Pipe supports, saddles, and hangers create a microenvironment that accelerates external corrosion — trapping moisture, debris, and corrosive contaminants between the pipe outer diameter and the support contact surface, where coating is frequently absent or damaged and where the geometry prevents routine visual inspection.
Why CUPS Is a Significant
Integrity Threat
Invisible at the Critical Location
The pipe-to-support contact zone is exactly where external visual
inspection cannot reach without support removal. Coating is frequently absent
at this location — damaged during installation or intentionally omitted to
avoid moisture trapping under the coating. This creates a situation where the
most corrosion-vulnerable area of the pipe is also the least accessible to
routine visual condition assessment.
Accelerated Corrosion in the Crevice Environment
The crevice between pipe and support
concentrates moisture, reduces oxygen availability (creating a differential
aeration cell), and traps corrosive species. These conditions collectively
produce corrosion rates significantly higher than those on exposed pipe
surfaces nearby — meaning that CUPS can produce critical metal loss in the
interval between inspection events, even when the surrounding pipe is in
satisfactory condition.
PAUT and UT Techniques for CUPS
Inspection
Scanning from Accessible Adjacent Locations
Where support removal is not practical
within the inspection scope, UT and PAUT can be applied from accessible pipe
surface locations adjacent to the support — directing refracted beams toward
the support contact zone and detecting and sizing metal loss within the beam's
coverage. Scan positions are optimised for each support geometry to maximise
the proportion of the contact zone that can be interrogated without support
removal.
Post-Removal Corrosion Mapping
Where supports are removed as part of the
maintenance programme or inspection scope, PAUT and encoded UT are deployed on
the exposed contact zone — providing 100% encoded coverage of the area that was
previously under the support, with C-scan output that maps the corrosion
distribution and identifies minimum remaining wall.
Long-Range UT for Multiple Support Assessment
Guided wave LRUT from a single accessible
location can screen multiple support zones along a pipe run — identifying those
that have significant metal loss and prioritising them for support removal and
direct inspection. This combines the efficiency of guided wave coverage with
the targeted accuracy of direct UT at the identified high-risk locations.
Reports include scan coverage diagrams, UT
and PAUT data from both adjacent scanning and post-removal direct inspection,
C-scan corrosion maps of the contact zone, minimum remaining wall, and
fitness-for-service disposition against the applicable piping code minimum wall
thickness. CUPS risk ranking and recommended support replacement or coating
reinstatement is provided for maintenance planning.