Flooded Member Detection (FMD) Using Gamma Radiation

Scansolution’s Flooded Member Detection (FMD) service provides a non-intrusive offshore diagnostic method to determine the presence of water inside platform structural members. Using gamma ray transmission technology, the system quickly identifies flooded, partially flooded, or dry members without removing marine growth or coatings. The data allows early detection of weld failures, internal corrosion, and wall defects, helping ensure platform stability, safety, and structural integrity.

Overview

Non-intrusive Reliable Subsea-Ready Detect water ingress in jacket legs, braces, caissons, and pipe-in-pipe annulus with rapid,

Why FMD Matters

Water ingress in members designed to remain dry reduces structural capacity, accelerates corrosion, and raises integrity risk. Scansolution’s gamma-based FMD gives you fast, defensible answers dry vs partial vs flooded without cleaning or intrusive work.

  • Works through coatings & marine growth
  • ROV-deployable; minimal diver exposure
  • Rapid screening per member (seconds)
  • Quantitative output for trending & decisions

Key Benefits

Non-Intrusive & Fast

No coating removal. No major cleaning. Immediate dry / partial / flooded classification at each scan point.

Accurate & Repeatable

Gamma attenuation provides a density-based signal, enabling consistent, repeatable results and clear audit trails.

ROV-Ready Deployment

Compact fork/clamp frames position source and detector across the member for safe, efficient subsea operation.y

How It Works

Principle

A collimated gamma beam passes across the member. The detector measures transmitted intensity. Comparing counts to dry and flooded baselines indicates internal condition, including partial flooding.Scansolution applies

Deployment

Typically ROV-mounted (observation to work-class) or diver-assisted where permitted. The system works through typical marine growth and coatings, reducing prep time and vessel days.

Typical Applications

Jacket Structures

Legs, braces, nodes screening programs for ageing assets and life-extension studies.

Caissons & Conductors

Rapid verification of internal condition without hot work or intrusive access.

Pipe-in-Pipe / Annulus

Identify water ingress or unexpected fill in annular spaces to plan remediation.

Technical Specifications (Generic)

Technique Transmission gamma with collimated source and opposing detector
Condition Detection Dry / partially flooded / fully flooded
Surface Condition Operable through typical marine growth and coatings
Deployment ROV-mounted fork/clamp or diver-assisted positioning (as permitted)
Data Handling Real-time count rate, logging, threshold classification
Output Member status (dry/partial/flooded) with plots and georeferenced references (where available)

Frequently Asked Questions

What is Flooded Member Detection (FMD)?

Flooded Member Detection (FMD) is a non-intrusive inspection technique used to determine whether subsea structural members are dry, partially flooded, or fully flooded using gamma transmission measurements.

No. Gamma-based FMD can typically be performed through coatings and marine growth, minimising preparation work.

The system is commonly deployed using an ROV holding a C-shape frame that positions the radiation source and detector on opposite sides of the member.

Yes. Differences in gamma attenuation may indicate dry, partially flooded, or fully flooded conditions depending on geometry and reference levels.

Typical applications include offshore jacket legs and braces, caissons, conductors, and other tubular subsea members.

Frequently Asked Questions

Speak with Scansolution about scope, access, and schedule. We recommend the best deployment for your asset.