government of india ministry of railways on... · widely used on indian railways for detecting...

GOVERNMENT OF INDIA

MINISTRY OF RAILWAYS

Centre

for

Advanced

Maintenance

TECHnology

Maharajpur, Gwalior - 474 020 (INDIA)

: 0751 - 2470869 & Fax : 0751 - 2470841

BBOOOOKKLLEETT OONN

UULLTTRRAASSOONNIICC TTEESSTTIINNGG

OOFF RRAAIILL (Need Based Concept)

CAMTECH/C/2005/USFD/1.0

August - 2005

EXECELLENCE IN MAINTENANCE

(For Official Use Only)

UULLTTRRAASSOONNIICC TTEESSTTIINNGG

OOFF

RRAAIILL

(Need Based Concept)

Foreword

Ultrasonic flaw detection (USFD) technique is

widely used on Indian Railways for detecting flaws in

rails for safety consideration of the track. This booklet

gives correct knowledge for detecting flaws in the rail.

This booklet mainly focuses on procedure,

calibration of machine, flaw marking and action to be

taken during USFD testing of rail (need-based concept),

for ensuring reliable testing and optimum output of

machines.

Civil Engineering branch of CAMTECH has

made excellent effort to bring out this booklet. I am sure

that this booklet would be useful as reference book for

USFD machine officials & field staff of engineering

branch.

CAMTECH/Gwalior R.N.Misra

Date : 01 .08.2005 Executive Director

Preface

Detection of flaws in rails and their timely

replacement is an ongoing process. Timely detection &

replacement of flaws is required to avoid fracture in track,

which at times can have dangerous consequences.

The objective of this booklet is to provide basic

information and technical details regarding USFD testing of

rail (Need based concept) for the USFD testing staff and

inspecting official. It covers frequency of testing, calibration

and sensitivity setting of machine, interpretation of oscillogram

pattern, and marking of flaws with action to be taken.

This booklet is not statutory & contents are for the

purpose of guidance only. It also does not supersede any

existing instructions from Railway Board, RDSO, Zonal

Railways and provisions of IRPWM, USFD manual (CS upto

15) on the subject.

I am grateful for the assistance given by Shri Neeraj

Shrivastava, STA/Civil/CAMTECH, who went through the

complete text, collected information, data etc. Nice data entry

has done by Shri Ramesh Bhojwani, Console Operator,

CAMTECH.

We welcome valuable suggestions from our readers

for further improvements.

CAMTECH/Gwalior Manoj K. Agarwal

Date : 01.08.2005 Director/Civil

CONTENTS

Sr. No. Description/Topic Page Nos.

Foreword i

Preface ii

Content iii

Correction Slip iv

1.0 General 01

2.0 Equipment 02

3.0 Probes 03

4.0 Periodicity of rail testing 04

5.0 Classification of flaws 06

6.0 Competency of testing 07

7.0 Procedure of ultrasonic testing

of rails

07

8.0 Action to be taken 17

Notes 18

***

ISSUE OF CORRECTION SLIPS

The correction slips to be issued in future for

this handbook will be numbered as follows:

CAMTECH/2005/C/USFD/1.0/CS. # XX

date ……

Where “XX” is the serial number of the

concerned correction slip (starting from 01 onwards).

CORRECTION SLIPS ISSUED

Sr. No.

of

C.Slip

Date

of

issue

Page no. and

Item No.

modified

Remarks


Booklet on Ultrasonic Testing of Rail August - 2005

1

Go to index

Ultrasonic Testing of Rail (Need based concept)

1.0 General

Rails are periodically inspected for detecting flaws and

their timely replacement to avoid fracture in track, which

at times can have dangerous consequences. Detection of

flaws is carried out either by visual examination of rails

or by ultrasonic flaw detection (USFD) technique.

In USFD, flaws are detected by using ultrasonic waves

i.e. sound waves of 2-4 MHz. These waves are

generated, transmitted to the rail and received back from

the rail by small piece of electric crystal fitted in the

probe which moves over the rail. Reflection received

back is displayed on the oscilloscope screen.

Ultrasonic waves transmitted from the probe get

reflected backward whenever they encounter any change

in medium. On flawless rail, the waves are reflected

from the rail table and later from the rail bottom. On the

oscilloscope screen these reflections appears in the form

of two peaks at the distance corresponding to rail height.

