Solving steel corrosion problems others choose to ignore.
$3M International Bridge Painting Project Begins
MONDAY, JULY 18, 2022
Last week, a painting project to coat the Canadian side of the Sault Ste. Marie International Bridge began, using a one-coat paint system.
The steel truss arch bridge spans the St. Mary’s River between Sault Ste. Marie, Michigan, and Sault Ste. Marie, Ontario, and is the only vehicular crossing between those locations within a 300-mile distance. The structure is also the largest trade crossing in Northwestern Ontario, playing a “vital role” for both Soo communities, according to the bridge’s website.
Latest Coating Work
The $3 million painting project will coat the curb and service walk railing on the Canadian half of the bridge. Work is being completed by prime contractor source: https://www.paintsquare.com/news/view/?25293
For the coatings, the contractor will use a high-ratio calcium sulfonate alkyd (HRCSA) one-coat paint system.
“This innovative product and process offers many benefits,” said Bridge Engineer Karl Hansen. “We anticipate cost savings, enhanced corrosion resistance, quicker completion time, and minimized disturbance to the environment and our customers.”
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| US Army Corps of Engineers, Richard McDonald, public domain, via Wikimedia Commons |
| Last week, a painting project to coat the Canadian side of the Sault Ste. Marie International Bridge began, using a one-coat paint system. |
According to the release, painting operations will be conducted at various locations around the Canadian side using moveable scaffolding. One lane of alternating traffic will be maintained during the painting.
“The International Bridge Administration (IBA) advises motorists to expect delays, remain alert for workers, and use caution when traveling through the work zone,” writes the IBA.
The project is fully funded through the Federal Bridge Corp. Limited with the help of a capital budget allocation approved by the Government of Canada. Work is expected to be completed by Nov. 1.
(Post-Interview video with contractor Matt Glavin, http://www.glavin.net, regarding his personal experience of working with HRCSA on the Canadian side of the Sault Ste. Marie bridge arch.)
When the word “Coating” is used, most people think of a paint that forms into a solid barrier film.
The HRCSA Self-Priming Topcoat is an unconventional coating system which is both chemically active and elastomeric.
Traditional barrier or sacrificial barriers cure across the steel micro voids leaving areas of exposed steel between the coating and the substrate – these micro void areas are vulnerable to rapid undercutting once the barrier is breached.
HRCSA is a reacted calcium sulfonate, calcium carbonate based complex that fully wets the surface as it neutralizes acids, displaces moisture and scavenges oxygen leaving no micro voids unfilled.
The high ratio of active calcium sulfonate thoroughly wets the micro voids creating a mono-molecular layer of cations which ensure chemical neutrality and no undercutting if the coating is breached. ( The HRCSA reacted formulation’s uniqueness is what gives it this performance advantage.) <Link to Specifications>
Once applied, the formulation’s artificially grown calcite crystals line up like fish scales to form a strengthened film with extended pathways for moisture and oxygen.
When acidic moisture (acid rain) passes through these crystals, a minute amount of the calcite dissolves to create a neutral base liquid void of acidity at the steel substrate.
Summarily, it neutralizes acids, displaces moisture, and scavenges oxygen.
When the word “Penetrant” is used, most people think of a low molecular weight epoxy or moisture cured urethane penetrants which were primarily designed to bind up existing rust on steel surfaces and a tiecoat.
Crevice corroded and pack-rusted joints and connections that are properly prepared (flushed, salt mitigated and dried) then pressure filled to refusal with HRCSA Penetrant-Sealer, Meld-coated with HRCSA self-priming topcoat and overcoated with same (wet on wet), creates a chemically active, flexible seal that actively stops corrosion inside the connection for years (even decades) to come.
HRCSA Penetrant can be fogged, or mist applied inside tubes.
In the following bridge preservation project, the HRCSA maintenance coating was applied to a minimally prepared steel substrate (WJ4 || WA1 ) inside a highly condensed period of time (2 weeks of rail line shut-down).
The US Federal Highway Administration strongly promotes maintaining existing infrastructure in a “Good State of Repair”. This has lead to a great emphasis on “doing more with less” by focusing on bridge preservation practices designed around extending the service life of the existing structures. Mitigating corrosion is a big part of this formula.
