Hot-Dip Galvanizing

HOT-DIP GALVANIZING

TABLE OF CONTENT

The company 3 Affiliations 4 Mission & values 5

Services 7 Specialties 7 Research & Development 7 Seminar 8

Hot-dip galvanizing 10 Sustainable development 17 Technical information 19 Design 21 Prevent distortion 26 Post-galvanizing treatments 27 THE COMPANY

With over 40-years experience in hot-dip galvanizing and a solid commitment towards its customers, Corbec inc. has become the leading galvanizer in central and eastern Canada.

Our two installations, conveniently located in the east-end of Montreal and in Quebec City, are equipped with kettle sizes allowing for the galvanizing of a wide range of steel products, such as:

• Engineered structures such as bridges, wind mills, electrical towers, etc. • Exposed architectural steel structures • Fences and farming equipment • Original Manufactured Equipment (OEM) • A variety of metal pieces and hardware

For many years, Corbec participates and is involved with galvanizing associations as well as technical and engineering societies throughout the world. Operations staff and management are up to date on developing technologies and general improvements in our industry. 3

Our coatings are in conformity with international standards and our turn-around time will respect your tightest schedules. 4

AGA – American Galvanizers Association. www.galvanizeit.org ICCA – Canadian Institute of Steel Construction. www.icca.ca OIQ – Ordre des Ingénieurs du Québec. www.oiq.qc.ca ACRGTQ – Association des constructeurs de routes et grands travaux du Québec. www.acrgtq.ca MISSION AND VALUES

Corbec Galvanizing the standard… As a leading hot dip galvanizer, we are committed to offering consistently superior quality, at a competitive price with reliable service. Our excellence is built on employee expertise and our ability to surpass industry expectations.

5 Corbec builds on its skills… With a view to becoming the leader in the Canadian market, Corbec will expand to meet emerging needs. To facilitate the implementation of its management model, Corbec will promote participative management and knowledge transfer. In the interest of remaining a leading-edge and innovative company, Corbec is committed to maintaining its involvement in research and development and enabling its employees to develop new capabilities. AFFILIATIONS

Corbec Our values... Corbec has built a reputation for reliability founded on its fundamental values, which the company has imparted to its employees, suppliers and other business partners. 6

AFFILIATIONS

FAIRNESS OPEN-MINDEDNESS RELIABILITY COOPERATION EFFICIENCY SERVICES SPECIALTIES R&D

SERVICES OFFERED

7 • Packing according to specifications • Timelines and deadlines according to your needs (advanced production scheduling) • Fast delivery (upon request) • Technical support

OUR SPECIALTIES

• Galvanizing process for bent rebar • Galvanizing large parts • Trailer galvanizing

RESEARCH AND DEVELOPMENT

Our research and development department works in conjunction with our client projects to develop new procedures and methodology adapted to their needs. We also work with specifier’s such as Ministère des Transports du Québec and Hydro Québec to improve contracts and specifications. SEMINARS

Corbec is pleased to offer training seminars, tailored to the needs of your production and design teams. At your offices or ours this activity will be customized for the size and goals of your group. Also, you can address your own set of questions prior to the seminar and we will prepare a presentation where your concerns will be at the forefront. Seminars are typically one to four hours and include an overview of the hot-dip galvanizing process. Seminars can, at your request, include a tour of one of our plants. Your team will be able to see, up-close, the production process and better understand the details surrounding hot-dip galvanizing. This activity sounds interesting? Please contact our coordinator of sales & marketing at 514-364-4000 or send a written request to [email protected]. HISTORY OF GALVANIZING

Hot-dip galvanized steel has been effectively used for more than 150 years. The value of hot-dip galvanizing stems from the relative corrosion resistance of zinc, which, under most service conditions, is considerably better than iron and steel. In addition to forming a physical barrier against corrosion, 9 zinc, applied as a hot-dip galvanized coating, cathodically protects exposed steel. Furthermore, galvanizing for protection of iron and steel is favoured because of its low cost, the ease of application, and the extended maintenance- free service it provides. HOT-DIP GALVANIZING

