Solving steel corrosion problems others choose to ignore.
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.
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.
Is what you are buying authentic HRCSA or a knockoff product?
It happens for us to hear market claims that “A certain product of this same type is being produced in ______ or ______ country.” Nor is it unusual to hear claims that “Our coating product performs equal to or better then HRCSA.” When asked to prove it, these claims always seem to vanish as quickly as they came.
How do you know if what you are getting is conformant to the generic HRCSA specification?
HRCSA’s 30 year history of field proven notable performance achievements comes from a coating system whose genuine HRCSA (High Ratio Co-Polymerized Calcium Sulfonate).
HRCSA Self Priming Topcoat– High Ratio Co-Polymerized Calcium Sulfonate HRCSA (Minimum 9.5% active sulfonate, must maintain a 9-11 to 1 ± 2% ratio Total Base Number to Active Sulfonate i.e. total base number of 85 to 104 to 9.5% Active Sulfonate as determined by Titration Testing
HRCSA Penetrant (Sealer) – High Ratio Co-Polymerized Calcium Sulfonate HRCSA (Minimum 15% active sulfonate, must maintain a 9-11 to 1 ± 2% ratio Total Base Number to Active Sulfonate ie. total base number of 135 to 165 to 15% Active Sulfonate as determined by Titration Testing
The following 3 downloads provide you with all that you need to test that you are getting what you asked for – and nothing less.
Fill in the following form and an online webinar with your nearest HRCSA licensee will be arranged. (Please allow 2-3 business days.)
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A close up look at a wire rope configuration can reveal coating challenges.
Single Component HRCSA topcoat for wire rope being applied by paint mitt.
If high pressure water cleaning, include a salt remover additive in your mix and be sure to use a cleaner that includes pressurized air to clear water from between the strands.
If sanding out corrosion hotspots, always wipe your wire rope with solvent soaked rag before overcoating with HRCSA topcoat.
There are no words to describe how seeing this a year after abrasive blasting and applying 3 coats makes the owner feel… <disappointed>, <resigned>, <frustrated>, <deceived>
When dealing with aged, in-place, corroded structures, traditional film-form coatings do not have the right chemistry needed to stop pack-rust growth.
When bearings freeze due to corrosion, pressure is introduced to the bridge superstructure.
When corrosion build between plates expands and out of plane bending occurs, the integrity of the structure is put at risk, the rating is affected, and fasteners are weakened.
Structure Critical Corrosion Can Shave Years of Service Life off Your Structure.
For years it was believed that “There is nothing you could do about rust bleed leaking from connections.” until as recently as 30 years ago when HRCSA formulations were created specifically to chemically step active corrosion inside connections. Although the HRCSA Self-priming topcoat is applied stand-alone on exposed steel substrate, there is one specific area where it it is provided a boost: inside pack-rusted joints and connections and other steel openings.
Step 1: High pressure water clean with salt remover to produce a clean, tightly adhered substrate and flushed joints and connections.
Step 2: Apply high pressure air to remove water and humidity from surfaces and inside connections
Step 3: Apply HRCSA Penetrant under pressure to fill capillary channels inside connections.
Step 4: Apply HRCSA Self-Priming Topcoat to Penetrant treated connections, rivet heads and sharp angles using a brush. Overcoat the entire structure.
The photo at the bottom is that of an HRCSA treated pack-rusted connection after 17 years in service.
The HRCSA melding process is achieved by first saturating, flushing, and blowing out connections and then flooding the inside of the connections with low viscosity HRCSA Penetrant/Sealer under pressure. This material chemically treats corrosion causing acids inside the crevice corroded or pack rusted joints or connections. Once applied, this material will remain chemically active inside the connection for as long as it is sealed in by the HRCSA Self-Priming Topcoat. Together, they form a mid-layer of chemistry we call the “meld zone”. This meld-zone serves as a chemical reserve that is a continuous source of corrosion-fighting chemistry as HRCSA continually wicks it way deeper and deeper into the crevice during structural movement (expansion and contraction). When this process is applied to bearing plates, the HRCSA chemistry applies lubricity as it frees up corrosion frozen bearings.
