VT of Bolts
VT of BoltsKhurram S Ahmad1VT OF BOLTSPreparation Tools
Instruments Conditions on the surface2VT OF BOLTSToolsExamination
toolsTape measureVernier caliperMicrometerThread gauge
3VT OF BOLTSTools Lighting tools Pocket torch Intense light
4VT OF BOLTSToolsAuxiliary tools Mirrors Magnifying lenses
5VT OF BOLTSInstruments / (for remote VT)TelescopeVideo-scope /
borescope / fiberscopeVideo camera
6VT OF BOLTSConditions on the surfaceDemonstrate and verify 18%
neutral grey card Illuminometer
7VT OF BOLTSConditions on the surface Surface cleanedBrush
(Stainless wire / nylon) Cleaning material (kerosene / acetone)8VT
OF BOLTSMost important point of VT for bolts and nuts To detect
service induced cracks9VT OF BOLTSOverview of the conditions
Deformation? Necking? Crack? Damage? Corrosion?10VT OF
BOLTSDismantled bolts After cleaning Try to screw into the nuts Not
smoothly? High resistance Deformation Carefully examined and
recorded
11VT OF BOLTSOther imperfections to detect Physical damage
Corrosion Crack Oxidation / Rusting Flaking off of plating coat
Loosening 12VT OF BOLTSDamage by toolsImproper use of tools
Fastening Dismantling
1314NeckingDecrease in local cross section area of a section of
boltPlastic deformation of the rod / shank Over-pretightening
Over-torque force Overloading in service VT OF BOLTSVisual
Testing1415DeformationChange in shape of fasteners Improper
assembling Improper dismantling Overloading during service VT OF
BOLTSVisual Testing1516Fracture / crackDamage to fastenerDue to
Improper assembling Over Loading Harmful Environment media
VT OF BOLTSVisual Testing1617Corrosion / RustingCorrosionDamage
or destructionAction of corrosive media RustingOxidation on the
surfaceVT OF BOLTSVisual Testing1718WearingLost of materialDue to
Repeating mechanical friction Between the fastener and other
materials During service of the fastener VT OF BOLTSVisual
Testing1819Flaking off of plating coat
Carefully examined and recordedVT OF BOLTSVisual Testing19
