no crosschecking is possible till the next check.

* CTE / S.C.Rly

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It is very common complaint among maintenance staff such as

(i) a declared defect during ultrasonic examination do not fail as expected.

(ii) a declared good rail or weld during ultrasonic examination do fail often.

3. PRINCIPLE INVOLVED IN THE USFD TESTING

(a) Vibrational waves of sound of frequency above the hearing range ofnormal human ear are referred as ultra sonics.Sound waves are of threetypes :

(i) Sub sonics : It has frequency below 1 cycle / second.(less than 1 Hz )

(ii) Sonics :It has frequency from 6 to 20,000 cycles / second..

(iii) Ultra sonics :It has frequency above 20,000 cycles / second. It is

inaudible.

(b) In Indian Railways ultra sonic testing is carried out with probes offrequency from 1.25 MHz to 4 MHz (1 MHz = 106 cycles / second).Theseprobes contains piezo electric crystals.

(c) Piezo electric crystals are of two types:

1. Natural crystal : (i) Quartz(ii) Rochel salt (sodium potassium tartarnate).

(iii) Tournaline.

2. Artificial crystals : (i) Barium titanate.

(ii) Lithium sulphate.

(iii) Lead zirconate titanate (PZT)

(iv) Lead meta niobate

(d) Natural crystals can withstand high temperature up to 6000 C.

Artificial crystals can withstand a high temperature up to 1300C. In Indian

Railways the artificial crystals “Barium titanate” is used.

4. The weakest link in rails is a thermit weld. The strength of thermit weld isequal to 56% of rail steel if the quality of execution is 100%. If the quality ofexecution is reduced the strength of weld decreases. So producing good weldsdepends on proper quality control. USFD testing of AT welds is one of the

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quality control system. In the similar way USFD testing of Rails is also one ofthe quality control system.

5. Periodicity of testing : As per GMT carried in section, the periodicity of testingis as follows:-:

5.1 Rails GMT Frequency

0-8 12 Months

8-12 9 Months

12-16 6 Months

16-24 4 Months

24-40 3 Months

above 40 2 Months

5.2 Welds :

(a) OLD AT WELDS : i) Initial testing

ii) After 80 GMT

iii) Subsequently after every 40 GMT

(b) SKV WELDS : i) Initial testing

ii) After 80 GMTiii) After 80 GMT further testing to be done if

failures in flange are more than 1% in a blocksection in a year.

iv) A round of testing to be carried out after8 years of life if the incidence of 1% of grossfailures in a block section are noticed.

(c) Testing of welds in : Testing of welds on all major bridges and 100 m onapproaches and on either approaches are to be tested once in a year.

major bridges

(d) Half moon cracks Testing welds : All welds to be tested for half mooncrack defect.

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(e) Gauge Face Corner of Rails : Gauge Face corner of rails to be testedin sections where traffic density is20 GMT and more.

6. Discussion on correction slip No. 10 of USFD manual 1998 :

6.1 As per the above correction slip para 4-1-1 (d) of chapter 4 i.e. “Checking of

equipment characteristic”

The characteristics of checking the “Dead Zone” of the probe was removed.The dead zone for single crystal probe is approximately 6 to 7 mm and fordouble crystal probe is 3 to 4 mm. If the dead zone of the probe is not checkedmonthly, there are chances of increasing the dead zone by which we caneither miss the flaw on the top of the rail or size of the flaw may differ.

6.2 As per Chapter 7 (ii) para 7.4 Action to be taken after detection of defects theclassification of defects are changed from REM to OBS and OBS (W). Action tobe taken for OBS & OBS (W) is to be clamped / joggled fish plated. For weld

flaw if it is clamped / juggled fish plated, it is safe. But for rails it is not safe,because in some rails we get multiple OBS flaws such as piping, head webseperation etc; If such rails are clamped / joggled fish plated at 2 or 3 places,it is not safe. It is better to replace the rail with 6 m long rail piece.

6.3 As per para 7.6 the interim action of “Defective weld” is that sectional PWI toimpose speed restriction of 30 Kmph till defective weld is replaced and post awatchman till joggled fish plates with clamps are provided, which practically isnot possible.It requires clarification.

