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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. 

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FILLET WELD FRACTURE TEST

FILLET WELD FRACTURE TEST Object :  To break the joint through the weld to permit examination of the fracture surfaces for flaws and to check root penetration and fusion. Method: The specimen is cut to length and a saw cut, normally 2 mm deep, is made along the center of the weld face. The specimen is fractured by bending or hammer blows. Reporting Results: Thickness of parent material.  Throat thickness and leg length.  Location of fracture. Appearance of joint after fracture. Depth of penetration / lack of penetration or fusion.

'NICK' BREAK (BEND) TEST

'NICK' BREAK (BEND) TEST Object :  As for fillet weld fracture, used on butt welds. Method: The specimen is cut transversely to the weld, and a saw cut is applied along the center of the weld face. The best place for the cut is at a start I stop. The specimen is fractured by bending or by hammer blows. The nick bend test will find internal defects. Reporting Results: Thickness of material.  Width of specimen.  Location of fracture.  Appearance of joint after fracture.

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.