Protecting major equipment with silica gel or bentonite clay desiccant: Parked aircraft, Laid-up ships, Stacked rigs
Sometimes, major and unwelcome changes in economic activity require businesses to idle valuable equipment. That means parked aircraft, laid-up cruise ships, stacked offshore rigs, and mothballed equipment.
Among the most common and costly threats to this idle equipment is the constant, uncontrolled accumulation of moisture. This is rarely a problem when assets are working, since engines and motors, computers and electronics, environmental and cooling systems, and fuel and control systems are operated, brought up to temperature, and purged of moisture accumulation on a daily basis.
However, as soon as daily use halts, moisture accumulation begins, bringing the threat of rust and corrosion, molds or mildew. Among the most cost-effective tools for eliminating excess moisture are desiccants, notably synthetic silica gel desiccant and naturally-occurring bentonite clay desiccant. Both of these highly adsorbent, free-flowing desiccants remain free-flowing even when fully saturated. Available in a variety of package configurations, they can also be recharged by low-temperature baking for further re-use. Desiccants are often used in combination with humidity indicator cards and plugs, which use color-changing spots to record changes in relative humidity in a sealed area.
Desiccants are often used in combination with humidity indicator cards and plugs, which use color-changing spots to record changes in relative humidity in a sealed area.
When used together with favorable weather/climate conditions, available heating/ventilation/air-conditioning (HVAC) or dehumidification equipment, and a little advance planning, desiccants can play an essential role in keeping valuable but idle assets in prime condition.
Moisture Protection for Parked Aircraft
Storage protocols for parked aircraft differ, depending on the duration. For short-term aircraft parking (30-90 days), many aircraft makers recommend weekly startup of engines, flight computers, and auxiliary power units to bring them up to temperature, assure proper circulation of air or lubricants, and disperse any accumulations of moisture. They also suggest regular circulation of fresh, dry air through the cabin, accomplished by opening up the hatches during the day.
If aircraft are parked for indefinite periods or at remote locations, experts agree that dispatching personnel to make weekly engine startups may not be practical or cost-effective. In these cases, long-term moisture protection for engines can be provided by the use of desiccants, based on specific guidance from your engine manufacturer. Typical moisture protection schemes for mounted engines involve placing the appropriate number of desiccant bags, together with a humidity indicating card, on racks in the inlet and exhaust of each engine, then masking and sealing the engine inlet and exhaust off with plastic.
Engines removed from aircraft for overhaul or long-term storage also require moisture protection. Typical industry practice is to place desiccants and humidity indicator cards in engine inlets and outlets, protect orifices with desiccant plugs, then mask and seal the engine with plastic. Be sure to consult OEM recommendations for detailed engine storage procedures.
Aircraft interiors, electronics, and control systems can be protected from moisture buildup and the threat of mold and mildew by first airing out the cabin and cockpit, then distributing desiccant bags prior to closure of hatches. When used in the proper quantity, desiccant bags can adsorb excess moisture and can prevent the onset of moisture-related problems. Periodic monitoring and replacement of spent desiccant is essential to ensure continued protection
When used in the proper quantity, desiccant bags will adsorb any excess moisture and help prevent the onset of moisture-related problems
Protecting Laid-up Cruise Ships from moisture damage
There’s a tremendous need for moisture control on cruise ships and other ocean-going vessels (OGV), a need that increases with the length of lay-up and the need to reduce staff and operating expenses. For cruise ships and OGVs in a “warm” lay-up condition for up to one-year, experts at Lloyd’s Register suggest that the first line of defense against moisture is to utilize onboard HVAC systems, supplemented by portable dehumidification systems, to reduce humidity and moisture buildup by continuously circulating air throughout the ship, with priority to protecting systems and protecting accommodations.
The Lloyd’s Register online guide, “Ship Lay-Up,” also suggests that all rooms and cabins should have doors opened to maximize airflow. Linens should be removed, cleaned and stored in a central location, with all sleeping mattresses stored on edges to prevent moisture buildup that could lead to mold or mildew. In these areas, heating or air conditioning should be used to maintain relative humidity between 45 and 55%. In confined or difficult to ventilate areas, utilize desiccant bags to adsorb additional moisture.
The Lloyd’s guidelines also note that control of relative humidity to approximately 50% or less is also vital to protect essential systems from moisture damage and corrosion, including:
- Radio and navigational controls, consoles, and equipment
- Computers, electronics, and communications systems
- Generators, switchboards, and electrical equipment
- Pumps and compressors
- Engines, machinery and controls
Essential equipment and systems that remain on deck, exposed to the elements, should be covered and sealed in place, with adequate desiccant bags provided to adsorb all moisture within the sealed area. For a complete list of lay-up recommendations, consult the Lloyd’s Register 2020 Ship Lay-Up guide which is available free online.
Protecting Stacked Offshore Rigs
No offshore rig contractor wants to lay-up or “stack” a rig, but when it happens, top priority is to protect electrical systems critical to rig operation and personnel safety. For a warm (powered) lay-up, rig experts suggest adding portable dehumidification and heating systems to manage relative humidity and keep air circulating. These should be supplemented by the placement of desiccant bags to keep every system dry, and every room and cabin mildew and odor-free.
Havequestions? Clariant experts are ready to help.
Clariant Cargo & Device Protection offers a complete portfolio of desiccants, container desiccants, oxygen absorbers, and humidity indicator solutions to protect goods and assets from damage due to oxygen and moisture. Our products include not only Sorb-It® silica gel desiccant and Desi Pak® bentonite clay desiccants, but also cargo desiccants such as Container Dri® II. These solutions, as well as expert recommendations, are available through a global sales network with worldwide manufacturing sites in Brazil, Indonesia, Turkey, the United States, and China.