„How using wireless measuring probes for coating thickness measurements increases the safety of renovating steel constructions”.

Wireless measuring technology for corrosion protection in quality management and the restoration and monitoring of pylons and large steel constructions.

Wireless measuring technologies have proven to be advantageous wherever corrosion coating can only checked while climbing such as the quality and safety inspections of large steel constructions like pylons and antennae. Here, praxis- oriented QNix® Keyless-gauges and the new modular QNix® 8500 measuring system are particularly valuable. Their very small measuring probes are equipped with a hand strap and allow free climbing with both hands. The wireless measuring gauges enable the user to check the coating thickness on the object completely and effectively. The use of small measuring probes such as the wireless miniaturized QNix® 8500 sat and the QNix® Keyless enable the user to work particularly fast and conveniently in each situation. Even under such difficult conditions as they occur on pylons, the work will be done in compliance with all safety regulations and without any cables hindering the work. Determining coating thickness accurately and fast using the only thumb-sized and 30 grams light QNix® radio probe, is an advance in the field of coating thickness measurement, which both facilitates work and improves quality control and operational safety considerably.

Steel corrodes – coating protects.
About 15 billion tons of crude steel have been manufactured word wide in the last 140 years. Its excellent physical characteristics make steel the most versatile material. All these advantages however are opposed by one undeniable disadvantage: steel corrodes!
Fortunately, corrosion damage can be avoided by either alloying steel with various other elements (chromium, nickel and others) or by covering it in an organic or inorganic protective coating (paint, galvanizing, powder lacquer). Such coatings are used in over 90 per cent of all cases.

Corrosion protection is becoming more important.
The cost of corrosion protection is usually quite low. Especially when compared to the expected obsolescence of equipment or constructions and the cost of an operation shut down.
In Germany, such costs amount to billions. 20 years ago, the cost of corrosion damage has already been estimated at 70 billion Deutsche Mark (the former German currency); 4.5% of Germany’s gross national product of that time. Today, the cost is considerably higher. At 4% of Germany’s current gross domestic product, the amount now reaches 70 billion Euros. (Source: Flyer Corrosion Protection of the Fachhochschule Ostwestfalen, Iserlohn).
Therefore, the issue of corrosion protection is becoming more important to the industry. Numerous rules and regulations, such as DIN EN ISO 12944, support the constant effort to avoid and reduce corrosion damage.

Modern coating materials protect against corrosion.
To ensure passive corrosion protection, organic coating materials are used. Inorganic coatings are mostly manufactured in a galvanizing process. It is the impermeability against affecting media of such coating materials that is the most important aspect of their various protective features.
Existing pores allow subsurface corrosion to spread and destroy the coating from underneath. Therefore, steel structures are layered with several coatings to protect the structure for a longer period of time. Careful selection of adequate coating materials and the quality of the coating process are of the utmost importance to the durability of the coated layers. To ensure the quality of a Duplex system for instance, the coating thickness of the galvanized layer and the organic coating on the steel underground have both to be measured in a controlled manner.
Here, the combined measuring mode of the QNix® 8500 measuring system from AUTOMATION Dr. Nix, Cologne offers a particularly convenient way of measurement. The zinc layer and the upper organic layer are being measured in one single measuring process and then recorded. The coating thickness of both layers can then be analyzed simultaneously.

Providing safety - standards for checking coating thickness
As the protection and safety of large steel constructions are of such importance, the DIN EN ISO 12944 Part 7 “Corrosion protection of steel structures by protective paint systems” regulates the execution and monitoring of coating work. The standard explicitly requires dry coating thickness to be checked with measuring procedures and methods that are in compliance with the EN ISO 2808:2007(D) as stated under item 6.3. The standard includes: magnetic measurement methods based on the measurement of changes in the magnetic field as implemented by AUTOMATION Dr. Nix (item 5.5.6) and measurements with Hall sensors as well as eddy current measurement methods (item 5.5.8).

Measurement gauges suited for everyday use are sought-after.
In praxis, ease-of-use and ease-of-calibration are of particular advantages to gauges measuring corrosion protection and coating thickness. Easy operation, a rugged construction and a design that is ideally suited for everyday use are only a few of the important requirements for a reasonable application of such gauges in the quality management of major projects.

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