What goes wrong

The mark was assumed

On this page11

A heavy-duty container was treated as specification packaging Our catalog was read as implying one The letter was read and the rest was not Liquid went into a solids packaging Specific gravity was ignored The closure was substituted The packing group was never determined An old mark was relied on Nobody asked for the test report The fix is to buy the certification, not the container References

Sturdy is not marked. The mark records a test, not an impression.

A heavy-duty container was treated as specification packaging

Because it looked industrial and it held the material fine. The mark records that a design type passed a test programme; nothing else does.

Our catalog was read as implying one

Which is the failure this property is written to prevent. We do not record marks, so no page of ours can establish that a container carries one.

The letter was read and the rest was not

An X packaging that is a solids packaging, or one tested to a specific gravity below the material being shipped. Nine elements, and the letter is one.

Liquid went into a solids packaging

Element five is the tell: the letter S is a solids or inner packagings designation and a number is a tested hydrostatic pressure.

Specific gravity was ignored

The designation may be omitted when it does not exceed 1.2, which means its absence carries information. A dense liquid in a packaging tested for a light one is outside the mark.

The closure was substituted

A marked container with a cap from somewhere else is not the tested assembly. This is the commonest way a genuinely compliant container stops being one.

The packing group was never determined

Which is the first step and is the shipper's. Without it the letter on the mark cannot be checked against anything.

An old mark was relied on

Element six is the last two digits of the year of manufacture, and reuse has its own conditions. A mark does not expire from view and the rules around reuse are not addressed here.

Nobody asked for the test report

The mark is a summary of documentation that exists. A supplier of specification packaging can produce it, and one who cannot has answered the question.

The fix is to buy the certification, not the container

From a supplier whose product is the compliance. We sell containers for the unregulated half of the operation and say so.

References

49 CFR 178.503(a), marking of UN specification packagings. In sequence: the United Nations symbol "as illustrated in paragraph (e)(1)(i)", or the letters UN on embossed metal receptacles; the packaging identification code designating type, material and category, with the letters V or W where applicable; a letter identifying the performance standard; the specific gravity or mass tested for; the test pressure or the letter S; "The last two digits of the year of manufacture"; the authorizing country, for example USA; "The name and address or symbol of the manufacturer"; and for reusable drums and jerricans the material thickness in millimetres. The example markings at (e)(2) are given as images rather than text. law.cornell.edu

49 CFR 178.503(a)(3), the letter identifying the performance standard under which the packaging design type has been successfully tested: "(i) X--for packagings meeting Packing Group I, II and III tests; (ii) Y--for packagings meeting Packing Group II and III tests; or (iii) Z--for packagings only meeting Packing Group III tests". law.cornell.edu

49 CFR 178.503(a)(4) and (a)(5). On specific gravity or mass: "For packagings without inner packagings intended to contain liquids, the designation shall be the specific gravity rounded down to the first decimal but may be omitted when the specific gravity does not exceed 1.2; and... For packagings intended to contain solids or inner packagings, the designation shall be the maximum gross mass in kilograms". On test pressure: "(i) For single and composite packagings intended to contain liquids, the test pressure in kilopascals rounded down to the nearest 10 kPa of the hydrostatic pressure test that the packaging design type has successfully passed; (ii) For packagings intended to contain solids or inner packagings, the letter 'S'". law.cornell.edu

Written from 49 CFR 178.503 and from the catalog as it stood on 19 October 2026. No specimen UN mark appears here, because the regulation gives its examples as images rather than as text. Nothing in this catalog is offered as UN specification packaging: we do not record whether a container carries a mark, and the mark belongs to a tested design type and is applied by its manufacturer. Packing group determinations, shipping names and documentation are the shipper's.