Chevron Cracking Examination

Internal, Centreline Location

Chevron cracks are characteristically located at or near the centreline of the bar, billet, or seamless pipe — in the region where deformation stresses concentrate during rolling or extrusion. This centreline position means that standard surface wave and near-surface UT techniques are completely ineffective, and that through-transmission and straight-beam compression wave techniques are required to inspect the critical zone.

Orientation Relative to Material Flow Direction

The chevron crack orientation — along the material flow direction at an angle to the radial cross-section — means that inspection beam angles must be specifically calculated for the product geometry (diameter, wall thickness) to achieve normal or near-normal incidence on the crack faces. Standard fixed-angle UT procedures developed for weld inspection are not appropriate for centreline chevron crack detection.

Seamless Pipe Specific Challenges

In seamless pipes, chevron cracks may be distributed along the full pipe length in the centreline zone. Rapid automated UT scanning of the full pipe body — from pipe end to pipe end — is required to achieve 100% coverage inspection within production timescales. Our automated UT pipe inspection systems are configured for centreline-zone chevron crack detection in seamless pipe of defined diameter and wall thickness ranges.