The unlikely story of shipping containers & how they are made.
Are you thinking of buying an Adaptainer container and want to see how they are manufactured? Maybe you are just curious – either way we are glad to give you a rare insight into how shipping containers are made.
What makes the topic more interesting is just how much modern day shipping containers have impacted people’s lives globally. And the unlikely story of the man behind their creation.
Shipping containers have changed the world we live in and the goods we buy.
Before modern day shipping containers existed the idea of getting cheap goods from the other side of the world was almost unheard of.
In 1956 one man changed it all.
Malcolm McLean was a US based trucker who had big visions.
Malcolm McLean, the pioneer of modern day shipping containers, was alive at a time when freight transportation was incredibly inefficient.
Cargo was transported individually in barrels and small wooden crates which meant that the loading and unloading process took a very long time to complete.
Cargo was also susceptible to theft and damage during transportation.
Once the cargo had finally unloaded from the ship it was then a cumbersome process to transfer it onto trains or road vehicles.
All this meant the cost of transporting cargo was expensive and unreliable.
But that was the way it had always been done and the unions at that time were fiercely protective over the jobs of port staff – anyone wanting to implement change was faced with stiff resistance.
However, Mr McLean had a plan – one that was to change the world to the one we live in today.
His idea was that there should be standardized cargo container dimensions to enable bulk cargo to be transported from one place to another using multiple transport modes (including ship, train and truck) without the contents of the container ever needing to be handled.
This would dramatically decrease the time needed for loading and unloading as well as reducing theft and damage risk.
Massive strikes by port workers underlined the reluctance of many at that time to embrace this new way of doing things.
However, after fierce protests and negotiations the unions finally conceded and the modern day shipping container was born.
Many other jobs were subsequently created by the explosion in trading that resulted directly from the change.
The rest is history as they say.
Today people around the world are using shipping containers for much more than simply shipping cargo including storage and hundreds of other uses using converted containers.
We took a trip out to the factory and put together a film which shows you the typical production process from start to finish, but if you prefer a written account of how shipping containers are made then we have that for you too!
Phase 1 Sub Assembly.
Unrolling and cutting of steel sheets.
It all starts with sheet steel that arrives normally in coil form at a local steel service centre where it’s de-coiled into flat sheet, burr edge is slit away and the sheet is cut to size.
Shot blasting and priming of sheets.
First the steel is de-greased and shot blasted to Swedish standard SA 2.5 (near white metal) as well as being primed with zinc rich primer.
The steel used is often copper enriched (so called Corten A, a USS trade name, or equivalent).
This means that if the paintwork is penetrated by damage, the exposed steelwork will react when oxidising in a way that inhibits corrosion.
Also a process takes place called ionic transfer whereby the steel and zinc reacts to form a coating that assists durability and results in an extended lifespan of the container.
After blasting and primer painting, the sheet steel undergoes pressing to form front panels, side panels and roof sheets.
Pressing includes creating corrugation on the side panel sheets which helps increase the strength of the container side walls.
Side panel sheets welded together and lashing rings added to top side rail.
The separate side panel sheets are then welded together to form one complete panel which fits the entire length of the container side wall.
Next a 60×60 RHS (rolled hollow section) top side rail has lashing rings added and welded all round for strength.
The side panel is then inverted on to the top side rail and tack welded in position, followed by full welding.
Side panel sub assembly is now complete.
Container Front Wall.
Front corner post, header, sill and front panel assembly.
The front corner posts are folded into shape.
Front panels are then pressed, ventilation holes are punched and two sheets joined together by seam welding.
Next the front header and bottom sill rail are prepared.
These components are assembled together in a jig with the addition of top and bottom corner castings.
Front panel assembly is now complete.
Container Rear Wall.
Rear corner post, header, sill and rear panel (main cargo doors) assembly.
Round pipe is cut to size, assembled with door cams at each end, door handle saddles and power rings to aid anti-racking and galvanised to specification, preferably hot dipped which is a better alternative than electrolysis
Next the rear corner post outer skins are punched and folded to shape, then welded to rear corner post inners.
Care must be taken to cater for distortion of the outer skin as a lot of heat is generated during the welding process. This can otherwise affect door hinge alignment.
Rear header rails are then pressed and assembled together with rear sills being prepared.
Door panels are fabricated by adding corrugations to flat sheet, ventilation holes are punched and installed within RHS (rolled hollow section) vertical frames and “C” section members top and bottom, often in a rotating frame to allow welding to be performed in the ideal downward position.
The doors are then assembledtogether with the other rear end assembly components detailed above together with corner castings, door hardware such as cam keepers, galvanised hinge blades and lock boxes in a jig for full welding.
The rear end frame is now complete.
Base frame preparation.
Next to prepare is the base frame.
“C” section cross members are pressed, fork pockets are fabricated in omega section profile, “C” section bottom side rails are pressed and all parts are welded together in an assembly jig.
Roof sheet die stamping and welding.
Roof sheets are stamped with a die that incorporates a pre-set camber to facilitate drainage when containers are in use, it’s important to avoid water pooling on the roof followed by freezing which would pose obvious dangers – for example when trucks negotiate corners whilst the ice is thawing.
The panel edges are trimmed and sheets welded together to form the final sub assembly roofing element.
Phase 2 – Main Assembly.
All six sub- assemblies transfer to the main assembly jig so that the container can be put together.
The base frame slides in first, next the front and rear end frames followed by side walls and the entire structure is tack welded together.
The structure then travels down the production line for full welding and attachment of roof sheets.
Finally it now resembles the familiar shape of a container.
Secondary shot blasting then cleans all the areas damaged by the welding processes. This is followed by the second phase of primer painting as well as top coating and the container is then baked in an oven.
Paint touch up is common prior to loading floor sheets, sealant is applied to the floor sheet peripheries which aids water-tightness in that location.
Next the floor sheets are drilled and secured using self-tapping screws.
Then plastic ventilators are riveted into position over the ventilation holes.
Following this galvanised lock rods with bushes and retainers, swivel customs catches and door handles are bolted on in compliance with procedures required for approval of transportation under customs seal.
CSC (Container Safety Convention) plates are then added to indicate all data applicable as well as approvals granted to the container.
Next rubber gaskets with shot moulded corners are installed with retaining strips, the bottom edge and upright being filled with butyl sealant to inhibit corrosion created if water were to become otherwise entrapped at this area.
Markings are then applied to comply with CSC (Container Safety Convention), UIC (International Union of Railways) and ISO (International Standards Organisation) regulations covering intermodal freight containers.
Next water testing checks for any pin holes that may have been missed during light testing.
Batch testing of the containers (normally one in fifty) ensures that quality meets the construction standard required.
Testing entails stacking test, racking tests, sidewall strength test, front end wall strength test, door strength test, roof test, floor test and maximum gross weight testing, this is done to ensure that the container does not bend beyond limits allowed when under full load (normally 30 tons gross weight).
Final inspection checks, repair and touch up then takes place in the outside container yard before delivery for shipment.
That’s how shipping containers are made!