X-ray and US testing of welds X-ray and US testing of welds in Ship Repairin Ship Repair

SHANTANU NEEMASHANTANU NEEMA

S. BINO JACOBS. BINO JACOB

WHY TESTING OF WELDS ?WHY TESTING OF WELDS ?

Testing of welds is an integral and the Testing of welds is an integral and the most important constituent of the ship most important constituent of the ship repair Quality Assurance (QA).repair Quality Assurance (QA).Evaluation of Welds are to be placed in Evaluation of Welds are to be placed in service.service.Prediction of Damage and Residual Life.Prediction of Damage and Residual Life.Accordance with the welding Codes and Accordance with the welding Codes and Standards to ensure safety, reliability and Standards to ensure safety, reliability and Economy.Economy.

Quality characteristicsQuality characteristics

Cracks, Inclusions, Porosities, Lack of Cracks, Inclusions, Porosities, Lack of Penetration, Lack of fusion, Lack of bond, Penetration, Lack of fusion, Lack of bond, Undercut, Alloy identification, CompositionUndercut, Alloy identification, Composition

Evaluation of welds for most stringent Evaluation of welds for most stringent service conditionsservice conditions

Choice of techniques or complementary Choice of techniques or complementary techniques to be selectedtechniques to be selected

Cost effectivenessCost effectiveness

Ship Repair

NDT QC

Visual Inspection

Leak Testing

Ultrasonic test

Radiographic test

Magnetic

Liquid penetration

Most important work is Ultrasonic Thickness gauging

Test Reports are provided by NDT Test Reports are provided by NDT department and approved by a third department and approved by a third party inspector.party inspector.

Acceptance standard used: Acceptance standard used:

ASTM, BSI, ISO, DINASTM, BSI, ISO, DIN

In India: BIS (Bureau of Indian In India: BIS (Bureau of Indian Standards)Standards)

X – Ray Radiographic TestX – Ray Radiographic Test

The X-ray radiographic testing method is especially superior as regards testing data and the ease of the testing method. However, when the defect is small, it is difficult to identify the existence of defects, defect type, defect shape, etc. using an X-ray film. On the other hand, it is difficult to employ skilled laborers and moreover, efficiency of identifying operation of X-ray film becomes important

Radiographic testing Radiographic testing can detect internal can detect internal defects in ferrous anddefects in ferrous andnonferrous metal.nonferrous metal.

This type of testing is This type of testing is useful for thin sections useful for thin sections and suitable to any and suitable to any type of material.type of material.

All discontinuities are All discontinuities are detected by viewing detected by viewing the weld shape and the weld shape and variation in the density variation in the density of the processed film.of the processed film.

Ultrasonic TestingUltrasonic Testing

Ultrasonic Testing can detect Ultrasonic Testing can detect discontinuities oriented both in the plane of discontinuities oriented both in the plane of and normal to the surface of welded and normal to the surface of welded components. Unfavorable geometries and components. Unfavorable geometries and coarse anisotropic grain structures pose coarse anisotropic grain structures pose difficulties in successful exploitation of this difficulties in successful exploitation of this technique.technique.

Can inspect as thick as 5 m.Can inspect as thick as 5 m.

Carried out at frequencies Carried out at frequencies between 1 to 25 MHz.between 1 to 25 MHz.Defects detected are: cracks, Defects detected are: cracks, shrinkage cavities, lack of shrinkage cavities, lack of fusion. Pores and bonding fusion. Pores and bonding faults.faults.

The detection, location, and The detection, location, and evaluation of discontinuities evaluation of discontinuities become possible because the become possible because the velocity of sound through a velocity of sound through a material is nearly constant, material is nearly constant, making distance measurement making distance measurement possible.possible.

