INDIAN RAILWAYS INSTITUTE OF CIVIL ENGINEERING, PUNE ���������������������� ����������������������������

PROJECT REPORT ON

A.T. WELDING WITH AUTOMATIC TAPPING SYSTEM (AN EXPERIENCE IN AGRA DIVISION)

� ������������������������������������������ !������"�����"�#��$�!�������%��

INTEGRATED COURSE BATCH NO. 613 17TH JULY – 29TH SEPTEMBER-2006

UNDER THE GUIDANCE OF Shri Rajesh Kumar Prof. Track-I Prepared by:-

1. Shri J.R. Meena AIE/RDSO/LKO 2. ,, Lokesh Verma AXEN/C/JBP

3. ,, Rajveer Singh ADEN/GONDA

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CONTENTS S.No. Item Page No. 1. Introduction ���&���%� 1

2. Probable Causes of AT welding Failure 1

�������������$����'������$��������������$�����% 3. Identified areas of upgradation (&&��$�����$��&��)����*��+�% 2-3 4. Global Leaders in AT Welding �������������$��!������,�-���!��.����% 4 5. Methodology for establishing superiority ��.������������������$������$��$���/���0��% 4-5 6. Lab Evaluation ��������1�����"�.����$����% 5-9 7. Field Trial '������*���% 10 8. Execution superiority features ��,���2�����.���������������% 10 9. Comparison of AT welding technique offered by Global leaders

in the field AT welding vis-à-vis that prevalent on the Indian Railways 11-14 ��������������"�#�"������2��������!������,�-���!��.���!�#��������������������������������0��$���������%�

10. Comments on results ������"��#�������������% 14-15 11. Constitution of steady team !0�����$������������������$�����3����% 15 12. Recommendations !0�����$������������������$����4��% 16-17

13. Conclusion ��,$�,�/�% 18-19

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1. Introduction ���&���%� Indian Railway have a AT weld population of over 4.3 million. Out of these, over 3 million welds are of SKV type. The population of SKV weld is growing at the rate of about 0.8 million per annum. Age wise over 1.3 million joints have served for more than 10 years. Indian Railway has a high failure rate of AT welds. Failure of even a very small percentage of welds executed annually poses a serious challenge in ensuring train safety. Weld failures on Indian Railway constitute a large percentage of the rail and weld failures taken together. Year wise figures of rail/weld failures from year 2000-01 to 2003-04 are summarized below: Year Rail Failures Weld Failures Total Failures 2000-01 3342(33.43%) 6657(66.57%) 9999 2001-02 3551(31.39%) 7763(68.61%) 11314 2002-03 3196(30%) 7488(70%) 10864 2003-04 2761(42.5%) 4941(57.5%) 8592

Total 12850(32.3%) 26849(67.6%) 39699

It can be seen from the above that approximately 68% of total rail and weld failures occurring on Indian Railway are weld failures.

Keeping in view the magnanimity of the problem as illustrated by the table above, a work to acquire state of the art technology to obtain improved quality of Alumino Thermit welds has been sanctioned by Railway Board under SRSF costing Rs.30 crores. The objective of the project is to acquire the state of the art AT welding technique as a complete package encompassing entire gamut of activities involved in the welding. The package would involve improvement in the consumables and equipment, training of welders and supervisors and the latest technological advances in this field from global leaders. It is expected that such package would ensure life of welds equivalent to that obtainable on advance Railways of World.

In view of above, it is essential to examine areas responsible for imparting higher failure rate to Indian AT welds. 2. Probable Causes of AT welding Failure (B.]Ò. ÉèʱbÆMÉ EÒ ÊÉ¡ ±ÉiÉÉ Eä ºÉƦÉÉÊÉiÉ EÉ®hÉ ): 95% of the weld failures are transverse fracture mostly initiating from foot as seen in the failure investigations of welds in M&C Dte. The major causes of weld failures are as under: Execution stage (Poor quality of execution):

i) Lack of adequate fusion caused due to inadequate heating ii) Too wet luting sand produces porosity in thermit steel and pin holes/porosity is observed

in weld collar.

