INSPECTION DIVER REVISION APP
Inspection Diver Study Guide (Concise)
A compact, field‑ready reference for inspection divers preparing for Underwater NDT Inspection Diver exams. Use alongside your company SOPs and project specifications.
1) What each grade tests — skills matrix
✓ = core; • = awareness/overlap
Level 1 NDT Inspection Diver Skills
Asset terminology & feature IDs (pipeline/risers/trees/manifolds) ✓
Visual inspection: GVI/CVI, cleaning standards, measurement & sketching ✓
Photography/video with overlay & commentary ✓
CP survey (Ag/AgCl/seawater), interpretation & troubleshooting ✓
UDTM (thickness) — setup, calibration, limits ✓
ID & %‑cover Marine growth methods (SACFOR, quadrats, line‑intercept) ✓
Fluorescent/visible MPI (field fundamentals) •
Toe‑grinding (method, acceptance, re‑inspection) •
Advanced UT (DAC/TCG, gates, skip distance) & ACFM basics •
Reporting, anomaly coding, workpack planning & QA/QC •
Level 2 NDT Inspection Diver Skills
Asset terminology & feature IDs (pipeline/risers/trees/manifolds) ✓
Visual inspection: GVI/CVI, cleaning standards, measurement & sketching ✓
Photography/video with overlay & commentary ✓
CP survey (Ag/AgCl/seawater), interpretation & troubleshooting ✓
UDTM (thickness) — setup, calibration, limits ✓
ID & %‑cover Marine growth methods (SACFOR, quadrats, line‑intercept) ✓
Fluorescent/visible MPI (field fundamentals) ✓
Toe‑grinding (method, acceptance, re‑inspection) ✓
Advanced UT (DAC/TCG, gates, skip distance) & ACFM basics ✓
Reporting, anomaly coding, workpack planning & QA/QC •
Level 3 Underwater Inspection Controller Skills
Asset terminology & feature IDs (pipeline/risers/trees/manifolds) ✓ (supervise)
Visual inspection: GVI/CVI, cleaning standards, measurement & sketching ✓ (plan/assure)
Photography/video with overlay & commentary ✓ (QA)
CP survey (Ag/AgCl/seawater), interpretation & troubleshooting ✓ (review/trend)
UDTM (thickness) — setup, calibration, limits ✓ (QA)
ID & %‑cover Marine growth methods (SACFOR, quadrats, line‑intercept) ✓
Fluorescent/visible MPI (field fundamentals) ✓ (acceptance)
Toe‑grinding (method, acceptance, re‑inspection) ✓ (sign‑off)
Advanced UT (DAC/TCG, gates, skip distance) & ACFM basics ✓ (method selection)
Reporting, anomaly coding, workpack planning & QA/QC ✓
2) Subsea assets — terminology & feature IDs (call‑outs for video/stills)
Pipelines/Flowlines
KP chainage; FJ‑### field joint; Anode (bracelet/sled); CWC (concrete weight coating); FJC (field joint coating); ILT (in‑line tee); PR/PL (pig receiver/launcher); SSIV; Hot‑tap; Expansion spool.
Terminations/Manifolds
PLET (termination), PLEM (manifolded termination), Manifold header, Guide base, Tie‑in porch, SUTA/SDU (umbilical termination/distribution), Stab plate.
Risers/Wellheads
TTR/SCR (top‑tensioned/flexible catenary riser), Riser clamp/fairlead/porch, Tree/X‑mas tree, Gooseneck/J‑tube.
Supports/Protection
Mudmats, Concrete mattresses, Mattress pins, Rock dump, Span (free length), Span shoulders.

Good practice: Every close‑up still should include ID slate + scale and a spoken overlay with: Date/Time • Asset/Feature ID • KP/Member/Clock‑face • Depth • Finding (with sizes) • Action.
3) Visual inspection (GVI/CVI) — quick procedure
Brief & permits
Hazards (current/impact), communications, tooling, cleaning limit.
Lighting/visibility check
Record conditions.
GVI pass at stand‑off
Identify features, gross damage, spans, coating holidays, anodes.
Escalate to CVI where needed
Local clean (minimal; avoid coating damage), expose weld toes/defects.
Measurements
Rule/scale, pit/radius gauge; record KP & clock‑face.
Stills
Orthogonal + obliques; scale in frame; captions.
Video commentary
Structured (see §11 templates).
Report
Defect type, sizes, evidence, acceptance/reference, recommended action.

Acceptance snapshots to know: weld toe condition (smooth transition, no sharp notches), flange faces (clean/undamaged), anodes (secure, % mass remaining), coating (no disbond/holiday).
4) CP survey — essentials
01
Reference cell:
Ag/AgCl/seawater; verify against standard; keep porous tip clean.
02
Probe placement:
preference for contact pad/near‑contact to reduce IR drop.
03
Typical protection band (project‑dependent):
readings more negative than ≈ −0.80 V (Ag/AgCl/seawater) often indicate protection. Use project criteria.