On defective rail, the waves are reflected from the rail

table and then from the flaw surface seldom reaching rail



2

bottom. In this case second peak is nearer and the

distance indicates the depth of flaw.

With correct calibration and correct interpretation of

oscilloscope pattern, it is possible to detect type of flaw,

its magnitude and location.

2.0 Equipment

For USFD testing, RDSO approved, portable machine

based on scan pulse-echo technique with ultrasonic flaw

detectors are used. These machines are fully

transistorised and battery operated. Machines are of two

types viz. single rail tester (SRT) and double rail tester

(DRT).

Single rail tester (SRT)

Single rail tester is capable of testing only one of the rails

at a time and is provided with five probes i.e. 00, 70

0

Forward (F), 700 Backward (B), 37

0 Forward (F) and 37

0

Backward (B).

The signal received from the defects by any of the above

probes is indicated on the cathode ray tube (CRT) screen.

In order to find out the origin of detection i.e. which

probe has picked up the defect, process of eliminating

the individual probe operation is utilised.



3

Double rail tester (DRT)

The double rail tester is capable of testing both the rails

at a time. However, for each rail, only three probes have

been provided i.e. 00, 70

0 Forward and 70

0 Backward.

This equipment, unlike the single rail tester, has multi-

channel facility i.e. the signal received from each probe

can be instantaneously distinguished without taking

recourse to process of elimination. This equipment has

also been provided with a threshold arrangement, LED

display and audio alarm in addition to the CRT screen.

Thus there are three modes of defect indication i.e., CRT,

audio alarm and LED display.

Total life of the USFD machines is eight-year.

3.0 Probes

For rail testing double crystal probes are used as

under :

Probe

Type

Freq. Crystal

/size

Remarks

00 Normal

probe

4 MHz 18 mm

circular/ 18

x 18 mm

square

For detecting

horizontal

defects in

head, web or

foot.



4

70

0 Probe 2 MHz 20 mm

circular/ 20

x 20 mm

square

For detecting

transverse

defects in

head.

370 Probes 2 MHz 20 mm

circular/ 20

x 20 mm

square

For detecting

defects

originating

from the bolt

hole (star

crack). (with

SRT only)

For detection of bolthole defects, the DRT works on the

principle of back wall drop, which in the event of a

bolthole crack shows reduction in echo-amplitude of the

back wall.

4.0 Periodicity of rail testing

There are two systems of USFD testing based on

inspection frequency and permissible defect size viz.

conventional and need based system. In need based

system, frequency of rail testing is as under :

Initial testing

Rails are tested at steel manufacturing plant with on line

ultrasonic testing equipment. In case initial testing of



5

rails has not been done in the rail manufacturing plant,

the rail shall be tested either at flash butt welding plant or

at site. In no case rail should be laid in track without

USFD testing.

Subsequent testing

After the initial testing of rails, in rail manufacturing

plant the first retesting is carried out after the test free

period i.e. after passage of 15 % stipulated service life in

GMT or after passage of 25 % stipulated service life in

GMT for rails rolled in April 1999 and onward.

After retesting, subsequent testing on all BG routes is

carried out after passage of 8 GMT subject to maximum

interval of 1 year as under:

Route Annual GMT Testing frequency

BG Up to 8 12 months

>8≤12 9 months

>12≤16 6 months

>16≤24 4 months

>24≤40 3 months

>40 2 months

* For other sections, Chief Engineer may adopt a

frequency at his discretion.



6

Whenever rails are not tested in rail manufacturing

plants, the test free period is not applicable and the rail

testing shall be done at the periodicity given above right

from the day of its laying in field.

5.0 Classification of flaws

Depending on the nature and extent of internal flaws and

the traffic density and speed on the section, the defects

are classified as under (As per Annexure VII of USFD

Manual -1998) :

I.M.R. (immediate removal): The flaw which is

serious in nature and can lead to sudden failure is

classified as I.M.R. Immediately after detection,

such portions shall be marked with red paint (three

cross) on the web of the rail on both faces.

O.B.S. (under observation): If the defect is such

that it is not expected to result in fracture till re-

scanning is done, it is classified as O.B.S. Such

defects shall be marked by red paint (one cross) on

both faces of the web.

