Keeping a container in working order

Base and levelling

Everything else depends on this. A container carries its load through the four corner castings, not through the middle of the floor. If one corner settles, the frame twists, and the first symptom is a door that will not close cleanly.

Set the unit on railway sleepers, concrete pads or compacted gravel under each corner. Check the base after the first winter and again after any period of heavy rain. Re-levelling is straightforward if you catch it early and expensive if you do not.

• Level in both directions, front to back and side to side.
• Allow a slight fall away from the door end so water runs off rather than pooling at the threshold.
• Keep the underside clear so air can circulate and the floor can dry.

Doors, hinges and seals

Door hardware does more work than any other part of the container and gets the least attention. Grease the hinge pins and the locking cam bars twice a year with a marine or general purpose grease. If a door starts to bind, check the base before you blame the hinges.

Door seals

The rubber gaskets around the door frame are what keep the unit dry. Wipe them clean, check for splits or flattened sections, and treat them with a silicone rubber conditioner so they stay flexible. A seal that has hardened will let water track along the bottom rail.

Cam bars and keepers

The vertical bars rotate to lock into keepers at the top and bottom of the frame. If the bars will not rotate fully, the door is not sealed even though it appears closed. Clean the keepers out and lubricate the bar bearings.

Locking mechanisms

Standard cam bar handles can be padlocked directly, but an exposed padlock is the weakest point on the container. A welded lock box shrouds the shackle and removes the obvious attack. Fit a closed shackle padlock rated for outdoor use, and keep the mechanism lubricated so it is not forced.

• Use a padlock with a stainless or brass body if the unit is near the coast.
• Lubricate the lock barrel with a dry PTFE spray rather than oil, which attracts grit.
• Check the lock box welds annually for corrosion at the weld line.

Rust prevention

Corten steel forms a stable oxide layer that slows further corrosion, which is why containers survive decades at sea. It is not immune, and the places it fails are predictable: horizontal surfaces where water sits, the base rails where debris collects, and any point where the original paint has been scraped through to bare metal.

Routine treatment

• Wire brush or abrade any surface rust back to sound metal.
• Apply a rust-inhibiting primer, then a compatible top coat.
• Touch up scrapes as they happen rather than waiting for the annual inspection.
• Keep the base rails clear of leaves, soil and standing water.

Coastal and industrial sites accelerate corrosion. If the unit is within sight of salt water, inspect twice as often and be more aggressive about touching up.

Roof and walls

The roof is the part nobody looks at. It is designed to shed water, not to hold it, and a shallow pool over a corrugation will eventually find a weakness. Sweep the roof clear of leaves and debris at least twice a year, and check that nothing is trapped against the perimeter rail.

Do not walk on the roof unnecessarily; the panels are thinner than the walls. If you must, spread your weight and stay over the cross members. Check the corrugated side walls for dents that have cracked the paint, and treat them before rust takes hold.

Floors

Most container floors are marine plywood on steel cross members. They are strong, but they are still timber. Keep them dry, sweep out grit that would otherwise grind through the surface coating, and deal with spills promptly.

• Reseal worn areas with a floor-grade sealant or paint.
• Use load spreaders under point loads such as jack stands or machinery feet.
• If a section becomes soft or delaminated, replace the board rather than covering it.

Ventilation and condensation

Condensation, sometimes called container rain, happens when warm moist air meets cold steel overnight. It is the most common complaint from new owners, and it is almost always a ventilation problem rather than a leak.

• Keep the factory vents clear; do not block them with stored goods.
• Add passive vents at high and low level if the unit is densely packed.
• Use desiccant products for sensitive contents in humid conditions.
• Allow air to circulate around stacked items rather than pressing them against the walls.

Insulated units reduce the temperature swing that causes condensation in the first place, which is why they are worth considering for anything moisture-sensitive.

Cleaning

Wash the exterior with water and a mild detergent, working from the top down. Avoid very high pressure washing directly at the door seals, which can force water past the gasket. Rinse thoroughly, particularly in coastal areas where salt residue accelerates corrosion.

Inside, sweep rather than wash where possible. If the floor needs washing, prop the doors open until it is fully dry to prevent trapped moisture.

Security

Security is placement as much as hardware. A container positioned with its doors facing a wall, a fence or another container is significantly harder to enter, whatever lock you fit.

• Point the doors towards a fixed obstruction where the layout allows.
• Fit a lock box and a closed shackle padlock.
• Light the approach; most opportunist entries prefer darkness.
• Do not advertise the contents with signage or an open door during loading.
• Keep the surrounding ground clear so an approach is visible.

Seasonal schedule

A short routine, done consistently, prevents nearly every avoidable problem.

Long-term storage

If the container will sit unopened for months, prepare it as you would a boat for winter. Clean and dry the interior completely, remove anything organic, place desiccant inside, and leave a clear air path between the vents.

Lubricate the door hardware before closing up, and open the unit every few months if you can. A container that is opened occasionally almost never develops a moisture problem; one that is sealed for two years sometimes does.

Before delivery

Preparation on your side is what makes delivery day straightforward. The delivery guide covers this in detail, but in summary:

• Confirm the approach is firm, level and wide enough for a tilt-bed truck.
• Check overhead clearance for branches, cables and gateways.
• Have the base pads or sleepers positioned before the truck arrives.
• Keep the placement area clear of vehicles and materials.
• Make sure someone is on site who can direct final positioning.