A new coating on steel will only last as long as the underlying surface allows. For offshore structures, ships and port facilities, the greatest invisible enemy is salt: chlorides and sulphates that lodge in the rust scars and continue to corrode beneath the fresh paint. This article explains how salts are measured, what the standard limit values are, and how to prepare the surface reliably before coating.<\/p>\n
Corroded steel is not smooth. Chloride and sulphate crystals accumulate in the depressions of the rust scars; these are not visible to the naked eye. If a coating is applied over them, these salts draw moisture through the coating. This leads to blistering (osmotic blistering), and corrosion resumes beneath the coating. The result is that the coating often fails long before its intended service life, and rectification work at sea or in dock is particularly expensive.<\/p>\n
In practice, the Bresle test<\/strong> implemented. A self-adhesive measuring cell (Bresle patch) is affixed to the steel surface and filled with a small, precisely measured quantity of distilled water. The water dissolves the salts from the surface. The method is described in ISO 8502-6<\/strong> described.<\/p>\n The conductivity of the solution is then measured (ISO 8502-9<\/strong>) and converted into an area density, usually expressed in mg\/m\u00b2 as sodium chloride. The conductivity measurement takes account of all water-soluble salts collectively; it does not distinguish between chlorides and sulphates.<\/p>\n There is no standard statutory limit. The decisive factor is the Project Specification<\/strong>, i.e. the specifications set by the coating manufacturer, the client or the regulations to which the contract refers. Two frequently cited examples:<\/p>\n You should therefore check, before you begin, which standard applies to your project and who will carry out the assessment \u2013 usually a corrosion protection assessor or inspector.<\/p>\n Rinsing with high-pressure fresh water removes loose salts from the surface. However, water alone often fails to reach the crystals deep within the rust scars. Even blasting does not always solve the problem: whilst it roughens the surface and removes rust, it can also work salt residues into the new surface. For this reason, both methods are often combined: blasting for mechanical preparation and a Salt remover<\/strong> for the remaining salts.<\/p>\n When coating monopiles for an offshore wind farm, the permissible residual salt content was set at 20 mg\/m\u00b2 NaCl, measured in accordance with ISO 8502-6 and ISO 8502-9. Although the steel was new and the piles had been washed with distilled water under high pressure as usual, the required value was not achieved. The on-site inspector was familiar with the Salt Remover from a previous project and recommended it \u2013 the feedback from the production team was positive. This example shows that even in the absence of visible corrosion, it is worth carrying out the measurement, and water alone is not always sufficient.<\/p>\n The Power Eco Metal Salt Remover<\/a> Eco-Nova\u2019s product is a water-based salt remover designed specifically for this stage of the process. Depending on the project, we supply it ready for use or as a concentrate to be diluted on site. On request, we can provide a test sample for a test area \u2013 this allows you to see, based on the Bresle value, how well the Salt Remover performs on your component. Find out more on our website Offshore & Shipyard<\/a>.<\/p>","protected":false},"excerpt":{"rendered":" Salzreste auf Stahl lassen neue Beschichtungen vorzeitig versagen. Wie der Bresle-Test funktioniert, welche Grenzwerte \u00fcblich sind und wie Sie Salze vor dem Beschichten zuverl\u00e4ssig entfernen.<\/p>","protected":false},"author":83,"featured_media":6065,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[81],"tags":[],"produktbereich":[221],"class_list":["post-6070","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-wissen-tips-zur-industriellen-reinigung","produktbereich-offshore"],"acf":{"kurzantwort":"Salze wie Chloride und Sulfate sitzen in den Rostnarben von korrodiertem Stahl und f\u00fchren unter einer neuen Beschichtung zu Blasen und Korrosion. Gemessen wird der Salzgehalt mit dem Bresle-Test (ISO 8502-6\/-9). Der zul\u00e4ssige Wert steht in der Projektspezifikation. Ein Salzentferner l\u00f6st die Salze, die Wasser allein nicht erreicht.","kernaussagen":[{"text":"Salzreste unter der Beschichtung f\u00fchren zu osmotischer Blasenbildung und vorzeitigem Versagen."},{"text":"Gemessen wird mit dem Bresle-Test nach ISO 8502-6 und der Leitf\u00e4higkeit nach ISO 8502-9."},{"text":"Der zul\u00e4ssige Restsalzgehalt steht in der Projektspezifikation, z. B. 20 mg\/m\u00b2 NaCl nach NORSOK M-501."},{"text":"F\u00fcr Anmischen und Sp\u00fclen nur destilliertes oder vollentsalztes Wasser verwenden."}],"faq":[{"frage":"Was ist der Bresle-Test?","antwort":"Ein Verfahren nach ISO 8502-6, bei dem eine Messzelle auf die Stahloberfl\u00e4che geklebt und mit destilliertem Wasser gef\u00fcllt wird. Die gel\u00f6sten Salze werden anschlie\u00dfend \u00fcber die Leitf\u00e4higkeit bestimmt (ISO 8502-9)."},{"frage":"Welcher Restsalzgehalt ist zul\u00e4ssig?","antwort":"Das legt die Projektspezifikation fest. H\u00e4ufig genannt werden 20 mg\/m\u00b2 NaCl nach NORSOK M-501 f\u00fcr Offshore-Anlagen und 50 mg\/m\u00b2 NaCl nach IMO PSPC f\u00fcr Ballasttanks."},{"frage":"Ersetzt ein Salzentferner das Strahlen?","antwort":"Nicht grunds\u00e4tzlich. H\u00e4ufig werden beide Verfahren kombiniert: Strahlen f\u00fcr die mechanische Vorbereitung, der Salzentferner f\u00fcr die verbliebenen Salze. Welches Verfahren gilt, entscheidet in der Regel der Gutachter."},{"frage":"Warum muss VE-Wasser verwendet werden?","antwort":"Leitungs- und Brauchwasser enthalten selbst Chloride. Damit w\u00fcrde man neue Salze auf die Oberfl\u00e4che bringen und das Messergebnis verf\u00e4lschen."}],"passende_produkte":[6067],"passende_themen":"","themen_verunreinigungen":[],"themen_anwendungen":[],"geprueft_am":null,"cta_art":"beratung","quellen":[{"titel":"ISO 8502-6:2020 \u2013 Extraction of water soluble contaminants for analysis (Bresle method)","url":"https:\/\/www.iso.org\/standard\/73862.html"},{"titel":"ISO 8502-9:2020 \u2013 Field method for the conductometric determination of water-soluble salts","url":"https:\/\/www.iso.org\/standard\/73863.html"},{"titel":"NORSOK M-501:2022 \u2013 Surface preparation and protective coating","url":"https:\/\/standard.no\/en\/sectors\/petroleum\/norsok-standards\/m-material\/m-5012022\/"},{"titel":"Bresle-Methode (\u00dcberblick, englisch)","url":"https:\/\/en.wikipedia.org\/wiki\/Bresle_method"}]},"yoast_head":"\nWhat are the limit values?<\/h2>\n
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Why water alone is often not enough<\/h2>\n
This is how salt removal works in practice<\/h2>\n
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From real-life experience<\/h2>\n
What matters<\/h2>\n
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Salt removers for offshore, shipyards and ports<\/h2>\n