6.4 As per chapter 9 (vi) para 9.5.1 Any flaw signal of 10% height or moreobtained from the normal probe either from the web or the foot location shallbe a cause for rejection of the AT weld. Practically the normal probe detectsflaw up to 90 mm (approx) in the A.T. weld. This has been proved by S.C. Rly& has been shown to RDSO for clarification . If the normal probe detects flawup to 90 mm only, then getting flaw signal of 10% beyond 90 mm (foot) is notpossible. If the sensitivity setting of normal probe is done with 3 mm dia holedrilled in the web foot junction of AT weld then only it is possible. So thesensitivity setting of normal probe for AT weld testing has to be revised.

6.5 As per para 9.4 4.5 the sensitivity setting of 70o 1.25 MHz probe is done with 3

mm dia hole drilled at the middle of flange through the AT weld. If the setting isdone with 3mm dia hole drilled horizontally in the center of flange i.e from thecentre of rail to the end of the flange then the result will be better.

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6.6 As per para 10.7.2 , additional hand probing of Web and Flange of Flash Buttweld with 70 degree probe has to be carried out as per para 7.8.2. Where asthe para 7.8.2 reads for Need Based Concept testing of Rails.

7. Latest developments in USFD testing :

(i) Flange testing of AT welds is done with 700 1.25 MHz. instead of 800

1.25 MHz probe.(ii) 450 probe of 2 MHz has been introduced for detecting half moon cracks

in foot web junction of AT welds.

(iii) 700 double crystal probe ( 2 MHz ) has been replaced by single crystalprobe for doing NBC Rail testing.

(iv) GFC testing of Rails has been introduced by shifting 70 degree probetowards gauge face as a trial base by 8 mm.

8. Clarifications required from RDSO / LKO:

a. When the Rail temperature increases the gain of the USFD machinedecreases because of the property of Perspex. Due to this, the flawecho decreases resulting in missing of flaw. The procedure given byRDSO / LKO for setting the USFD machine for temperature variation isambiguous. A clear procedure has to be developed for setting the USFDmachine for temperature variation.

b. The USFD testing of Flash butt welding in Flash Butt Welding plant isdone by 450 2 MHz probe is ambiguous, When tested by 450 probe, noflaw signal is displayed whereas when tested by 700 2 MHz probe

after laying the rails in the track, flaw signal is displayed. It is suggestedthat testing of rail head of FB welding by 700 2 MHz probe is also doneat the plant it self.

c. As per correction slip N0 13, USFD testing of SEJ, Para 12.8.5.2.1, theFlaw peak between 0 to 20% of full screen height shall be classified asOBS. The action taken for OBS is to be clamped/joggled fish plated,which is not practically possible in SEJ.

9. CONCLUSION:-

RDSO is requested to clarify all the above points so as to enable the field staffto carry out the testing without any ambiguity.

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INDIAN RAILWAYS PERMANENT WAYMANUAL 1986 - (EDITION)

Advance Correction Slip No. 87 Dated. 25-07-2003

The existing Para - 170 (6) of Indian Railways Permanent Way Manual may bereplaced as under:-

(6) (a) Where the beat of Keyman consists of PRC sleepers - The Keymanshould ensure that, in addition to his normal duty of inspection and tightening offittings, he should also carry out in a systematic manner from one end, greasing ofthe ERC and eyes of inserts at the rate of 20 sleepers per day. Greasing shall bedone as per the procedure laid down in para 1411 (5) (b) of IRPWM.

(b) Where the beat of Keyman consists of PRC as well as other types ofsleepers, SE (P. way) should make roster of keyman on monhly basis in theproportion of the beat, so that work mentioned in para 170(5) and 170(6)(a) are

completed in respective length. On any particular day however, he will do duties eitheras per 170(5) or 170(6)(a) only.

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EDITORIAL BOARD

Shri Budh Prakash Director/IRICEN Chairman

Shri S. K. Jain Professor/IRICEN Member

Shri Ramesh Pinjani Professor/IRICEN Member

Shri Ghanshyam Bansal Professor/IRICEN Member

Shri R. K. Verma Sr. Professor/IRICEN Executive Editor

p way bulletin dec03

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