Corrosion Under Insulation (CUI) is the core cause of many of the international petrochemical industry’s most severe problems including forced shutdowns, lost manufacture, early refurbish and substitution along with other factors like safety and environmental consequences that can cost billions of dollars per occurrence.
CUI, which includes the corrosion of vessels or piping under insulation due to water infiltration, is insidious because it can stay unnoticed until the insulation is separated for inspection or leaks happen. Usually Water penetration can result from many reasons including wash downs, monsoons, flooding, and sprinkler systems, as well as exposure to fog, moisture, or common condensation and evaporation of atmospheric humidity.
Fortunately, even when conventional coatings have allowed CUI and corrosion to take place a new approach can stop the corrosion to considerably extend capability and tools life in oil and gas industry applications.
Stopping Existing Corrosion and CUI
Traditional corrosion protection usually involves applying polymer paints or sometimes rubber type coatings as well. Such methods form a physical fence to keep corrosion promoters such as oxygen and water away from steel substrate. Though, this only works until the paint is dented, whittled, or breached and corrosion promoters go into the gap between the substrate and coating. Then the coating can act like a conservatory – trapping water, oxygen and other kind of corrosion promoters – which permits the corrosion to spread.
Some of the world’s major petrochemical companies, including China Petroleum & Chemical Corporation, however, are finding achievement with a new move towards stopping CUI and corrosion.
China Petroleum & Chemical Corporation, which is commonly known as Sinopec Corp., is one of the largest integrated energy and chemical companies in the whole world, with upstream, midstream as well as downstream operations. In Sinopec’s Jianghan Oilfield project which is located in Hubei province, Jianghan Plain in China, there are several facilities for oil and gas extraction, transport, and storage space.
However, with Hubei’s sub-tropical monsoon average temperature CUI and corrosion are stern issues that cut down equipment life and necessitate excessive preservation. In this situation, traditional coatings have been futile, and stopping corrosion that is by now in progress is often the last alternative.
In compare to customary polymer coatings that always sit on top of the substrate, the corrosion resistant CBPC coating bonds through a chemical reaction with the substrate, and minor surface corrosion actually recovers the response. The surface of steel is passivated and through that an alloy layer is created. This makes it quite impossible for corrosion promoters like oxygen and moisture to get behind the coating the way they can with usual paints.
Although conventional polymer coatings instinctively bond to substrates that have been comprehensively prepared, if scratched, moisture and oxygen will travel under the coating’s film from all sides of the gouge.
By contrast, the similar damage to the ceramic coated substrate will not spread corrosion because the carbon steel’s shell has been chemically altered into an alloy of steady oxides. Once the steel’s surface is steady, it will no longer react with the surroundings and consequently cannot corrode. The corrosion blockade is sheltered by a ceramic layer that additionally resists corrosion, water, fire, scrape, collision, chemicals, and temperatures up to 400 °F. Beyond this, the ceramic provides an exclusive role that assists to end the valuable safeguarding cycle of replacing distinctive barrier type coatings every few years.
While the storage space tank’s original coatings were enclosed beneath a mineral wool insulating layer, due to rainfall, condensation, and humidity invasion through the scratched insulating layer, these coatings had failed, permitting CUI in a number of areas. And after peeling off the insulating layer, the metal surface beneath was set up by sandblasting, then the CBPC coating was functional. The application has efficiently stopped the CUI matter and is usual to expand the storage tank’s practical life for years to come.
A traditional three coat system was regularly used to uphold corrosion protection for the pumping station, so coating application took at least three days to permit drying time for each layer. Including surface grounding, total mandatory maintenance downtime was at least seven days, which slowed down production.
One of the furthermost benefits of the CBPC coating, though, is the rapid return to service that lessens facility downtime. The time saved on an anti-corrosion coating plan with the ceramic coating comes both from cut down surface preparation and accelerated remedial time.
With traditional coatings, widespread surface preparation is necessary and done a little at an instance to evade surface oxidation, usually known as ‘flash rust’, which then needs re-blasting. But with the CBPC coating, the flash rust is in fact enviable. There is no need to ‘hold the blast’. The cause for this an exclusive CBPC characteristic is due to the existence of iron in the rust, which helps to produce the magnesium iron phosphate alloy layer. It is this alloy layer that permits CBPCs to so efficiently defend carbon steel from corrosion.
In disparity, a corrosion resistant coating for carbon steel developing the ceramic coating in a single coat needs approximately no curing time. Return to service can be achieved in as little as one hour, which can potentially save thousands of dollars per day in abridged oil and gas facility downtime. Because of these unique properties, total coating application with surface grounding of the pumping station will usually take two days and the benefit can be put into service instantaneously.
With CUI and corrosion a recurrent problem for oil and gas facilities with an enormous carbon steel structures, utilizing CBPC coatings that can control oxidization for decades and decrease downtime will only assist the bottom line.
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