Galvanic Series of Metals CORRODED END (Anodic or less noble) Magnesium Zinc Aluminium Cadmium Steel Lead Tin HISTORY OF GALVANIZING Nickel Brass Bronzes Copper Nickel-Copper Alloys Stainless Steels (passive) Silver Gold Platinum 10 Protected End (CathodicProcessus or more noble)de galvanization

Galvanization process

Cooling and Finition Drying Zinc Flux bath Rinsing Solution Pickling Caustic Rinsing Cleaning

What is hot-dip galvanizing Hot-dip galvanizing is a metallurgical bond between steel and molten zinc, produced in specific installations and under controlled conditions. The process, of molecular adhesion between two metals is unique and simple, yet provides excellent molecular adherence and cathodic protection. THE ADVANTAGES

Galvanizing provides great resistance

Once the freshly cleaned material is submerged in the molten zinc bath @ 450C (840 degrees F), a metallurgical bond is created composed of inter-metallic layers and a pure zinc layer.

The first inter-metallic layer is actually harder than the base steel. This quality is what gives galvanized steel its great impact and abrasion resistance. The soft, pure zinc layer helps absorb some of the shock and the inter-metallics protect the base material. 11

Microphotography of metallic coating

Coat ETA 100% Zn Index of hardness 70 DPN Coat Zeta 94% Zn 6% Fe Index of hardness 179 DPN Coat Delta 90% Zn 10% Fe Index of hardness 244 DPN Coat ETA 100% Zn Index of hardness 70 DPN Coat Gamma 75% Zn 25% Fe Base steel Index of hardness159 DPN Hot-Dip GalvanizedHot-Dip Galvanized Steel’s Steel’s Estimated Estimated Service Service Life inLife Soil in Soil

High Chlorides (>20 PPM) Low Moisture (<17.5%) High Chlorides (>20 PPM) High Moisture (<17.5%) 300 300

pH=9.4 H 2 O=5.0% 250 pH pH=7.9 H 2 O=10.5% 250 H 2 O

200 pH 200 H 2 O

150 pH=6.6 H 2 O=17.5% 150 pH=8.6 H 2 O=17.6% Service life (years) life Service 100 (years) life Service 100 pH pH=7.4 H 2 O=26.8% H 2 O pH H O 50 50 2 12 pH=6.0 H 2 O=40.0% 0 0 1.0 2.0 3.0 4.0 5.0 6.0 1.0 2.0 3.0 4.0 5.0 6.0 Zinc Coating Thickness (mils) Zinc Coating Thickness (mils)

Low Chlorides (<20 PPM) High Moisture (>7.0) Low Chlorides (<20 PPM) Low Moisture (<7.0) 300 300

pH=7.0H 2 O=5.0% pH=9.0 H 2 O=5.0% 250 250 pH 200 H 2 O 200 pH=7.8 H 2 O=19.3% pH H 2 O 150 pH 150 H 2 O pH=6.0 H 2 O=19.4% Service life (years) life Service (years) life Service 100 100 pH=7.0 H 2 O=40.0% pH H 2 O 50 50 pH=5.0 H 2 O=40.0% 0 0 1.0 2.0 3.0 4.0 5.0 6.0 1.0 2.0 3.0 4.0 5.0 6.0 Zinc Coating Thickness (mils) Zinc Coating Thickness (mils)

Service life is defined as the time to necessary part replacement 1 mil=25.4 pm=056 oz/ft3 or underground maintenance. 13 could beexposedtoavariety ofclimateconditions. The ASTM haspublishedtheresultsofaresearchconductedindifferentenvironmentswherezinccoatings Coating service-lifeisforeseeableaslongclimateconditions-inwhichthecoatingsareexposedknown. HDG coatingshaveaforeseeableservice-life

