BIMETALLIC CORROSION WORKSHOP PRESENTATION ON 01 – 02 JUN 2017

PRESENTATION 03: ESKOM EVALUATION . PRESENTED BY: AFRISUN COATING ENTERPRISES (PTY) LTD PRESENTER: DANIEL VAN DER WESTHUIZEN PRESENTATION 03: ESKOM EVALUATION

DUPLEX- & OVERCOAT SYSTEM Uncontrolled steel chemistry Serious problem for Eskom steel lattice electrical towers Looking for a duplex coating over galvanized steel to mitigate corrosion

PROBLEM : STEEL CHEMISTRY HDGASA We are confronted with imported steel chemistry that is not always conducive to a quality hot dip galvanized finished product Imported steel have shown that the percentage Si and P content is not controlled, leading to differences in hot dip galvanized steel surface finishing’s Uncontrolled steel chemistry has a direct influence on the quality of the surface finish of hot dip galvanized steel Volume 10 Issue 3 2013 Hot Dip Galvanizing Today

GALVANIZING PROCESS During galvanizing the article is completely immersed in a bath of molten zinc between 435º - 455º C. The chemistry of the bath is at least 98% pure zinc in accordance with ASTM B6. The zinc reacts with the iron in the steel to form a series of metallurgical bonded zinc-iron alloy layers.

STEEL CHEMISTRY Silicon < 0.03% and zinc temperature 450°C - Zinc coating thicknesses range between 50 µ to 65 µ Silicon > 0.15% to < 0.25% and zinc temperature 450°C – Zinc coating thicknesses range between 120 µ to 200 µ Phosphorous < 0.01% preferred > 0.02% Zinc coating excessively thick > 200 µ - Brittle, susceptible to chipping or flaking

THE SANDELIN CURVE The Sandelin curve, compares the zinc coating thickness to the mass percentage of silicon in the steel. The area on the graph labelled “I” is called the Sandelin area. The coatings in “I” tend to be thick and dull grey. This area is known as the Sandelin range since Dr. Sandelin, a metallurgist, performed the experimental work to show this behaviour of galvanized steel. The Sandelin area is roughly between 0.05% and 0.15% silicon. The area on the graph labelled “II”, which represents a steel content of greater than 0.25% silicon, shows the coating thickness increases with increased silicon content and then starts to level off at around 0.4% silicon.

Alloy Layers in Galvanizing DPN - Diamond Pyramid Hardness Number

Relationship between dipping time and thickness of zinc coating in steels with different silicon contents.

ENVIRONMENTAL CONDITIONS Depletion rate of Zn depends on the period of time and environmental conditions the galvanized structure has been exposed to. Lifecycle of the galvanizing depends on the applied or specified DFT.

KIPTS EVALUATION: DUPLEX- & OVERCOAT SYSTEM Eskom LES requested that the HIGH RATIO CALCIUM SULPHONATE ALKD (HRCSA) branded as ARMOR-SHIELD CSA be tested before any application to steel will be considered.

EVALUATION HIGH RATIO CALCIUM SULFONATE ALKYD (HRCSA) AS AN ACTIVE DUPLEX COATING FOR GALVANIZED STEEL

ESKOM EVALUATION Nov 2013 – Nov 2015 LOCATION: Koeberg Insulator Pollution Testing Station (KIPTS) POLUTION LEVEL: CX5+ (ESKOM) DURATION: 24 MTHS

KIPTS EVALUATION: DUPLEX- & OVERCOAT SYSTEM TO DETERMINE PRODUCT PERFORMANCE BASED ON VARIOUS DEGREES OF SURFACE PREPARATION PROCEDURES DUE TO ON-SITE APPLICATION KIPTS 2nd HIGHEST POLLUTION ZONE IN THE WORLD

KIPTS EVALUATION: PREPARATION PROCEDURES No Prep Wire brushing & dusting Wire brushing & water washing Wire brushing, water washing with salt removal additive

SAMPLES PROVIDED OLD & NEW GALVANIZED STEEL

SAMPLES MOUNTED Then coated with ARMOR-SHIELD CSA

NEW GALVANIZING SURFACE PREP: NONE 8760 HRS 13 Nov 2014 13 Nov 2013

NO CORROSION OR UNDERCREEPAGE

NO UNDERCREEP OR CORROSION AT SCRIBE 27 Months 815 Days 19 560 Hours NO UNDERCREEP OR CORROSION AT SCRIBE

CX 5+ ENVIRONMENT 8760 HRS 13 Nov 2013 13 Nov 2014 PANEL: Grit Blasted (near white metal) Single coat Armor-Shield CSA CX 5+ ENVIRONMENT 8760 HRS 13 Nov 2013 13 Nov 2014