The British structure featured in today’s discussion reveals how structures can be preserved cost effectively and with minimal preparation – regardless of tight time schedule pressures.
The two circled areas of concern in this photograph are active corrosion hotspots which showed up after the application of chemically active HRCSA materials that triggered the delaminating of tightly adhered black oxide patches. HRCSA chemistries cause heavily contaminated black oxide spots to detach. (See repair procedure bottom of page).
The browned areas reveal bridge immersion from brackish Ouse River water during two separate floodings.
In the circled area, rust bleeding is coming from where previously salt contaminated delaminating coating was missed during surface preparation before the application of the HRCSA self-priming topcoat. A complete repair of this active corrosion hotspot can be achieved in very short order using a right angle sander, solvent wipe and brushed on application of single component, single coat HRCSA self-priming topcoat.
This photo demonstrates the excellent surface wetting and polar bonding of the HRCSA system on heavily pitted and previously heavily corroding substrate (Pressure washed then coated). Salts had been very effectively mitigated during surface preparation else it would have shown through the applied coating material. The coating profile shows no signs of deterioration and is working properly to protect the substrate from the elements.
Another fine example of excellent surface wetting and polar bonding of the HRCSA system to heavily pitted and corroded steel substrate. The coating shows no signs of deterioration and is working properly. Pitted areas (black oxide delaminations) can be quickly and easily repaired using the attached repair procedure below.
Further evidence of discoloration caused by the brackish flood waters as they rose up the side of the girder. Although the coating may be have been discolored there is no corrosion or damage triggered by the brackish floodwaters.
In the following examples, inadequate surface preparation and salt removal causing premature coating failures on the sections highlighted below.
The corrosion of structural steel is an electrochemical process that requires the simultaneous presence of moisture and oxygen. Essentially, the iron in the steel is oxidized to produce rust, which occupies approximately six to ten times the volume of the original material. The rate at which the corrosion process progresses depends on a number of factors:
Micro-climate: In the photo above, this bridge is exposed to heavy de-icing salts during the winter. Due to multiple seasonal freezes, thaw cycles there is allot of moisture present which can migrate into the crevices. Result (electrolyte).
To avoid long term damage from crevice corrosion, these are the corrosion risks that could exist in LED lighting installed on steel bridges.
From a corrosion mitigation point of view, these are the following corrosion risks that we see could exist in LED lighting installed on steel bridges.
Galvanic corrosion (also called bimetallic corrosion or dissimilar metal corrosion) is an electrochemical process in which one metal corrodes preferentially when it is in electrical contact with another, in the presence of an electrolyte.
Grounding example (dissimilar metals). Do lighting configurations operate on independent floating grounds?
HRCSA is Non-conductive up to 100KV. Where HRCSA is applied as an electrical insulator between metals, HRCSA can impede the electrochemical process from taking place.
HRCSA Chemistry can insulate connections, so Corrosion has no place to start: The photo below represents BEST PRACTICE for fastening dissimilar metals together. HRCSA Penetrant/Sealer applied under pressure into gaps around the fastener shaft areas followed by a brush applied application of HRCSA self-priming topcoat both between the dissimilar plates as well as overtop the fasteners can help you achieve the same protection.
Repairs are fast & easy: Where existing installations show signs of dissimilar metal corrosion, HRCSA user-friendliness can put affordable and long lasting corrosion mitigation repairs within reach.
Applying HRCSA at the time of installation can be done with little effort.
Conclusion: When attaching dissimilar metals together, HRCSA is a user friendly cost effective alternative for preventing corrosion..
Hydro towers are surface prepared by power tool cleaning using angle grinders to remove scale, solvent wipe followed by pressure applied HRCSA Penetrant/Sealer inside the connections (as seen in the photo on left) and HRCSA Self Priming Topcoat by paint brush applied to stripe coat bolts, hard edges and final overcoating the entire zone.
Where A588, COR-TEN steels produce corrosion concerns, Chemically Active HRCSA is becoming the “go to” coating system because of it’s a) minimalistic surface preparation requirements, b) ability to chemically stop crevice corrosion, ability to fully wet weathering steel substrate, d) durability and e) HRCSA IS NON-CONDUCTIVE UP 100KVA – AN IMPORTANT FEATURE FOR COR-TEN TOWERS BECAUSE CORROSION PRODUCTS CAUSE ARCHING ON COR-TEN STEEL TOWERS.