04
Process:
clean small pad if needed → stabilise reading → log KP/depth/temp/flow → compare trends near anodes/joints.
05
Troubleshooting:
erratic = cable fault/coating holiday; less‑negative near defects = poor contact/IR drop; big gradients = broken continuity or shielding.
Deliverables: calibration sheet, raw logs, overlay video of contact points, map of KP readings.
5) UDTM (thickness) — setup & checks
1
Velocity (steel): ~5920 m/s. Use echo‑to‑echo to cancel coating delay.
2
Calibration: step‑wedge → set velocity → verify on bare metal pad.
3
Technique: clean/flat pad; consistent pressure; repeat 3× at each point; note temperature.
4
Limitations: roughness/marine growth; tight radii/small OD; high flow; geometry.
5
Back‑of‑slate calc example: t(mm) ≈ (v (m/s) × time(µs))/2000. E.g., 1.70 µs → ~5.0 mm.
6) Marine growth — ID & %‑cover
SACFOR abundance
Superabundant, Abundant, Common, Frequent, Occasional, Rare.
%‑cover methods
  • Photo‑quadrat (grid/point-count) perpendicular, scale in frame → tally points → % per taxon.
  • Line‑intercept growth length ÷ tape length ×100.
Common taxa (diver cues)
  • Hydroids (feathery; stinging); Bryozoans (lacy calcareous sheets); Ascidians (sea squirts; gelatinous tunic, siphons); Sponges (porous with oscula); Barnacles (calcareous plates); Coralline algae (pink/red crusts); Mussels (byssal clusters).
Safety
Hydroid stings; sharp shells; silt/backscatter management for imagery.
7) Level 2 NDT Inspection Diver core NDT — what to know cold
7.1 Fluorescent MPI (wet)
Light & vision
UV‑A ≈ 365 nm; dark adaptation ~5 min; keep white light low (use tent/hood). Verify UV intensity at working distance.
Magnetisation
Yoke (AC/DC) or prods; two directions (perpendicular to expected crack). Confirm with QQI/pie gauge; ensure firm pole contact (no lift‑off).
Bath/flow
Correct concentration, agitate, control flow; streaming water washes particles off.
Interpretation
Sharp, continuous linear fluorescence → crack‑like; geometry edges/background → non‑relevant; re‑magnetise in second direction.
Post
Demagnetise if required; clean; restore coating; complete records (UV/lux, QQI photos, settings).
7.2 Toe‑grinding (fillet weld toes)
Aim:
remove small surface cracks & reduce stress concentration with a smooth blended radius over ≥150 mm length.
Tools:
hydraulic grinder, suitable burrs/flap; gauges; tethers; PPE; staging for current.
Method:
mark length → light passes (avoid heat/blueing) → cross-check profile → deburr → avoid grooves aligned with stress.
Acceptance:
continuous blend; minimum radius per spec; re-inspect (MPI two directions / ACFM); document before/after with scale.
7.3 Advanced UT & ACFM
UT
Plan skip distances; set gates; use DAC/TCG for consistent sensitivity; mitigate dead zone (delay line/dual‑element). Angle-beam 45–70° common.
ACFM
Through-coating surface crack detection with length/depth estimates; maintain stable lift‑off; manage EM noise; great when light control/cleaning is limited.
8) Level 3 Underwater Inspection Controller focus — planning, QA/QC & supervision
1
Plan the work
Scope, hazards, permits, roles; tools & calibration; dark‑room plan for fluorescent MPI; grind workpack with hold points.
2
Evidence pack
Overlay-rich video; captioned stills with scale; measurement tables; UV/lux & QQI records; UT/ACFM calibration files; anomaly log.
3
Decision trees
CVI → MPI → ACFM → UT depending on coating, access, lighting, and objective.
4
Reporting
Objective language; KP/clock-face; sizes with method; acceptance criteria cited; clear recommendation & priority.
5
Auditability
Unique IDs, filenames tied to KP/feature; operator IDs; settings; backups; sign‑offs.