Time to First Maintenance* (years) 100 90 10 20 30 40 50 60 70 80 0 1. 0 1.5 *Time tofirstmaintenanceisdefinedasthetime5%rustingofsteelsurface. 2.0 Average ThicknessofZinc(mils 2.5 3.0 3 .5 ) 4.0 1 mil=25.4μm0.56oz/ft Industrial Tropical Temperate Marine Suburban Rural 4.5 Ke y rine Ma

5.0 2 Rust takes its toll on painted surfaces

Here is what happens to painted steel when scratched…The exposed steel corrodes and forms a rust « bubble ». This “bubble”, larger than the surface occupied by the steel will expand and lift the paint off the surface, creating a blister. In the meantime, the cavity of corrosion and the blister continue to progress.

Zinc coating Steel discovered is protected

Base steel

Galvanizing offers sacrificial protection

Here is what happens in the case of galvanized steel when scratched…Thanks to its galvanic protection, the zinc coating sacrifices itself to protect the steel to which it is bonded. This sacrificial protection will prevail as long as zinc is within proximity.

Should the hot-dip galvanized coating Conventional Current be damaged or scratched, the steel will find protection against corrosion thanks to the surrounding zinc that has higher Electrons External Circuit Electrons electrochemical properties than those of steel. Since corrosion is an electrochemical process, it will attack the surrounding zinc rather than the exposed steel. Thus said, contrary to other types of processes claiming to corrosion protection, it is not required to touch-up Cathode Anode noticeable cracks, flaws or gaps on galvanized coatings.

Electrolyte

Figure 1 : Bi-metallic couple Galvanizing is a cost-efficient process

15 Studies have shown that HDG is highly competitive when it comes to cost-comparison as a whole: each type of coating product has its set of characteristics to battle corrosion (and ultimately protect steel). However, these products often entail particular application, as well as relative life-span and relative savings. Galvanizing is a cost-efficient process

16 When compared to other types of products labeled anti-corrosive and subject to environmental standards, HDG costs have risen at a slower pace: Initial HDG costs are competitive with the costs of other products. Life-cycle cost analysis show that HDG is a wise investment compared to other products simply by considering the low/no-maintenance costs required over the project’s life-span.

Please consult the calculation tool to compare the costs of galvanization against other available protection systems online at the American Galvanizers Association website by visiting : www.galvanizingcost.com SUSTAINABLE DEVELOPMENT

Hot-dip galvanizing is a responsible choice. • Raw materials are preserved because steel does not corrode, therefore, no spending is incurred for the usual recycling of scrap metal; • Nearly maintenance free, HDG cannot be compared to paint-protection: in this case, protection is a thin barrier that, once broken, is an open door to corrosion. Galvanizing helps maintain steel’s structural integrity and saves taxes when prescribed for public construction; • Very little metal is re-introduced in the environment and when recycling occurs, the energy used to melt zinc is inversely related to the amount of zinc recycled.

LCA of galvanized steel Raw Material & Energy Inputs Inputs for Maintenance = 0 Energy Inputs

17 Production Use End-of-Life Steel Bridges Zinc Metal Light Poles Galvanizing Process Parking Garages Truck Frames Sign Structures

Émissions CO2 Zinc Corrosion Products SO2 etc.

Steel & Zinc Recycle Loop (100%) For all but the most aggressive, corrosive environmental conditions, there are no energy or raw material inputs during use (75 + years). For hot-dip galvanized steel, naturally occurring zinc oxide, zinc hydroxide, and zinc carbonate.

