• 28 parts
  • Checked September 2026

Parts of a Shipping Container

Tap each part of a 20-foot container as the quiz names it, from the corner castings to the check digit.

Parts of a Shipping Container

Name Date

Tap the doors

1 of 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
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Write the name of each numbered part.Answer key

  1. Doors
  2. Corner casting (corner fitting)
  3. Side panel (side wall)
  4. Roof panel
  5. Floor
  6. Forklift pockets
  7. Corner post
  8. Locking bar (locking rod)
  9. Door handle
  10. CSC plate (safety approval plate)
  11. Top side rail
  12. Bottom side rail
  13. Door header
  14. Door sill
  15. Cross members
  16. Front end wall
  17. Vent (ventilator)
  18. Lashing ring
  19. Hinge
  20. Door gasket (door seal)
  21. Cam
  22. Cam keeper (cam retainer)
  23. Owner code
  24. Category identifier
  25. Serial number
  26. Check digit
  27. Size and type code
  28. Weight marks (max gross and tare)

Drawn for this site on 2026-09-30 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

Next step Next: the forklift that lifts a box by its pockets

All 28 parts on the diagram

Show the list

Start here: 10 main parts 10

  1. Doors Two doors close one end of the box, called the rear.
  2. Corner casting (corner fitting) One at each of the eight corners, for lifting, stacking and locking.
  3. Side panel (side wall) Corrugated steel sheet; the folds stiffen the wall.
  4. Roof panel The top closure; cargo must never be loaded on it.
  5. Floor Usually plywood or planks, fixed to the cross members below.
  6. Forklift pockets Paired tunnels across the underside; forks enter from the side.
  7. Corner post One of four uprights that carry the weight of boxes stacked above.
  8. Locking bar (locking rod) A vertical rod with a cam at each end.
  9. Door handle Swing it out to turn its locking bar and free the cams.
  10. CSC plate (safety approval plate) Required on every container in international trade; shows the maximum gross weight.

The frame that carries the load 5

  1. Top side rail Runs the length of each side, joining the two top corners.
  2. Bottom side rail The floor's cross members are fixed between the two of them.
  3. Door header The beam over the door opening; the upper cam keepers sit here.
  4. Door sill The beam under the door opening, joined to the two bottom corners.
  5. Cross members Beams under the floor that run between the bottom side rails.

Panels, floor and fittings 3

  1. Front end wall The closed end opposite the doors.
  2. Vent (ventilator) Lets air pressure even out while keeping rain outside.
  3. Lashing ring A tie-down point inside for the straps that hold cargo still.

Door hardware 4

  1. Hinge A blade on the door turns on a lug of the post.
  2. Door gasket (door seal) A rubber strip on the door edges that keeps water out.
  3. Cam The fitting at each end of a locking bar; turns with it.
  4. Cam keeper (cam retainer) Fixed to the header or sill; it catches and holds the cam.

Marks and the safety plate 6

  1. Owner code Three letters registered with the BIC in Paris.
  2. Category identifier U: freight container. J: detachable equipment. Z: trailer or chassis.
  3. Serial number Six digits, given by the owner to this one box.
  4. Check digit One digit worked out from the other ten characters; catches copying errors.
  5. Size and type code 22G1 means 20 feet long, 8 feet 6 high, general purpose.
  6. Weight marks (max gross and tare) Painted figures: the most it may weigh loaded, and its empty weight.

