QUALITY ASSURANCE AND CONTROL DEPT

MANUAL ULTRASONIC TESTING (FOR WELD)

1. SCOPE:

This procedure is established to conduct manual ultrasonic examination as per customer requirement / Approved QAP using Angle beam pulse echo ultrasonic technique to detect weld defects.2. APPLICABLE CODE & STANDARD:

IS 7340 (L. Edn.), IS 4260 (L. Edn.)& ASME Section V (L. Edn.)3. RESPONSIBILITY:Personnel performing Ultrasonic Examination shall be responsible for interpretation & evaluation of indications during the examination & preparation of examination reports. An ASNT Level III shall be responsible for overall supervision.

4. PERSONNEL QUALIFICATION:NDT personnel shall be qualified as per ASNTSNTTC1A.

1) Level II shall be responsible to set up the equipment, calibrate, perform tests and reports the result.

5. STAGE OF EXAMINATION:The Ultrasonic Examination shall be carried on pipes as per customer requirement / Approved QAP at manual UT station.

6. METHOD OF EXAMINATION:Angle beam contact method.

7. TECHNIQUE:Pulse echo technique.

8. SCANNING SURFACE:The surface shall be free from dirt, loose scale, rust, spatter and other foreign matters which may interfere with Testing process.

9. COUPLANT:

Water shall be used as couplant.

10. CALIBRATION STANDARD BLOCK: 10.1 IIW V1 / V2 Block.

11. INSTRUMENT CALIBRATION: 11.1 Screen Height Linearity:

Position an angle beam search unit on a calibration block, as shown in the below figure A.

that indication from the both the and T holes give a 2:1 ratio of amplitudes between the

two indication. Adjust the sensitivity (gain) so that the larger indication is set at 80% of full

screen height (FSH) without moving the search unit adjust the gain to successively set the

larger of the indication from 100 % to 20% of FSH., in 10 % increment (or 2 dB steps if a fine

control in not available).and read the smaller indication at each setting. The reading shall be

50% of the larger amplitude, within 5% of FSH. The settings and reading shall be estimated to

the nearest 1% of full screen. Alternatively, a straight beam search unit may be used on any

calibration block that provides amplitude differences, with sufficient signal separation to

prevent overlapping of the two signals.

Figure. A

11.2 Amplitude Control Linearity:

Position an angle beam or Normal beam transducer as shown in figure A. Such that

Indication obtained from the calibration block is peaked on the screen. Increase /decrease the dB as shown in the below table.

TABLE : 1

S. No

Indication set at % of

FSH

dB control

change

Indication limits

% of FSH

1

80

- 6

32 to 48

2

80

-12

16 to 24

3

40

6

64 to 96

4.

20

12

64 to 96

The procedure for evaluating the amplitude control linearity shall be performed at the

beginning each period of extended use or every 3 month which ever is less.

11.3 Horizontal Linearity: Horizontal linearity has significance when determination of the depth of a discontinuity is

Required.

A block having good ultrasonic transmission, flat and a thickness of about one tenth of

The specified sweep range will usually be adequate.

Adjust the instrument gain, sweep- delay and sweep length control to display eleven

Non-interfering back reflection back reflection at the 20% and 80% scale divisions

Respectively.

After the third and ninth back reflections are positioned accurately on the 20% and

80% scale divisions as described, and record the scale position of each other multiple.

Echo division should be with in ( 5% FSW as shown in the Figure B as follows: The procedure for evaluating the Horizontal linearity shall be performed at the

beginning each period of extended use or every 3 month which ever is less.

Figure - B

12. CALIBRATION FREQUENCY:Instrument calibration shall be done at the beginning of each shift and then after every 4 hours.

13. REFERENCE STANDARD BLOCK:Calibration shall be performed on the same pipe which shall be used for Auto UT calibration.

14. CALIBRATION PROCEDURE:Calibration shall be done for instrument setting the first echo from half skip distance from the hole at 80% of FSH. Set the second and third echo from full skip and one and half skip from the hole with same reference sensitivity and a DAC curve shall be drawn. The scanning sensitivity shall be reference sensitivity +6 dB.

15. SCANNING SPEED:The scanning speed shall not exceed the 6 Inch / second.

16. TESTING PROCEDURE:The scanning shall be done in V shape (zigzag) with 10% overlapping and the scanning to be done as per customer specification and QAP.1) Marking of the Discontinuity : - All relevant indication found during the scanning will be taken in

consideration and will be marked as follows:

Discontinuity echo which exceeding DAC level shall be marked and transducer shall moved in linear

direction (forward and backward) to this point until the discontinuity echo disappear on the CRT and

That position shall be marked and considered as boundary of the discontinuity.

2) Retesting of suspect area indication by MUT is performed with RT and found to be free of indication; the area shall be subjected to further MUT. If the indication is confirmed with the repeat MUT and is not caused by geometrical features or acoustic coupling condition, then the MUT indication shall be classed as material rejected.

17. ACCEPTANCE CRITERIA: Any indication exceeding the reference threshold level shall be the cause of rejection. Defective length shall be removed by cut-off (if length tolerance permits) & after removal of defective, same end shall be retested.

18. DOCUMENTATION: Examination results shall be recorded in standard report Formats No. : WCL/SP/QC/F/06 Rev. 00

ANNEXURE - I

SCANNING PATTERN FOR MANUAL UT OF WELD

ANNEXURE - IIMANUAL ULTRASONIC TESTING CALIBRATION BLOCK FOR ANGLE PROBE:

POSITIONING OF THE PROBE TO MAKE DAC

1 to 1 SKIP

WELD SEAM

1.6 mm dia. TDH

C

A

B

Position A (1/2 V path) Get Reflection & set it to 80% of FSH. Note down Gain, fix the gain

Position B (V path) Get Reflection & Note down amplitude and position (with the same gain)

Position C (1 V path) Get Reflection & Note down amplitude and position (with the same gain)

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