Shipping container certification: CSC plates, surveys, and what they mean
Are you storing, or are you shipping?
Every shipping container carries a metal plate that once cleared it for the open ocean. Most container sites wave at that plate and move on. This guide explains what it actually is, when it matters, and the one question that decides everything: are you storing, or are you shipping?
The short answer
Certification exists for one purpose: international shipping.
No certification of any kind
A container that sits on your property and stores things needs no certification of any kind. A container moving by truck inside the United States needs none either. The rules only wake up when a box is lifted onto a ship or crosses a border.
If that is not your plan, you can stop reading now and go pick a size.
Read on
If putting the box on a ship is your plan, read on, because most of what dealers say about "certified" containers is looser than the actual rules.
The rest of this page is for you.
What the CSC plate is, and who requires it
Open the left door of almost any container and you will find a riveted metal plate marked "CSC Safety Approval." That plate exists because of an international treaty: the International Convention for Safe Containers, adopted through the IMO in 1972, usually shortened to CSC 1972. The treaty's goal is simple. Containers get stacked nine high on ships and lifted by their corners thousands of times. The plate certifies that the design can take those loads.
In the United States, the treaty is implemented through federal regulations at 49 CFR Parts 450 through 453, administered by the US Coast Guard. Those rules govern who approves container designs, how containers must be examined over their working life, and what the plate must show.
Here is the part that matters for buyers: the CSC regime applies to containers in international transport. That is the treaty's whole scope.
International vs domestic: the distinction that decides everything
This is the wall the entire topic hangs on, so it gets its own section.
A container needs a valid CSC examination status to be loaded on a ship for international carriage. It does not need one to sit in a farmyard in Ohio. It does not need one to ride a tilt-bed truck from a depot to your property. It does not need one to move by road or rail inside the country. Domestic transport and storage sit outside the CSC system entirely, a point the Bureau International des Containers makes in its own explainer on the convention.
So a used container whose examination status lapsed years ago is not "illegal" or "expired" in any way that affects a storage buyer. It is simply no longer cleared for the one job it retired from: crossing oceans. For everything a storage buyer does with it, the plate is history, not paperwork.
PES vs ACEP, in plain words
The CSC system gives container owners two ways to keep a box in good standing.
PES, the Periodic Examination Scheme
Works like a car inspection. The container gets its first examination within five years of manufacture, then re-examinations at intervals of no more than 30 months, under 49 CFR 452.1. Each passing exam earns a decal showing the Next Examination Date, usually shortened to NED. If the date on the decal is in the future, the box is current. If it has passed, the status has lapsed.
ACEP, the Approved Continuous Examination Program
How the big fleets do it. Instead of dated stickers on millions of boxes, a shipping line or leasing company runs a Coast-Guard-approved inspection program covering its whole fleet, under 49 CFR 452.7. Boxes under ACEP carry a marking in the form ACEP/USA followed by a year, and no NED decal at all. The box is covered as long as it belongs to that owner's program.
That last clause is the trapdoor, and it leads to the next section.
What happens when a container leaves the fleet
Here is the subtlety that trips up almost everyone, including plenty of dealers: the CSC plate does not expire when a container is sold. The plate certifies the design, and it stays riveted to the door for the life of the box. What changes at sale is the examination status.
When a shipping line retires a container and sells it, the line removes the box from its ACEP. The program that covered it no longer applies, and there is usually no valid NED decal underneath, because fleet boxes never needed one. The Container Owners Association spells out the consequence in its technical guidance, COA TG03: once the box is sold out of the fleet, the buyer becomes responsible for its CSC maintenance.
Age tells you which side of the line a box sits on. A one-trip container is typically still inside its first five-year window from manufacture. The used boxes that fill dealer yards were generally retired after a decade or more of service, long past any exam that covered them. Either way, if you ever want the box on a ship again, restoring its examination status becomes your job, not the seller's.
The grades ladder: WWT, CW, IICL-6, and why none of them is a certification
Dealers grade used containers, and the grades form a rough ladder. Scroll the table sideways on a small screen
| Grade | What it means | Is it a certification? |
|---|---|---|
| Wind and water tight (WWT) | A dealer grade, not a shipping standard. It means the box is structurally sound and keeps weather out. It is the workhorse grade for storage. This is the grade Steel Box Direct sells, and it is sold for storage, not for shipping. | No |
| Cargo worthy (CW) | The box is judged fit to carry cargo at sea. Useful, but be careful: the criteria vary from seller to seller unless the grade is tied to a named standard, such as the COA's Common Cargo Worthy criteria or the UCIRC repair criteria. | No |
| IICL-6 | The strictest common standard, used by leasing companies, with tighter tolerances than cargo worthy. | No |
A grade describes physical condition. Certification is a regulatory status with a date on it.
