How Tough Are ISO Containers?

A comparison between the humble ISO container and its DNV offshore cousin

Why NATO and the United Nations Choose Robust ISO Containers

As incredibly tough as DNV containers are, don’t ever underestimate the strength of ISO boxes. They’re the unsung heroes.

ISO containers will soak up merciless punishment in some of the planet’s most challenging environments.

They’re a dependable go-to storage solution for the world’s military and humanitarian missions. On UN aid projects, the supplies stored in ISO containers can be the difference between war-ravaged and impoverished people staying alive or not.

‘Onshore’ is not some soft option. It doesn’t automatically imply some cushy, temperate climate. Quite the contrary: some onshore climates can be very temperamental indeed. ISO containers are used as traverse vans in Antarctica. They’ve become living quarters, science labs and comms centres on the world’s coldest (-94.7°C) and windiest (199mph) continent.

So failure is most definitely not an option for these mission-critical storage and accommodation units.

But if an ISO container is more than up to the job, why and when should you make the leap to ultra-tough DNV units? The answer is simple: when the container needs to be transferred from one offshore vessel or platform to another. The unstable transfer between two entities sometimes causes the container to bang against the side of the platform or vessel. The DNV standard of container is designed to withstand the brute force of any accidents whereas an ISO container is not.

Offshore or Onshore? Shipping or Storage?

As you’ll gather from that last paragraph, the key word there is ‘offshore’. DNV containers are designed to live out on oil rigs for years at a time. As mud labs, offices and other crew habitats, they can be the only thing separating the platform’s workforce from the very worst howling gales, storms and tempests that a capricious world can hurl at them.

DNV containers are also recommended for very long shipping journeys on routes known for their rough conditions – especially if the cargo is particularly valuable.

ISO containers too are designed to be watertight when being shipped across oceans. So they’re more than capable of withstanding onshore weather, even the more extreme examples that we’re seeing more of today. What they don’t like is staying offshore in the bleak, watery wilderness for months and years.

To put that in context, we have containers spending up to seven years onshore in places such as Somalia, compared with a DNV unit spending three to six months on an oil rig.

But that shouldn’t stop offshore companies from using ISO containers for their onshore activities.

ISO containers are the perfect solution for onshore storage. Unless you’re expecting conditions worse than Antarctica, specifying a DNV container for onshore work can be expensive and wasteful.

The following numbers will make that very clear…

Cost of ISO Containers vs DNV Containers

Buying a basic 20ft dry van ISO container will cost you between a fifth and seventh of the price for the equivalent DNV unit – and the comparatively low purchase cost of a 20ft ISO dry van is reflected in its rental price (it’s just a 20th of the cost of leasing a DNV box).

However, you don’t need us to tell you that all is not rosy in the world when it comes to container pricing. The words “how much?!” have probably emerged from your lips on more than one occasion when speaking with shipping companies.

Here are the current spot freight rates by major route on the Drewry Word Container Index. (Those of a nervous disposition should avoid looking at the graph.)

Shipping containers are in short supply, despite the fact that production is at an all-time high. The three Chinese companies – CIMC, DFIC and CXIC – that make 80% of the world’s containers are manufacturing them at record rates. But sadly, this is still not enough to meet global demand.

It’s said that in reality there are more than enough containers…but they’re simply in the wrong places. However, that’s no comfort when you can’t get the boxes you want at a sensible price.

Especially not when coronavirus closed China’s Yantian International Container Terminal at the end of May, impacting more than 600,000 TEU. The outbreak shut the west side of the terminal – one of the largest in the world. Yantian continues to operate but in June 2021 it was still only at 30% capacity.

And the 20,124 TEU Ever Given’s extended sojourn in the Suez Canal didn’t help either. As if the last few years haven’t been challenging enough for the shipping world, that was all we needed – definitive proof that a 400m-long boxship can’t squeeze sideways through a 205m-wide shipping canal. For the record, this is where you’ll currently find the vessel.

So much for the overcapacity and lower freight rates that helped to hasten the demise of Korea’s Hanjin Shipping in February 2017. There was a creeping inevitability that one of the big 10 shipping lines would go under: that dubious privilege went to Hanjin with debts of $5.4 billion (then £4.1 billion, now £3.88 billion).

Meanwhile, industry experts expect container shortages to continue into 2022. But fear not, we’re here to help with plenty of ISO and DNV units for purchase and lease and available from our global network of depots. Including some rather interesting designs for specialised applications but we’ll get to those later…

How Strong is an ISO Container?

