Handle small fasteners or large assemblies with ease. The coating thickness curve shown in the figure below relates the effect of silicon in the base steel to the thickness of the zinc coating. The total zinc coating mass applied depends mainly on the mass and thickness of the steel being galvanized. Cling film comes in at 10-12 microns thick and a typical bacterium is 1-10 microns long. Categories are not blended. Galvanizers Association For requirements for threaded fasteners refer to AS 1214. In addition to steel thickness, the composition of the steel alloy itself is also relevant. All three articles will need to be measured and found acceptable in-order-to accept the lot. When using a magnetic gage, a specialized probe may be needed to measure tight configurations. What is the thickness of a galvanized coating? The total zinc coating mass applied depends mainly on the mass and thickness of the steel being galvanized. Thickness and Acceptance Criteria Example – Example 1 – Pole Structure. According to International Standard ISO 1461 [link is to spec at Amazon], minimum coating thickness standard for steel thickness 1 mm is 35 micrometer (local) and 45 micrometer (average). In reality, this may not be the case because multiple material categories and coating grades are often present in each specimen. Pipe and Tubing. In addition to steel thickness, the composition of the steel alloy itself is also relevant. The 5 spot readings are averaged. 2. Prevent product failure by ensuring coating thickness and uniformity of … Table 2 indicates that the galvanizing thickness of Coating Grade 100 is 100 microns or 3.9 mils. AS/NZS 2312.2 provides recommendations on techniques to minimise distortion and embrittlement, the effect of steel chemistry on the appearance and thickness of coatings. The galvanizer and inspector will need drawings to determine the wall thickness, if an open end is not available for measurement. How this microscopic coating then weathers is predictable but complex and fluctuates with atmospheric conditions. Required fields are marked *. Each test sample will have an average, one for each specimen making up the sample. If the number of articles is such that twice the number cannot be obtained, then twice the number of readings is performed on the articles. The corrosion rate of a galvanized coating is generally linear. For example, 18 gauge steel, according to a gauge conversion chart, is 0.0478 inch or 1.214 millimeter. Customised hardness rendered thanks to continuous annealing at the galvanizing line. These variables are represented in the table below. Zinc coating thickness is linearly related (on a macrolevel) to the time to first maintenance of hot-dip galvanized steel. The stripping and microscopy methods are destructive tests, are single point measurements, and are not efficient for the measurement of multi-specimen articles. Bolting Galvanized Steel Once the product is removed from the bath, high-pressure air is used to remove any excess molten zinc to create a closely controlled coating thickness. The countdown has begun to the annual GAGAs - Galvanizers Association Galvanizing Awards... Privacy There are provisions in ASTM A123 for resampling of the lot which requires that twice the number of articles be taken as a sample. While pre- and post-galvanizing weighing is non-destructive, it only provides the average weight of galvanizing across the entire item and is only suitable for single-specimens articles. This process results in a material with the strength and formability of steel plus the corrosion protection of zinc. of articles coating coating coating mass (all components thickness thickness minimum including castings) minimum minimum g/m2 mm µm µm <8 25 35 250 *8 40 55 390 Notes: 1. Steel sheet coated with zinc or 55%Al-Zn is widely used at the civil construction, mainly for roofing and cladding applications. This is especially true for fabricated items as discussed later. AS/NZS 4680:2006 specifies the following minimum average coating thicknesses: NOTE: 1 g/m2 coating mass = 0.14 µm coating thickness. Photos 3, 4 and 5 depict the different material categories present in each of the three pole sections. The specimen coating thickness shall be the average of a minimum of 5 readings at widely dispersed points. Your email address will not be published. and thus need to be measured separately, if galvanized. Jinan Sino Steel Co., Ltd was one large Steel Holding Company, as a window of foreign trade of Chinese Steel industry, our company has been conducting extensive exchanges and friendly co-operations with domestic and overseas companies on the ba Under the international system of units (SI) the micron is represented by the Greek symbol μm, which signifies one thousandth of a millimetre. Linkedin, Know your Microns – Galvanized Steel Coating Thickness. In most dry inland situations this can be infinitesimally slow, less than 1 micron per year, and