Think about it… Zinc is a natural and vital substance. Galvanizing does not modify the environment’s balance. Whether it be nutritional supplements, sunscreens, medication or diaper creams, all contain beneficial amounts of zinc, primarily in the form of zinc oxide. The industry generally works towards the promotion of sustainable development by ensuring that its production and use is in harmony with the natural environment and the needs of society. Corbec Corporation is the first galvanizing company in Canada to fully process all polluted airs from its installations. Our newly installed energy efficient covers also contribute to the health and security of our workers. Zinc Production

Energy Input Energy Input

Energy Input

Zinc Ore from Mines (raw material) Zinc Concentration

Emissions Other Re ned Primary Metals Solid Waste (Cu, Cd, Etc.) Emissions (SO 2 , CO 2 , Etc.) Solid Waste Zinc Metal Ingots Zinc Refining (Ready for galvanizing Zinc EAF Dust kettle) End-of-Life Recycling Automobiles, appliances, galvanizied products, etc.

Recycled Process Residues Skimmings and dross from galvanizing process Recycled Sulphuric Acid Emissions (CO2 ) Hot-Dip Galvanizing 18

The final step to determining the LCA production phase for hot-dip galvanizing is to evaluate the energy demands and emissions generated by the hot-dip galvanizing process itself. The gate-to-gate study considers the additional energy and emissions of the process beyond the inputs of the steel and zinc. Figure 10 below depicts the additional products and enegy required to coat the steel with zinc.

Figure 10 Energy Input Energy Input Cleaning Materials acids, water, flux Energy Input Surface Preparation degreasing, pickling, and fluxing Steel Product energy inputs counted in steel production Galvanizing HDG Steel Product Recycled Sulphuric Acid Kettle ready for use Wastes (solid, acid) Emissions ( CO 2 , acid mist)

Zinc Metal Ingots energy inputs counted Emissions 2 Recyclable Process in zinc production (CO ) Residus skimmings, dross in zinc production

Zinc metal production and oxides into cosmetics, tires, etc. TECHNICAL INFORMATION

Steel Selection

For an optimal coating, steel has to be selected wisely. Following information is based on ASTM A 385. Generally, galvanized coatings are chosen for their anti-corrosive properties, not for their appearance. The relative corrosion resistance of the normal or abnormal coating is, in all considerations, equal. Types of zinc coatings

Type of coating zinc

1 mil 19

Metallized Hot-Dip Galvanized Zinc Paint Galvanized Sheet Electroplated STEEL SELECTION

4 basic elements that can affect the galvanized coating:

1. Carbon in excess of about 0.25% 2. Silicon in the range of 0.04% to 0.15% or above 0.22% can produce galvanized coating growth rates much higher than those for steels with silicon levels below 0.04% and between 0.15% and 0.22%. 3. Phosphorus in excess of 0.04% 4. Manganese in excess of about 1.3%

Zinc Grip (Arbitrary Unit) ETA (100% Zn) 70 DPN hardness 9 ZETA 8 (94% Zn 6% Fe) Dispersion zone values 179 DPN Hardness 7 related to different authors DELTA 6 (90% Zn 10% Fe) GAMMA 5 (75% Zn 25% Fe) 4 250 DPN hardness 3 BASE STEEL 159 DPN Hardness 2 1 Fig. 1 Photomicrograph of Normal Galvanized Coating A B C 0 20 0 0,1 0,2 0,3 0,4 0,5 0,6 0,04 0,15 Si (Mass %) a Silicon effect

Coating Thickness (um) 400 Coating Thickness (um) 350 400 300 250 300 200 150 200 100

100 50 A B C A B C 0 0 0,05 0,1 0,15 0,2 0,05 0,1 0,15 0,2 0,25 0,3 0,12 P (Mass %) 0,09 Si + 2,5 (Mass %) b Phosphorus Effect c Combined effect of silicon and phosphorus CONCEPTION

Vent and draining holes

Thicker coating at weld due to higher silicon content of weld metal

Weld splatter will be galvanized into the coating and should be removed during fabrication to avoid unsightly appearance.

