Corrosion is a formidable enemy for high-pressure systems. It is a natural phenomenon that can be triggered by a variety of different factors in both the external and internal environment of a pressure vessel. Thankfully, pressure vessels that exhibit signs of corrosion can be treated and returned to optimal working condition. Better yet, corrosion can be prevented before it starts through regular maintenance and testing. Treating and preventing corrosion in pressure vessels starts with an understanding of the specific factors that trigger it in the first place.
Corrosion can result from conditions inside or outside of the pressure vessel. Some common causes of corrosion inside a vessel include exposure to chelants, dissolved oxygen, and copper deposits. Chelants are chemical compounds that are deliberately added to pressure vessels to keep the minerals inside soluble, but can cause corrosion when exposed to salt. Oxygen, whether in dissolved form or otherwise, is also responsible for corrosion. Copper deposits, furthermore, trigger corrosion through electrolysis.
The external environment can also produce corrosion. Unequal stresses on certain points in a high-pressure system, combined with high temperatures, can speed up the process of corrosion by exposing vulnerabilities. Examples of corrosion due to stress include caustic embrittlement and transgranular cracking. Caustic embrittlement requires the presence of sodium hydroxide, while transgranular cracking is triggered by the accumulation of hot gases. Both result in cracking and loose or leaky tubes.
The best way to reduce the risk of corroded pressure vessels is to take steps to prevent it. It is up to you to maintain your pressure vessel as soon as it is filled. Maintenance involves regular inspections from industry professionals, and will ensure that the system will have a long service life. After the process of corrosion has begun, it is much more difficult and costly to treat. To avoid wasting unnecessary time and money on your vessel, you should conduct regular follow ups even when the equipment shows no visible sign of damage.
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