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iii) Use of damp crucible during thermit welding or presence of moisture in the portion produces porosity throughout the weld section.

iv) Inclusions in the weld steel due to improper cleaning and/ or overuse of the crucible

leading to weld failure.

v) An improper judgment regarding completion of reaction of portion, tapping the molten metal into the mould either too early or too late.

3. Identified areas of upgradation (&&��$�����$��&��)����*��+�%�:

Some of the areas which are perceived to be the weakness on IR and therefore in need of up gradation are described hereafter.

Execution of Welding:

The emphasis needs to be in the reduction in element of human error. Therefore, the technique should offer optimum level of automation/mechanization. Few of the features in vogue on advance Railways of World are: One-shot crucible: Used only for one weld, the one shot crucible is made from a refractory compound agglomerated by means of synthetic resin. The thermic factor of this crucible is notably better than the conventional crucible and its use results in cleaner steel and consistent weld quality. The need for accurate adjustment of crucible on its frame is eliminated.

One-shot crucible

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Auto Thimble: The use of auto thimble ensures that the pouring commences at the correct temperature.

Crucible with Auto Thimble

Use of adequately mechanized preheating technique: Compressed air/petrol, oxygen/propane systems of preheating ensuring that mechanized means are available to ensure desired pressure of gas. In conventional air/petrol preheating system such control is done manually. Therefore ,desired pressure in tank can not be assumed to be proper at all times.

Preheating System Acquiring Skills: The quality control regime followed by advance Railway systems in world as regards to training of welders/supervisors and their regular monitoring is superior. The acquisition of the technique should be coupled with the training and monitoring regime commensurate with the technique being offered.

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Alignment of Rails Using ‘A’ Frames

4.0 Global Leaders in AT Welding �������������$��!������,�-����!��.����%:

Based on literature survey, it was found that there are following leading firms in the field of alumino thermit welding in the World:

i) M/s Elektro Thermit GmbH & Co, KG, Gerling Strasse, 65. D-45139, Essen,

Germany. ii) M/s Railtech International, ZL du Bas Pre-59590, Raismnes, France.

5.0 Methodology for establishing superiority ��.������������������$������$��$���/���0��% :

Based on the discussion with the firms following methodology was formulated with approval of Railway Board:

5.1 Establishing superiority of technique (laboratory stage)- The firms should send internal

test results for 5 welds using technique proposed to RDSO for evaluation. 5.2 Establishing superiority of technique in Indian Conditions (field stage)- Firms will

weld 50 joints with their own welders, portions, consumables, supervisors in open line section. There should not be any defects when tested by USFD and weld should be free from fins, blow holes etc. Weld should survive at least 15 GMT traffic without developing any defect/failure. Higher fatigue strength will be specified for these welds as compared to welds executed with existing technology. In addition, 50 welds will be executed by Indian Railway welders using the consumables and technique provided by the firm to provide exposure of the technique to Indian Railway welders. However, the welds executed by Indian Railway Welders will not be used for various tests for evaluation of the technique.

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110

120

130

140

150

160

10 15 20 25 30Deflection,mm

Tran

sver

se B

reak

ing

Loa

d,t M/s RAILTECH,

France,

M/s Elektro-Thermit,Germany

M/s ITC,KanpurCAP,2pc.,60KgUIC

5.3 Extensive field trials: This work should be completed in a time frame of 6 to 8 months

and the welds so executed will be monitored by RDSO for a period of 1 year. The evaluation criteria for in-service trials are proposed as under:

a) Defective welds when tested by USFD at the end of evaluation period should be less than 0.2%.

b) Firms while submitting the offer should indicate the allowable % age of weld failure up to the end of evaluation period.

using same methodology, stress range and stress reversal range. The firms offering the welding technology therefore, would have to conduct tests accordingly. In the meanwhile full understanding of fatigue strength determination methods and their relative superiority will have to be adjudged after discussions / deliberations with some of the advance Railways specially France, Germany, UK etc.

6. Lab Evaluation ��������1�����"�.����$����%:

The results of lab evaluation of the welds namely, USFD test, hardness test, transverse breaking load/deflection test, macro examination, spectrographic analysis and fatigue test and reaction bar tests are surmised below:

6.1 Transverse breaking load/Deflection test:

From the above, it can be seen that: • Transverse breaking load and deflection obtained for the technology offered in the project

are comparatively higher than existing techniques.

