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LARSEN & TOUBRO LIMITEDPAGE NO.- 1 OF 11

DATE:-05..11.07MSQ UP GRADATION (EPCC 1)

PROJECT REV.NO.- 0

PROCEDURE FOR ULTRASONIC

TESTING

PROCEDURE NO.-

LT/MSQ/P/UT/011

CONTENTS:

1.0 PURPOSE

2.0 SCOPE

3.0 REFERENCES

4.0 INSPECTION PERSONNEL

5.0 UT EQUIPMENTS

6.0 CALIBRATION FOR TESTING

7.0 TESTING PROCEDURE

8.0 ACCEPTANCE & REJECTION CRITERIA

9.0 ATTACHMENTS.

APPROVED BY L & T REVIEWED / APPROVED BY JACOBS

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TESTING

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1.0 PURPOSE:

The purpose of this procedure is to provide sufficient guidelines to operators,

examiners, inspectors, and engineers etc. to apply ULTRASONIC TEST method

correctly and efficiently as a Non-Destructive Test tool for determination of

discontinuities in welds.

2.0 SCOPE:

The Scope of this procedure covers all structural steel column welds (Build-up

Sections) which are likely to be fabricated at job site/shop of MSQ Up gradation

Project, Panipat Refinery, Panipat, Haryana. This procedure will be valid for Plate-to-

Plate welded joint only. Thickness of structural members varies from 10 mm to 50

mm. Material Spec IS 2062 Gr. A/B. & IS 2002 Gr. II

3.0 REFERENCE:

AWS D1.1, Sec 6

SNT-TC-1A of ASNT.

4.0 INSPECTION PERSONNEL

Ultrasonic Testing shall be performed by NDT Level II personnel in accordance with

SNT-TC-1A. NDT qualification shall include demonstration of ability to apply the rules

of the AWS D 1.1 code in the accurate detection and disposition of discontinuities.

5.0 UT EQUIPMENTS

5.1 Basic Unit

The UT equipment shall be the pulse echo type suitable for use with transducers

oscillating at frequencies between 1 and 6 MHz. The display shall be an A scan

rectified video trace.


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The Horizontal linearity of the test instrument shall be qualified over the full sound

path distance to be used in testing in conformance with 6.30.1 of AWS D1.1.

The instruments gain control shall meet the requirement of 6.22.4 and shall be

checked for correct calibration at 2 month intervals in conformance with 6.30.2.

5.2 PROBES / SEARCH UNITS

5.3 Ultrasonic search unit with frequency 1 4 MHz shall be used.

5.2.1 TYPE OF SEARCH UNITS

5.2.1.1Straight beam (Longitudinal wave) search unit transducers shall have an active area

of 10 mm dia crystal size.

5.2.1.2Angle beam search units crystal shall be 8 x 9 mm rectangular. The search unit shall

produce a sound beam in the material being tested within plus or minus 2 o. If one of

the following proper angles: 70o, 60o or 45o. The dimensions of the search unit shall

be such that distance from the leading edge of the search unit to the index point shallnot exceed 1.

5.3 Resolution

For straight beam search unit, the transducer shall be set in position F on the IIW

block as specified in the AWS D1.1. Transducer and instrument shall resolve all three

distances. For angle beam search unit, RC block shall be used as per clause no.

6.29.2.5.

5.4 Internal Reflection:

Angle beam search unit shall meet the criterion of clause 6.24.3. Internal reflection

check shall be verified at a maximum time interval of 40 hours of instrument use as

per clause 6.30.3.


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5.4 Probe Parameters

Type Size

0o Normal beam Probe 10 mm dia

Angle Probe

45o, 60o, 70o Angle probe 8mm X 9mm crystal

Frequency of probes 2MHz to 4MHz.

6.0 CALIBRATION FOR TESTING

6.1 Calibration of Base Unit

The detector until shall be calibrated by an approved Third party yearly or after any

major repair or service done to the equipment. In addition to this, the equipment

qualification shall be performed as per AWS D 1.1 clause.