ISO intermodal containers – like their DNV counterparts – are manufactured from COR-TEN® ‘weathering’ steel. When exposed to the elements, this steel forms a dark brown oxidation to help protect it against deeper corrosion. So it doesn’t need painting – but it gets painted anyway for added protection. DNV containers have stronger reinforcement to meet the higher standard but – other than that – they’re built from the same steel type as ISO containers.

Typically, 20ft ISO containers have a tare (unladen) weight of 1.5 tonnes. They can handle a maximum load of 28.5 tonnes. So you’re looking at a maximum gross weight of 30 tonnes. Do not overload them.

Overloading, improper weight distribution and insufficient dunnage have very real safety implications. Floors can be particularly vulnerable: understructure components get bowed down. Last May’s technical bulletin TB-021 from the Institute of International Container Lessors (IICL) shows precisely what can happen: scroll down to pages 5 and 6 of the bulletin and look at the photos.

Here’s a sobering statistic: one-in-four containers that pass through US ports get damaged “at some interchange points,” according to leading supply chain intelligence platform FreightWaves.

So we’re extremely serious about container condition and safety. International Maritime Organization (IMO) safety regulations stipulate that ISO containers must be inspected before they are put into service, within five years of construction and no more than 30 months later.

But being a lessor, we also inspect the containers every time they come back. We’re extremely rigorous about it – especially when it comes to the floor. All our containers are CSC certified and registered with major inspection companies such as Lloyd’s Register and Bureau Veritas.

How Watertight is an ISO Container?

“Very watertight” is the short answer. They have to be – they’re going to sea. Robust rubber seals around the doors prevent water ingress. And we check meticulously for any tears or holes throughout the lifespan of the container. We’re obsessive about water tightness – and also air ingress, the invisible enemy.

Air ingress can create a mini weather system inside your container as it is shipped from one climate to another. This can lead to ‘container rain’, ‘container sweat’ or ‘cargo sweat’ –damaging the container and its contents.

Ever mindful of this hold meteorology, we can advise you on the four best ways to deal with container rain: choice of pallets, insulation, ventilation (where appropriate) and desiccants. We also offer moisture traps as an accessory.

Cargostore Refrigerated ISO Container

ISO Reefer Containers, Gensets, Low-Cost Smart Energy Systems

As the world’s biggest supplier of DNV reefers, we’re well placed to advise you on ISO reefers too.

Dual temperature reefers can significantly reduce your container leasing, transportation and storage costs: one unit can do two jobs – chilling and freezing. It also saves on electricity with the price of three-phase 415V being what it is.

Event reefers are the ones to specify if you anticipate continually having to enter the container to retrieve items. Benefits include:

  • non-slip chequer-plate floors (improving safety in icy reefers)
  • a mantrap button that stops personnel from getting trapped inside the freezer – pressing the button detaches the exterior lock (it can then be easily replaced afterwards)
  • a mantrap alarm – an audible warning and visible beacon to alert others when someone is trapped inside
  • sliding thermal door curtains – helping to keep your container cold, saving energy
  • easy-open doors.

Our 10 ISO reefer solutions range from clip-on diesel gensets, smart energy systems and 10ft containers right up to our huge multi-container BlizzardStore (units ship separately and are then joined on-site – watch the 41-second video).

The refrigeration systems for our ISO reefers are manufactured by Carrier Transicold, which operates 51 factories, 39 R&D centres and employs 53,000 people in more than 180 countries. So we’re talking reassuringly reliable units with global support.

Specialised ISO Containers  

ISO containers with side doors are becoming increasingly popular with clients in stability and aid. Faster loading and unloading is never more important than when you’re in a frontline role.

We’ve gone a stage further by adding mid-decking to some of these units. They’re currently on trial in a maritime stability and aid role. Half-height ISO containers – a highly specialised option – are also available.

Other options include bulker units with roof hatches – bulk cargo is loaded via the top and unloaded via the end doors.

Why Cargostore for ISO Containers?

Cargostore is one of the world’s fastest-growing suppliers of ISO and DNV 2.7-1 CCUs for onshore, offshore and shipping.

You’ll find our ISO containers on ships and onshore around the globe – especially in Africa and the Middle East. Our containers support a wide range of commercial operations, large scale event catering, mining, stability and aid including peacekeeping and UN humanitarian missions.

Buy or lease from our wide range:

Benefit from:

  • Expert technical advice and fast quotes from our highly experienced team
  • Seamless transition to a smooth and efficient finance team – fast credit checks and paperwork
  • Excellent operational aftercare – proactive assistance for unit repairs and troubleshooting
  • Offices in London (HQ) and Abu Dhabi, a local representative in Holland and depots worldwide.

Get Expert Advice On ISO and DNV Containers

Contact Cargostore now in London, Abu Dhabi or Holland to discuss your shipping, offshore and onshore project requirements.

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