31 MTHS – 21 400 HRS PANEL GRIT BLASTED TO NEAR WHITE METAL FULLY COATED WITH ARMOR-SHIELD CSA 31 MTHS – 21 400 HRS

CLOSE-UP OF SCRIBE AFTER 31 MTHS – 21 400 HRS NO CORROSION OR UNDERCREEPAGE AT SCRIBE - CSA IS AN ACTIVE BARRIER

BACK OF PANEL AFTER 31 MTHS – 21 400 HRS NO PROTECTION

NOV 2013 PANEL (OVERCOATED) GRIT BLASTED TO NEAR WHITE METAL FULLY COATED WITH EPOXY THEN ½ COATED WITH ARMOR-SHIELD CSA EACH HALF SCORED NOV 2013

NOV 2014 (12 months later) CORROSION & UNDERCREEPAGE ON EPOXY (PASSIVE BARRIER) NO CORROSION OR UNDERCREEPAGE ON CSA (ACTIVE BARRIER)

ENLARGED PIC NO PROTECTION AT SCRIBE DIRECT CONTACT WITH ATMOSPHERE UNDERCREEPAGE CAUSING DELAMINATION AND ACCELERATED CORROSION

ARMOR-SHIELD CSA TOPCOAT AS AN OVERCOAT PROVIDES PROTECTION AGAINST CORROSION

An Investigation Into The Methodology To Develop An Insulator Pollution Severity Application Map For South Africa by D Pietersen, JP Holtzhausen, and W.L. Vosloo “Corrosivity and insulator pollution levels at the coast (KIPTS) are 2-3 times those at sites 800 m from the coast, reflecting the exceptional pollution concentration over the first few hundred meters from the seacoast, which is mainly attributed to the high NaCl (salt) concentration levels and high relative humidity in the region closer to the coast.”

ARMOR-SHIELD CSA : CONCLUSION OF TEST Taking into consideration the severe environmental conditions found at Koeberg Insulator Pollution Testing Station (KIPTS) which is classified as a CX5+ pollution environment and being exposed to natural weathering for 17 664 hours (24 months), the local South African 1 500 hours Salt Test (ASTM B117) result and the extensive Accelerated Laboratory Tests (ALT) done for the FEDERAL HIGHWAY ADMINISTRATION by the Turner-Fairbanks Research Centre for 6 840 hours, the performance of the HRCSA clearly indicates that this coating, based on Calcium Sulphonate Alkyd (CSA), is the ideal duplex coating over galvanizing and the best coating to protect steel against corrosion.

3RD PARTY TESTING IN USA U.S Army Corps of Engineers (2 866 hrs) PowerTech Inc. – Canada (4 000 hrs) Kentucky Transport Authority (5 000 hrs) Federal Highway Authority (ALT – 6 840 hrs) (Marine – 24 month) – Outdoor Nov 2012 DEC 2003

FHA TEST RESULTS: SALT SPRAY (6 840 HRS) EPOXYMASTIC CALCIUM SULPHONATE ALKYD

ARMOR - SHIELD CSA Passes the Toughest of Industry Testing for Long Term Performance RATING ASTM D4838 Colour - 10 ASTM D7114 Blistering - 10 ASTM D1654 Rust Undercutting - 10 ASTM D 5767 Gloss - 10 ASTM D5894-05 Cyclic Salt Fog / UV Exposure of Painted Metal - 10 ASTM D522 Mandrel Bend Test (3.2 mm) - 180º (Passed)

SA SALT FOG TEST RESULTS (ASTM B117) 1 500 HRS The coating showed no defects after 1500h salt fog exposure. A cross cut scribe was made through the coating down to the metal substrate and no under-film creep occurred at this scribe mark during the test period. Testing Laboratory: Metlab Germiston (SANAS approved)

SA SALT FOG TEST RESULTS (ASTM B117) 1 500 HRS Discussion of Results The results showed excellent corrosion protection for the period tested [1500h]. Rule of thumb - 1000h salt spray exposure test = 3 yrs marine exposure

ARMOR - SHIELD CSA ADVANTAGES NO DAMAGE TO GALVANIZING NO ENVIRONMENTAL CONTAMINATION NO HEALTH & SAFETY CONCERNS (CURED COATING IS NON-TOXIC) QUALITY CONCERNS – DO NOT NEED TO DISMANTLE STRUCTURES VERY COST EFFECTIVE PROCESS (LONG LIFE CYCLE)

CORROSION PREVENTION COAT IT WITH ARMOR-SHIELD CSA! THE ONLY ACTIVE PROTECTION SYSTEM OF IT’S KIND!

I THANK YOU. ARE THERE ANY QUESTIONS I THANK YOU! ARE THERE ANY QUESTIONS? AFRISUN COATING ENTERPRISES (PTY) LTD 012 662 0330 / 082 789 2582