Significance of defects in welds, Mechanical Engineering

SIGNIFICANCE OF DEFECTS IN WELDS

 

In the correct sense of the word, a defect is a rejectable discontinuity or a flaw of rejectable nature. Certain flaws acceptable in one type of product need not be of acceptable nature in another product. A defect is definitely a discontinuity but a discontinuity need not necessarily be a defect. Acceptance or rejection of flaws is based on different factors and to mention a vital few are:

  • Stresses to which the parts will be subjected during service.
  • Type of material used.
  • The temperature and pressure to which the parts will be stressed.
  • Its thickness.
  • The environment (corrosive or non corrosive).
  • Safety.
  • Consequences of failure.
  • Cost and accessibility for repair, etc.

 


Acceptance standards dictate the type of inspection and testing the weld is subjected to before giving a judgement. The quality control incharge shall analyse whether the flaw is critical, major or minor and whether the flaws are inherent because of the process or are due to the processing or service conditions. It is of immense importance to see that the base material used for fabrication shall be of good quality and attested materials are demanded in the manufacture of space vehicles and ships, submarines, pressure vessels, power boiler components, heavy duty cranes, structures, bridges, etc., wherein the failure of weld will lead to loss of life, money and reputation.

The weld defects can be broadly classified into two types. They are:

  • Planar defects or two dimensional defects.
  • Voluminar defects or three dimensional defects.

 


Planar defects such as crack, lack of fusion, lack of penetration, severe undercut are critical in nature and  involve lack of bonding and are not tolerated to any extent. Voluminar defects such as slag inclusion, cavities, pores, etc. are tolerated to a certain extent depending on the product class. Geometric defect such as excess reinforcement, underfill or underflush, root concavity are also permitted to a certain extent. If they form sharp notches, they are smoothened out wherever accessible to avoid stress concentration.

Posted Date: 9/17/2012 8:46:53 AM | Location : United States







Related Discussions:- Significance of defects in welds, Assignment Help, Ask Question on Significance of defects in welds, Get Answer, Expert's Help, Significance of defects in welds Discussions

Write discussion on Significance of defects in welds
Your posts are moderated
Related Questions
What is Octree Encoding Octress are hierarchical variant of spatial-occupancy enumeration, designed to address that approach's demanding storage requirements. Octress are in tu

Free body diagrams of cylindrical rollers: The t wo cylindrical rollers A and B which are identical, each having weight W are supported by an inclined plane and vertic

Resultant of coplanar concurrent force system: The resultant force, of given system of forces can be found out by the resolution method, which is discussed below: Assume th

Need someone to help in doing a connecting rod for an engine by using abaqus software version12 or 6.11?

Geometric modeling is an integral part of any Computer-Aided-Design (CAD) system. A geometric model is defined as the complete representation of graphical and non-graphical informa

actual division 2km is shown as 1 cm in a map.construct a clean scale to measure km which can travel a distance upto 30 km.Show measurement of 18 km in the scale

Q. Stacking in the Applicators storage? Stacking in the Applicator's storage yard shall be in accordance with good safety practices and/or OWNER Specifications. Sufficient spac

TYPES OF TOOL AND EQUIPMENT: We can classify the required tools and equipment into following four categories to understand their uses : General tools, Measuring equipm

Fundamental geometric transformation: The fundamental geometric transformation is Rotation, Translations and Scaling. Other transformations involve reflection and shearing. Tr

Engine Oil Replacement and top up steps • The engine oil should be changed only when motorcycle has run through the prescribed kilometers. • Change the engine oil every 4000 k