Temperature cycling is defined as the process of cycling through two temperature extremes, typically at relatively high rates of change. An example of this is e.g. a process vessel which heats up from 80oC to 300oC (176oF to 572oF) over two hours during a filling process which occurs twice a week, before returning to 80oC (176oF). Cyclic temperatures are common to Oil & Gas facilities and can occur due to a variety of factors:
- As part of general process
- At shutdowns
- During high pressure steam cleaning
- Due to unplanned maintenance
Cyclic temperature service is known to be particularly damaging to protective coating systems, and so regularly causes issues for onsite maintenance personnel. This damage is usually due to the increased stress that regular cycling can put on a coating film; the expansion and contraction of coating molecular bonds leads to cracking and early failure.
High temperature coating film showing cracking after temperature cycling (10x magnification)
Coatings typically specified for ultra-high temperature service are usually inert multi polymeric matrix (IMM), inorganic copolymer or titanium modified inorganic copolymer (TMIC). The challenge of these coatings is the balancing act that must be walked between thermal properties and anticorrosive performance. In order to assess the suitability of these coatings for cyclic temperature service, an accelerated laboratory testing program was carried out to investigate the performance.
Details of the benchmarking can be found here
Coatings specified for service in rapidly changing high temperatures environments need to have the flexibility to resist the increased stress of expansion and contraction on a molecular level.
Intertherm 751CSA is a titanium modified inorganic copolymer specifically designed for cyclic temperature service. Suitable for protecting steelwork that is exposed to a wide range of highly corrosive environments, including pipes, valves and vessels subjected to wet and dry cycling, Intertherm 751CSA is a ‘Cold Spray Aluminum solution to cyclic temperature maintenance. Capable of providing corrosion protection to steel in both atmospheric service and under insulation operating in rapid thermal cyclical conditions between -321°F (-196°C) and 751°F (400°C), Intertherm 751CSA has over 10 years of track record ensuring the integrity of assets in the most challenging of environments.