Method Radiography(X-ray/Gamma-ray)

Ultrasonic

1. Linear weld geometry Y** Y**2. Non-linear weld geometry

N? Y**

3. Surface defects Y** Y*4. Volume defects (Internal)

Y** Y**

5. Planner defects (Internal)

Y? Y**

6. Length measurement Y** Y*7. Measurement of Small Ligament

N Y*

8. Through wall size measurement

N? Y**

Major Advantages of X-ray testingMajor Advantages of X-ray testing

Information is presented pictorially.Information is presented pictorially.A permanent record is provided, which can be A permanent record is provided, which can be viewed at a time and place distant from the test.viewed at a time and place distant from the test.Sensitivity is declared on each film.Sensitivity is declared on each film.Radiographic testing (RT) usually is suitable for Radiographic testing (RT) usually is suitable for testing welded joints that can be accessed from testing welded joints that can be accessed from both sides both sides Although this is a slow and expensive NDT Although this is a slow and expensive NDT method, it is a dependable way to detect method, it is a dependable way to detect porosity, inclusions, cracks, and voids in weld porosity, inclusions, cracks, and voids in weld interiors. interiors.

Major Disadvantages of X-ray testingMajor Disadvantages of X-ray testingInappropriate for surface defects and for Inappropriate for surface defects and for automation, unless the system incorporates automation, unless the system incorporates fluoroscopy with an image intensifier or other fluoroscopy with an image intensifier or other electronic aids. electronic aids. Can't cope with thick sections, and the testing Can't cope with thick sections, and the testing itself can pose a possible health hazard. itself can pose a possible health hazard. X-ray testing does not indicate the depth of a X-ray testing does not indicate the depth of a defect below the surface.defect below the surface.Only qualified personnel should conduct this test Only qualified personnel should conduct this test because false readings can be expensive and can because false readings can be expensive and can interfere seriously with productivity, and because interfere seriously with productivity, and because invisible X-ray and gamma radiation can be invisible X-ray and gamma radiation can be hazardous.hazardous.

Major Advantages of US testingMajor Advantages of US testing

Ultrasonic flaw detection can be used to test Ultrasonic flaw detection can be used to test thickness of 5 m and length up to 9 m.thickness of 5 m and length up to 9 m.This type of testing can determine defect This type of testing can determine defect position, size, and type. position, size, and type. It's a portable type of testing that offers extreme It's a portable type of testing that offers extreme sensitivity when required and can be fully sensitivity when required and can be fully automated.automated.Access to only one side is necessary for testing, Access to only one side is necessary for testing, and no consumables are used. and no consumables are used. can detect discontinuities oriented both in the can detect discontinuities oriented both in the plane of and normal to the surface of welded plane of and normal to the surface of welded components.components.

Major Disadvantages of US testingMajor Disadvantages of US testing

No permanent record is available unless No permanent record is available unless one of the more sophisticated test results one of the more sophisticated test results and data collection systems is used. and data collection systems is used. A considerable degree of skill is necessary A considerable degree of skill is necessary to get the most information from the test. to get the most information from the test. very thin sections can be difficult to test very thin sections can be difficult to test with this method.with this method.Test indications require interpretation, Test indications require interpretation, except for digital wall thickness gauges. except for digital wall thickness gauges.

EXAMPLEEXAMPLE

Repair cargo damage to double bottom tank Repair cargo damage to double bottom tank top in cargo hold.top in cargo hold.

• • Cut out and remove damaged plate and Cut out and remove damaged plate and internal longitudinal and transverse stiffenersinternal longitudinal and transverse stiffeners• Prepare new stiffener plates, tank top plate • Prepare new stiffener plates, tank top plate insert, and prepare all surfaces for weldinginsert, and prepare all surfaces for welding• Fit new structural members and accomplished • Fit new structural members and accomplished production weldingproduction welding• Ultrasonic test (shear wave inspection) of • Ultrasonic test (shear wave inspection) of repair weld (angle beam 100% weld)repair weld (angle beam 100% weld)

After Repair of Ship .…..After Repair of Ship .…..

Depending on which Classification Society the Depending on which Classification Society the vessel is classed; the regulations of that vessel is classed; the regulations of that particular class are discussed. Actually there particular class are discussed. Actually there are two surveys that are carried out are two surveys that are carried out simultaneously:simultaneously:

1.1. Close up inspection by Class Surveyor, Close up inspection by Class Surveyor, 2.2. Thickness measurement survey by an Thickness measurement survey by an

approved company. approved company.

