CATHODIC PROTECTION RETROFIT SYSTEM


CP Retrofit System

    • To extend service life of a structure.
    • CP depletion is faster than originally anticipated.
    • "Hot spots" on a structure which need special treatment.
    • Cathodic protection is becoming insufficient.

CP Retrofit Can Be Carried Out On :

    • Onshore and offshore pipelines.
    • Jetty piles.
    • Sheet piles.
    • Offshore jackets.
    • Tank bottoms
    • Plant's underground structures

Retrofit Anode Sacrificial Magnesium System



Retrofit Anode Impressed Current System



Retrofit Anode Impressed Current System


Retrofit Anode Sacrificial Aluminium System



Typical example of cathodic protection retrofitting : pipeline casde

What input needed for evaluating the remaining pipeline anodes?

    • Pipeline installation date (year).
    • Pipeline length & size.
    • Pipeline ambient temperature.
    • Hot section & the respective temperature.
    • Type of pipeline coatings.
    • Check for concrete coatings.
    • Original anode type, dimensions, weight, spacing etc.
    • Check the underwater ROV Survey Reports on the pipeline for:
    • Video log - to spot the anodes
    • Pipe Potentials – by ROV
    • Current Output – calculate through the field gradient (FG) measured by ROV.
    • Computed anode remaining life.
    • Comments on the anode depletion percentage eg: 25-50%, 50-75%, 0-25%, 75-100% .

Typical examples of anode & sled demension

- Anodes specification :

    • Type: Galvalum III or equivalent
    • Current capacity: 2500 A.Hr/kg
    • Dimension: 1100 mm (L) x 225mm (W) x 200 mm (H)
    • Utilisation: 0.8

-Anode sled:

    • Type: Galvalum III or equivalent
    • Size: 2000 mm x 2000 mm (75mm x 9mm flat core)
    • No. of anodes per sled : 4 (four)
    • Total Anode Weight per sled : 524 kg (in air)
    • Estimated Total Sled Weight : 1000-1200 kg





Typical anode sled

- Basic concepts for anode sled design:

    • Stand anode weight.
    • Maintain anodes at best operation conditions (e.g. in seawater).
    • Stable, stationary underwater.
    • Save space in the loading/working barge (e.g. can stack).
    • Easy/quick underwater installation to reduce cost.



Typical Anode Sled Installation

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