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Specialist Coating


Inspection & Consulting


FEATURE SPONSOR


PROTECTIVE COATINGS


PROJECT C ‘MINOR DETAIL – MAJOR PROBLEM’ OFFSHORE WINDFARM


Poor coating & QC practice on 5,400 overlooked stainless steel grating-studs on carbon steel structures for 30 out of 71 widely-dispersed offshore wind turbines turned a minor detail into a significant problem.


5,400 main platforms & resting-platforms grating-studs. Opening the coating showed substantial areas of surrounding carbon steel corroding due to ‘galvanic corrosion’. Clearly, these studs and especially the ‘mixed weld’, had not been treated to Norsok M-501 standards. Coating- thickness on the studs was less than required. Masking-tape was found under paint. Some surface-profiles were poor.


No similar coating-breakdown was found on the 41 foundations produced by Contractor A under the watchful eye of our QC-inspectors.


Although Contractor A made a higher investment in proper Quality Control, clearly Contractor B paid out circa five times Contractor A’s initial budget – a 500% advantage, even on a single project.


Full QA/QC control could have prevented a minor infringement becoming a major calamity from the start.


Howard Jess CONCLUSIONS


Most studs were not treated properly to Norsok M-501 standards; an average corroded area of 17cm2


per stud, times


180 studs per foundation, times 30 foundations was the result. Offshore remediation costs mushroomed quickly to €1.5 million.


The project was overseen by two joint- venture contractors with no in-house QA/ QC skills or certifications.


Contractor A hired 3 to 4 certified coating-inspectors from Howard Jess Solutions/SCICON Worldwide to act as an independent QC with stop/go authority over the coating of 41 foundations.


Meanwhile, Contractor B used two separate freelance inspectors to survey the production of 30 foundations under their own QC-department.


Two years after offshore-installations, ALL 30 Contractor B foundations showed corrosion-breakthrough around some


There are no corrosion-protection shortcuts. Premature coating-failures offshore can increase in-house coating- budgets by ten or even a hundred-fold.


All parties, from owner to main-contractors and sub-contractors, must make sure Quality Control & Assurance is a top priority at all times. Small details in large numbers can escalate offshore repair-costs rapidly.


When large figures are at stake, the price- difference between well-trained, certified coating-inspectors with sound offshore corrosion-protection experience and less qualified inspectors often drawn from industries with little offshore experience, is “penny-wise, pound-foolish”.


If hiring experts seems expensive, try hiring amateurs!


Gunnar Ackx


Jon Herbert


Jon Herbert talks to Howard Jess and Gunnar Ackx.


ED’S NOTE This is an


abridged version please see the complete article ‘Offshore


Click to view more info


coatings – Failure or Cost- saving Opportunities?’ By using this link.


www.windenergynetwork.co.uk


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