VISUAL INSPECTION OF WELDING

VISUAL INSPECTION OF WELDING

INTRODUCTION
Inspection starts with examination of the material prior to fabrication, scabs, seams, scale or other harmful surface conditions may be detected in visual inspection.

The inspector should check the following :

Weld preparation, dimensions and finish.
Clearance dimensions of backing strips.
Alignment and fit up to the pieces being welded.
Verification of cleanliness.

Visual Inspection During Welding
Visual inspection checks details of the work while welding is in progress. Among the details to be checked are :

Welding process.
Cleaning.
Preheat and inter pass temperature.
Joint preparation.
Filler metal.
Flux or shielding gas.
Chipping, grinding, or gouging.
Post heating temperature and time.

Visual Inspection After Welding
Visual inspection is useful for finished-product verification of such items as :

Profile irregularities of the weldment.
Conformity to drawing requirements.
Acceptability of welds with regard to appearance (eg: surface roughness).
The presence of unfilled undercut, overlaps and cracks.
Evidence of mishandling from center punch or other inspection markings or excessive grinding.

ULTRASONIC TEST

ULTRASONIC TEST INTRODUCTION This method is used to test a variety of both metallic & non metallic products such as welds, forgings, castings, sheets, etc. It has an advantage of detecting sub-surface discontinues with accesses to only one side of the specimen. In this method beams of high frequency sound waves are introduced into the material being tested. The sound waves travel through the material with some loss of energy & are reflected back . This is detected & analysed to detect the presence of flaws. This test employs ultrasonic waves. These waves are mechanical waves that consist of oscillations or vibrations. METHOD TRANSMISSION SYSTEM This method employs two Transducers, one for sending & other for receiving the pulses. These may be short or continuous & are transmitted through the material. The result gets displayed on the CRO connected. The settings of the CRO can be adjusted with respect to time & distance. Prior to testing couplant is used to prov...

BEND TESTS

BEND TESTS Object: To determine the soundness of weld metal, heat affected zone and weld zone.These tests may also be used to give some measure of the ductility of the weld zone. It is not usual to use transverse and longitudinal bend tests for the same application. Method: All specimens to be removed and prepared without causing significant distortion or heating. The cap and root are ground flush. The specimen is bent by the movement of a former of prescribed diameter, the relevant side of the specimen to be placed in tension. Angle of bend and diameter of former should be as specified in the appropriate standard. Reporting Results: Thickness of specimen Direction of bend (root or face) Angle of bend Diameter of former Appearance of joint after bending e.g. type and location of flaws

DESTRUCTIVE TESTING

DESTRUCTIVE TESTING Destructive tests on raw materials, welded joints are usually made as part of the approval of material/ welding procedure or a welder. Commonly used destructive tests are: Hardness Bend Tensile Charpy Fracture tests Macro section TYPES OF TEST Quantitative (For measuring a 'quantity') Tensile Charpy Hardness C.T.O.T. (crack tip opening test) Qualitative (For assessing joint 'quality') Bend test Nick break Macro Fillet fracture The test pieces are cut from the test weld and their location is often specified in the standard. The areas for test are shown below.

Mechanical Engineering

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