None of these grades is a CSC examination status. Buying a container advertised as cargo worthy does not mean it has a valid exam. Carriers know the difference even when listings blur it.
What a recertification survey covers, and who can perform one
To put a lapsed box back in good standing, a qualified examiner inspects it against industry criteria and, if it passes, affixes a new NED decal and issues a report. The survey works over the whole structure: corner castings and corner posts, top and bottom rails, cross members and the underside (which is why the box usually goes up on a forklift), the floor, the doors and their gaskets, the wall panels, the roof bows, and overall weathertightness.
Who is allowed to do this? Less than you would guess. 49 CFR 452.3 requires only that examinations be performed by "qualified personnel, trained and experienced." There is no US government license called container surveyor, and "licensed maritime inspector" on a vendor page is loose language. In practice, the credential that carries weight is certification from the IICL, the Institute of International Container Lessors, earned through a proctored exam and renewed on a five-year cycle. The IICL publishes the only real directory of certified inspectors, and container depots coordinate most surveys, since the box, the forklift, and the inspector are all in one place. We keep that directory's full US roster, grouped by state, in our container inspector finder.
One exception worth knowing: containers that have been structurally modified are a different animal. Under 49 CFR 451, modified designs need review by an administration-appointed Approval Authority, such as ABS acting under Coast Guard delegation. A standard survey cannot bless a cut-up box.
On cost, published figures from providers give the range. IPL publishes survey pricing of $75 to $250 per container. A greater-Cincinnati inspector publishes a rate of $125 per hour including travel, plus a depot handling fee. Your number depends on where the box is and who examines it, but that is the published landscape.
How long a survey is good for
Two clocks run at once here, and they are different clocks.
The regulatory ceiling is 30 months: under the PES rules, no examination interval may exceed it.
Commercial practice is tighter. Surveyors and carriers commonly treat a survey certificate as current for something like six to 18 months, at their discretion, so confirm the window with your carrier when you book. A carrier booking cargo wants recent paper rather than a decal with two years left on it.
Meeting the regulation keeps you legal. Meeting the carrier's expectation gets you booked. You need both, and they are not the same thing.
What carriers actually demand
The carrier is the final gatekeeper, so its checklist is the real finish line. Hapag-Lloyd publishes its requirements for shipper-owned containers, and they are concrete. Other carriers publish their own versions. Scroll the table sideways on a small screen
| Item | Hapag-Lloyd's published requirement |
|---|---|
| Plate and paper | A valid CSC plate and a current inspection certificate |
| Stacking weight allowance | At least 192,000 kg |
| Racking test value | At least 15,000 kg |
| Dimensions | Conforming to ISO 668 |
| Identification | A proper ISO 6346 identification number |
The pattern is the same: the plate, current paper, and a box that meets the structural minimums. No certificate, no booking.
Enjoy knowing about it, or work backward from the booking
Do not pay extra for it
If you are buying a container for storage, a workshop, or any use that keeps it on the ground, certification is a topic you can enjoy knowing about and never act on. Nothing above applies to you. Do not pay extra for it.
Work backward from the booking
If you know you will ship internationally, work backward from the booking. Buy a cargo worthy container from a depot, tell the seller it is for export, and arrange the survey when you book, because your carrier will want a fresh certificate anyway. What almost never pays is buying a storage-grade box and trying to certify it up later. That path runs through a survey, possible structural repairs, and your carrier's judgment, and it usually costs more than starting with the right box.
Where Steel Box Direct fits
Steel Box Direct sells one honest grade: used wind and water tight containers, for storage and on-site use, not certified for ocean shipping. That is stated plainly on our condition guide, which explains exactly what WWT means in practice. If a WWT box fits your plan, our containers for sale page covers the three sizes we stock. And if you want to decode the plate and markings on a box you already own, the container reference walks through ISO 6346 IDs, the CSC plate, and full dimensions in plain English.