9) Mini‑glossary (high‑yield)
1
  • ACFM alternating current field measurement
  • CVI/GVI close/general visual inspection
  • CP cathodic protection
  • CWC concrete weight coating
  • DAC/TCG distance‑amplitude curve / time‑corrected gain
  • FJ field joint
2
  • FJC field joint coating
  • HIPPS high‑integrity pressure protection system
  • ILT in‑line tee
  • KP kilometre post/chainage
  • MPI magnetic particle inspection
  • PLET/PLEM pipeline end termination/manifold
3
  • PR/PL pig receiver/launcher
  • QQI quantitative quality indicator (shim)
  • SCR/TTR steel catenary riser / top‑tensioned riser
  • SDH side‑drilled hole
  • SSIV subsea isolation valve
  • SUTA/SDU subsea umbilical termination/distribution
  • TOFD time‑of‑flight diffraction
  • UDTM ultrasonic digital thickness measurement
  • UV‑A ultraviolet A (≈365 nm)
10) One‑page checklists (pin these to your slate)
GVI/CVI (10‑step)
  1. Brief/permits
  1. Vis/lighting
  1. GVI sweep
  1. Clean minimally
  1. Measure
  1. Stills orthogonal+oblique
  1. Overlay tidy
  1. Commentary structured
  1. Note acceptance vs spec
  1. Log actions
CP Survey (10‑step)
  1. Verify electrode
  1. Cable check
  1. Prepare contact pad
  1. Place cell; stabilise
  1. Log KP/depth/temp
  1. Repeat/average
  1. Compare to criteria
  1. Map gradients
  1. Troubleshoot anomalies
  1. Photos of contact points
UDTM (10‑step)
  1. Clean flat pad
  1. Calibrate velocity
  1. Echo‑to‑echo mode
  1. Verify on bare steel
  1. Consistent pressure
  1. Repeat 3×
  1. Record temp/settings
  1. Beware curvature
  1. Cross‑check outliers
  1. Save screen caps
Fluorescent MPI (10‑step)
  1. Dark plan (tent/hood)
  1. UV intensity check
  1. Lux low
  1. Dark‑adapt
  1. Surface clean
  1. Magnetise dir-1
  1. Apply ink
  1. Inspect; record
  1. Magnetise dir-2
  1. Demag & restore coating; log QQI/UV
Toe‑grinding (10‑step)
Workpack/permits
Mark ≥150 mm
Secure staging
Light passes
Control heat
Check profile/radius
Deburr
MPI/ACFM re‑inspect
Photos before/after with scale
Sign‑off
11) Templates — talk & write like an inspector

Video commentary skeleton (A‑LODER): Asset → Location (KP/Clock-face/Depth) → Observation (condition/cleaned) → Dimensions (method/units) → Evidence (stills/scale/UV/QQI) → Recommendation (action/priority).
Report sentence starters:
"At KP 12.300 / FJ‑084 / 9 o'clock, weld toe cleaned; linear indication ~45 mm long detected by fluorescent MPI (UV-A verified). Second direction confirms; demag applied. Recommend: toe-grind ≥150 mm and re‑inspect."
"UDTM on cleaned pad indicates 7.6 mm (echo-to-echo, v=5920 m/s, 18°C). Repeat x3: 7.6/7.5/7.6 mm."
Measurement phrases:
  • "Measured with pit gauge; uncertainty ±0.2 mm."
  • "CP reading −0.92 V Ag/AgCl/seawater, 26 mSW, 9°C; stabilised 10 s."
12) Exam strategy (MCQ + written)
01
MCQ: read stem → predict → then scan options; eliminate two; watch units (mm vs m); beware "always/never."
02
Short answers (3–4 marks): define + two key points + one practical example.
03
Extended answers: open with scope/purpose, then ordered steps; finish with acceptance & documentation.
04
Time‑box: don't stall mark and return. Use sketches for weld geometry/beam paths.
05
Common pitfalls: missing overlay IDs; no scale; forgetting second magnetisation; poor CP contact; UDTM without echo‑to‑echo; unblended grind grooves.
Final reminders
Match your answers to project criteria (potentials, acceptance radii, lighting limits).
Use objective language and evidence.
Safety first: tool control, current management, visibility, and comms.
Good luck — and remember: clean, measure, evidence, recommend.
Inspection Equipment Reference
Imaging Equipment
High-resolution underwater cameras with overlay capabilities, video systems with timestamp and depth data, lighting systems with variable intensity control, and measurement scales.
Measurement Tools
Pit gauges, calipers, radius gauges, ultrasonic thickness meters, CP reference electrodes, and digital multimeters with waterproof housings.
Cleaning & Preparation
Hydraulic grinders, wire brushes, needle guns, water jets, and specialized marine growth removal tools designed for underwater use with proper tethering.
Common Subsea Defects
Weld Defects
Toe cracks, lack of fusion, porosity, undercut, and excessive reinforcement. Typically require MPI or ACFM for confirmation after visual identification.
Corrosion
General surface corrosion, pitting, crevice corrosion at joints, and galvanic corrosion at dissimilar metal interfaces. Measure depth with pit gauges and document with scale.
Mechanical Damage
Impact damage, abrasion, deformation, and free spans exceeding allowable limits. Document with measurements and multiple angle photographs.
Coating Failures
Disbondment, holidays, blistering, and mechanical damage. Check for correlation with CP readings and document extent with measurements.
Communication & Documentation Best Practices
Communication
  • Use clear, concise terminology consistent with industry standards
  • Confirm understanding of instructions before proceeding with inspection tasks
  • Report findings immediately when critical defects are identified
  • Maintain regular communication with surface team regarding progress and conditions
Documentation
  • Follow consistent file naming conventions that include date, location, and feature ID
  • Ensure all measurements include method, units, and uncertainty
  • Cross-reference video timestamps with still images and written observations
  • Maintain calibration records for all inspection equipment
  • Complete inspection logs immediately after dive while observations are fresh

Remember that your documentation may be used for critical engineering assessments and legal purposes - accuracy, objectivity and completeness are essential.