All calibrations and tests shall be made with the reject control turned off.

6.2 Daily Calibration Tests

The Operator shall carry out and keep record of daily calibration checks of the

following:

Time-base linearity

Gain

Sensitivity

Probe IndexCalibration of Angle Beam search units shall be done with the use of an approved

calibration block, each angle-beam search unit shall be checked after each eight

hours of use to determine that the contact face is flat, the sound entry point is correct

and the beam angle is within allowed tolerance.


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6.3Calibration of Time Base

Time base and range calibration shall be set to accurately cover the entire ultrasonic

beam distance for each probe selected for examination of the sample, using basic

calibration blocks with artificial or defect reflectors at the commencement of each job

or probe change. The calibration shall be checked frequently throughout the

examination.

6.4Reference Calibration Blocks

The International Institute of Welding (IIW V1 & V2) UT reference block shall be the

standard used for both distance calibration and IIW V1 block shall be used for

sensitivity calibration. Other portable blocks may be used provided the reference

level sensitivity for instrument / search unit combination shall be adjusted to be the

equivalent of that achieved with the IIW block. The use of a corner reflector for

calibration purpose shall be prohibited.

6.5Beam Index for Angle Probe

The angle probe is positioned in the V1 block to obtain maximum echo for 100mm

radius. The index point is verified with the marking in the calibration block.

6.6Straight Beam Calibration

Sweep The horizontal sweep shall be adjusted for distance calibration to present

the equivalent of at least two plate thicknesses on the display.

Sensitivity The sensitivity shall be adjusted at a location free of indications so thatthe first back reflection will be 50 to 75% of full screen height.

6.7Angle Beam Calibration

Sweep The horizontal sweep distance shall be adjusted to represent the actual

sound path distance by using the IIW block.

The distance calibration shall be made using either the 5 in (152mm) scale or 10 In.

(250mm) scale on the display, whichever is appropriate. If, however, the joint


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configuration or thickness prevents full examination of the weld at either of these

settings, the distance calibration shall be made using 15 in. or 20 in. (400mm or

500mm) scale as required.

Amplitude or Sensitivity The Transducer shall be set in a position on the IIW V1

block to the indication from the 1.5mm hole to attain a horizontal reference-line height

indication. The maximum decibel reading obtained shall be used as the Reference

Level. b.

Calibration for sensitivity and horizontal sweep shall be made by the UT operator just

prior to and at the location of testing each weld.

Recalibration shall be made after a change of operators, each 30 minute maximum

time interval, or when the electrical circuit is disturbed in any way which includes the

following:

1. Transducer change

2. Battery change3. Electrical outlet change

4. Coaxial cable change

5. Power outage (failure).

6.8INFORMATION TO OPERATOR

The following information shall be provided to the operator before start of test.

Material type grade & form (cast, rolled, forged etc.)

Joint preparation details

The welding process

Details of the previous reports

Details of any post weld heat treatment

Differing thickness

Mis-match & non-alignment


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Referencing code section

6.9SURFACE CONDITION

The weld and adjacent parent material to the extent of examination shall be kept free

of slag, scale, paint, rust and weld spatter.

Any temporary attachment, which might cause restriction to scanning, shall be

removed.

Surface condition of the weld shall be as weld condition.

7.0 TESTING PROCEDURE

7.1 Couplants

Mixture of grease and oil shall be used as Couplant. Special emphasis shall be given

for post cleaning using cleaner.

7.2Testing of Welds.

7.2.1 Welds shall be tested using an angle beam search unit as shown in Table 6.7 of

AWS D1.1. The testing angle and scanning procedure shall be in conformance with

the above-referred Table. (See attachment)

7.2.2 All butt joint welds shall be tested from each side of weld axis. All welds shall be

tested using the applicable scanning patterns as per the referred standard to detect

both longitudinal and transverse discontinuities.

