Development of New Alloys for Si Reactivity Control
Nai Yong Tang
Teck Cominco Metals Ltd.
Silicon contained in steel can significantly alter coating microstructure, thereby resulting in excessive steel reactivity in general galvanizing. After intensive R&D work over several decades, this reactivity can now be controlled by alloying the zinc bath with nickel if the silicon content of the steel does not exceed 0.20%. It has been demonstrated that, at any stage of a commodity price cycle, nickel addition always results in net savings to galvanizers. To combat a fully developed reactivity problem associated with a silicon level in steels well in excess of 0.2% is a much more difficult task.
Alloying the bath with suitable chemical elements can prevent the delta sublayer from disintegration and stabilize the gamma and gamma 1 sublayers during galvanizing.
Unfortunately, such elements are rare and frequently introduce side-effects. The introduction of aluminum to general galvanizing baths can revolutionize coating microstructure, thereby ushering in a totally new approach to silicon reactivity control. However, there are numerous technical challenges which must be resolved before aluminum-containing alloys can get wide acceptance in the general galvanizing industry.
Hot Dip Galvanized Rebar Research Update
Doug Rourke
International Zinc Association
The global zinc and general galvanizing industries have been researching and promoting hot dip galvanized reinforcing steel for over 40 years. The effort has had some market success due in part to the body of research that exists supporting the selection of galvanized rebar over other protection systems.
This paper reviews the results of six recent galvanized rebar research projects conducted by the
International Zinc Association (IZA) through its affiliated research arm, the International Lead
Zinc Research Organization (ILZRO). Results from these projects advance our understanding of galvanized rebar performance in key areas such as zinc’s initial reaction in fresh concrete, but also highlight the discrepancies between accelerated laboratory test data and real world observed performance.
Some of the key findings to be discussed are as follows:

Ongoing 8-year accelerated laboratory corrosion testing at Florida Atlantic University has shown that galvanized rebar, and particularly Galfan coated rebar, show less electrochemical activity and therefore less corrosion than uncoated “black” rebar in identical concrete test samples.

Test work at the University of Waterloo focused on the initial reaction between chromated, non-chromated, weathered and annealed galvanized surfaces and fresh

concrete. Results show that initial corrosion in OPC, regardless of the zinc coating surface condition, is less than 1 µm before coating passivation occurs.
 Professor Darwin at Kansas University found that zinc’s chloride threshold for corrosion initiation is quite varied but on average greater than that of uncoated rebar.

Research from Australia confirmed that existing fabrication guidelines for 410 MPa rebar developed 20 years ago are also applicable for higher strength 500N (MPa) rebar currently in use in Australia.
Kettle Substitution Using Holding Vessels: Technical and Operational Advantages
Mario Ubiali
Zinco Service Srl
The presentation aims at making a clear and documented comparison between the traditional pump-out procedures and those involving the use of electric holding vessels.
By using visual materials such as digital videos and pictures, along with extensive data collected in 7 years on the field, advantages for the galvanizer will be presented and explained. The entire procedure will also be detailed in order to explain the complexities of kettle changes and the direct and collateral risks involved in such crucial operations. Particular emphasis will also be given to health and safety issues involved, as well as implications in terms of environmental impact.
Stormwater Monitoring and Treatment
Frank Gaudet, PE
Environmental Engineer
This paper reviews the stormwater monitoring programs at the 4 AZZ galvanizers in Texas. The monitoring program employs rain gauges and automated sampling machines to collect samples from optimal storm events. On-site rain gauges store months of rain data which can be downloaded to a PC and then reviewed to select qualified storm events. Sampling machines are triggered by flow in the drainage outfalls and then collect a single sample for every rain event.
The samples are used for periodic visual inspections and for water quality tests required by the stringent Texas stormwater regulations.
Over ten years of monitoring data are summarized and evaluated. Correlations to rainfall variations are examined for meaningful relationships. The findings include dissolved and particulate components of zinc in stormwater, which is important in the design of control systems. Specialty sample results show the zinc content of runoff from downspouts from a galvanizer roof and from the surface of galvanized products.
Additional findings demonstrate a relationship between zinc soil contamination at the former
AZZ Crowley plant and stormwater quality. These findings are reviewed for water quality improvements following remediation of the site.