unlike other coatings, a galvanized coating deteriorates in a linear fashion. AS/NZS 4680 specifies the following minimum local and average coating thicknesses based on the steel thickness. Multi specimen, multi component. FIGURE 2 – COATING CROSS SECTION ZINC COATING STEEL BASE METAL *Layers not shown to scale. We updated our privacy and cookie policy to improve the functionality of this website. The following photos and table are an example of dividing a structure (pole) for measurement and deciding how many surfaces must be measured. Assign each article to one of the two categories. (Note: Not shown in Photo 2 are the end cap and handhold cover plate which would likely be less than 160 sq. A minimum of 5 spot readings of multiple readings each (generally accepted to be three [3]) are taken spaced evenly over the specimen (article). Acceptance Criteria – Example 1 Pole Structure. To put that in perspective, it is often cited that the human eye can perceive objects no smaller than 40 microns and that the average human hair is a mere 50 microns in diameter. Step 3. A large enough flat area of surface must be available for the probe to make unimpeded contact (see Photo 1). This layer’s thickness can be controlled and the different thicknesses are designated below. This article is based on the use of magnetic gages to measure galvanizing thickness according to ASTM-A123, including the number of galvanized articles to be sampled, the number of thickness measurements to be taken, and the acceptance criteria. Details on all four methods can be found in ASTM A123, but this article only addresses the use of the magnetic thickness gages. Once the Coating Grade for the item is identified in Table 1, Table 2 of ASTM A123 (below) is used to further define the thickness or weight of the galvanizing that is required. Any of the three [3] averages for the article may be one coating grade below the requirement providing the grand average for the article meets the coating grade requirement. click to see corrosion rates in your area). The actual thickness of galvanized coating achieved varies with steel section size, surface profile and surface composition. ; Rust-resistance and a longer product life, due to a perfect zinc coating on the strips, made by computerized processes. per sq.ft. The following table identifies the material categories in the left, middle, and right sections of the pole example together with the requirements for galvanizing thickness. The following example demonstrates how Tables 1 and 2 of ASTM A123 are used to determine the minimum galvanizing thickness or weight required. The thickness of the galvanized coating is influenced by the overall size, shape, and thickness of the piece, and the chemistry of the steel itself. Figure 2: This chart shows the anticipated longevity of the hot-dip galvanized coating in various atmospheric environments, based on the coating thickness. The weight of the galvanizing is 705 grams/square meter or 2.3 ounces/square foot. The hot dip process, pioneered by AK Steel, provides a tight metallurgical bond between the steel and the coating. In the bath, the steel product is sent around a submerged roll and reacts with the molten metal to create the bonded coating, and then removed in a vertical direction. The material categories are: Plate, Structural Shape, Strip and Bar. For one-side or differential coating, please inquire. Hot Dipped Galvanized – sheet or strip steel bathed in a molten solution containing not less than 98% pure zinc to uniformly coat for corrosion resistance. The three averages are compared to each other and to a grand average of the three averages for acceptance of the article. Hot Dip Galvanizing Thickness and Steel Thickness. When it comes to the specification of hot dip galvanizing, most contractors know that to be standards compliant, 7mm steel requires an average coating thickness of ‘85 microns’. Wire, and Rebar (see Table 1 of ASTM A123 below). Excerpts from ASTM A123Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products: 1. Note that the following is a summary of the information from the definitions. *Single Specimen Articles. Coating weight or thickness can be measured by one of four methods. HOT DIP GALVANIZED STEEL, known as ZINCGRIP® Steel, is continuously coated on both sides with a zinc coating. Silicone which is used to deoxidise steel will affect coating thickness too: the more silicone present, the more reactive the zinc and the greater the thickness of the galvanized coating. Any of the three [3] averages may be one coating grade below the requirement provided the grand average is the coating grade requirement. The individual categories the two categories designated below depict the different material categories present in each.. Wire, and the acceptance criteria are discussed galvanic sacrificial cut edge protection to prevent corrosion of Sheet! 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