COR-TEN steel performs impressively on flat surfaces, but, like all systems, has limitations – particularly where there are connecting plates and other regions noted below.
| Performance & Condition | Weathering Steel | Performance & Condition | Weathering Steel |
| Fatigue Life | Reduced by weathering | Road Salt Effect | Accelerated corrosion and loss of section and mass |
| Constant Wetting | Corrodes the same as unprotected carbon steel | Appearance Problems | Stains concrete |
| Faying Surfaces | Corrodes the same as unprotected carbon steel | Sea Coast Environment | Poor corrosion protection, chlorides cause pitting and rapid section loss |
| Painting | Expensive preparation and excessive paint absorption | Chemical (Airborne) Contamination | Poor corrosion protection, accelerated patina consumption |
| Tubular Shapes | Traps moisture inside, resulting in increased corrosion rate | Vegetation | Moisture may accelerate corrosion, especially on faying surfaces, enough to exert excessive force on bolted connections |
| Inspection | Can’t distinguish patina rust from loose corrosion products of accelerated corrosion | Electrical Industry | Corrosion products cause arcing |
| Corrosion Rate | Unknown | High humidity/Fog | Poor corrosion protection |
More complex joints and connections (such as the above) are surface prepared using power tool cleaning to remove scale then high pressure water cleaned to remove salts, oil, dirt, etc.
Photo above: High pressure water cleaned COR-TEN steel (with salt remover) is ready for HRCSA coating application where HRCSA Penetrant/Sealer is pressure-applied inside the bearing joint and the HRCSA Self-Priming Topcoat is applied (wet-on-wet) to the entire zone to be painted.
Using a Star tip for fogging and misting HRCSA Penetrant/Sealer is fogged and applied inside Box Beams and other Tubular shapes to create a polar bonded anti-corrosive coating on the inside where humidity can otherwise cause serious corrosion damage.
Chemically active HRCSA’s greatest feature is it’s ability to fully wet the steel substrate (eliminating undercutting) and due to it’s polar bonding characteristics, fill all micro voids on the steel substrate.
HRCSA also offers the ability to be applied onto salt free, light to medium rust.
This application was developed for the treatment of buried hydro tower legs which needed to be excavated, treated and backfield during 1- 8-hour shift.
HRCSA is elastomeric, simply cover the steel member you wish to place in the ground with a tar paper cover while the coating is still fresh and then add some coating around the edges to seal the open space at the top of the tar paper steel interface. The freshly coated and wrapped member was buried in the ground and left for a period of 10 months.
After 10 months it was excavated, removed from the ground, brought into the shop and the tar paper removed. The coating was not damaged, and the member was corrosion free. Some tar paper remained stuck to the coating, but the coating itself remained intact with no corrosion present on the steel member.
HRCSA is elastomeric, simply cover the steel member you wish to place in the ground with a tar paper cover while the coating is still fresh and then add some coating around the edges to seal the open space at the top of the tar paper steel interface. This test was done over the period of a year. The freshly coated and wrapped member was buried in the ground and left for a period of 10 months.
HRCSA Self-Priming Topcoat can be used for coating exposed rebar. Remove spalled concrete. Pressure wash with salt remover – let dry. Apply HRCSA Self-Priming Topcoat on the exposed rebar and cover with concrete (no need to wait for cure).
Might you have a specific steel corrosion problem in mind? Enquire now!
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The capital spend difference between dry abrasive blast equipment with negative air containment and high pressure water cleaning surface preparation equipment (water recovery and flow-through tarps) can slash your overall surface preparation spend by ~ 50%. Naturally, those costs savings can easily be eaten by labor costs if you do not have the right equipment.
Field experience has shown that 480 bar / 23 lpm hot water (60C) with rotating tip provides the ultimate impact, and balance between effectiveness, efficiency and worker safety.
When it comes to cleaning, pressure alone is not enough – you also need adequate flow to do an effective cleaning job. The pressure is for cleaning, the volume is for washing.
