Subsea Pipeline Bracelet Anode (McCoy Formula) Calculator

Determine electrical discharge resistance (R_a) of half-shell bracelet sacrificial anodes on subsea pipelines per the McCoy formula and DNV-RP-F103.

Bracelet Anode Geometry

Pipeline Outside Dia D (mm): 16-inch pipe

Anode Axial Length L (mm):

Anode Radial Thickness t (mm):

Seawater Resistivity ρ (Ω·cm):

Marine Growth Hard Shell Fouling:

Anode Alloy Density (kg/m³): Aluminum alloy ~ 2750 | Zinc ~ 7140

Discharge Resistance & Anode Weight

Anode Resistance R_a:

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Single Anode Net Mass:

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Current Output at ΔV=0.25V:

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Anode Outer Diameter:

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McCoy Formula Validity:

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Frequently Asked Questions

Why are bracelet anodes used instead of stand-off anodes on subsea pipelines?

Pipelines are laid using S-lay or J-lay barges with roller stingers or tensioners. Projecting stand-off anodes would snap off during pipelaying. Flush half-shell bracelet anodes clamp securely around the pipe without interfering with stinger rollers or concrete weight coatings.

What is the McCoy formula for bracelet anode resistance?

Published by A.E. McCoy, Ra = 0.315·ρ / √A accurately approximates the electrical grounding resistance of short, flush cylindrical bracelet anodes on coated subsea conduits.

How does marine growth biofouling affect subsea bracelet anodes?

Hard calcareous fouling (barnacles, oysters, tubeworms) encrusts anode surfaces, insulating active aluminum grains and increasing discharge resistance Ra by 30% to 100%, derating current output.