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Corrocoat products provide engineering structures and equipment with long-term and cost-effective protection against corrosion.
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A UK fabricator of vessels and tanks for multiple industries required additional chemical resistance for two storage tanks due to enter service in the chemicals processing industry. The internal surfaces of the tanks would be subject to constant immersion in sulphuric acid.
Following arrival of the tanks, to our workshop, all internal surfaces were abrasive blasted to achieve the required cleanliness levels and surface profile. This was followed by a blow down, sweep and vacuum to completely remove the dust. The internal angles of the floor/wall were then radiused to ensure full continuity of the coating.
The floor/wall interface of the tanks were laminated using multiaxial glass fabric thoroughly wetted with epoxy laminating resin and rollered into place to remove any trapped air, aid adhesion and provide increased structural strength.
Plasmet AR3, a two pack solvent free polyamine cured epoxy, resistant to strong concentrations of sulphuric and other acids, was spray applied to the required DFT.
AR3 is primarily produced for protection against strong concentrations of sulphuric acid. The product can also be used for other acids and in some strong alkali service duties. Applications include bund areas, tanks, pipe work, floors, decking, structural steel and more.
We were recently awarded a contract to protect 300 new pipe spools of various dimensions by a multinational energy client. Corroglass 600 series was the coating system selected for this project, as it offered the best long-term corrosion protection on the FPSO.
With pipe diameters between 50mm and 300mm. a number of coating strategies were employed including Corroserves’ in-house pipe-blasting and pipe-coating technology, piperolling and a carefully controlled flood and drain technique.
Used primarily on small bore pipes of complicated geometry, the flood and drain technique allows coating to be applied by our trained technicians, into areas which would otherwise not be accessible. This technique has been successfully used for lining pipes with Corrocoat materials for over 40 years.
As part of the Q.A. requirements, the end client requested that a pipe lined by flood and drain should be cut and assessed after coating, to show the excellent coverage, which was advised would be achieved using this application method.
A pipe containing two bends and a tee piece were supplied by the client for the assessment.
The internal surfaces of the pipe were first abrasive blasted and then coated with Polyglass VE Pipegrade, using the flood and drain method. Application was carried out 4 times, allowing the coating to gel between coats and ensure that the coverage was sufficient.
The spool was allowed to cure for 7 days prior to being split along its length, using an angle grinder.
As you would expect, there was a small amount of mechanical damage at the edge of the cuts, but away from these areas the coating was found to be uniform and intact.
Dry Film thickness readings we found to be a minimum of 1,260µm with an average of 1,436µm and a standard deviation of 135.63µm. Readings were taken every 150mm along the length of the pipe. The pipe was spark tested at 17000 KV AC and no defects were found.
Adhesion was then tested in accordance with ASTM D4541. The surface of the coating and the adhesion dollies were abraded with P60 sandpaper. The test dollies were attached using the same batch of Polyglass VE Pipegrade as the adhesive, then tested after 24hrs using a hydraulic adhesion test.
The results of the test were exceptional. The coated test spool had average adhesion value of greater than 20MPa, which was the limit for the test equipment.
Dolly 1 and 3 could not be removed from the surface, whilst the remaining dolly gave a value of exactly 20Mpa.
In conclusion, the coating thickness, integrity and adhesion was found to be excellent along the length of the spool piece, validating the method of application and as would be expected for this high performance Corrocoat lining.
The external of a large process tank at a resin plant was previously blasted and coated by a competitor in the US. Three months after completion, the client found that the contractor had blasted hundreds of holes in the roof of the tank and had just painted over them. This allowed rainwater to contaminate the contents of the tank. When confronted, the contractor advised that their scope of work did not include filling holes. In desperate need of a solution, the client turned to Corrocoat USA.
The team in the US vapour blasted the existing coating to achieve a commercial blast consistent with SSPC SP6. The surface was then primed with Plasmet ZF (red) ahead of using Epoxy Laminating Resin and quadriaxial fiberglass mat to laminate a composite fiberglass layer across the entire tank roof. The team then chose a suitable polyurethane topcoat to offer UV protection in a colour that matched the remainder of the tank.