IMRW/OBSW: These are the defects at weld

location detected during through rail testing

requiring similar action as rail.



7

Go to index

6.0 Competency for testing

Inspector carrying out the ultrasonic testing of rail shall

be RDSO trained, in the techniques of USFD testing.

7.0 Procedure of ultrasonic testing of rails

The procedure for ultrasonic testing of rails is divided in

the following steps:

a. Visual inspection of equipment and accessories

b. Calibration of the equipment

c. Sensitivity (gain) setting of the equipment and

probes

d. Checking of the equipment and probes

e. Testing and interpretation

a. Visual inspection of equipment and accessories

(daily check)

Ultrasonic equipment is to be inspected daily before start

of work for proper functioning of plugs, holders, cables,

etc. In addition battery condition, proper functioning of

echo-control, proper control and smooth movement of

control wheel and alignment of the probe shall be

checked by the USFD operator before commencement of

the tests.



8

b. Calibration of the equipment

The ultrasonic rail tester is to be calibrated for 300 mm

depth range (longitudinal wave) with the help of 60 X 50

X50 mm block of steel to grade 45C8 of IS : 1875-1992.

Procedure of calibration

Switch on normal probe

Adjust the on set of the surface echo from the

Perspex of normal probe to zero by using horizontal

shift control knob/delay knob, provided in the

electronic unit.

Place the calibration block below normal probe

using water as couplant.

Adjust the range by H-shift/Delay and range control

knob simultaneously so that following signals

appear on the screen.

The location of signals for 300 mm has been

indicated below.

On set of the surface echo from the perspex at 0

main scale div.

60 mm signal at 1 main scale Horizontal Division.







9

The equipment is now calibrated for 60 mm of steel

per main scale horizontal div. for longitudinal wave.

c. Sensitivity (gain) setting of the equipment and

probes (weekly check)

The sensitivity of the USFD equipment shall be set up

once in a week with the help of standard rail pieces as

mentioned below:

(i) Place the testing trolley on the standard rail

piece having artificial flaws. Check the

alignment of probes to make sure that they

travel centrally in line with the axis of the rail

head and web.

(ii) Set the acoustic barrier of the normal probe at

right angle to the longitudinal direction of rail.

(iii) Adjust the gap of 0.2 mm approx. in between

the contact face of the normal probe and the

delay probe shoe. Check the gap by keeping the

straight edge of a 150 mm steel scale on the sole

using a feeler gauge or a stainless steel blade.

(iv) Adjust the gap of the angle probes as in (iii)

above.

(v) Open the water nozzle and regulate water flow

on the probes at an optimum speed.

(vi) The function of various probes is checked and

the sensitivity adjusted as under :



10

Normal probe: The equipment shall be able to

detect 5 mm dia. hole at the web-foot junction of the

standard rail. The amplitude of the flaw echo shall

be adjusted to 60% of full screen height by the

adjustment of gain knob of USFD. (position of

potentiometer knobs in the junction box should be

set at 50% rotation)

Angle probe 700 (forward & backward): The

equipment shall be able to detect 12 mm dia. hole in

the head portion of the standard rail respectively by

both forward and backward probes. The amplitude

of the flaw shall be set to 60% of screen height.

When the probe is in the reflecting range, a pulse

appears on the screen which during travel source

higher amplitude. The equipment should be

progressively moved till maximum height of the

pulse is obtained. At this location the height of the

pulse shall be adjusted to 60% of full screen height

by adjusting individual potentiometer provided in

the junction box.

Once the sensitivity/gain setting has been done it

should not be disturbed during testing.



11

d. Checking the equipment characteristics (monthly

check)

The characteristics of the equipment shall be

checked at least once in a month according to

IS:12666 - 88.

Following characteristics are checked -

Linearity of time base of flaw detector

Linearity of amplification of flaw defector

Penetrative power

Resolving power

Probe index

Beam angle

e. Testing and interpretation of Oscillogram

pattern

After sensitivity setting actual testing of rails is to be

carried out by moving the equipment over the rail and

the oscillogram pattern is interpreted for detecting flaws

and their classifications as under :



12

Go to index

(a) Rail defects

By Normal probe

Nature of defect Oscillogram

pattern

Classifi

-cation

1. Within fishplated

area

(i) Any defect

connected with rail end

in any location (head,

web, foot junctions) of

the rails end covering

both the bolt hole length

or covering first bolt

hole.