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• The values obtained are significantly higher than the limits specified in IRST-19. 6.2 Hardness: Comparative values of Hardness test results obtained for AT welding technique of 60Kg (90UTS) rail joints

Hardness Test (BHN)/3000Kg/10mm.ball/10Sec. of M/s HTI,Raipur S.

No. M/s ITC,Kanpur CAP,2pc.,60Kg

M/s HTI,Raipur CAP,2pc.,60Kg

M/s RAILTECH, France M/s Elektro-Thermit, Germany

PM HAZ WM HAZ PM PM HAZ WM HAZ PM PM HAZ WM HAZ PM PM HAZ WM HAZ PM 1. 269 285 269 255 269 277 285 285 302 269 255 255 269 262 255 269 277 269 281 262 2. 277 269 269 277 269 277 285 285 288 269 255 255 269 248 269 285 285 269 281 269 3. 269 269 269 269 269 269 277 277 285 269 255 255 275 269 248 269 281 273 281 269 4. 277 262 269 285 269 255 285 285 289 285 262 258 269 269 269 269 281 273 281 277 5. 269 277 269 285 269 269 277 277 285 277 255 269 275 269 269 269 273 269 281 269 6. 269 269 269 285 269 277 289 289 297 277 269 262 275 275 255 262 269 255 277 269 7. 269 269 277 277 269 285 285 285 294 277 269 269 269 269 269 269 273 269 281 269 8. 277 269 277 269 277 269 285 285 285 269 269 255 269 255 255 269 285 255 285 269 9. 269 269 269 277 269 269 292 292 302 285 255 269 269 281 269 269 273 269 281 269

10. 269 277 269 277 269 269 297 297 298 293 255 277 277 262 255 269 285 265 269 262 11. 277 269 277 269 277 262 269 269 285 269 255 277 277 262 255 277 285 265 285 277 12. 269 277 277 277 269 269 277 277 289 269 255 269 277 255 255 277 281 269 273 269

Specified 269 Actual PM+ 20

269+20 Actual PM +

20

269 269 Actual PM+ 20

269+20 Actual PM+ 20

269 269 Actual PM+ 20

269+ 20

Actual PM+ 20

269 269 Actual PM+ 20

269+20 Actual PM +

20

269

From the above it may be seen that: • In case of Railtech, the hardness in the HAZ for four samples is beyond the specified

limits. • In case of ElektroThermit, the hardness of the weld metal has been found to be lower

than the specified limits for four samples.

6.2 Fusion Zone and Heat affected zone (HAZ): Extent of Fusion Zone and HAZ for A.T.

S K ET C H SH O W ING W IDT H O F FZ /HA Z O N M A CR O E TC HE D L O NG IT UD IN AL /VE RT ICA L

S EC T IO N CU T T HR O U G H A .T . W EL D

71. 4557

A

B

C

D

E

F

G

H

I

J

HA Z

W Z

HE A D

W EB

F O O T

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Welding Technique of 60Kg. (90UTS) Rail with CAP Preheating Technique in vogue on IR and state of the art AT welding techniques are presented in comparative format below:

M/s HTI,

Raipur

M/s ITC, Kanpur M/s RailTech, France M/s Elektro Thermit, Germany

Pre-heating time 4.5 minutes 4.5 minutes 6.0-7.0 minutes 5.5-6.0 minutes Range Aver. Range Aver. Range Aver. Range Aver.

A 67-71 68.333 67-71 68.333 45.8-51.5 48.416 83.6-91.6 88.02 B 34-38 35.333 34-38 35.333 30.7-35 33.116 46.9-51.8 49.15 C 47-55 51.166 47-55 51.166 39.5-49.7 42.933 42-50.9 45.88 D 27-35 31.5 27-35 31.5 38-41 39.416 37.1-42.6 38.60 FU

SIO

N

ZON

E

(in

m

m.)