Zinc drips off causing spikes (dags) and a very rough surface 21 Combination of good drainage angles

Natural drain to one point Combination of good and bad drainage angles

Multiple hanging Size of fame and head height of points for best hoists affect quality of drain drainage angles On immersion, the air travels up the underside surfaces causing air pockets at each plate

On withdrawal, zinc travels or flows down the upper surfaces, pooling at each plate

22 There will always be air or Angles zinc traps even on channels.

crop plates before welding Remember, where zinc pools so will flux

Angle fabrications

zinc or air trap

air pockets

zinc pockets hole or cut corners VENT HOLE CORRECT

A Vent hole prevents air traps and Optional hole resulting ungalvanized internal areas position or even floatation AIR

Preferred fill/drain hole position Larger opening for faster flow of zinc into unit

B AIR Incorrect vent Trapped zinc sloshes out hole Vent hole and runs solidify during cooling causing heavy, unsightly buildup from Fill/drain incorectly positioned hole hole

Correct drain hole Zinc C 23 Center hole drainage is Vent hole Suggested design for not recommended flanged hollow sections

ZINC Preferred vent hole position

Optional Residual zinc hole position Zinc run

Open end or drain hole at the correct position and size E

Open end If no lug is possible opposite full/drain facility holeing will be required for jigging VENT HOLE CORRECT

A Space matching surfaces? Vent hole prevents air traps and Optional hole resulting ungalvanized internal areas position or even floatation Avoid welding units AIR back to back.

Preferred fill/drain hole position Larger opening for faster flow of zinc into unit Suggested design B AIR Incorrect vent Trapped zinc sloshes out hole Vent hole Do not forget to vent and and runs solidify during drai hollow sections cooling causing heavy, unsightly buildup from Fill/drain incorectly positioned hole hole

Correct drain hole Vent and drain holes too small! Zinc C Center hole drainage is Vent hole 24 Suggested design for not recommended flanged hollow sections Vent and drain hole size. Vent and drain holes that are too ZINC small in hollow sections increase Preferred vent immersion time and may cause hole position unsightly excessive zinc drainage runs as the zinc freezes D during the draining period.

Optional Residual zinc hole position Zinc run Zinc will flow around and down circular units leaving drainage runs along units. Open end or drain hole at the correct position and size E

Open end If no lug is possible opposite full/drain facility holeing will be required for jigging Chart 1. – Drainage holes for overlapping surfaces – steel thickness ≤ 1/2” (1.25 cm) Overlapping surface po2 [cm2] Holes Unwelded surfaces < 16 [< 103] None None > 16 et < 64 [> 103 &< 413] 3/8" [1 cm] 1" [2.5 cm] > 64 et < 400 [> 413 &< 2580] 1/2" [1.25 cm] 2" [5 cm] each increment of 400 [2580] 3/4" [2 cm] 4" [10 cm]

Chart 2. – Drainage holes for overlapping surfaces – steel thickness ≥ 1/2” (1.25 cm) Overlapping surface po2 [cm2] Holes Unwelded surfaces < 16 [< 103] None None > 16 et < 64 [> 103 &< 413] None None > 64 et < 400 [> 413 &< 2580] 1/2" [1.25 cm] 2" [5 cm] each increment of 400 [2580] 3/4" [2 cm] 4" [10 cm] 25 PREVENTING DISTORTION

Chart 1. – Drainage holes for overlapping surfaces – steel thickness ≤ 1/2” (1.25 cm) Bolted and welded assemblies varying in thickness can cause deformities or distorsion. This is caused by the variations in heating and cooling of the pieces. It is recommended to galvanize these structures prior to assembly. Assembly can then be completed by welding and reconditioning or by means of bolting or riveting with pre-galvanized hardware. Distortion can also occur during the release of welding stresses in the kettle. Therefore, proceed with welding within guidelines to balance out these stresses.

Reasons for distortion

Distortion is almost always attributable to:

• Release of existing or created stresses in the steel (welding, laminating, forming); • Expansion constraints for assemblies of varying thicknesses when galvanizing; • Assemblies requiring different immersion speeds.

Folding of plate will introduce a certain This can be avoided by: amount of strentgh and reduce the possibility of distortion • Design symmetry and proper sequencing of assembly; • A design that allows for quick immersion and withdrawal in the zinc kettle.