Field experience suggests that 23 lpm (6gpm) +/- 10%) volume does an excellent washing job and a pressure point of 480 bar (min 350) has produced an adequate cleaned steel substrate for overcoating or recoating with HRCSA.
Makes removal of salts and contaminants from the surface more effective. Here, field experience has shown that 60C does a superb job at optimizing contaminant removal during cleaning.
Field experience confirms that 0 degree rotating tip “Cutting nozzle” is needed to remove undercutted coating systems, flush out corrosion pits and open up capillary channels inside pack-rust corrosion cells located inside joints and connections.
Combining the above mentioned forces with a salt removing chemistry provides assurance that
Example of a 480 bar / 23 lpm / hot water with rotating tip cleaning operation at work.
Example of multi-nozzle pressure washing clamp preparing steel for overcoating with HRCSA
Although the vast majority of HRCSA project Surface Preparation is done with High Pressure Water Cleaning and/or hand tool cleaning.
It does happen, on occasion, where abrasive blasting is required (engineer specified, heavy black oxide removal, etc.). Because HRCSA is not profile dependent, the following WAB (Wet Abrasive Blast) configuration using crushed glass has proven quite popular.
Most contractors who work with HRCSA already own 7,000 psi, 6gpm, hot water high pressure water cleaners. They maximize their profits by avoiding the cost of negative air containment [1,000 gallons of fuel / day]. When specifications ask for RECOATING, wet abrasive blasting can be achieved by combining their washers with blasters. Environmentally friendly abrasion can be found with crush glass media.
The magic lies in the quality and design of the injection nozzle used.
Example of WAB (Wet abrasive blasting) using crushed glass media with pressure washer and media injection pot as per above configuration.
Field Uses:
Photo: It is critical for black oxides to be removed and to mitigate the heavy concentrations of salts at the exposed steel substrate.
NOTE: Hand tools are also used to remove surface black oxides.
Be sure to remove black oxides at all interfaces.
Pack-rusted Joints: Do not blast.
NOTE: The corrosion inside a pack-rusted connections to only be high pressure water cleaned with salt remover (then blown dried with clean, dry, 100 psi air pressure). DO NOT introduce abrasives into the pack rust otherwise you will clog the capillary channels. These must remain open.
“In 1990, the federal government gave the I-35W bridge a rating of “structurally deficient”, citing significant corrosion in its bearings.“
“The inspection carried out June 15, 2006 found problems of cracking and fatigue.”
I-35W Mississippi River bridge – Wikipedia
Society tends to take it’s infrastructure for granted. We rarely give the structures we depend on for our livelihood little notice (other than perhaps cursing the potholes that mess up our suspensions and alignments).
Nonetheless, those unseen structure critical connections that hold the bridge together are, well, critical. When leaking expansion joints, faulty drainage or nearby pollution emitting plants introduce non-visible contaminants to the steel, insidious damage slowly introduces it’s self in the form of corrosion-frozen moving parts such bearings, pin connectors, wire rope all of which can have a very negative impact on the superstructure’s integrity.
When bearings seize, the superstructure becomes restricted in it’s ability to flex and move with contractions, expansions, traffic load changes and even high winds in some areas.
Additionally, when movements are restricted, imagine the pressures that take place at the connection plates and on the fasteners? In the very least, the coating that’s protecting the connection is sure to crack and let corrosion causing contaminants and water in. Once corrosion sets in inside the connection, the steel at the connection converts into corrosion by-product – which can be 10 times as voluminous as the steel from whence it came – resulting in both thinner steel at the connection AND even more pressure on the fastening plates and fasteners.
Compound this effect with heavy traffic loads, and, well, history has it’s story stories to tell.
Field Proven HRCSA is unique in it’s ability to chemically stop active corrosion INSIDE CORRODING CONNECTIONS (for 15-20 years) and also inside pin connectors, and corrosion frozen bearings.
When it comes to bearings and pin connectors look no further. HRCSA not only stops the corrosion between the plates by displacing moisture, scavenging oxygen and neutralizing acids, but it also causes black oxides to detach from the steel interface (thereby unrestricting it’s movements) while also adding lubricity to the plates and a coating that stretching with microcracking.
How’s that for functional elegance?