E 52-66 59.166 52-66 59.166 58-60.8 58.9 53.8-60.3 55.45 F 18-21 19.166 18-21 19.166 20-29.5 23.116 12.1-17.4 15.57 G 27-35 32.166 27-35 32.166 26.2-31 28.516 31.8-34.7 33.20 H 19-24 21 19-24 21 18-23.5 21.166 23.1-25.5 24.30 I 21-32 27.166 21-32 27.166 21-27 24.083 23.8-25.9 24.45

HE

AT

AFF

EC

TE

D

ZON

E (i

n m

m.)

J 17-19 18.3 17-19 18.3 12-16.3 14.283 16.0-19.6 17.68

A+F (Max.) 89 95 75.37 106.9 B+G 70 79 64.1 86.5 C+H 76 82 67.7 75.4 D+I 66 74 66 66.8 E+J 85 84 75.8 79.9

A+F(Min.) 85 89 68 104.0 B+G 61 70 59.5 79.3 C+H 68 76 61.8 66.1 D+I 48 66 59.8 61.6 E+J 75 85 70.0 70.3

A+F(Aver.) 87.5 92.833 71.533 103.58 B+G 67.5 76.833 61.633 82.35 C+H 72.166 77.833 64.066 70.18 D+I 58.666 68.833 63.5 63.05 E+J 77.5 76.5 73.261 73.13

Range (Min.-Max.),mm. Location

ITC HTI Rail Tech ElektroThermit Top of weld head 85-89 89-95 68-75.37 104-106.9 Head-web region 61-70 70-79 59.5-64.1 79.3-86.5 Web 68-76 76-82 61.8-67.7 66.1-75.4 Web-foot region 48-66 66-74 59.8-66 61.6-66.8 Weld Bottom 75-85 85-89 70-75.8 70.3-79.9 Figures in Green and Red colour represent lowest and highest values respectively. Following can be concluded from above:

• The HAZ of RailTech welds is amongst the lowest. • The HAZ of ElektroThermit welds is amongst the highest.

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6.4 Weld metal chemistry : Comparative values of weld metal chemistry for A.T. Welding Technique of 60Kg. (90UTS) Rail with CAP Preheating Technique in vogue on IR and state of the art techniques of Railtech and Elektrothermit are as under:

Values observed during Lab evaluation Element(%) Specified values in

IRST-19(%) M/s HTI,Raipur (%)

M/s ITC,Kanpur (%)

M/s RAILTECH, France (%)

M/s Elektro Thermit, Germany (%)

C 0.5-0.7 0.58-0.62 0.56-0.69 0.645-0.664 0.47-0.56 Mn 0.8-1.3 1.17-1.26 0.86-1.17 0.79-1.02 0.53-0.65 P 0.05 (Max.) 0.05 0.026-0.040 0.032-0.033 0.019-0.023 S 0.05 (Max.) 0.03 0.014-0.041 0.008-0.012 0.005-0.007 Si 0.5 (Max.) 0.35-0.66 0.67-0.92** 0.65-0.86 0.71-0.83 V* 0.1-0.15 0.11-0.13 0.006-0.007** 0.010-0.011 0.009-0.01 Mo* 0.1-0.25 0.02 - 0.02 0.02 Al 0.15-0.65 0.19-0.21 0.268-0.573 0.087-0.20 <0.06-0.230 Cr 0.2 (Max.) - 0.014-0.028 0.03 0.08-0.11 Ni - - 0.012-0.017 - -

*Either Vanadium (V) or Molybdenum (Mo) may be used as grain refiner ** Lab evaluation was undertaken before the complete weld metal chemistry was specified in

IRST-19-1994. It is seen form the above table that the weld metal chemistry obtained for M/s RailTech, France is within the limits specified as per IRST-19-1994 for most of elements except for Si, V /Mo, Al & Mn. In case of M/s ElektroThermit, Germany, the limits specified for Al,V/Mo, Si, Mn, C are not matching to the values obtained. It may however, be noted that while offering the state of the art technique firms will have to be given freedom to adopt suitable chemistry for obtaining desired results. 6.5 Fatigue test: IRS-T-19 specifies the requirement of fatigue strength of weld as 24Kg/mm2 (20Kg/mm2 tension, 4Kg/mm2 compression). It also specifies that in event of a firm developing welding technique for both 52Kg and 60Kg rail sections, the fatigue testing is required to be done only for the lower section. Due to this, fatigue strength data for UIC 60 welds were not available. Therefore, it was decided to undertake fatigue testing of UIC 60 rail section welds of welding techniques in vogue on IR to obtain benchmark value. Both the firms had provided fatigue strength of their weld produced by the technology offered. However, study of the details sent by them revealed that the test set up is quite different from the one prescribed in IRS-T-19. On this account, ready comparison of fatigue strength with specified values in IRS-T-19 was not possible.