(ii) Any defect

connecting both bolt

holes.

(iii) Any defect

originating from bolt

holes and extended up

the head web junctions

or web/foot junctions.

For (i) & (ii)

No back echo,

Flaw echo with/

without multiples

Or

Drop in back echo

with flaw echo

with/ without

multiple

For (iii)

No back echo

with/ without flaw

echo

IMR

IMR



13

2. Outside fishplated

area (A) Any horizontal

defect progressing at an

angle in vertical plane in

the rail head at the

following locations -

In tunnel

On major bridges &

bridge approaches

(100 m)

In the vicinity of

holes near the weld.

No back echo

with shifting flaw

echo

Or

No back echo and

no flaw echo.

IMR

(B) Any horizontal

defect progressing

transversely toward the

rail head or foot at any

other location.

No back echo

with/ without

shifting flaw

echo.

OBS

3. Vertical longitudinal

split (piping) in any

length.

In case of partial/

complete loss of

back echo, side

probing shall be

carried out with 00

probe. If any flaw

echo with/without

multiples is

observed (in any

length).

IMR



14

By 700 Probe

Any transverse defect in

the rail head.

Flaw echo of 50%

horizontal scale

movement and

60% of full scale

height or more.

IMR



following locations-

In tunnel

On major bridges &

bridge approaches

(100 m).

In the vicinity of

holes near the weld.

Flaw echo of 30%

horizontal scale

movement and

20% of full scale

height or more.

IMR


the rail head at any other

location.

Flaw echo of 30%

to 50% horizontal

scale movement

and 20% to 60% of

full-scale height.

OBS



15

(b) Defects at weld location (AT+FBW)

By Normal probe

Nature of defect Oscillogram

pattern

Classifi

- cation

A) Any horizontal defect

progressing at an angle

in vertical plane in the

rail head at the following

locations-

In tunnel

On major bridges &

bridge approaches

(100m)

No back echo

with Shifting

flaw echo.

IMRW

B) Any horizontal defect

progressing transversely

in the rail head at any

other location

No back echo

with Shifting

flaw echo.

OBSW



16

Go to index

By 700 probe


the rail head

Flaw echo of

50% horizontal

scale movement

and 60% of full-

scale height or

more.

IMRW



following locations -

In tunnel

On major bridges &

bridge approaches

(100m).

Flaw echo of

30% horizontal

scale movement

and 20% of full-

scale height or

more.

IMRW


the rail head at any other

location.

Flaw echo of

30% to 50%

horizontal scale

movement and

20% to 60% of

full-scale height

or more.

OBSW



17

8.0 Action to be taken

Classif

ication

Painting

on both

faces of

web

Action to be

taken

Interim Action

IMR/

IMRW

Three

cross with red paint

Replacement by

a sound tested rail piece of not

less than 6 m.

within 3 days of detection.

PWI / USFD shall

impose speed restriction of 30 kmph

immediately. He should

communicate to section PWI about the flaw

location who shall

ensure that clamped joggled fishplate is

provided within 24

hours.

OBS/ OBSW

One cross with red

paint.

Rail/weld to be provided with

clamped joggled

fishplate within three days.

PWI/USFD to specially record

the observations

of the locations in his register in

subsequent

rounds of testing.

PWI/USFD to advise sectional PWI within 24

hours about the flaw

location. Keyman to watch

during daily patrolling till it is joggled fish-

plated.

***



18

Go to index

NOTES

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.



19

OUR OBJECTIVE

The contents of this booklet are for guidance only

& are not statutory. It also does not supersede any

existing instructions from Railway Board, RDSO

and zonal Railways & the provisions of IRPWM,

USFD Manual on the subject.

Contact person : Director (Civil)

Postal Address : Centre for Advanced

Maintenance Technology,

Maharajpur, Gwalior (M.P.)

Pin code – 474 020

Phone : (0751) - 2470869, 2470803

Fax : (0751) - 2470841

To upgrade Maintenance

Technologies and Methodologies and

achieve improvement in productivity and

performance of all Railway assets and

manpower which inter-alia would cover

Reliability, Availability, and Utilisation. ________________________________

government of india ministry of railways on... · widely used on indian railways for detecting...

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