The client was extremely impressed with the final result and the quality assurance and will continue to work with Corrocoat US on future projects.
Our partners at Corrocoat Benelux won a contract with a client specialising in the construction industry to coat ten new large bore pipes and four cooling water tanks, including the tank inserts.
The equipment was destined for a large salt plant in Europe, where the pipes would be used to transport brine and the tanks would be used to store cooling water. The internals of the pipe pieces and tanks were coated with Polyglass VEF at a minimum thickness of 1200µm and a general paint system at a thickness of 340-400µm was used for the externals.
Due to the large size of the pipe pieces and tanks, overhead cranes, a forklift truck and a lorry were used to transport the equipment throughout the workshop for the work to be carried out, whilst a pipe sprayer was used to apply the coating on the inside of pipes and ensure an even layer of coating.
The whole project was carried out within the requested delivery time to the full satisfaction of the customer. Throughout the process, various steps were witnessed by an independent NACE surveryor, hired by Corrocoat Benelux to reassure the client that all of their requirements had been met.
Al-Sabaiea, our partners in Kuwait recently worked on a project to restore and protect a tanker for a client operating in the oil and gas industry. The tanker was used to mix and transport strong Hydrochloric acid for upstream oilfield services, to and from site.
The previous coating on the tank had suffered chemical attack and upon visual inspection, the team discovered that the internal pipes and body of the tank had started to severely corrode. One of the internal pipes had multiple holes causing leakage, which meant it was no longer functional.
The team used a composite repair technique utilising quadraxial laminating cloth 610g/m2 over the external of the pipe, wetted out with Corroglass 600 laminating resin to restore the damage. Corrofill VE was then used to level the surface of the pipe back to its original thickness. Corrofill was also used to restore some of the other pipes in the tanker (which were still in a good working order and required little repair), back to their original condition.
After the pipes were restored, the team used Polyglass VEF to provide corrosion protection for the rest of tanker and Polyglass VE Veilcoat to finish.
Our partners in the Netherlands, Corrocoat Benelux, recently won a contract with a multinational company that provides mission-critical flow creation products and industrial solutions, to provide corrosion protection for a compressor housing unit from the automotive industry.
Following 8 years in service, the epoxy coating in the internal cooling water area became detached, causing a leakage in the cooling water area to the air section. Having started refurbishment of centrifugal compressor housings in 1999, Corrocoat Benelux have seen hundreds. However, unbeknown to the team, this would be the largest housing they would work on to date, with the unit weighing an enormous 13 ton. Upon arrival to the workshop the team approached a logistical challenge getting the unit offloaded and ready to begin the repair work. The overhead crane onsite was only capable of lifting 6 ton, so the team arranged for a mobile crane to move the housing unit. With a tight schedule of just two weeks given to complete the work, the coating team didn’t disappoint working around the clock to ensure that the job was completed to the client’s satisfaction.
The team sandblasted the housing internal and external before applying the Corroglass 600 series internally, with the the externals being coated with Plasmet ZF and a top coat of AP1.
Our Czech partners, Corrotech, recently provided corrosion protection of the internal parts of two 2 x 12m2 fire foam tanks, for a client in the Energy Industry at a Nuclear Power Plant.
The tanks stored a fire foam concentrate which had caused damage to the existing internal linin, resulting in pitting corrosion. The Corrotech team carried out the work in-situ at the Nuclear Power Station and began by removing all of the existing deposits and paint before decontaminating the surface from soluble metallic salts.
Following abrasive blasting, the team discovered a number of sharp edges and bad quality welds which needed to be mechanically adjusted ahead of the coating system being applied.
The coating selected for this job was Corrocoat Zip E, an epoxy glassflake coating offering durable protection in aggressive atmospheric conditions – ideal for the long term protection of internal substrates of these fire foam tanks.