In view of this, it was decided that fatigue test on AT welds executed by state of the art technology should be conducted using the method followed on Indian Railways. Accordingly, the test joints executed by M/s Rail Tech, France and M/s Elektro Thermit, Germany (USFD tested and certified good) were brought to TM lab and fatigue testing on these joints was undertaken.

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The setup available with TM lab was utilized for this purpose as shown in photograph below. Existing technology (M/s ITC Kanpur) M/s ITC was requested to provide samples for fatigue testing. The weld samples provided by M/s ITC, were produced using CAP preheating technique and welding was done in the firm’s premises at Kanpur using portions from the batch no.050196. While testing as per test scheme, one sample failed at 1505000 cycles at 24Kg/mm2 stress range whereas all three samples tested at 23Kg/mm2 stress range survived as shown in Table below.

The setup available with TM lab at RDSO Summary:

The fatigue test results obtained so far are summarised below:

S. No.

Rail section Fatigue strength as per IRST-19-1994

Fatigue strength of AT welds technique prevalent on IR

Fatigue strength of RAILTECH welds

Fatigue strength of Elektro-Thermit

1. 52 Kg (90UTS) 24 Kg/mm2 24 Kg/mm2 -- -- 2. 60 Kg (90UTS) -- 23 Kg/mm2 24 Kg/mm2 24 Kg/mm2

It can be seen from the above that fatigue strength of AT welds executed using AT welding technology offered by Global leading firms M/s RailTech, France and M/s ElektroThermit, Germany is found to be 24 Kg/mm2 which is at par with the value specified in IRS-T-19 and marginally higher than actual value of limited fatigue test conducted on welds of existing welding technology on IR.

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7.0 Field Trial '������*���%: a) 49 nos. of field trial joints were executed at Farah station yard in Agra - Mathura section of

Agra Division/NCR in September 2004. Welding expert deputed from M/s Rail Tech, France, executed all the above joints. Out of these 48welds were executed in cess and one weld was executed in-situ. These joints had accumulated traffic of 44 GMT. These joints have been inspected jointly by RDSO, representatives of firm and NCR on 24.08.05-26.08.05. Visual observation was done after welds were executed. This indicated formation of side fin in one joint executed in-situ on account of improper fixing of 3 piece mould. The finish of rest of the joints were found to be satisfactory and superior to that achieved in the IR technology.

b) 50 nos. of field trial joints were executed at ‘Baad’ station yard in Agra - Mathura section of

Agra Division/NCR w.e.f. 24.4.05 to 28.4.05. Welding expert deputed from M/s Elektro-Thermit, Germany, executed all the above joints. Principal Chief Engineer/NCR/Allahabad has been requested to send the performance report of these trial joints as per the proforma at every 1 ½ month interval. NCR forwarded two reports in July 05 & August 05. As per these reports, physical condition of all the trial joints has been found satisfactory. The AT welding parameters adopted for welding techniques offered by global leading firms vis-à-vis welding technique prevalent on Indian railways are as follows:

Sr. No. Activity RailTech,

France ElektroThermit, Germany

ITC,Kanpur HTI,Raipur

1. Pre-heating time 6-7 min. 5.5-6.0 min. 4.5 min. 4.5 min. 2. Mode of Tapping Auto thimble Auto thimble Manual Manual

i) Tapping time Range

20-28 sec. 22-45 sec. 20+3 sec. 20+3 sec.

ii) Mean tapping time

22.68 sec 29.96 sec. ---- ----

iii) Std. Deviation of tapping time

1.59 sec 4.44 sec ---- ----

3. Mould waiting time

5-6 min. 6-6.5 min. 4.5-5.5min. 5.0-5.5 min.

