For the sample of single-specimen articles, the entire article represents the specimen to be measured. AISI Thickness Tolerance Ranges Galvanized Steel Sheets Thinkness. Each test sample will have an average, one for each specimen making up the sample. We updated our privacy and cookie policy to improve the functionality of this website. As long as the environment remains stable, case studies show that the coating throws up no unpleasant surprises and can be relied upon. Coating Weight Coating Thickness to reach 1 oz/ft2 Hot-dip galvanizing (batch or continuous), electroplating, zinc plating 1.7 mils (43 µm) Metallizing (zinc spraying) 1.9 mils (48 µm) Mechanical plating 2.2 mils (55 µm) Zinc-rich paint 3-6 mils (75-150 µm) Required fields are marked *. Coating weight or thickness can be measured by one of four methods. The carbon, sulfur and manganese content of the steel also may have a minor effect on the galvanized coating thickness. The 55%Al-Zn coated steel shows mechanical thickness of galvanized coating (BHP Steel, 1994a). What should a coating thickness gauge read on a G90 galvanized coating? The Galvanized Sheet Gauge is based on the U.S. Standard Gauge. Thickness measurement and Acceptance Criteria. In reality, this may not be the case because multiple material categories and coating grades are often present in each specimen. The actual thickness of galvanized coating achieved varies with steel section size, surface profile and surface composition. Single specimen, single material component. Features. 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 thickness of the galvanized coating is influenced by the overall size, shape, and thickness of the piece, and the chemistry of the steel itself. Galvanized Coating Thicknesses. (Note: Not shown in Photo 2 are the end cap and handhold cover plate which would likely be less than 160 sq. The corrosion resistance provided by the zinc coating is in direct proportion to the coating's thickness. Cling film comes in at 10-12 microns thick and a typical bacterium is 1-10 microns long. A minimum of 5 spot readings of multiple readings each (generally accepted to be three [3]) are taken spaced evenly over the specimen (article). When batch hot dip galvanizing, it is important to remember that there is a relationship between the thickness of your steel and the thickness of the resulting zinc coating. 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). Step 1. Save my name, email, and website in this browser for the next time I comment. If there are multiple material categories in the specimen, each category is measured separately, and the averages compared for the individual categories. Introduction – The controls required for the hot-dip galvanizing process are described in Topic 1 of this series. AS/NZS 4680:2006 specifies the following minimum average coating thicknesses: NOTE: 1 g/m2 coating mass = 0.14 µm coating 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’. Galvanizers Association per sq.ft. ft. heavier or .0037 inch thicker than the weight or thickness of the corresponding U.S. Standard Gauge Number, regardless of coating weights. Gage No. The number of articles to be sampled, the number of thickness measurements to be taken and the acceptance criteria are discussed. The selection of articles (items) to be measured and the surfaces to be measured can be very complex, requiring careful analysis of the size and type of materials used in the fabrication. FIGURE 1 – COATING DESIGNATION 70G50GE *SST = Single Spot Test as defined by ASTM A879. This process results in a material with the strength and formability of steel plus the corrosion protection of zinc. ; Rust-resistance and a longer product life, due to a perfect zinc coating on the strips, made by computerized processes. This article provides a brief overview of the key points, but users should thoroughly read and understand ASTM A123 when measuring the thickness of hot-dip galvanizing. The specimen coating thickness shall be the average of a minimum of 5 readings at widely dispersed points. As coating life expectancy figures quoted are based on the minimum coating thickness they are therefore usually very conservative. Prevent product failure by ensuring coating thickness and uniformity of … inches lbs. Hot Dip Galvanizing Thickness and Steel Thickness. Use of high silicon steel enables a still thicker coating of 200 μm to be specified. It does indeed pay to know your microns. 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. And what does ‘85 microns’, actually look like? Coating Thickness vs. Visually inspect each of the three areas to determine the number and type of material categories present. In addition to steel thickness, the composition of the steel alloy itself is also relevant. Assign each article to one of the two categories. It is a simple industry standard that is easy to retain and is applicable to many construction needs. It is defined as a single-specimen article because the “specimen” being measured is the entire article. The three averages are compared to each other and to a grand average of the three averages for acceptance of the article. This layer’s thickness can be controlled and the different thicknesses are designated below. 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. *Multi-Specimen Articles. Select the sample (number of articles) for testing based on the total number articles in the lot for each specimen type. 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. If a material category appears in only one specimen, there are no specimens to average and thus, the material category requirement is evaluated on that single specimen. In the example in A123 above, the three averages are compared to the dry film thickness requirement for compliance and are averaged together to verify compliance to the required thickness. Pipe and Tubing. Site by Un.titled, Facebook The countdown has begun to the annual GAGAs - Galvanizers Association Galvanizing Awards... Privacy A gauge conversion chart can be used to determine the actual thickness of sheet metal in inches or millimeters. 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. Your email address will not be published. Actual coating weights are often much more than the minimum specified in the standard. Thinkness. The definition of a lot is flexible in that it can be a shift’s production, a day’s production, or a truck load, but it generally consists of articles of the same size and shape. Fiber Steel Stainless Steel Glass Polyester Urethane Galvanized Type Type CHEMICAL Aluminum Polyester Powder Enamel 304 316 Acetyldehyde S U — — — S S Acetic Acid (10%) L S U U U S U Acetone S L L U L S S Aluminum Chloride (10%) U S U U U U M Aluminum Sulfate (10%) L S U U U U S Ammonia Gas L S — — — S S Ammonium Chloride U S U U U S S Galvanized Sheets - Continental Steel & Tube Company. How this microscopic coating then weathers is predictable but complex and fluctuates with atmospheric conditions. 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. 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.
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