How this list was compiled: Part names and facts were checked on 2026-09-20 against six references, and a part is ringed only if at least two of them name it. (1) MIL-HDBK-138B, the US Department of Defense container inspection guide of 2002, approved for public release, read for its nomenclature: https://everyspec.com/MIL-HDBK/MIL-HDBK-0099-0199/MIL-HDBK-138B_4075/ . (2) The Container Handbook of the German Insurance Association, sections 3.1 and 3.4: https://www.containerhandbuch.de/chb_e/stra/stra_03_01_00.html , https://www.containerhandbuch.de/chb_e/stra/stra_03_04_00.html . (3) The IMO/ILO/UNECE CTU Code, IMO circular MSC.1/Circ.1497: https://wwwcdn.imo.org/localresources/en/OurWork/Safety/Documents/1497.pdf . (4) Wikipedia: https://en.wikipedia.org/wiki/Intermodal_container , https://en.wikipedia.org/wiki/ISO_6346 , https://en.wikipedia.org/wiki/Twistlock . (5) The Bureau International des Containers: https://www.bic-code.org/identification-number/ , https://www.bic-code.org/marking-of-containers/ , https://www.bic-code.org/size-and-type-code/ . (6) The International Convention for Safe Containers, 1972: https://www.imo.org/en/About/Conventions/Pages/International-Convention-for-Safe-Containers-(CSC).aspx and https://www.admiraltylawguide.com/conven/containers1972.html . The standards themselves (ISO 668, ISO 1161, ISO 1496-1, ISO 6346) are sold by ISO and were not read; only public summaries of them were. The wording of every label, hint and fact is our own. Re-checked on 2026-09-30: all 28 names found again in two or more of the six references above, each fetched again: the US handbook, the insurers' Container Handbook, the CTU Code, Wikipedia (wikitext of Intermodal container, ISO 6346 and Twistlock), the BIC's three pages and the 1972 convention text. The sample number on the drawing is LTDU 204815 4: the BIC register at https://www.bic-code.org/bic-codes/ answered No code found for LTDU on 2026-09-30 (and showed a registered owner for a known code tried as a control), and the check digit 4 was worked out again by the ISO 6346 rule (sum 4525, remainder 4). Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; own work, nothing traced or copied. The three figures are laid out as three frames of one shape (the whole box on top, the door end and the marks side by side under it), not on the 1400 by 1080 grid the brief in art describes; the parts and what each figure shows are as briefed. The safety approval plate is ringed on its enlargement beside the marks. Licence: own work

How it works

The parts of a shipping container, drawn as a 20-foot dry box from the door end with a window cut in one side. A second drawing shows the doors straight on; a third reads the painted number and codes.

Read the full guide

The frame carries the load

The quiz asks 10 main parts first, then the other 18: frame, shell, doors, marks. Four corner posts carry the weight of a stack down into the corner castings, while the side panels, the end wall and the roof bear the least load. Cargo never goes on the roof panel.

How shipping container doors lock

The doors are held by locking bars, two on each door here: upright rods with a cam at both ends. The cams sit in cam keepers on the door header and the door sill. Swing a handle out and its bar turns: the cams press on their keepers and force the door open.

  • Checking a used box? The international CTU Code asks that doors lock and seal shut and that door gaskets are in good condition.

Questions and answers

What are the main parts of a shipping container?

A steel frame of four corner posts, side rails, a door header and sill, with a corner casting at all eight corners. Side panels, a roof panel and a front end wall close it. The floor lies on cross members; two doors close the rear.

What are the corner castings on a shipping container for?

Lifting, stacking and securing. Each is a steel block with oval holes. Cranes lift the box by them, and twistlocks turn inside them to lock it to the box below, a trailer or a rail car.

What do the numbers on a shipping container mean?

Four letters, six digits, one last digit. The first three letters are the owner code, registered with the BIC in Paris; the fourth is U on every freight container. Six digits are the owner's serial number; the last is a check digit against copying errors.

What does 22G1 mean on a shipping container?

It is the size and type code. The first 2 means 20 feet long; the second means 8 feet 6 inches high and 8 feet wide. G1 is a general purpose box with passive vents high in the cargo space.

What is a CSC plate on a shipping container?

The safety approval plate that the International Convention for Safe Containers of 1972 requires. It gives the date of manufacture, the maximum gross weight, the allowable stacking weight and the racking test load, and it is usually fixed to the left-hand door.

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