4. Chipping time 45-60 Sec. 20-34sec. 1.0-1.5 min. 1.0-1.5 min.

8.0 Execution superiority features ��,���2�����.���������������% :� 8.1 Execution Methodology has following superior features in case of Rail Tech

International, France :

i) Use of A-frame for alignment/level.

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ii) Refractory material lining in mould for better weld surface finish. iii) One shot crucible for cleaner steel. iv) Auto thimble for reducing manual intervention. v) Use of readymade luting paste ensuring consistency required for luting. vi) Handy compressor unit vii) Use of sleek trimmer with manual trimming option.

8.2 Execution methodology has following superior features in case of Elektrothermit GmbH, Germany.

i) Refractory material lining in mould for better weld surface finish. ii) One shot crucible for cleaner steel iii) Auto thimble for reducing manual intervention. iv) Use of readymade luting paste ensuring consistency required for luting.

9.0 Comparison of AT welding technique offered by Global leaders in the field AT welding vis-à-vis that prevalent on the Indian Railways ��������������"�#�"������2��������!������,�-���!��.���!�#��������������������������������0��$���������%:�

Operation M/s RailTech, France M/s Elektro Thermit,

Germany Technique prevalent on Indian Railways

Alignment

1M Straight edge with filler gauge used for alignment of rails. In field, A-frame in combination with above used for guarding against movement due to temperature variation.

Uses 1M straight edge with wooden wedges similar to Indian Railways.

1M straight edge as shown above being utilized for the purpose along with wooden wedges.

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Mould

Three piece mould was

offered. This obviates fins at bottom of weld collar. Fixing of bottom plate requires skilled person. Inner lining of the mould was made up of superior finish refractory material to provide good surface finish to weld.

Two piece mould was offered. Inner lining of the mould was made up of superior refractory material finish to provide good finish weld. The mould is so designed that weld trimming is possible only by weld trimmer.

Two piece/Three piece mould with zircon wash are prevalent. The weld finish achieved is not as good.

Fixing of mould

Fixing of mould requires skill. Readymade luting paste is being utilized for sealing the gaps between the moulds. Slot is provided in the mould for effective sealing of gaps.

Fixing of mould requires skill much skill. Readymade luting paste is being utilized for sealing for the gaps between the moulds. Slot is provided in the mould shoe for effective sealing of gaps.

Luting sand is being used for the sealing the gap between mould. Water is added to achieve the desired consistency, often leading to porosity in the weld due to excessive moisture in sand.

Pre-heating

Compressed Air-petrol pre-heating system was offered manufactured by the firm themselves. The system is quite handy.

Compressed Air-petrol pre-heating system prevalent on Indian Railways was utilized for the purpose.

Compressed Air-petrol pre-heating system prevalent on Indian Railways.

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Crucible

One shot crucible with auto thimble

One shot crucible with auto thimble containing portion within.

Multiple use crucible being used on Indian Railways.

Portion

Portion packed in moisture proof polythene bag and corrugated carton.

Portion filled within the one shot crucible with auto thimble.

Portion packed in moisture proof polythene bag, jute bag and corrugated carton.

Tapping procedure

Tapping through Auto thimble

Tapping through Auto thimble

Manual tapping

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Trimming of weld

Performed by sleek trimmer

manufactured by firm. Manual operation is also possible in event of failure of power pack.

Trimmer used is hydraulic one and is same as in use on IR

Hydraulic trimmer being used on IR.

Finishing of weld

Rail Tech make profile

grinder. Profile grinder is the same as is in use on IR.

Profile grinder is the being used on IR.

10.0 Comments on results ������"��#�������������% 10.1 Rail Tech International, France 10.1.1 Transverse breaking load and deflection obtained in the tests on PLK technique are

comparatively higher and better than existing techniques as well as specified limits in IRS-T-19.

10.1.2 Hardness of weld metal is satisfactory although hardness in HAZ in four welds is

marginally out of limits specified in IRS-T-19. 10.1.3 The extent of HAZ of welds is amongst the lowest. 10.1.4 The standard deviation of the tapping time is only 1.59 sec. 10.1.5 The weld metal chemistry is at variance with IRS-T-19 for Si, V/Mo, Al and Mn.

