Revised: OLE-RR 002 REV 1
Approved
Written 8/11/26 by Ray Thibodeaux
EWO: EWO-31851
Finding
Bottom head general thinning below t-min over a band roughly 14 inches wide at the 6 o'clock position. Weld overlay or insert plate required before return to service.
Formal write-up
Title
D-215 Bottom Head Thinning
Cause
Corrosion
Findings
UT grid across the bottom head returned a low reading of 0.212 in against a t-min of 0.250 in. The affected band runs circumferentially about 14 in and is centred on the 6 o'clock position, consistent with a standing caustic heel.
Acceptance criteria
API 510 section 7 · API 579-1 Part 4
Measurements
Location: Grid B3
Location: Grid B4
Location: Grid C3
Recommended options
- Option 1 (recommended): insert plate the affected band to the original thickness, full penetration, PT the finished welds.
- Option 2: weld overlay build-up. Faster but leaves a variable profile that complicates the next UT survey.
Justification
The measured thickness is below the required minimum for the design pressure, so the head cannot be returned to service as found. An insert plate restores a uniform wall that future surveys can trend against.
Photos (1)
