Q1. You ask whether a letter of interpretation issued under Reference No. 14-0123 that describes a scenario where ISO Standard 11119-2 cylinders do not require a special permit (DOT-SP) or competent authority (CA) approvals is applicable to other companies with the same scenario.

A1. The answer is yes. Letters of interpretation reflect the administration's current application of the HMR to the specific facts presented by the person requesting the clarification. They are provided to help the public understand how to comply with the HMR. Letters of interpretation do not create legally-enforceable rights.

As described by Reference No. 14-0123, dated November 3, 2014:

"A cylinder designed and constructed in conformance with the applicable requirements prescribed in 49 CFR 178.70, 178.71(a) and 178.71(l) for an ISO Standard 11119-2 is a UN standard fibre-reinforced, composite gas cylinder with a load sharing metal liner. Cylinders that are fully in conformance with ISO 11119-2 do not require a DOT-SP or CA Approval. To certify that these cylinders are an authorized UN standard packaging, manufacturers mark them in conformance with § 178.71(p), (q), and (r)…An ISO Standard 11119-2 cylinder that varies from this design is not an authorized packaging in the United States until its variations are reviewed and approved by PHMSA's Associate Administrator for Hazardous Materials Safety in the form of a DOT-SP or CA. The cylinder must be marked with the DOT-SP or CA number if the DOT-SP or CA requires that it be marked with that number; otherwise, the marking of that number is not required. In addition, the HMR require ISO Standard 11119-2 cylinders to be refilled in conformance with §§ 173.301, 173.301b, 173.304b; and periodically retested in conformance with § 180.205."

Please note, the marking requirements in § 178.71 of the HMR were redesignated to paragraphs (q), (r), and (s) by the final rule HM-215M published January 8, 2015 [80 FR 1075].

Q2. You ask whether the cylinders you describe in your letter, which you state are to be used on the surface in marine environments only, require the "UW" mark prescribed in §§ 173.301b(g), 178.71(l)(2) and (q)(18) for composite cylinders certified to ISO-11119-2 intended for underwater use.

A2. The answer is no, provided the cylinders are not intended for underwater use or manufactured in accordance with the requirements for underwater use (see § 178.71(l)(2)). However, the requirements to mark the "UW" may be followed as a voluntary option for cylinders which are not intended for underwater use. Therefore, it is recommended that PonyPak consider whether its use of ISO Standard 11119-2 cylinders in a marine environment warrants the use of cylinders which have been subjected to the saltwater immersion test in accordance with 8.5.11 of the Standard.