46 CFR §54.10-3

1. (a)Only marine inspectors will apply the Coast Guard Symbol. They will not apply any other code symbol to pressure vessels.
2. (b)All pressure vessels not exempted under provisions of § 54.01-15 must be subject to shop inspection by a marine inspector referring to procedures outlined in UG-92 through UG-103 of Section VIII of the ASME BPVC (incorporated by reference; see § 54.01-1) and §§ 50.30-10, 50.30-15, and 50.30-20 of this subchapter. The marine inspector will then stamp the vessel with the Coast Guard Symbol.
3. (c)Pressure vessels exempted under provisions of § 54.01-15, except as provided in paragraph (d) of this section, are not required to be stamped with the Coast Guard Symbol.
4. (d)Pressure vessels described in § 54.01-5(c)(3), except pressure vessels in systems regulated under subpart 58.60 of this subchapter, must be visually examined by a marine inspector prior to installation. The marine inspector also reviews the associated plans and manufacturers' data reports. If, upon inspection, the pressure vessel complies with the applicable requirements in § 54.01-5, the marine inspector stamps the pressure vessel with the Coast Guard Symbol.