6 prerequisites of Visual Inspection

An inspection personnel serves in fulfilling the quality requirements of welded items. For this he must have good work experience about quality control activities. Following are the key characteristics of a welding inspector;

  • Properly trained to use inspecting tools 
  • Make interpretation according to the specific requirements. 
  • Must be competent in finding welding flaws and defects.  

Not only this but also he knows how to record the examined information. BS EN 970 calls for the basic requirements for visual inspection. Following are the specifications that must be fulfilled for quality inspection of welded items.

1. Trained Inspection Personnel
First requirement of sound inspection, is a skillful personnel who have ability to understand the codes and interpret the requirements. He must be familiar with whole quality inspection plan. Before appointment for the job, his vision should be examined and during job regular checkups must be conducted. Now a days for a good career some inspectors used to get certification along with practical experience.

See Welding schools for educational training of welders and Inspectors.

2. Pre-conditions
For visual inspection there are also some requirements for inspector’s vision that is good light, suitable position in shop, easy access to required surface. In some industries where daylight is inadequate or scanty, additional lights are provided to support operations and activities. One of the most important factor that matters a lot, is the shop layout. Proper positioning of machines and items keeps the activities/operations smooth.  

Proper lighting – not only in welding shop for items inspection but also in office so that inspector may not lose their vision.  
Access to the surface – for correct inspection, keeping inspector’s eye at a view angle not less than 30 degree.  

3. Correct usage of equipment
An inspector must have detailed knowledge about tools and equipment; how to use, their calibration and correct use for the specific purpose. Before inspection make sure that equipment is properly calibrated. Use of different gauges and measuring taps for making correct measurements. Moreover detailed knowledge of different measuring scales for the measurement of lengths in specific job/item. Different gauges are available for the observation of joint size, angle, high-low, alignment etc.

4. Magnifying objects
Use of magnifying objects like mirror/lens, to enlarge the image where direct vision can’t help inspection. Now a days latest fiber optic systems are available for viewing complex joint profiles.

5. Liquid contrast
Use of liquids or other dyes to make color contrast between the weld imperfections and background that supports visual inspection. Non-destructive test like dye penetrant, serves for such purpose where complex surface cracks are made visible to inspector.

6. When to Inspect
The most important concern is, when the inspection is required? In large firms, throughout inspection is needed where complex pressure equipments are fabricated. Not only inspector but also different people of organization including client come to examine different stages of production.

Before welding, some inspection activities are involved to provide confidence that operation requirements are fulfilled. Part of inspection activities is implemented to ensure quality control during production of welded items. And a part of inspection activities are implemented after welding to find out imperfections so that suitable remedy can be applied on them. Many other inspection stages are also involved like blasting, coating, pneumatic and hydrostatic test in case of pressure equipment (as mentioned above).  

Comments