Vanadium/Molebdenum are not used for grain refining. Grain size of welds has been studied at RDSO.

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10.1.6 The fatigue strength of welds is 24Kg/mm2 which at par is with the specified fatigue

strength in IRS-T-19. The fatigue strength is marginally higher than that of welds of existing technology which has been found to be 23Kg/mm2.

10.1.7 2.04 % of welds have developed defects in rail head with passage of 44 GMT. 10.2 Elektrothermit GmbH, Germany. 10.2.1 Transverse breaking load and deflection obtained in the test are comparatively higher and

better than existing techniques as well as specified limits in IRS-T-19. 10.2.2 Hardness of weld metal is below the specified value in IRS-T-19 in case of four welds

out of 12 test welds. 10.2.3 The extant of HAZ of welds in amongst the highest. 10.2.4 The standard deviation of the tapping time is 4.44 sec. 10.2.5 The weld metal chemistry is at variance with IRS-T-19 for S, Al, V/Mo, Mn and carbon

vanadium/molebdenum are not used for grain refining. Grain size of weld has been studied at RDSO.

10.2.6 The fatigue strength of welds is 24/Kg/mm2 which is at par with the specified fatigue

strength in IRS-T-19. The fatigue strength is marginally higher than that of welds of existing technology which has been found to be 23Kg/mm2.

11.0 Constitution of steady team !0�����$������������������$����4��%

In order to consolidate the gains made, it was considered essential to study all aspects of welding technology on offer including the manufacturing of portions and consumables, conditions prevailing on the Railways abroad, welders and their training etc. Keeping above in view, Railway Board constituted a study team for the above vide their sanction letter No.2005/E(O)II/14/159 dt:9-12-2005 comprising of following members: S K Agarwal, ED/Track(P)/Railway Board Harsh Kumar, ED/F(X) II/Railway Board A K Mondal, AED/M&C/RDSO P Funkwal, Director/Track/RDSO V K Bali, Dy CE/TM/HQ/NR

The above team visited M/s Railtech International, France from 14-12-05 to 16-12-05 and M/s ElektroThermit GmbH, Germany from 19-12-05 to 21-12-2005.

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12.0 Recommendations of steady team !0�����$������������������$�����3����%:

12.1 Amendments to IRS-T-19 a) Study team recommends following amendments in IRS-T-19 in order to bring benefits in

terms of quality with welds executed using existing technology with immediate effect: b) Permanent marking of welds by punch marks on non-gauge face side of weld be

introduced as prevailing on SNCF to address traceability issue. c) Portion manufacturing firms needs to maintain welder records which shall form part of

quality management system of the firms covering following:

� Welding training and competence � Weld records � Number of welds produced in a given period � Number of welds rejected � Number of welds failed in service

d) Audit of portion manufacturing firms and other approved welding execution firms

regarding training of welders and maintenance of records pertaining to welders by IR authorities needs to be introduced. These firms should also have internal auditing mechanism for checking and ensuring quality of welds being achieved by their welders in field and record of these checks shall be maintained.

e) The welders acquiring competency certificate for the first time should not be deployed on main lines till they graduate to become skilled welders.

f) Incorporation of well structured training and certification norms for welding agencies for execution of welds with portion manufactured by approved portion manufacturers in line with those prevailing in Europe.

g) Execution of welds by departmental welders needs to be reviewed critically as even after ensuring full traceability, practically no disincentive can be handed to the defaulting personnel( mostly gang men working as welder) in the present scenario.

h) Reprocessing of the rejected batch of portions should be abolished. Once a portion batch fails to meet acceptance tests, it should be disposed off.

i) Quality control measures in manufacturing of moulds needs to be introduced by all portion-manufacturing firms. These measures must include Quality Assurance Programme (QAP) for manufacturing of moulds, inspection of moulds, rejection criteria etc.

j) Random inspection of moulds (dimensional accuracy, finish etc.) needs to be incorporated in the schedule of inspection carried out at the time of acceptance of welding kits. Any mould failing the acceptance tests should become the cause for rejection of the corresponding batch of moulds.

