International standards focus on the inspection of ship's coating thicknesses.
As protective coatings reduce corrosion and are thereby increasing a ship's stability, the quality of coatings in ship construction are increasingly becoming subject of international regulations [1], [2], [3]. Particularly the ship's ballast water tanks are of importance here. They are prone to corrode and therefore a danger to the ship's structure; especially as corrosion damage is so difficult to detect.
In this regard, the "Safety of Life at Sea" (SOLAS) regulation II-1/3-2 for ballast water tanks and double hulls is the first international convention concerned with corrosion prevention that has been established.
It results in the latest, very extensive IMO resolution MSC215(82): the "Performance Standard for Protective Coating" PSPC. Goal of this standard is to ensure that the quality of coating lasts at least during the 15 years of a ship's average service life. This standard applies to all ships over 500 gross registered tons regarding their ballast water tanks and to double hull ships with an overall length of 150 meters and building contracts placed after July 1 2008. In coordination with the new IMO resolution, the IACS (International Association of Classification Societies) has issued procedural requirements (IACS PR 23) demanding the continuous documentation of work in a so-called "Coating Technical File" (CTF). This CTF is to be kept on board during the whole lifetime of ship. The file includes specifications of the coating system, and records of the shipyard and the shipping company or the ship owner considering inspection, maintenance and repair work.
This results in new challenges for shipyards, shipping companies and classification societies, as, according to sections 6.1.1-3 of the new IMO resolution, all measurements have to be documented within the CTF by an accredited inspector.

Precise and effective analysis of coating thickness measurements in practical use.
Regarding the quality control of usually epoxy-based coatings, the IMO standard MSC215(82) requires coating thickness to be evaluated according to the 90/10 rule. This rule specifies that 90% of all measurements have to be equal to or excess the required coating thickness. The remaining 10% of the measurements must not fall below 0.9 times the required coating thickness [5]. Furthermore, shipyards work in accordance with DIN EN ISO 12944-5 [6]. Its controversial part 5 refers, since January 2008, to the ISO 19840 and the ISO 2808 regarding rough surfaces in particular [7], [8]. The qualification of personnel in accordance with certain training standards such as FROSIO or NACE is just as important as fast and reliable measuring gauges to record, for instance, 40.000 measurements a day in rough environment and difficult locations, as shown in figure 1.
Regarding the reliability of coating thickness measurements during several thousand measurements a day, the exchangeable measuring probes (figure 2) of the QNix® 8500 measuring system are equipped with ruby measuring heads. As rubies have a much higher hardness than any metal overlay the probes offer highest wear resistance.

Shipyards organize the construction of a ship in so-called ship sections that are coated and measured separately before assembly. The use of methodical recording allows single sections to be saved in individually named batches, as shown in figure 3. Each single layer of the usually applied multi-layer systems is measured fast and methodically with regard to time and location. This is important, as it provides an effective method of operation and increases the cost-efficiency of the quality management. To achieve a comprehensive analysis and documentation of measurements for the "Coating Technical File" the gauge conveniently allows measurements to be transmitted wirelessly using a personal computer, as shown in figure 4.
The direct transfer of measuring data to Microsoft Excel enables users not only to analyze the measurements statistically according to their personal requirements but also to individually document the data for use in the "Coating Technical File". Together with Excel, the QNix® 8500 measuring system provides a convenient method to combine the recording, analysis and documentation of measurements in one device. This guarantees institutions responsible for construction, inspection and verification a fast and effective processing and documentation of measurement data. This will be of even more important in future, when the new IMO regulation MSC res. 244(83) documentation will presumably make the maintenance and repair work of ships with at least 500 gross registered tons mandatory [9].

Summarization
The terrible ship disasters of the past that were, among other things, due to extensive corrosion damage [4], are the reason why IMO, classification societies, ship owners and shipyards focus their attention on corrosion protection. Modern coating thickness measuring devices such as the modular QNix® 8500 provide fast and exact coating thickness measurements and an effective and convenient documentation of these measurements using a PC. Especially, since the implementation of the "Coating Thickness File", which is to be kept as record of a ship's whole service life, the various organizations have to be able to analyze and individually document the required measurements of coating thickness.

Manufactured exclusively in Germany, measuring gauges from AUTOMATION Dr. Nix provide high quality, fast customer-oriented service and simple and individual data processing capabilities using a PC and Microsoft Excel. This guarantees the highest degree of productivity, flexibility and an increase in the user's value creation.

Literature
[1] Timothy E. Dunbar, Neil Pegg, Farid Taheri and Lei Jiang
"A computational investigation of the effects of localized corrosion on plates and
stiffened panels"
Marine Structures, Volume 17, Issue 5, September 2004, pages 385-402
[2] J. K. Paik and A. K. Thayamballi
" Ultimate strength of ageing ships"
Proceedings of the Institution of Mechanical Engineers, Part M
Journal of Engineering for the Maritime Environment
Volume 216, Number 1 / 2002; pages 57-77
[ 3] Brian Goldie
"Marine coatings under the regulatory spotlight"
Journal of Protective coatings & linings, Volume 25 , Number 2 ; Feb. 2008, pages 48 - 52
[ 4] Thorsten Lohmann und Daniel Engel
"Aktuelle Entwicklungen im Bereich Korrosionsschutz bei der IMO und IACS"
Tagungsband zur 7. Tagung " Korrosionsschutz in der maritimen Technik", pages 15-22
[ 5] Resolution MSC.215(82)
„Performance standard for protective coatings"
IMO Naval Architectural Group - Maritime Safety Committee (MSC)
[ 6] DIN EN ISO 12944
" Korrosionsschutz von Stahlbauten durch Beschichtungssysteme"
CEN Europäisches Komitee für Normung
International Organization for Standardization (ISO)
[ 7] ISO 19840
"Beschichtungsstoffe - Korrosionsschutz von Stahlbauten durch Beschichtungssysteme
- Messung der Trockenschichtdicke auf rauhen Substraten und Kriterien für deren
Annahme"
CEN Europäisches Komitee für Normung
International Organization for Standardization (ISO)
[ 8] DIN EN ISO 2808
" Paints and varnishes - Determination of film thickness"
CEN Europäisches Komitee für Normung
International Organization for Standardization (ISO) (TC 35/SC 9)
[ 9] RESOLUTION MSC.244(83)
" ADOPTION OF PERFORMANCE STANDARD FOR PROTECTIVE COATINGS
FOR VOID SPACES ON BULK CARRIERS AND OIL TANKERS"
IMO Naval Architectural Group - Maritime Safety Committee (MSC)