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.

Chemical compositions of steel

Chemical Composition :- The chemical composition of steel is of great importance since it determines the potential mechanical properties of the finished steel product and controls the degree of corrosion resistance and weld- ability of the material For this reason structural steel specifications always provide a table of chemical composition limits within which the steel producer must develop his own particular recipe. The purpose of the specified chemical composition is not to provide the detailed chemical formula necessary to produce a certain type of steel but to provide safeguards. The steel producer is informed that he must keep within the limits which are deemed to be acceptable for the type of steel considered. Within these limits, which may be broad or narrow, the steel producer has complete freedom to use his skill and knowledge to make steel with the required mechanical properties. Each producer selects a combination of quantities of elements, which fall within the r...

CHARPY V NOTCH IMPACT TEST

CHARPY V NOTCH IMPACT TEST Object : To determine the amount of energy absorbed in fracturing a standardized test piece at a specified temperature. Method : A machined, notched specimen is broken by one blow from a pendulum. Because scatter occurs in the results, at least three specimens are used to assess the joint represented. Testing is carried out at a temperature specified in the appropriate application standard. Reporting Results: Location and orientation of the notch. Testing temperature. Energy absorbed in joules. Description of fracture appearance. Location of any defects. The Charpy impact test, measured in joules, is an assessment of TOUGHNESS. Transition temperature (curve) in steel.

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.

Mechanical Engineering

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