12.2 Evolving Upgraded Standards for Welding Study Team recommends that IR urgently evolve an integrated approach to address

deficiencies in all spheres of welding activities namely execution, quality of

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consumables, welder training and certification etc. by upgrading AT welding Specifications and manual and put in place phase wise program for its full implementation in a period of 3 years to achieve about 0.4% weld failure rate. The Study Team recommends following specific areas to achieve above:

Execution of Welds a) Self-driving system for ensuring a good quality welds is a must. b) The complete system of granting competency to the welder, training and certification of

welder needs thorough reforms to bring it to the level of European norms in terms of provisions and reliability of welds.

c) The permanent marking of weld for traceability purposes needs to be decided and implemented immediately.

d) Availability of adequate number of trained welders commensurate with workload of

welding as well as adequate number of supervisors per welding team needs to be ensured by the weld executing agencies to eliminate possibility of poor quality in execution of welds. Frequency of inspection of welding team by the supervisor needs to be laid down and a record of his inspections needs to be maintained.

Quality of Consumables e) Improvement in the welding processes such as one shot crucible, auto thimble which

have become the norm in the advanced railway system are required to be introduced on IR to gain enhanced level of weld reliability.

f) A major upward shift in the quality of welding kit (mould quality and finish, abolishing clause regarding reprocessing of portion, tolerances in portion quality) has become imminent. The improvement in the quality of mould alone can offset major portion of cost of advance technology, since improved quality of mould would result in elimination of fins, thus avoiding periodic ultrasonic flange testing of welds for half moon shaped defect and increased fatigue strength.

Process Approval g) The system of granting process approval to welding process supplier needs review

especially as regards to the capability of the process suppliers in terms of quality systems prevailing for welder training, R&D work related to welding process (e.g. mould design) and quality control systems in manufacturing of portions and consumables.

h) The complete system of evaluation of a process including methods/procedures of testing etc. needs to be revised thoroughly based on international norms.

i) The initial and periodic ultrasonic testing regime for the welds is commensurate with the

quality of welds legislated and actually produced. This should be reviewed based on the inputs in the quality of welds with use of advanced technology to obtain corresponding savings in cost of testing.

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13.0 Conclusions ��,$�,�/�%: It is noted that the quality of execution of welds is of paramount importance for it can make or mar the entire efforts of any previous stage. It was learnt that the quality of welds will not improve merely by increasing quality of the portion or the crucible etc. these have to be in conjunction with improving the quality of welds. Poor workmanship of welders can completely nullify any other quality improvement at any other stage. It is there fore suggested that in the first phase we must improve the quality of welds being executed by the welders. Following suggestions are made to improve the quality of the welds being executed:

Well-designed tools and equipment to accomplish various activities involved in welding.

A well structured training for welders. The system of certification of welder and

re-certification has to be revamped.

Full traceability of welder, portion and consumable used. This alone ensures that welders are performing in conformity with the quality standards laid down.

Overall control on quality of welding is achieved by a well-designed overall

system and environment prevailing on Railway rather than purely by technology. The key elements of the quality control system are:

Welding agency is required to maintain welder records which forms a part of quality management system and include welder training and competence details, number of welds produced in a given period, number of welds rejected/failed.

The second set of suggestions is given below which aim to improve the other areas of the process.

� One-shot crucible and auto thimble have become the norm in most of the

advanced railway systems.

� Critical components of welding namely portion and crucible are centralized in order to keep strict quality control. The quality control starts from raw material level.

� In order to continuously maintain and improve quality through R&D, it is

essential that a process supplying firm is big enough to plough back a part of its earning in to R&D. This needs to be considered an important criterion while granting approval to a process-supplying firm by railways.

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� German systems emphasize more on organization for quality control and

training.

� The quality control in production of portion is of the highest order. Strict control over quality and quantity of ingredients is ensured. The accuracy in weight of ingredients and finished portions is extremely tight.

� Superior quality control on portions and other consumables.

� No reprocessing of portions batch is undertaken on failing to meet

acceptance standards.

� Process supplier is required to provide a process manual specifying critical parameters of welding process and their safe bounds and training requirements for welders.

� Self driving system for ensuring a good quality welds is in place:

� Prevention is considered more important than cure.