The presentation will review stormwater control methods applied at several AZZ plants. Small basins are used at one plant to capture stormwater and then chemically precipitate the zinc contamination. Another location uses a filtering swale for cleansing stormwater.
Beyond TSS: Evaluation of Emerging/New Technologies For Removal of Copper, Zinc and
Lead
Scott Lindblad
Water Tectonics Inc.
Traditional methods of heavy metal reduction have typically been through the use of filtration, adsorption, and plant uptake. These methods can effectively reduce heavy metal concentration, but their performance is often diminished over time due to rigorous maintenance needs. Another drawback to traditional methods is they can use up a large amount of real estate which can be proportional to the removal rate.
The goal of this study was to evaluate the performance of several new technologies available for heavy metal reduction. We chose an electrocoagulation treatment system and a hydrodynamic separator equipped with a porous filter housed in a catch basin structure. The technologies were tested individually using simulated run-off mimicking different land use applications: suburban, dense urban, and industrial. After looking at the removal rates and efficiencies of the new technologies by themselves, we then added some of the traditional methods of metals removal.
We found the combination of the two provided the best overall reduction across all land use application.
Cost was also a consideration in this study as it is a strong predictor of what is feasible to install and maintain. Maintenance is a huge part of effective reduction rates, and systems that are too expensive to maintain simply do not get maintained or installed. Maintenance cost was significantly less for some of the stand alone applications. When a new technology was incorporated into a traditional treatment train maintenance costs were also reduced.
Based on application and required discharge limits we concluded a single technology could be effective; however, more often than not, these new products used in a treatment train were the most effective and sustainable solution.
Coating Galvanized Structures: A New Way Forward
Richard Schertzer
Madison Chemical Industries, Inc.
Abrasive blasting of galvanized structures is the generally accepted method of surface preparation for duplex coatings designed for heavy to severe service. Of particular concern are coatings for embedded portions of tubular structures, one of our major businesses.
We wanted to determine if a less intensive and less costly surface preparation was possible.
Often, results were only marginal due to a number of equipment, process, and quality issues.

Recent formulation improvements to other Madison Chemical polyurethane products were integrated into our duplex coatings to improve adhesion - one of the most critical components of extended corrosion protection. Other experiments confirmed that a proprietary acid cleaning solution performed comparably to a high-quality abrasive blast finish. We combined these discoveries and obtained adhesion pull values approximately 33% higher than those obtained from the traditional coating/surface preparation method; 3200 vs. 2400 pounds per square inch
(psi) - a significant improvement.
This alternative approach is ideal for coaters utilizing blasting equipment requiring significant or repeated maintenance and for shops just getting started in duplex coating of galvanized structures by providing significantly lower operating costs. Madison commercialized these developments earlier this year under the GalvaCladTM banner.
Galvanized Coatings
Bailey Metals Testing
Recent fires in California have engulfed much of the landscape and manmade structures. Along with the destruction of manmade structures, several miles of galvanized coating were exposed to elevated temperatures attributed to these fires. Published data shows fires can reach in excess of
2000 ºF by the typical observance of a deep orange coloration in the flames. With a broad temperature range for typical wild fires, questions have been raised by the insurance industry regarding the identification of galvanized coating damage attributed to such fires.
This paper examines the affect of temperature on the degradation of hot-dip galvanized coatings.
Samples of a galvanized chain link fence were exposed to temperatures ranging from 375 ºF to
2000 ºF for a period of 1 hour in a furnace at atmospheric pressure, then macro examined to document the physical appearance. Cross sections of all samples, including the as-received condition, were examined metallographically to document the morphology of the microstructures relative to the typical Eta, Zeta, Delta and Gamma layers observed for hot-dip galvanized coatings. Semi-quantitative analysis of the resulting layers is also addressed along with the wire base alloy to investigate possible diffusion occurrences.
TxDOT’s Experience with Galvanized Steel Structures
Karl Janak
The Texas Department of Transportation
The Texas Department of Transportation (TxDOT) has several galvanized steel structures within their highway facilities, including signs, lighting, and traffic signal support structures, along with railing, and various other structures. The zinc coating on hot-dip galvanized steel has served as an excellent barrier protection to extend the service life of these structures, but a few problems have been encountered during some galvanizing operations. This presentation will address
TxDOT’s positive encounters with galvanizing along with some challenges galvanizers have faced when coating TxDOT structures, such as high mast illumination poles and overhead sign support monotube structures.