In thin-wall applications, when possible, use reinforcements that are omega or diamond- shaped. When in doubt, request advice from your galvanizer

Large sheets can be break pressed which will reduce the distortion to smaller areas. Twisting may occure even though the measures have been taken POST-GALVANIZING TREATMENT

Although the look of galvanized steel is gaining in popularity, namely for residential applications, painting over galvanized steel is often required. Thankfully, this practice is widely used and its technique, usually mastered by paint professionals. Here is an overview of the specific conditions that need to be followed in order to proceed with post-galvanizing painting. The following content addresses surface preparation in relation to painting over galvanized steel.

Why paint?

The first answer that comes to mind is « for the look »! Paint can simply be prescribed by the architect but, it can also serve as identification or extra protection in a hostile environment. Painting over galvanized steel is known as Duplex system

Benefits are …. • Paint acts as a protection barrier for galvanized steel; • Galvanizing’s corrosion protection properties are enhanced and optimized by the application of paint; • Scaling of paint is reduced thanks to the presence of the underlying galvanized steel; • Galvanizing and paint together offers longer-lasting surface protection, 1.5 to 2.5 times their individual service-life. Galvanized steel goes through a process of oxidation (or aging) that is illustrated with the help of what is called « passivation cycle »:

Ellapsed time

Free flowing air 02 0 - 48 h

Zinc Oxide ZnO Moisture from rain (dew) H O2

48 h - 6 months 28 Zinc Hydroxide Zn (OH)2

Free flowing air 0 2 + CO2

6 months - 2 years Fully developed patina

Zinc Carbonate 27nCO3 Zn(OH)2

When should paint be applied? Galvanized steel has three (3) “stages of aging” (when oxides are present) and painting can be executed at any stage, providing that the proper surface preparation is applied… • Immediately after the galvanizing treatment. • When the galvanized steel is at 50% of its life span • When the thickness of the galvanized sheet is ≤1mils • At the first sign of rust 29 STANDARDS COMPLETE LIST OF ASTM AND CSA STANDARDS GOVERNING HOT-DIP GALVANIZING

The following documents are not available on our web site. However, you can contact ASTM and purchase them directly.

A 123/A 123M-02 Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products. A143/A 143M-03 Practice for Safeguarding Against Embrittlement of Hot-Dip Galvanized Structural Steel Products and Procedure for Detecting Embrittlement. A 153/A 153M-03 Specification for Zinc Coating on Iron and Steel Hardware. A 384/A 384M-02 Practice for Safeguarding Against Warpage and Distortion During Hot-Dip Galvanizing of Steel Assemblies. 30 A 385-03 Practice for Providing High-Quality Zinc Coatings (Hot-Dip). A 767/A 767M-00b Specification for Zinc-Coated (Galvanized) Steel Bars for Concrete Reinforcement. A 780-01 Practice for Repair of Damaged and Uncoated Area of Hot-Dip Galvanized Coatings. B 6-0 Specification for Zinc. D 6386-99 Practice for Preparation of Zinc (Hot-Dip Galvanized) Coated Iron and Steel Products and hardware Surfaces for Painting. E 376-03 Practice for Measuring Coating Thickness by Magnetic Field or Eddy- Current Exam Method. CAN/CSA Hot-dip Galvanizing of Irregular Shaped Products. G 164-M92 HEAD OFFICE

Telephone: 514.364.4000 Toll free: 1 800 463.8313 Fax. : 514.365.9222

Montreal plant Quebec plant

400 George V (corner Victoria) 50, rue Lisbonne Lachine St-Augustin-de-Desmaures (Quebec) H8S 2R7 (Québec) G3A 0M6

Telephone: 514.637.7076 Telephone: 418.628.1055 Fax: 514.639.4630 Fax: 418.628.3031

Kettle size Kettle size 6’ 6’ 48’ 56’

10’6’’ 12’