The most important factors that decide The most important factors that decide the extent of both surveys are the age and the the extent of both surveys are the age and the general condition of the vessel. general condition of the vessel.

Standards for Radiographic Testing of weldby different Standard making organizations

Organization

Standard No. Title

ASTM E390 Reference radiographs for steel fusion welds

ASME Sec III (1)NB2560, NB5320

Radiographic and ultrasonic examination of boilers fabricated by welding.

Acceptance standards for radiography of boilers fabricated by welding.

Examination and repair of tubular products and filters with filler meta, and acceptance standards for welds

Sec VIII(1)UW 11, UW 51,52

Radiographic examination of pressure vessels.

BSI BS499Part 3

Terminology of and abbreviation for fusion weld imperfections as revealed by radiography.

BS 2600 Methods of Radiographic examination of fusion welded butt joints in steel.

BS 2910 Methods\s for radiographic examination of fusion welded circumferential butt joints in steel pipes.

BIS IS 1182 Recommended practice for radiographic examination of fusion welded butt joints in steel plates.

IS 2953 Glossary of terms used for interpretation of welds and casting radiographs.

IS 4853 Recommended practice for radiographic inspection of fusion welded butt joints in steel plates.

IS 7810 Code of practice for radiographic examination of resistance spot e\welds of aluminium s alloys

ISO ISO/R 947,1062407

Recommended practice for radiographic inspection of fusion welded butt joints in steel pipes (up to 50 mm thick) and plates (up to 50 mm in R 947 and 50-200 mm in R 106)

ISO 2437 Recommended practice for X-ray inspection of butt joints for aluminium and its alloys and magnesium and its alloys from 5 to 50 mm thick

DIN DIN 54/11Part I/II-73

Testing of welds of metallic materials by X ray of Gamma rays.

Standards for Ultrasonic Testing of weld by different Standard making organizationsOrganization Standard No. Title

ASTM E164 Recommended practice for ultrasonic contact examination of weldments.

E273 Ultrasonic inspection of longitudinal and spiral welds of welded pipes and tubing.

ASME Sec. I PW II

RT and UT examination and acceptance standards for boilers fabricated by welding.

Sec. III (1)NB 2560, 5330

Examination and repair of tubular products and fittings welded with filler metal with ultrasonic acceptance standards for welds.

Sec VIII (1)UW 11, 53

Radiographic and Ultrasonic examination of pressure vessels fabricated by welding, techniques of testing.

Sec VIII (1)Appendix UAppendix 9

Appendix U for non mandatory appendix and Appendix 9 for mandatory ultrasonic examination of welds

BSI BS 3923 Methods for ultrasonic examination of welds.

Part I Manual examination of fusion welded butt joints in ferritic steels

Part II Automatic examination of fusion welded butt joints in ferritic steels.

Part III Manual examination of nozzle.

BIS IS 4260 Recommended practice for ultrasonic testing of ferrous welded pipes and tubular products.

IS 7343 Code of practice for ultrasonic testing of ferrous welded pipes and tubular products.

ISO ISO 2400 Reference blocks for the calibration of equipments for ultrasonic testing of welds in steel.

REFERENCES:REFERENCES:

Welding Engineering Handbok, VOL I, Welding Engineering Handbok, VOL I, Radiant publication By Dr. Baldev Raj and Radiant publication By Dr. Baldev Raj and C.V. SubramanianC.V. SubramanianNon-Destructive tests of welds By Dr. Non-Destructive tests of welds By Dr. Baldev Raj and T. Jayakumar Baldev Raj and T. Jayakumar

www.ndt.net/articleswww.ndt.net/articleshttp://http://www.thefabricator.comwww.thefabricator.comA review of common NDT, assessment, its A review of common NDT, assessment, its tools, advantages and disadvantages By tools, advantages and disadvantages By Mark Willcox and George DownesMark Willcox and George Downes