7.2.3 Scanning plan shall be prepared for each type and thickness of weld joint.

7.3 Extent of Testing

The entire base metal through which ultrasound must travel to test the weld shall be

tested for laminar reflectors using a traight-beam search unit. If any area of base

metal exhibits total loss of back reflection or an indication equal to or grater than the

original back reflection height is located in a position that will interface with the

normal weld scanning procedure, its size, location, and depth from the A face (see


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Annex 1) shall be determined and reported on the UT report, and an alternate weld

scanning procedure shall be used.

7.3. Indication Level a

When a discontinuity indication appears on the screen, the maximum attainable

indication from the discontinuity shall be adjusted to produce a horizontal reference

level trace deflection on the screen. The adjustment shall be made with the calibrated

gain control, and the instrument reading in decibels shall be used as the Indication

Level, a, for calculating the Indication Rating, d.

7.4 Attenuation Factor, c

The Attenuation factor, c shall be attained by subtracting 1 in. (25mm) from the

sound path distance and multiplying the remainder by 2. This factor shall be rounded

out to the nearest dB value.

7.5 Indication Rating, d.

The Indication Rating, d represents the algebraic difference in decibels between the

indication level and the reference level with correction for attenuation as indicated in

the following expressions:

Instruments with gain in dB: a b c = d.

7.6 Basis for Acceptance or Rejection.

Each weld discontinuity shall be accepted or rejected on the basis of its indication

rating and its length in conformance with Acceptance Criteria mentioned. Only thosediscontinuities which are unacceptable need be recorded on the test report.

7.7Size Evaluation Procedure

Straight Beam Testing The approximate size evaluation of the reflector shall be

made by beginning outside of the discontinuity and moving the transducer toward the

area of the discontinuity until the indication on the display begins to form. The leading

edge of the search unit at this point is indicative of the edge of the discontinuity.


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Angle Beam Testing The following procedure shall be used to determine lengths

of indications which have dBratings more serious than for a Class D indication as per

Acc Criteria. The length of such indication shall be determined by measuring the

distance between the transducer centreline locations where the indication rating

amplitude drops 50% (6dB) below the rating for the applicable discontinuity

classification.

7.8 Inaccessibility

If part of a weld is inaccessible to testing with the requirements mentioned in the

table 6.7 of AWS D1.1 due to laminar content, the testing shall be conducted using

one or more of the following alternative procedures as necessary to attain full weld

coverage.

Weld surface(s) shall be ground flush

Testing from Both sides. (Face A & Face B)

Other search unit angles shall be used.

Other scanning patterns can also be used. (See sr. no. 3 of Annex 1)

8.0 ACCEPTANCE & REJECTION CRITERIA

The applicable Acceptance & rejection criterion is as per Table 6.3 of AWS D1.1.

(See attachment).

9.0 ATTACHMENTS

Annex 1 - Details of Job Thickness, Weld joints, and Scanning patterns / methods.Annex 2 Table 6.7 of AWS D1.1 for selection of Testing Angle.

Annex 3 -Acceptance & Rejection Criteria, Table 6.3 of AWS D1.1.

10.0 DOCUMENTATION

The records of test reports shall be maintained in the format no. LT/MSQ//UT/025

Rev. 00.


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Single side scanning for Single V

60o Butt Joint up to Full Beam

path (1 V)

Double side scanning for Double V 60o

Butt Joint. Up to half bem path on both

sides ( V)



PROJECT REV.NO.- 0


TESTING

PROCEDURE NO.-

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ANNEX 1 - Details of Job Thickness, Weld joints, and Scanning patterns / methods.

1. For Job Thickness 10 & 12mm. Angle of Probe 70o, Freq. of Probe 2MHz.

2. For Job Thickness 20, 25 & 32m-m. Angle of Probe 70o, Freq. of Probe 2MHz.


Face B

Face A

Full Beam Path (1 V) Half Beam path ( V path)

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3. When the Web plate joint fitted with Flange plate, Scanning to be done as per the

below sketch for web & flange joining area.


Flange Plate

Web PlateWeb Plate to Web

Plate Joint

Normal

Probe Angle Probe

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