Di-shield is a polyester co-polymer mixed with glassflake and other fillers to give excellent dielectric properties. Di-shield will cure at low temperatures, has excellent adhesion and is able to withstand the high pH generated in the vicinity, of impressed current and sacrificial anodes. Di-shield will continue to cure under water once applied, it requires no primer and is of buttery consistency to prevent slumping, whilst allowing ease of application at the required thickness.
This material was developed specifically to provide a dielectric shield in the area of impressed current and sacrificial anodes, for example on ships or other subsea structures where in the vicinity of the anodes you could have an increased current density/potential if there was any damage to the coating in the vicinity of the anode. This is essentially to reduce the risk of cathodic disbondment in those areas, in a similar ay to a cathodic disbondment test environment.
Cathodic Disbondment and Testing
Metal substrates are sometimes protected from corrosion using impressed current or sacrificial anodes. Cathodic disbondment is disbondment or delamination at a damage site, caused by the passage of the resultant voltage. The water is electrolysed to form hydroxyl ions at the substrate and on some coatings significant delamination can occur. Cathodic disbondment testing can be assessed in a laboratory most commonly by applying a known voltage across a plate with an artificial defect for a specified test period. There are various test methods used. The resistance of coatings to disbondment is a key factor in many applications and the ability to resist this effect is closely related to the immersed adhesive strength and the permeation resistance of the lining. Corrocoat’s glassflake filled linings have demonstrated excellent resistance to cathodic disbondment.
*Find out more on Cathodic Disbondment Testing – Anti Corrosion & Corrosion Protection Coatings by Corrocoat here.
After years of service, the cementitious substrate of a sulphuric acid containment at a pulp and paper plant was acidified. This happened as a result of an acid base reaction due to ground moisture, which occurred beneath previous repairs and caused repeated failure.
The client turned to our partners at Corrocoat US to provide a solution and requested that the restoration work be planned around normal operations.
The containment was first blasted with 40k psi equipment, incorporating a salt remover to expose all areas weakened by acidification and also remove soluble sulphur salts. This was followed by grinding and cutting to allow for proper forming and placement of Epoxy Polymer Concrete. The bottom of the tank was mechanically prepared with power tools and treated to remove soluble sulphur compounds. Prior to priming the cementitious surfaces were treated to return to alkalinity and ensure integrity of the concrete.
The curbs and surface were restored to their original dimensions using Corrocoat Epoxy Polymer concrete in conjunction with normal forming. Once the concrete was cured and the form removed, all transitions from grade to vertical were laminated, including from the tank pedestal onto the tank walls to protect the underside of the tank floor from releases.
Upon hardening the fibreglass was hand sanded and solvent cleaned prior to applying Plasmet AR3 in 3 successive coats to provide a film of 40-48 mils. Plasmet AR3 was selected as it is equally resistant to caustics and acids and is approved by FDEP for mineral acid containment applications.
Our Czech partners, Corrotech, as part of their ongoing relationship with customers in the power generation industry, were approached to provide corrosion abrasion protection for two flue gas ducts.
Each carbon steel duct was 630 m2 and required the removal of coarse sediments as well as previous coatings and the decontamination of soluble salts from the surface. Following the first stage, surface preparation to ISO 8501-1 with cleanliness Sa 2½, an application of primer Polyglass PPA (our peroxide catalysed, glass flake polyester primer) was applied. This primer was selected provide sufficient time for the internals of each duct to be blasted and then coated.
Stripe coating of Polyglass VEHA was then carried out, with Corrofill VE being used with the paint system to compensate for the unevenness and profiling of all welds. Lamination Resin 600 and Quadraxial fibreglass cloth 600g/ m2 were then applied to the whole surface, covering the fixtures and fittings of the internal surfaces and offering reinforcement of the inner sides of any manways.
The ducts were finished with an application of abrasion barrier Polyglass VEFWR and quality assurance procedures were completed as per the designed inspection and test plan. This project was carried out alongside another job on site to repair and protect an absorber ABS 1, and was completed by 4 engineers over a period of 8 days.
