RADIOGRAPHY 
                                       OBJECTIVES 
          To: 
      • understand the principle of radiographic 
          testing methods 
      • Know the technique of testing 
      • Become familiar with standards & codes 
      • Learn the applications.  
           
                                           INTRODUCTION 
            Radiography: 
       • one of the oldest & the most widely used NDT which 
            uses X-rays or   -rays radiation to examine the interior 
            of the materials. 
       • gives a permanent film record of defects that is easy 
            to interpret. 
       • applied for assessing the quality of the welded joints 
            also. 
       • can detect flaws or discontinuities in welds such as 
            cracks, porosity & blow holes, slag, flux or oxide 
            inclusions, lack of fusion between the weld metal & 
            the parent metal, incomplete penetration, tungsten 
            inclusion, etc. 
         
                PROPERTIES OF X- RAYS &  - RAYS 
       X- rays are highly penetrating electromagnetic 
      radiations of wave length shorter than UV-rays (X- 
      rays: 5 to 0.0004A,  - rays: 0.1 to 0.005A)  
      These rays have the following properties: 
    • Invisible electromagnetic radiations. 
    • Can penetrate matter. Penetration is less if density of 
      matter is more and thickness is more  
    • Are differentially absorbed. 
    • Travel in straight lines. 
    • Produce photochemical effects on films. 
    • May be refracted, reflected and diffracted  
    • Damage living tissues 
    • Ionise gases through which it pass.