Aluminum in the Galvanizing Bath
Barry Dugan
Horsehead Corporation
Aluminum is the element most commonly added to the zinc bath. Galvanizers use a variety of methods to add the aluminum, targeting different concentrations. Unfortunately, every galvanizing operator has their own horror story of the over-addition of this element. Barry Dugan will present the results of the AGA survey was conducted earlier this year, which surveyed almost 100 kettles.
Hazardous Waste Compliance
Frank Gaudet, PE
Environmental Engineer
This paper will review the hazardous waste issues important to galvanizing operations, drawing from the experience of 20 galvanizing plants and their efforts to comply with the complex hazardous waste regulations. The author has 16 years of experience with galvanizing wastes, as well as experience with dozens of EPA and State agency inspections of galvanizing plants. The distinctions between hazardous and non-hazardous wastes are emphasized with a discussion of the options for treating hazardous waste.
The presentation will highlight common violations found by government agency inspectors at galvanizing plants, including violations involving documents. The current push by the EPA for proper disposal of fluorescent lights is one of the warnings in the presentation that will benefit all galvanizers.
There will be a brief discussion of the “Closure” requirements for hazardous waste storage tanks.
A galvanizer must prove the area around a hazardous waste storage tank is clean to obtain approval from the environmental agency; often, the proof must include an evaluation of riskbased clean-up standards which consider the danger of residual amounts of zinc in soil and groundwater.
USEPA versus Zaclon LLC on Galvanizers' Strip Acid: Who won, who lost, and what does it mean?
James Krimmel
Zaclon LLC
In October 2005 the USEPA cited Zaclon for recycling Galvanizers' strip acid without following
RCRA requirements. Zaclon answered the material, as used by Zaclon, is exempt from RCRA requirements. In June 2006 the case was heard before USEPA's chief administrative law judge, who issued her decision in June 2007. The decision was made final in November 2007.

Jim Krimmel, President of Zaclon LLC, will discuss the Judge's decision and how it effects the recycling of strip acid. Along the way, he'll provide insights into the EPA hearing process, lessons learned, and discuss the fall-out from the decision.
Kettle Skimmings and the DEP
John Roy
Connecticut Galvanizing
Barry Dugan
Horsehead Corp
“I’m from the DEP, and I’m here to help you.” Experience this tale of woe as retold by John
Roy of Connecticut Galvanizing and Barry Dugan of Horsehead Corporation. What happens when a state agency considers kettle skimmings as a hazardous material?
Evaluating the Performance of Hexavalent Chromium-free Passivation Treatments on Hot
Dip Galvanized Surfaces
R. Feser, C. Schulz, M. Steffen
Laboratory for Corrosion Protection, University of Applied Sciences, Iserlohn, Germany
F. Goodwin, D. Rourke
International Zinc Association
Quenching work pieces after galvanizing in a dilute aqueous sodium dichromate or chromic acid solution is a well established and effective method of inhibiting white rust formation during storage and shipping. However, occupational health and environmental concerns regarding the use of hexavalent chromium have significantly reduced its use in Europe and North America.
Treatment suppliers have developed Cr+6-free alternatives but their performance is not well known.
This study compared the performance of over 50 commercially available Cr+6-free passivation treatments using three accelerated corrosion tests. All treatments were compared against a standard hexavalent chromium treatment as well as parts receiving no treatment. It should be noted that the application conditions for most treatments tested was incompatible with use in a galvanizing quench tank. However, two of the treatments tested are commercially available products currently in use by galvanizers in Europe. Test results from these two treatments were better than no treatment but not nearly as good as a standard hexavalent chromium passivation.
The extensive amount of corrosion data generated in this project is a useful baseline for future performance evaluations of new Cr+6-free passivation treatments that become available in the market. Additional work in this area should include testing treatments applied from in-plant production quench tanks. This would help determine treatment performance over time (as contaminants build-up in the quench tank) and provide guidance as to treatment replenishment and disposal.

AGA Hexavalent Chromium Study
Christine Kleen, Tom Langill
American Galvanizers Association
The AGA conducted this study to provide the galvanizing industry quantitative information on how much hexavalent chromium is on the surface of a chromate quenched galvanized part. The study also determined how long after atmospheric exposure the hexavalent chromium becomes no longer detectable on the galvanized steel surface. Three different chromate quench baths were tested in this study. The baths were at a range of chromate concentrations in an attempt at giving results that covered the various levels found throughout the industry. Testing began in the fall of 2007, with the conclusion of the study at the end of the year. A hexavalent chromium testing kit was used to determine the quantity of hexavalent chromium on the surface.
Hexavalent chromium is a hazardous material. Many different factors determine the potential danger of exposure to hexavalent chromium. These include the duration of the contact, the form of hexavalent chromium, and the exposure quantity. The AGA study also provided information on the safety of handling chromate-quenched galvanized products. Results from the study show that for concentrations in the quench tank up to 0.3%, there will no longer be any hexavalent chromium on the surface of the galvanized steel after four months.