Desiccant technology is effective in creating a year round humidity controlled environment to avoid corrosion during surface preparation. Corrosion rates accelerate exponentially over 50%RH and most coating compliance is 80%RH on the metal surface. The effect of thermal inertia usually required the surrounding air to be 20-30%RH (4°C -6°C temperature difference from surface to air) less than the required surface humidity to allow for this. Other methods of heating requires full surface heating which causes very high energy costs. Refrigeration is only effective in climates which is humid all year round and are still unable to achieve the dryness required due to the surface humidity requirement.
Benefits with dehumidification :
- Avoid corrosion
- Comply with coating specification
- No delays due to weather,
- Ability to schedule works year round Benefits for Marine
- Able to conduct works in or out of water
- Able to store engine and electronics in place
- Able to effectively mothball of temporary layup
- Also useful in composite and coat compliance
Benefits for Surface preparation and coating internals of vessels and storage tanks
- Year round humidity control
- Hold the blast
- Create coating across entire surface at one time.
- Fast job duration with better chance of a quality lining outcome
References:
Korea : SG rotors used in various shipyards
China: SG rotors used in various shipyards
Netherlands: Seaway supply, Doornbos Equipent
Australia: Geogon project NW shelf gas tanks
Norway: Westwood Shipping lines Billabong Shipping AS, GearBulk , Hoegh fleet shipping AS, Grieg Shipping A/S, Green Shipping.
SURFACE TREATMENT and COATING S
CASE – Gorgon Gas Project
The Gorgon Gas Project is a natural gas project off the North West shelf of Western Australia, involving the development of sub-sea gas gathering infrastructure and liquefied natural gas in the Greater Gorgon gas fields. The project also includes a domestic gas component. It is currently under construction and once completed, will become Australia’s fourth Liquefied Natural Gas export development.
Q&A – Surface Preparation & Corrosion Prevention
Q: Why is humidity control important for surface preparation and corrosion prevention?
A: Corrosion rates increase exponentially above 50% RH, and most coating specifications require a surface humidity of 80% RH or lower. Maintaining proper humidity levels ensures compliance with coating standards and prevents rust formation during preparation.
Q: How does desiccant dehumidification compare to other methods for humidity control?
A: Desiccant technology provides consistent year-round humidity control without the high energy costs of full-surface heating. Unlike refrigeration, which is only effective in consistently humid climates, desiccant systems achieve the required surface dryness by reducing ambient RH by 20-30% below the surface humidity threshold.
Q: What are the key benefits of dehumidification in surface treatment?
A:
- Prevents corrosion during preparation
- Ensures compliance with coating specifications
- Allows for scheduling work year-round, avoiding weather delays
Q: How does humidity control benefit marine applications?
A:
- Enables maintenance and surface treatment both in and out of water
- Protects engines and electronics during storage
- Supports effective mothballing and temporary layups
- Improves coating compliance for composite and metal surfaces
Q: What are the advantages of dehumidification in vessel and storage tank coating?
A:
- Maintains optimal humidity levels throughout the year
- “Holds the blast,” preventing flash rusting
- Ensures uniform coating application across the entire surface
- Reduces project duration while improving coating quality
Q: Where has this technology been successfully implemented?
A: Desiccant technology has been used in shipyards across Korea, China, and the Netherlands, as well as in major Australian projects like the Gorgon Gas Project. It has also been deployed in Norway for fleets including Westwood Shipping Lines, Billabong Shipping AS, GearBulk, Hoegh Fleet Shipping AS, Grieg Shipping A/S, and Green Shipping.
Q: What was the role of humidity control in the Gorgon Gas Project?
A: In this large-scale LNG development, desiccant dehumidification played a critical role in surface treatment for gas storage tanks, ensuring proper coating application and long-term durability in the harsh offshore environment.