Measuring the Effect of Cathodic Protection on the Performance of Thermally Sprayed Aluminium Coatings at Elevated Temperature - Publishable Summary

Sep 18, 2026

Quantitative methods will assess how cathodic protection (CP) interacts with thermally sprayed aluminium (TSA) coatings on subsea pipelines and risers under elevated temperature and thermal cycling. The study will measure coating current demand for selected CP values and determine potential and corrosion rate at Ecorr during long-term exposure. It will also evaluate TSA compatibility across representative potentials, including effects of coating composition and sealing, and report implications for CP design codes and standards.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages5

Reading Time13 min

AccessFree to download

Background

Objectives

Project Progress

Benefits

Participants

Scope of Work

WP1 Preliminary Evaluation

WP2 Constant Elevated Temperature

WP3 Thermal Cycling

Measuring the Effect of Cathodic Protection on the Performance of Thermally Sprayed Aluminium Coatings at Elevated Temperature PUBLISHABLE SUMMARY 24323 Background Thermally sprayed aluminium (TSA) coatings are increasingly used to mitigate the corrosion on subsea pipelines and structures. Other than the results of work published in the early 1990s relating to the effect of various levels of cathodic protection (CP) at ambient North Atlantic seawater temperatures, there are limited published data covering the interaction of TSA and CP when applied to hot and thermally-cycled risers and hydrocarbon transportation pipelines. To address the issues highlighted above, this project will use quantitative methods to measure coating current demand under selected CP values and to measure potential and corrosion rate at Ecorr during long-term testing at elevated temperature and during thermal cycling. With many new fields involving the installation of increasingly difficult-to-maintain and remote deep-water facilities and extraction of hotter hydrocarbons, generation of such data will provide oil producers and installation companies with increased confidence in the long-term reliability of TSA coatings in subsea service. The implication of project results for cathodic protection design codes and standards will be reported. TWI Ltd, Granta Park, Great Abington, Cambridge CB21 6AL, United Kingdom. Tel: +44 (0)1223 899000 Measuring the Effect of Cathodic Protection on the Performance of Thermally Sprayed Aluminium Coatings at Elevated Temperature Objectives The main objective of this project is to generate data demonstrating the compatibility of TSA with cathodic protection applied across a range of representative potentials. This will include measurement of the effects of selected environmental conditions (elevated temperature and thermal cycling) and variation in coating specification (composition and use of sealants) . Project Progress 􀂄 The information gathered so far indicates the effectiveness of TSA in protecting steel at elevated temperatures without CP even when damaged. 􀂄 TSA shows healing of the damaged region by the deposition of calcareous matter in seawater even at elevated temperatures. 􀂄 The CP limit imposed by the commonly used standards can be detrimental for the TSA coating system. 􀂄 Designing a CP system for hot risers coated with TSA should include studies to assess the effect of the applied potential on the coating system. Benefits 􀂄 Generation of environment-specific cathodic protection design data, which will provide oil producers and installation companies with increased confidence in the long-term reliability of TSA coatings in inaccessible, deep-water service. 􀂄 Extended operating life of facilities in remote locations with reduced maintenance costs. 􀂄 The opportunity to reduce anode mass on subsea structures by up to 80%(thus reducing structural mass and cost) . Participants The Sponsor Group currently comprises: 􀂄 ExxonMobil Development Company 􀂄 Total E&P France 􀂄 BG Group TWI Ltd, Granta Park, Great Abington, Cambridge CB21 6AL, United Kingdom. Tel: +44 (0)1223 899000 Measuring the Effect of Cathodic Protection on the Performance of Thermally Sprayed Aluminium Coatings at Elevated Temperature Scope of Work The following work packages are being undertaken: WP1 Preliminary Evaluation of the Effect of Temperature on the Behaviour of TSA Coating Under Different Applied Potentials. Preliminary work was undertaken to confirm the detail of the test conditions proposed for WP2 (Elevated Temperature) and WP3 (Thermal Cycling) based on representative environmental service conditions provided by Sponsors and laboratory testing comprising: 􀂄 Uncoupled response (free corrosion potential / Ecorr) of two unsealed TSA alloy compositions (on an inert substrate) up to 90ºC. 􀂄 Coupled response of unsealed TSA (on an inert substrate) with applied potentials at 30°C, 60

FAQs

What is the project’s primary goal regarding TSA and cathodic protection?

Generate data demonstrating TSA compatibility with cathodic protection across a range of representative potentials, including effects of elevated temperature, thermal cycling, and coating specification changes.

Which measurements are planned during the long-term tests at elevated temperature?

Coating current demand for selected CP values, and potential and corrosion rate at Ecorr, recorded during extended exposure under representative service conditions.

How will thermal cycling conditions be simulated in WP3?

Using half-buried, vertical TSA-coated pipes with oil cycled from 130°C to 10°C, immersed in chilled artificial seawater, with CP levels determined from WP1 and WP2 and potential/current recorded over up to 12 months.

Sep 18, 2026

Uploaded by Berry Peter