VISUAL EXAMINATION (VT)

 

Visual testing is one of the first NDT techniques ever applied. It’s a very basic and common inspection method. Various inspection tools are used during the examination to measure the welding seam profile and to compare the welding appearance to the applied acceptance criteria. Boroscopes, mirrors, telescopes and magnifying glasses can be used to aid the inspector.

Our experienced inspectors are able to provide an initial quality check of welded components in accordance with international standards, prior to the application of more time-consuming inspection procedures.

WHAT IT WILL FOUND?

Extensive surface breaking cracks, lack of sidewall fusion if surface-breaking, excessive weld cap height or underfill, undercut, crater cracking and piping, overlap, burnthrough, spatter and stray arcing may be visible on the top surface. Lack of/excess root penetration, root concavity, lack of root fusion, shrinkage grooves and burnthrough may be visible from below. If access to a side elevation is possible then misalignment (hi-lo), weld angle and weld sequence may also be checked. With a weld gauge, misalignment and weld angle can be also checked on the upper or lower surface.

APPLICATIONS

Since 1994 we have built a reputable track record within the Offshore, Maritime, Waste to Energy and Renewable industries. We can carry out Visual Examinations (VT) at many structures:

  • Structural elements offshore constructions
  • Inserts
  • Corrosion survey
  • Legs (jack-ups)

ADVANTAGES & BENEFITS

Visual examination is applicable to most surfaces, but is most effective where the surfaces have been cleaned prior to examination, i.e. any scale, loose paint has been removed by wire brushing etc. However, care must be taken to avoid peening.

An enhanced visual inspection using boroscopes or endoscopes can be used to check the internal surfaces of pipes or tubes for corrosion and/or erosion damage. On pipe containing a protective inner lining, boroscopes may be used to check that the lining is free of breaks, holes and blisters. Also, if the inner surface of the pipe or tube is sufficiently clean, boroscopes may be able to detect surface-breaking cracks, provided that they are sufficiently large.